Recently, several studies pointed out the capability of the histogram analysis of the apparent diffusion coefficient computed from diffusion-weighted images and of the mean diffusivity and FA computed from DTI to reveal brain-tissue damage in early clinical stages of neurodegenerative diseases. A recent study including 27 patients with de novo drug-naïve PD hypothesized that global measurements of brain volume and structure, such those possible with SIENAX software (part of FSL 4.0 http://www.fmrib.ox.ac.uk/fsl/) and histogram analysis of DTI could reveal subtle tissue changes in the early clinical phase of PD (Tessa et al., 2008). Accordingly, a group of patients with drug-naive de novo PD and a group of 16 healthy controls, were investigated with SIENAX and DTI. Results showed no significant differences for total brain, GM, and WM volumes and histogram-derived mean diffusivity metrics between controls and the whole group of patients with PD or any subgroup of patients with PD. As compared with controls, patients with PD as a whole and patients with the akinetic-rigid type showed an increase of the twenty-fifth percentile of the FA histogram. In patients with the akinetic-rigid type, there also was a trend toward an increase of the mean and fiftieth and seventy-fifth percentiles, and a reduction of the skewness of the FA histogram. This finding is consistent with the hypothesis that subtle GM loss is present in patients with PD since the early clinical phases and that this feature is more pronounced in patients with akinetic-rigid type. Another recent study including only patients with newly diagnosed PD used high-resolution DTI at 3 Tesla to evaluate rostral, middle, and caudal ROIs within the SN on a single slice of the midbrain and this study found that PD patients could be completely separated from the control group based on reduced FA values in the caudal ROI of the SN, such that further confirmatory studies seem to warrant. By using statistical parametric mapping analysis of DT imaging, changes in FA were found in the frontal lobes, including the supplementary motor area, the presupplementary motor area, and the cingulum in non demented PD patients relative to controls, whereas VBM analysis in the same patients revealed no volume loss (Karagulle

facilitated along the direction of fiber tracts and restricted perpendicular to the fibers.

diffusion tensor (Le Bihan, 2003).

multisystem disorder.

Kendi et al., 2008). These results confirm that the neurodegenerative process extends beyond the basal ganglia in PD (Tessa et al., 2008).

Olfactory impairment, which is common in PD and often predates clinical diagnosis, may be a useful biomarker for early PD. One study (Rolheiser et al., 2011) compared newly diagnosed PD patients with a matched control group using both olfactory testing and diffusion tensor imaging of the substantia nigra and anterior olfactory structures. Fourteen PD patients with stage 1-2 of Hoehn & Yahr were matched to a control group by age and sex. All subjects completed the University of Pennsylvania Smell Identification Test, as well as a series of MRI scans designed to examine diffusion characteristics of the olfactory tract and the substantia nigra. Olfactory testing revealed significant impairment in the patient group. Diffusion tensor imaging revealed significant group differences in both the substantia nigra and anterior olfactory region, with fractional anisotropy of the olfactory region clearly distinguishing the Parkinson's subjects from controls. This study has suggested that there may be value in combining behavioral (olfaction) and MRI testing to identify early Parkinson's disease (Rolheiser et al., 2011; Fulton & Barret, 2008).

Concluding DWI/DTI imaging especially bears several advantages. DWI/DTI imaging may detect diffusion abnormalities in the basal ganglia and infratentorial structures in patients with PD at an early stage of disease. Furthermore, DWI/DTI imaging sequences are widely available on whole body MR scanners and can be acquired within a few minutes.

#### **3.5 Functional Magnetic Resonance Imaging**

fMRI is based on the increase in blood flow to the local vasculature that accompanies neural activity in the brain. This results in a corresponding local reduction in deoxyhemoglobin because the increase in blood flow occurs without an increase of similar magnitude in oxygen extraction (Roy & Sherrington, 1890; Fox & Raichle, 1985). Since deoxyhemoglobin is paramagnetic, it alters the T2 weighted magnetic resonance image signal (Ogawa et al, 1990). Thus, deoxyhemoglobin is sometimes referred to as an endogenous contrast enhancing agent, and serves as the source of the signal for fMRI. Using an appropriate imaging sequence, human cortical functions can be observed without the use of exogenous contrast enhancing agents on a clinical strength (1.5 T) scanner (Bandettini et al., 1992, 1993; Kwong, et al, 1992; and Turner, et al, 1993; Schneider et al, 1993). Functional activity of the brain determined from the magnetic resonance signal has confirmed known anatomically distinct processing areas in the visual cortex (Belliveau, et al, 1991; Ogawa, et al, 1992; Schneider, et al, 1993), the motor cortex, and Broca's area of speech and language-related activities (Hinke et al., 1993; Kim et al., 1995). Further, a rapidly emerging body of literature documents corresponding findings between fMRI and conventional electrophysiological techniques to localize specific functions of the human brain (Atlas et al., 1996; Puce, et al, 1995; Burgess, 1995; Detre, et al, 1995; George, et al, 1995; Ives, et al, 1993). Consequently, the number of medical and research centers with fMRI capabilities and investigational programs continues to escalate.

The main advantages to fMRI as a technique to image brain activity related to a specific task or sensory process include:

Early Marker for the Diagnosis of Parkinson's Disease 19

In a study combining fMRI and OERPs analysis in patients with PD, non-detectable OERPs patients exhibited reduced activity in the anterior cingulate gyrus and portions of the left striatum, while detectable ERP patients exhibited higher activation, especially in the amygdala, parahippocampal cortex, inferior frontal gyrus, insula, cingulate gyrus, striatum, and inferior temporal gyrus. The relationship between the expression of olfactory ERPs and cortical activation patterns seen during olfactory stimulation in fMRI in PD patients supports the idea that OERPs are a sensitive marker of neurodegeneration in olfactory regions, independent of the typically observed nigro-striatal degeneration in PD (Welge-

Olfactory dysfunction is more common in PD compared to atypical parkinsonian syndromes like PSP or MSA (Doty, 1991, 1993; Wenning et al., 1995). In a study including 37 patients with PD (Hoehn and Yahr I to IV) and 13 patients with MSA, CBD or PSP, 86 % of PD patients showed diminished sense of smell, or severe hyposmia, and 14 % were found to have moderate hyposmia, whereas 70 % of the patients with atypical parkinsonian syndromes exhibited moderate to mild hyposmia and 30 % normosmia (Muller et al., 2002). Olfactory testing may be an additive, helpful and inexpensive diagnostic instrument to support the discrimination of PD from healthy subjects and atypical parkinsonian

For the clinical assessment of olfactory function, several validated psychophysical tests exist. The best-validated olfactory tests include the University of Pennsylvania Smell Identification Test, the Connecticut Chemosensory Clinical Research Center Test and the Sniffin' Sticks Test (Cain et al., 1988; Doty et al., 1984; Hummel, 1997, 2007; Kobal et al., 2000). The Sniffin' Sticks is based on pen-like odor dispensing devices. It consists of three tests namely for odor threshold, discrimination and identification, the sum of which is defined as "TDI score". This score can give an indication of patient's olfactory performance

A useful help for the clinical diagnosis of olfactory deficits is represented by system using human electro-physiological methods such as OERPs that requests an adequate methods to

Based on the principles of air-dilution olfactometry, Kobal and Platting introduced a chemosensory stimulation with stimuli having a rectangular shape with rapid onset, precisely controlled in terms of timing, duration, intensity, not simultaneously activating other sensory systems (Kobal & Platting, 1978). This can be achieved by the olfactometer which is a complex instrument for creation of well defined, reproducible smell or pain

In conclusion the detection of early olfactory dysfunction, less frequent in other form of parkinsonism, can be used to assess risk for developing PD in asymptomatic subjects.

The defining features of PD are characterized by their insidious onset and inexorable but variable progression. Reliable and well validated early markers for PD to identify individuals "at risk" before motor and non motor symptoms, accurately diagnose individuals at the threshold of clinical PD, and monitor PD progression throughout its course would dramatically improve patient care and accelerate research into both PD cause and therapeutics. During the past two decades, much progress has been made in identifying and assessing PD markers, but as yet, no fully validated marker for PD is available.

(normosmia: TDI≥30.5, hyposmia: TDI≤30.5, functional anosmia: TDI≤16.5).

produce a selective and controlled stimulation of the olfactory system.

stimuli in the nose without tactile or thermal stimulation.

Lüssen et al., 2009).

**5. Conclusions**

syndromes, before onset of motor symptoms.

The function or dysfunction of the several cortical regions involved in many disease, like PD, can be investigated in vivo by means of functional imaging techniques such as fMRI.

## **4. Olfactory dysfunction as a early diagnostic marker for Parkinson's Disease**

Olfactory dysfunction is a frequent non-motor symptom in PD and may be considered as an early clinical feature of the disease preceding motor symptoms by years (Ansari & Johnson, 1975). More than 96% of patients with PD present with olfactory dysfunction, compared with an established olfactory loss of at least 25% in the normal population over 52 years of age (Haehner et al., 2009). The majority of PD patients are functionally anosmic or severely hyposmic. Several studies have demonstrated an absence of correlation between olfactory loss and both duration of disease (Doty et al., 1988; Hawkes et al., 1997) and the clinical severity of PD (Ramaker et al., 2002), while other studies have found a correlation between the severity of PD and certain measures of olfactory function, such as latencies of olfactory event-related potentials (OERPs) (Hummel, 1999) and results from an odor discrimination task (Tissingh et al., 2001).

The cause of hyposmia in PD is not yet fully understood. It has been proposed that the develop of inclusion bodies, starting from the medulla oblongata and the anterior olfactory nucleus before the involvement of other central nervous structures, constitutes the reason of olfactory impairment before the motor symptoms appearance (Braak et al., 2003).

Moreover olfactory loss in PD is not a primary consequence of damage to the olfactory epithelium but rather result from distinct CNS abnormalities (Hummel et al., 2010). Studies based on biopsies from the olfactory epithelium did not reveal specific changes in the nasal mucosa of PD patients compared to patients who were hyposmic for other reasons (rhinitis, smoking or toxic agents). With regard to volumetrics of the olfactory bulb (OB) results indicated that there is little or no difference between PD patients with anosmia/hyposmia and healthy normosmic controls in terms of OB volume (Huisman et al., 2004; Hummel et al., 2010; Müller et al., 2005). Support for these results has come from a study that found an increase of (inhibitory) dopaminergic neurons in the OB in PD patients (Huisman et al., 2004). These findings have been interpreted within the context of a possible compensatory mechanism in response to the loss of dopaminergic neurons in the basal ganglia.

While cardinal motor symptoms in PD are closely related to a severe loss of dopaminergic cells in the nigro-striatal pathway, early clinical features such as olfactory impairment are more likely to be associated with extranigral pathology. Indeed atrophy in olfactory regions of the limbic and paralimbic cortex in early PD patients was found (Wattendorf et al., 2009). Moreover fMRI in PD patients indicated altered neuronal activity in the amygdaloid complex and hippocampal formation during olfactory stimulation (Takeda et al., 2010; Welge-Lüssen et al., 2009; Westermann et al., 2008). In addition, neuronal activity in components of cortico-striatal loops appears to be up-regulated indicating compensatory processes involving the dopaminergic system (Westermann et al., 2008).

Changes in olfactory function can also be observed using electrophysiological techniques such as recording OERPs (Kobal & Pattig, 1978). OERPs are the result of the sequential activation of numerous brain areas, starting with amygdala and regions of medial temporal lobe followed by the mid-orbito-frontal cortex and insular cortex, along with regions of the temporal lobe (Kettenmann et al., 1997). In PD patients OERPs are typically strongly delayed or even absent (Hawkes et al., 1999).

The function or dysfunction of the several cortical regions involved in many disease, like PD, can be investigated in vivo by means of functional imaging techniques such as fMRI.

**4. Olfactory dysfunction as a early diagnostic marker for Parkinson's Disease**  Olfactory dysfunction is a frequent non-motor symptom in PD and may be considered as an early clinical feature of the disease preceding motor symptoms by years (Ansari & Johnson, 1975). More than 96% of patients with PD present with olfactory dysfunction, compared with an established olfactory loss of at least 25% in the normal population over 52 years of age (Haehner et al., 2009). The majority of PD patients are functionally anosmic or severely hyposmic. Several studies have demonstrated an absence of correlation between olfactory loss and both duration of disease (Doty et al., 1988; Hawkes et al., 1997) and the clinical severity of PD (Ramaker et al., 2002), while other studies have found a correlation between the severity of PD and certain measures of olfactory function, such as latencies of olfactory event-related potentials (OERPs) (Hummel, 1999) and results from an odor discrimination

The cause of hyposmia in PD is not yet fully understood. It has been proposed that the develop of inclusion bodies, starting from the medulla oblongata and the anterior olfactory nucleus before the involvement of other central nervous structures, constitutes the reason of

Moreover olfactory loss in PD is not a primary consequence of damage to the olfactory epithelium but rather result from distinct CNS abnormalities (Hummel et al., 2010). Studies based on biopsies from the olfactory epithelium did not reveal specific changes in the nasal mucosa of PD patients compared to patients who were hyposmic for other reasons (rhinitis, smoking or toxic agents). With regard to volumetrics of the olfactory bulb (OB) results indicated that there is little or no difference between PD patients with anosmia/hyposmia and healthy normosmic controls in terms of OB volume (Huisman et al., 2004; Hummel et al., 2010; Müller et al., 2005). Support for these results has come from a study that found an increase of (inhibitory) dopaminergic neurons in the OB in PD patients (Huisman et al., 2004). These findings have been interpreted within the context of a possible compensatory

While cardinal motor symptoms in PD are closely related to a severe loss of dopaminergic cells in the nigro-striatal pathway, early clinical features such as olfactory impairment are more likely to be associated with extranigral pathology. Indeed atrophy in olfactory regions of the limbic and paralimbic cortex in early PD patients was found (Wattendorf et al., 2009). Moreover fMRI in PD patients indicated altered neuronal activity in the amygdaloid complex and hippocampal formation during olfactory stimulation (Takeda et al., 2010; Welge-Lüssen et al., 2009; Westermann et al., 2008). In addition, neuronal activity in components of cortico-striatal loops appears to be up-regulated indicating compensatory

Changes in olfactory function can also be observed using electrophysiological techniques such as recording OERPs (Kobal & Pattig, 1978). OERPs are the result of the sequential activation of numerous brain areas, starting with amygdala and regions of medial temporal lobe followed by the mid-orbito-frontal cortex and insular cortex, along with regions of the temporal lobe (Kettenmann et al., 1997). In PD patients OERPs are typically strongly

olfactory impairment before the motor symptoms appearance (Braak et al., 2003).

mechanism in response to the loss of dopaminergic neurons in the basal ganglia.

processes involving the dopaminergic system (Westermann et al., 2008).

delayed or even absent (Hawkes et al., 1999).

task (Tissingh et al., 2001).

In a study combining fMRI and OERPs analysis in patients with PD, non-detectable OERPs patients exhibited reduced activity in the anterior cingulate gyrus and portions of the left striatum, while detectable ERP patients exhibited higher activation, especially in the amygdala, parahippocampal cortex, inferior frontal gyrus, insula, cingulate gyrus, striatum, and inferior temporal gyrus. The relationship between the expression of olfactory ERPs and cortical activation patterns seen during olfactory stimulation in fMRI in PD patients supports the idea that OERPs are a sensitive marker of neurodegeneration in olfactory regions, independent of the typically observed nigro-striatal degeneration in PD (Welge-Lüssen et al., 2009).

Olfactory dysfunction is more common in PD compared to atypical parkinsonian syndromes like PSP or MSA (Doty, 1991, 1993; Wenning et al., 1995). In a study including 37 patients with PD (Hoehn and Yahr I to IV) and 13 patients with MSA, CBD or PSP, 86 % of PD patients showed diminished sense of smell, or severe hyposmia, and 14 % were found to have moderate hyposmia, whereas 70 % of the patients with atypical parkinsonian syndromes exhibited moderate to mild hyposmia and 30 % normosmia (Muller et al., 2002).

Olfactory testing may be an additive, helpful and inexpensive diagnostic instrument to support the discrimination of PD from healthy subjects and atypical parkinsonian syndromes, before onset of motor symptoms.

For the clinical assessment of olfactory function, several validated psychophysical tests exist. The best-validated olfactory tests include the University of Pennsylvania Smell Identification Test, the Connecticut Chemosensory Clinical Research Center Test and the Sniffin' Sticks Test (Cain et al., 1988; Doty et al., 1984; Hummel, 1997, 2007; Kobal et al., 2000). The Sniffin' Sticks is based on pen-like odor dispensing devices. It consists of three tests namely for odor threshold, discrimination and identification, the sum of which is defined as "TDI score". This score can give an indication of patient's olfactory performance (normosmia: TDI≥30.5, hyposmia: TDI≤30.5, functional anosmia: TDI≤16.5).

A useful help for the clinical diagnosis of olfactory deficits is represented by system using human electro-physiological methods such as OERPs that requests an adequate methods to produce a selective and controlled stimulation of the olfactory system.

Based on the principles of air-dilution olfactometry, Kobal and Platting introduced a chemosensory stimulation with stimuli having a rectangular shape with rapid onset, precisely controlled in terms of timing, duration, intensity, not simultaneously activating other sensory systems (Kobal & Platting, 1978). This can be achieved by the olfactometer which is a complex instrument for creation of well defined, reproducible smell or pain stimuli in the nose without tactile or thermal stimulation.

In conclusion the detection of early olfactory dysfunction, less frequent in other form of parkinsonism, can be used to assess risk for developing PD in asymptomatic subjects.

### **5. Conclusions**

The defining features of PD are characterized by their insidious onset and inexorable but variable progression. Reliable and well validated early markers for PD to identify individuals "at risk" before motor and non motor symptoms, accurately diagnose individuals at the threshold of clinical PD, and monitor PD progression throughout its course would dramatically improve patient care and accelerate research into both PD cause and therapeutics. During the past two decades, much progress has been made in identifying and assessing PD markers, but as yet, no fully validated marker for PD is available.

Early Marker for the Diagnosis of Parkinson's Disease 21

Brooks, D.J. Morphological and functional imaging studies on the diagnosis and progression

Cain, W.S.; Gent, J.F.; Goodspeed, R.B. & Leonard, G. Evaluation of olfactory dysfunction in

Clark, J.B. N-acetylaspartate: a marker for neuronal loss or mitochondrial dysfunction.

Clarke, C.E. & Lowry, M. Systematic review of proton magnetic resonance spectroscopy of

Davie, C.A.; Wenning, G.K.; Barker, G.J.; Tofts, P.S.; Kendall, B.E. et al. Differentiation of

Dexter. D.T.; Wells, F.R.; Lees, A.J.; Agid, F.; Agid, Y. et al. Increased nigral iron content and

Doty, R.L.; Deems, D. & Steller, S. Olfactory dysfunction in Parkinson's disease: a general

Doty, R.L.; Golbe, L.I.; McKeown, D.A.; Stern, M.B.; Lehrach, C.M. et al. Olfactory testing

disease. *Neurology*, Vol.43, No.5, (May 1993), pp. 962-965, ISSN 0028-3878 Doty, R.L.; Perl, D.P.; Steele, J.C.; Chen; K.M.; Pierce, J.D. Jr. et al. Olfactory dysfunction in

Doty, R.L.; Shaman, P.; Kimmelmann, C.P. & Dann, M.S. University of Pennsylvania Smell

Eckert, T.; Sailer, M.; Kaufmann, J.; Schrader, C.; Peschel, T. et al. Differentiation of

Edelman, R.R.; Ahn, S.S.; Chien, D.; Li, W.; Goldmann, A. et al. Improved time-of-flight MR

*Laryngoscope*, Vol.94, No.2, (February 1984), pp. 176-178, ISSN 1531-4995 Duguid, JR.; De La, P.R. & DeGroot, J. Magnetic resonance imaging of the midbrain in

*Neurochemistry,* Vol.52, No6, (June 1989), pp. 1830-6, ISSN 0022-3042 Di Costanzo, A.; Trojsi, F.; Tosetti, M.; Schirmer, T.; Lechner, S.M. et al. Proton MR

Vol.38, No.8, (August 1988), pp. 1237-1244, ISSN 0028-3878

Vol.21, No.1, (January 2004), pp. 229-235, ISSN 1053-8119

No.2, (August 1992), pp. 395-399, ISSN 0033-8419

Vol.98, No.1, (January 1988), pp. 83-88, ISSN 1531-4995

(November 2001), pp. 573-577, ISSN 1351-5101

1995), pp. 204-210, ISSN 0364-5134

2007), pp. 1651-1662, ISSN 0938-7994

ISSN 0016-867X

747, ISSN 0364-5134

ISSN 0340-5354

0378-5866

of Parkinson's disease. *Journal of Neurololy,* Vol. 247, No2, (April 2000), pp. 11-18,

the Connecticut Chemosensory Clinical Research Center (CCCRC). *Laryngoscope*,

*Developmental Neuroscience,* Vol.20, No.4-5, (July-October 1998), pp. 271-276, ISSN

the striatum in parkinsonian syndromes. *European Journal of Neurology,* Vol.8, No.6,

multiple system atrophy from idiopathic Parkinson's disease using proton magnetic resonance spectroscopy. *Annals of Neurology,* Vol.37, No.2, (February

alterations in other metal ions occurring in brain in Parkinson's disease. *Journal of*

spectroscopy of the brain at 3T: an update. *European Radiology*, Vol.17, No.7, (July

deficit unrelated to neurologic signs, disease stage, or disease duration. *Neurology,*

differentiates between progressive supranuclear palsy and idiopathic Parkinson's

three neurodegenerative diseases. *Geriatrics,* Vol.46, No.1, (August 1991), pp. 47-51,

identification test: a rapid quantitative olfactory function test for the clinic.

Parkinson's disease. *Annals of Neurology,* Vol.20, No.6, (December 1986), pp. 744-

idiopathic Parkinson's disease, multiple system atrophy, progressive supranuclear palsy, and healthy controls using magnetization transfer imaging. *Neuroimage*,

angiography of the brain with magnetization transfer contrast. *Radiology*, Vol.184,

Nonetheless, there is increasing evidence that POM evaluation and advanced in vivo brain imaging will provide critical clues to assist in the early diagnosis and medical management of PD patients.

These methods are broadly defined as characteristics that are objectively measured and evaluated as indicators of normal biological processes, pathogenic processes, or pharmacological responses to a therapeutic intervention.

The lack of success of recent disease-modifying therapeutic trials coupled with the huge expense of other methods, such as the nuclear medicine, has highlighted the need for such an ambitious approach to identify and validate early markers of PD progression for future clinical studies of disease-modifying drugs.

## **6. References**

Nonetheless, there is increasing evidence that POM evaluation and advanced in vivo brain imaging will provide critical clues to assist in the early diagnosis and medical management

These methods are broadly defined as characteristics that are objectively measured and evaluated as indicators of normal biological processes, pathogenic processes, or

The lack of success of recent disease-modifying therapeutic trials coupled with the huge expense of other methods, such as the nuclear medicine, has highlighted the need for such an ambitious approach to identify and validate early markers of PD progression for future

Abe, K.; Terakawa, H.; Takanashi, M.; Watanable, Y.; Tanaka, H. et al. Proton magnetic

Allen, P.S. In vivo nuclear-magnetic-resonance spectroscopy applied to medicine. *Canadian*

Ansari, K.A. & Johnson, A. Olfactory function in patients with Parkinson's disease. *Journal of Chronic Diseases,* Vol.28, No.9, (October 1975), pp. 493-497, ISSN 0021-9681 Atlas, S.W.; Howard, II R.S.; Maldijian, J.; Alsop, D.; Detre, J.A. et al. Functional magnetic

Avison, M.J.; Hetherington, H.P. & Shulman R.G. Application of NMR to studies of tissue

Bandettini, P.A.; Jesmanowicz, A.; Wong, E.C. & Hyde, J.S. Processing strategies for time-

Bares, M.; Bràzdil, M.; Kanovsky, P.; Jurak, P.; Daniel, P.; et al. The effect of apomorphine

Barker, G.J.; Tofts, P.S. & Gass, A. An interleaved sequence for accurate and reproducible

Bonavita, S.; Di Salle, F. & Tedeschi, G. Proton MRS in neurological disorders. *European Journal of Radiology,* Vol.30, No.2, (May 1999), pp. 125-131, ISSN 0720-048X Bowen, B.C.; Block, R.E.; Sanchez-Ramos, J.; Pattany, P.M.; Lampman, D.A. et al. Proton MR

*Neuroradiology*, Vol.16, No.1, (January 1995), pp. 61-68, ISSN 0195-6108 Braak, H.; Del Tredici, K.; Rüb, U.; De Vos, R.A.I.; Jansen Steur, E.N.H. et al. Staging of brain

*Medicine*, Vol.30, No2, (August 1993), pp. 161-173, ISSN 07403194

Vol.52, No.6, (August 2000), pp. 589-595, ISSN 0361-9230

(February 1996), pp. 329-338, ISSN 0148-396X

Vol.14, No.4, (1996), pp. 403-411, ISSN 0730-725X

No.2, (April 2003), pp. 197-211, ISSN 0197-4580

1986), pp. 377-402, ISSN 0883-9182

resonance spectroscopy of patients with parkinsonism. *Brain Research Bulletin,*

*Association of Radiologists Journal,* Vol.41, No.1, (February 1990), pp. 39-44, ISSN

resonance imaging of regional brain activity in patients with intracerebral gliomas: findings and implications for clinical management. *Neurosurgery*, Vol.38, No2,

metabolism. *Annual Review of Biophysics and Biophysical Chemistry*, Vol.15, (June

course data sets in functional MRI of the human brain. *Magnetic Resonance in*

administration on smooth pursit ocular movements in early Parkinsonian patients. *Parkinsonism & Related Disorders*, Vol. 9, No.3, (January 2003), pp. 139–144, ISSN

clinical measurement of magnetization transfer ratio. *Magnetic Resonance Imaging,*

Spectroscopy of the Brain in 14 Patients with Parkinson Disease. *American Journal of*

pathology related to sporadic Parkinson's disease. *Neurobiology of Aging,* Vol.24,

pharmacological responses to a therapeutic intervention.

clinical studies of disease-modifying drugs.

of PD patients.

**6. References**

0008-2902

1353-8020

Early Marker for the Diagnosis of Parkinson's Disease 23

Horsfield, M.A. Magnetization transfer imaging in multiple sclerosis. *Journal of*

Huisman, E.; Uylings, H.B. & Hoogland, P.V. A 100% increase of dopaminergic cells in the

Hummel, T. (1999). Olfactory evoked potentials as a tool to measure progression of

Hummel, T.; Kobal, G.; Gudziol, H. & Mackay-Sim, A. Normative data for the

Hummel, T.; Sekinger, B.; Wolf, S.; Pauli, E. & Kobal G. "Sniffin' Sticks": olfactory

Hummel, T.; Witt, M.; Reichmann, H.; Welge-Luessen, A & Haehner A.

Inglese, M.; Horsfield, M.A. & Filippi, M. Scan-rescan variation of measures derived from

Kettenmann, B.; Hummel, C.; Stefan, H. & Kobal, G. Multiple olfactory activity in the

Kim, K.; Hirsch, J.; DeLaPaz, R.L.; Relkin, N. & Lee, K.M. Comparison of cortical areas

Kobal, G. & Plattig, K.H. Objective olfactometry: methodological annotations for recording

Kobal, G.; Klimek, L.; Wolfensberger, M.; Gudziol, H.; Temmel, A. et al. Multicenter

*Neuroradiology,* Vol.22, No.4, (April 2001), pp. 681-684, ISSN 0195-6108 Karagulle Kendi, A.T.; Lehericy, S.; Luciana, M.; Ugurbil, K. & Tuite, P. Altered diffusion in

*Neuroimaging,* Vol.15, No.4, (2005), pp. 58-67, ISSN 1051-2284

Vol.19, No.6, (June 2004), pp. 687-692, ISSN 0885-3185

No.1-2, (February 2010), pp. 119-122, ISSN 0022-510X

Vol.38, No3, (March 2008), pp. 501-5, ISSN 1936-959X

No.5, (October 1997), pp. 493-502, ISSN 0379-864X

pp. 589-594, ISSN 0740-3194

Blackwell Science, Oxford, UK

1997), pp. 39-52, ISSN 0379-864X

(1993), pp.1763, ISSN 0270-6474

7590

243, ISSN 0937-4477

multicenter pilot study. *Magnetic Resonance in Medicine,* Vol.33, No.5, (May 1995),

olfactory bulb may explain hyposmia in Parkinson's Disease. *Movement Disorders*,

Parkinson's disease. In: *Focus medicine* – *New development in the drug therapy of Parkinson's Disease,* T. Chase & P. Bedard, (Eds.), 47-53, ISBN 0-632-05174-4,

"Sniffin'Sticks" including tests of odor identification, odor discrimination, and olfactory thresholds:an upgrade based on a group of more than 3.000 subjects. *European Archives of Oto-Rhino-Laryngology,* Vol.264, No.3, (March 2007), pp. 237-

performance assessed by the combined testing of odor identification, odor discrimination and olfactory threshold. *Chemical Senses,* Vol.22, No.1, (February

Immunohistochemical, volumetric, and functional neuroimaging studies in patients with idiopathic Parkinson's disease. *Journal of the Neurological Sciences,* Vol.298,

brain magnetization transfer ratio histograms obtained in healthy volunteers by use of a semi-interleaved magnetization transfer sequence. *American Journal of*

the frontal lobe in Parkinson disease. *AJNR American Journal of Neuroradiology*,

human neocortex identified by magnetic source imaging. *Chemical Senses,* Vol.22,

activated by primary and secondary languages in human brain using functional magnetic resonance imaging (fMRI). *Abstracts: Society of Neuroscience*, Vol.21, No3,

olfactory EEG-responses from the awake human. *EEG EMG Z Elektroenzephalogr Elektromyogr Verwandte Geb.*, Vol.9, No.3, (September 1978), pp. 135-145, ISSN 0012-

investigation of 1.036 subjects using a standardized method for the assessment of olfactory function combining tests of odor identification, odor discrimination, and

Federico, F.; Simone, I.L.; Lucivero, V.; Iliceto, G.; De Mari, M. et al. Proton magnetic

Firbank, M.J.; Harrison, R.M. & O'Brien, J.T. A comprehensive review of proton magnetic

George, JS.; Aine, CJ.; Mosher, JC.; Schmidt, MD.; Ranken, DM. et al., Mapping function in

*Neurophysiology,* Vol.12, No5, (September 1995), pp. 406-429 ISSN 1676-2649 Gupta, A.; Dawson, V.L. & Dawson, T.M. What causes cell death in Parkinson's disease? *Annals of Neurology,* Vol.64, No6, (December 2008), pp. S3-S15, ISSN 0364-5134 Haehner, A.; Boesveldt, S.; Berendse, H.W.; Mackay-Sim, A. Fleischmann, J. et al. Prevalence

Hagmann, P.; Jonasson, L.; Maeder, P.; Thiran, J.P.; Wedeen, V.J. et al. Understanding

Hattingen, E.; Magerkurth, J.; Pilatus, U.; Morez, A.; Seifried, C. et al. Phosphorus and

Hawkes, C.H.; Shephard, B.C. & Daniel, S.E. Olfactory disfunction in Parkinson's disease.

Hawkes, C.H.; Shephardm, B.C. & Daniel, S.E. Is Parkinson's disease a primary olfactory

Hinke, R.M.; Hu, X.; Stillman, A.E.; Kim, S.G.; Merkle, H. et al. Functional magnetic

Hirsch, E.C. & Hunot S. Neuroinflammation in Parkinson's disease: a target for

Holshouser, B.A.; Komu, M.; Moller, H.E.; Zijlmans, J.; Kolem, H. et al. Localized proton

*Disorders,* Vol.15, No.7, (August 2009), pp. 490-494, ISSN 1353-8020

223-229, ISSN 0392-0461

pp. S205-U219, ISSN 0271-5333

pp. 3285-3297, ISSN 0006-8950

446, ISSN 0022-3050

1474-4422

473-480, ISSN 1460-2725

(June 1993) pp. 675-678 ISSN 0959-4965

0893-133X

resonance spectroscopy in Parkinson's disease and atypical parkinsonian disorders. *Movement Disorders*, Vol.12, No.6, (November 1997), pp. 903-909, ISSN 0885-3185 Federico, F.; Simone, I.L.; Lucivero, V.; Mezzapesa, D.M.; De Mari, M. et al. Usefulness of

proton magnetic resonance spectroscopy in differentiating parkinsonian syndromes. *Italian Journal of Neurological Sciences*, Vol.20, No.4, (August 1999), pp.

resonance spectroscopy studies in dementia and Parkinson's disease. *Dementia And Geriatric Cognitive Disorders*, Vol.14, No.2, (July 2002), pp. 64-76, ISSN 1420-8008 Fox, P.T. & Raichle, M.E. Stimulus rate determines regional brain blood flow in striate cortex. *Annals of Neurology,* Vol.17, No3, (March 1985), pp.303-305, ISSN 0364-5134 Fulton, HG. & Barrett, SP. A demonstration of intravenous nicotine self-administration in

humans?  *Journal of Clinical*

of smell loss in Parkinson's Disease - a multicenter study. *Parkinsonism & Related*

diffusion MR imaging techniques: from scalar diffusion-weighted imaging to diffusion tensor imaging and beyond. *Radiographics*, Vol.26, Sp. Iss, (October 2006),

proton magnetic resonance spectroscopy demonstrates mitochondrial dysfunction in early and advanced Parkinson's disease. *Brain,* Vol.132, No.12, (December 2009),

*Journal of Neurology Neurosurgery and Psychiatry,* Vol.62, No.5, (May 1997), pp. 436-

disorder? *Qjm-An International Journal of Medicine,* Vol.92, No.8, (August 1999), pp.

resonance imaging of Broca's area during internal speech. *NeuroReport*, Vol.4, No6,

neuroprotection? *Lancet Neurology,* Vol.8, No.4, (April 2009), pp. 382-397, ISSN:

NMR spectroscopy in the striatum of patients with idiopathic Parkinson's disease: a

multicenter pilot study. *Magnetic Resonance in Medicine,* Vol.33, No.5, (May 1995), pp. 589-594, ISSN 0740-3194

Early Marker for the Diagnosis of Parkinson's Disease 25

Schneider, W.; Noll, D.C. & Cohen, J. D. Functional topographic mapping of the cortical

Schocke, M.F.; Seppi, K.; Esterhammer, R.; Kremser, C.; Mair, K.J. et al. Trace of diffusion

Sofic, E.; Riederer, P.; Heinsen, H.; Beckmann, H.; Reynolds, G.P. et al. Increased iron (III)

Srinivasan, R.; Vigneron, D.; Sailasuta, N.; Hurd, R. & Nelson, S. A comparative study of

Takeda, A.; Saito, N.; Baba, T.; Kikuchi, A.; Sugeno, N. et al. Functional imaging studies of

Tambasco, N.; Pelliccioli, G.P.; Chiarini, P.; Montanari, G.E.; Leone, F. et al. Magnetization

Tedeschi, G.; Litvan, I.; Bonavita, S.; Bertolino, A.; Lundbom, N. et al. Proton magnetic

Tessa, C.; Giannelli, M.; Della Nave, R.; Lucetti, C.; Berti, C.A. et al. A whole-brain analysis

Tissingh, G.; Berendse, H.W.; Bergmans, P.; DeWaard, R.; Drukarch, B. et al. Loss of

Watanabe, H.; Fukatsu, H.; Katsuno, M.; Sugiura, M.; Hamada, K. et al. Multiple regional

*Psychiatry,* Vol.75, No.1, (January 2004), pp. 103-109, ISSN 0022-3050 Wattendorf, E.; Welge-Lüssen, A.; Fiedler K.; Bilecen, D.; Wolfensberger, M. et al. Olfactory

(September 1993), pp. 150-152, ISSN 0028-0836

No.4, (May 2004), pp. 523-528, ISSN 0730-725X

Vol.45, No.4, (April 2003), pp. 224-230, ISSN 0028-3940

(February 2010), pp. 36-39, ISSN 0022-510X

(April 2008), pp. 674-680, ISSN 01956108

1541-1552, ISSN 0006-8950

537-543, ISSN 0306-4522

No.4, (April 1995), pp. 247-250, ISSN 0001-6314

9564

3185

ribbon in human vision with conventional MRI scanners. *Nature*, Vol365, No6442,

tensor differentiates the Parkinson variant of multiple system atrophy and Parkinson's disease. *Neuroimage*, Vol.19, Suppl.9, (2004), pp. S53-S53, ISSN 08853185

and total iron content in post mortem substantia nigra of parkinsonian brain. *Journal of Neural Transmission,* Vol.74, No3, (August 1988), pp.199-205, ISSN 0300-

myo-inositol quantification using LCmodel at 1.5 T and 3.0 T with 3D 1H proton spectroscopic imaging of the human brain. *Magnetic Resonance Imaging*, Vol.22,

hyposmia in Parkinson's disease. *Journal of the Neurological Sciences*, Vol.298, No.1-2,

Transfer changes of gray and white matter in Parkinson 's disease. *Neuroradiology*,

resonance spectroscopic imaging in progressive supranuclear palsy, Parkinson's disease and corticobasal degeneration. *Brain,* Vol.120, No.9, (September 1997), pp.

in de novo Parkinson disease. *AJNR American Journal of Neuroradiology*, Vol.29, No4,

olfaction in de novo and treated Parkinson's disease: possible implications for early diagnosis. *Movement Disorders*, Vol.16, No.1, (January 2001), pp. 41-46, ISSN 0885-

1H-MR spectroscopy in multiple system atrophy: NAA/Cr reduction in pontine base as a valuable diagnostic marker. *Journal of Neurology, Neurosurgery, and*

Impairment Predicts Brain Atrophy in Parkinson's Disease. *The Journal of Neuroscience*, Vol.29, No.49, (December 2009), pp. 15410-15413, ISSN 0270-6474 Welge-Lüssen, A.; Wattendorf, E.; Schwerdtfeger, U.; Fuhr, P.; Bilecen, D. et al. Olfactory

induced brain activity in Parkinson's disease relates to the expression of eventrelated potentials—an fMRI study. *Neuroscience,* Vol.162, No.2, (August 2009), pp.

function in atypical parkinsonian syndromes. *Acta Neurologica Scandinavica*, Vol.91,

Wenning, G.K.; Shephard, B.; Hawkes, C.; Petruckevitch, A.; Lees, A. et al. Olfactory

olfactory thresholds. *European Archives of Oto-Rhino-Laryngology,* Vol.257, No.4, (April 2000), pp. 205-211, ISSN 0937-4477

Le Bihan, D. Looking into the functional architecture of the brain with diffusion MRI. *Nature Reviews Neuroscience*, Vol.4, No.6, (June 2003), pp. 469-480, ISSN 1471-0048 Lekwuwa, G.U.; Barnes, G.R.; Collins, C.J.S.; Limousin, P. Progressive bradykinesia and

Lin, A.; Ross, B.D.; Harris, K. & Wong, W. Efficacy of proton magnetic resonance

Marino, S.; Sessa, E.; Di Lorenzo, G.; Lanzafame, P.; Scullica, G.; et al. Quantitative analysis

Marino, S.; Lanzafame, P.; Sessa, E.; Bramanti, A.; Bramanti, P. The effect of L-Dopa

*Neurological Sciences*, Vol. 31,No. 3 (June 2010), pp. 381-385, ISSN 0022-510X Muller, A.; Reichmann, H.; Livermore, A. & Hummel T. Olfactory function in idiopathic

Ogawa, S.; Lee, T.M.; Nayak, A. S.; & Glynn, P. Oxygenation-sensitive contrast in magnetic

Pike, G.B.; Hu, B.S.; Glover, G.H. & Enzmann, D.R. Magnetization transfer time-of-flight

Ramaker, C.; Marinus, J.; Stiggelbout, A.M. & Van Hilten, B.J. Systematic evaluation of

Ross, B. & Bluml, S. Magnetic resonace spectroscopy of the human brain. *The Anatomical*

Roy, C. & Sherrington, C. On the regulation of the blood-supply of the brain. *The Journal of*

Rutledge, J.N.; Hilal, S.K.; Silver, A.J.; Defendini, R. & Fahn S. Study of movement disorders

Savoiardo, M.; Girotti, F.; Strada, L. & Ciceri, E. Magnetic resonance imaging in progressive

*Disorders*, Vol.17, No.5, (September 2002), pp. 867-876, ISSN 0885-3185 Rolheiser, T.M.; Fulton, H.G.; Good, K.P.; Fisk, J.D.; McKelvey, J.R. et al. Diffusion tensor

(April 2000), pp. 205-211, ISSN 0937-4477

No.2, (April 2005), pp. 197-214, ISSN 1545-5343

Vol.109, No.5-6, (May 2002), pp. 805-811, ISSN 0300-9564

*Medicine*, Vol.14, No1, (April 1990) pp.68-78, ISSN 07403194

*Journal of Neurology,* (February 2011), ISSN 0340-5354

*Record,* Vol.265, No.2, (April 2001), pp. 54-84, ISSN 0003-276X

*Physiology,* Vol.11*,* No1-2, (January 1890), pp.85-108, ISSN 1469-7793

(June 1992), pp. 372-379, ISSN 0740-3194

1987), pp.365-379, ISSN 0361-803X

Vol.42, (1994), pp. 93-110, ISSN 0303-6995

ISSN 0014-3022

olfactory thresholds. *European Archives of Oto-Rhino-Laryngology,* Vol.257, No.4,

hypokinesia of ocular pursuit in Parkinson's disease. *Journal of Neurology Neurosurgery and Psychiatry,* Vol.66, No.6, (June 1999), pp. 746–753, ISSN 0022-3050

spectroscopy inneurological diagnosis and neurotherapic decision making. *NeuroRx: the journal of the American Society for Experimental NeuroTherapeutics,* Vol.2,

of pursuit ocular movements in Parkinson's disease by using a video-based eye tracking system. *European Neurology*, Vol. 58, No. 4, (September 2007), pp. 193-7,

administration on pursuit ocular movements in suspected Parkinson's disease.

Parkinson's disease (IPD): results from cross-sectional studies in IPD patients and long-term follow-up of de-novo IPD patients. *Journal of Neural Transmission,*

resonance image of rodent brain at high magnetic fields. *Magnetic Resonance in*

magnetic resonance angiography. *Magnetic Resonance in Medicine,* Vol.25, No.2,

rating scales for impairment and disability in Parkinson's disease. *Movement*

imaging and olfactory identification testing in early-stage Parkinson's disease.

and brain iron by MR. *AJR American Journal of Roentgenology,* Vol.149, No2, (August

supranuclear palsy and other parkinsonian disorders. *Journal of Neural Transmission,*

**2**

*Kiev, Ukraine*

**Diagnosis of Parkinson's Disease**

**by Electrophysiological Methods**

Elena Lukhanina, Irina Karaban and Natalia Berezetskaya *Department of Brain Physiology, A.A. Bogomoletz Institute of Physiology,*

Effective differential diagnosis of Parkinson's disease (PD) needs in informative indices that objectively reflect the functional state of the extrapyramidal system. And also, when evaluating an efficacy of antiparkinsonian therapy, it is essential to have both, qualitative and quantitative characteristics, permitting to correct treatment and predict a disease course. One of informative diagnostic method in PD is surface (interference) electromyography. As know, a nigrostriatal dopamine deficit results in disturbances of the central supraspinal control over the muscle tonic activity and voluntary movements (Valls-Solé & Valldeoriola, 2002). Electromyographically, the extrapyradimal insufficiency shows itself by a high level of bioelectrical activity of muscles at rest, changes of motor unit conduction velocity and synchronization (Farina et al., 2004; Semmler & Nordstrom, 1999). The traditional methods to evaluate surface electromyograms (EMGs) are based on amplitude and spectral analysis. However, myoelectric signals are nonlinear by its nature (Nieminen & Takala, 1996). A surface EMG is formed by the summation of a number of single muscle fiber action potentials. Therefore different world clinics have been searching for new relevant methods based on nonlinear time-series analyses of EMG to quantify the motor features of the disorder in PD (Del Santo et al., 2007; Meigal et al., 2009). Some other novel EMG characteristics, such as dimensionality based on fractal analysis or higher order statistics of EMG distribution have also proved to be sensitive to neuromuscular status (Swie et al.,

Although the cardinal symptoms of the disease are movement disorders the manifestations of PD also comprise a variety of diverse abnormalities including disturbance of sensory gating and cognitive decline (Lewis & Byblow, 2002). Several authors suggested that movement disorders in PD might be also developed because of dysregulation of sensory processing that affects sensorimotor integration (Abbruzzese & Berardelli, 2003). This is an important issue because one of the proposed key functions of basal ganglia is the gating of sensory input for motor control (Kaji, 2001). Numerous studies have demonstrated marked changes in the somatosensory (Rossini et al., 1998), acoustic (Teo et al., 1997;) and visual (Sadekov, 1997) evoked potentials in PD patients. Evaluation of brain evoked potentials may have potential in the assessment of the severity of PD. In contemporary neurophysiology,

**1. Introduction**

2005).

*Parkinson's Disease Treatment Centre, Institute of Gerontology,*

## **Diagnosis of Parkinson's Disease by Electrophysiological Methods**

Elena Lukhanina, Irina Karaban and Natalia Berezetskaya *Department of Brain Physiology, A.A. Bogomoletz Institute of Physiology, Parkinson's Disease Treatment Centre, Institute of Gerontology, Kiev, Ukraine*

## **1. Introduction**

26 Diagnostics and Rehabilitation of Parkinson's Disease

Westermann, B.; Wattendorf, E.; Schwerdtfeger, U.; Husner, A.; Fuhr, P. et al. Functional

Wilms, H.; Zecca, L.; Rosenstiel, P.; Sievers, J.; Deuschl, G. et al. Inflammation in Parkinson's

Wolff, S.D. & Balaban, R.S. Magnetization transfer contrast (MTC) and tissue water proton

Wolff, S.D.; Eng, J. & Balaban, R.S. Magnetization transfer contrast: method for improving

Yonca, A.; Pervin, I.; Ali, D.; Sezer, K. & Naighan, I. Magnetization Transfer Ratio in Early

Youdim, M.B.H.; Ben-Schachar, D.; Yehuda, S. & Riederer, P. The role of iron in the basal ganglia. *Advances in Neurology,* Vol.53, (1990) pp.155-162, ISSN: 0091-3952

19-24, ISSN 0022-3050

135-144, ISSN 0740-3194

133-137, ISSN 0033-8419

189-192, ISSN 1076-6332

6128

imaging of the cerebral olfactory system in patients with Parkinson's disease. *Journal of Neurology, Neurosurgery, and Psychiatry,* Vol.79, No.1, (January 2008), pp.

diseases and other neurodegenerative diseases: cause and therapeutic implications. *Current Pharmaceutical Design,* Vol.13*,* No18, (June 2007), pp. 1925-1928, ISSN: 1381-

relaxation in vivo. *Magnetic Resonance in Medicine,* Vol.10, No.1, (April 1989), pp.

contrast in gradient-recalled-echo images*. Radiology*, Vol.179, No.1, (April 1991), pp.

Period of Parkinson Disease. *Academic Radiology*, Vol.14, No.2, (February 2007), pp.

Effective differential diagnosis of Parkinson's disease (PD) needs in informative indices that objectively reflect the functional state of the extrapyramidal system. And also, when evaluating an efficacy of antiparkinsonian therapy, it is essential to have both, qualitative and quantitative characteristics, permitting to correct treatment and predict a disease course. One of informative diagnostic method in PD is surface (interference) electromyography. As know, a nigrostriatal dopamine deficit results in disturbances of the central supraspinal control over the muscle tonic activity and voluntary movements (Valls-Solé & Valldeoriola, 2002). Electromyographically, the extrapyradimal insufficiency shows itself by a high level of bioelectrical activity of muscles at rest, changes of motor unit conduction velocity and synchronization (Farina et al., 2004; Semmler & Nordstrom, 1999). The traditional methods to evaluate surface electromyograms (EMGs) are based on amplitude and spectral analysis. However, myoelectric signals are nonlinear by its nature (Nieminen & Takala, 1996). A surface EMG is formed by the summation of a number of single muscle fiber action potentials. Therefore different world clinics have been searching for new relevant methods based on nonlinear time-series analyses of EMG to quantify the motor features of the disorder in PD (Del Santo et al., 2007; Meigal et al., 2009). Some other novel EMG characteristics, such as dimensionality based on fractal analysis or higher order statistics of EMG distribution have also proved to be sensitive to neuromuscular status (Swie et al., 2005).

Although the cardinal symptoms of the disease are movement disorders the manifestations of PD also comprise a variety of diverse abnormalities including disturbance of sensory gating and cognitive decline (Lewis & Byblow, 2002). Several authors suggested that movement disorders in PD might be also developed because of dysregulation of sensory processing that affects sensorimotor integration (Abbruzzese & Berardelli, 2003). This is an important issue because one of the proposed key functions of basal ganglia is the gating of sensory input for motor control (Kaji, 2001). Numerous studies have demonstrated marked changes in the somatosensory (Rossini et al., 1998), acoustic (Teo et al., 1997;) and visual (Sadekov, 1997) evoked potentials in PD patients. Evaluation of brain evoked potentials may have potential in the assessment of the severity of PD. In contemporary neurophysiology,

Diagnosis of Parkinson's Disease by Electrophysiological Methods 29

Studies were performed in two groups: 48 patients with PD, 1.5-3.5 Hoehn-Yahr scale (23 men and 25 women, mean ± SE age 62.2 1.6, range 49-75 years) and 42 age-matched healthy controls (20 men and 22 women, mean ± SE age 65.8 ± 1.43, range 58-74 years). All of them were right-handed persons. The study patients, who regularly underwent treatment at the Parkinson's Disease Centre of Institute of Gerontology, gave their written informed consent to participate in this investigation. They had 4-13-year history of an idiopathic PD and received an antiparkinsonian medication (an individual dose 0.250-12g of levodopa/carbidopa, daily). All patients were studied in the OFF state. For the quantitative evaluation of levodopa therapy 20 patients (in which the clinical "ON-OFF" phenomenon was verified) were studied also in the ON state, one hour after an intake of the single individual dose of levodopa/carbidopa. The motor activity of PD patients was evaluated in

For each subject, we recorded the surface EMG from the flexors and extensors (mm. biceps and triceps brachii) of the right and left arms. The subject lay on his back, with the arms lying on the horizontal surface. The EMGs were recorded using four bipolar skin electrodes (0.5x1.0 cm) with an interelectrode distance constant of 1.5 cm. Bioelectrical potentials were amplified with a band pass of 10 Hz - 10 kHz. The amplified analogue signals were fed to a computer, which digitized them at a sampling rate of 1000 Hz and then stored the data for further measurements. The time of each recording was 10 sec. EMG recordings were made:

2. During a voluntary m. biceps brachii contraction started after a command to bend the arm at the elbow, fingers touching the shoulder. The sound signal served as a command to initiate arm bending, and it was simultaneously registered on EMG. An electrical contact enclosure marked the start of arm lifting, being recorded

3. During a tonic m. biceps brachii strain under weight holding (2 kg) in the hand, with

In resting EMG recordings, the average and maximal EMG amplitudes were calculated to evaluate the muscle ability for relaxation. An artefact-free section on the EMG record was selected by the experimenter. The single EMG wave amplitude was defined as the difference between the values of upper and lower peaks. The oscillations with no less than 2 V amplitude were considered. The resting average EMG amplitude was calculated based on minimum 100 measurements. The maximum amplitude value was calculated on the same

The resting EMG recordings were also used for assessing the burst muscle discharges For this purpose, the Fourier spectrum diagrams for the low frequency area were constructed. In doing this, part of the data with negative EMG amplitude meanings were discarded. Data with the positive EMG amplitude meanings underwent a Butterworth digital sinus low pass filtering with a band pass of 0-20 Hz As a result, the envelope of EMG amplitude was formed, which then served as the data array for fast Fourier transformation. The data for each lead were divided into several successive sections, each containing 512 points, which underwent the fast Fourier transformation. The obtained spectra were averaged, and the envelope of EMG amplitude frequency with a maximal power was determined (Fig 1). The statistical significance of the frequency peak was determined by means of constructing the

**2.1.1 Methods**

ON state, according to sections II-III of the UPDRS.

1. At a resting state, being cautious that the subject is relaxed.

simultaneously with the EMG on a free channel.

95% confidential intervals (M 2 S.D).

arm lifted upward and stretched forward, for 5 sec.

EMG section. The amplitude distribution histograms were constructed.

studies of the central mechanisms underlying the organization of motor function and its impairments increasingly involve analysis of endogenous cortical event-related potentials, a set of potentials which includes contingent negative variation (CNV). The CNV extent depends on the level of attention, motivation, and volitional effort (Deecke, 2001). The magnitude of this potential is known to decrease in diseases accompanied by motor disorders, including PD (Aotsuka et al., 1996; Pulvenmuller et al., 1996). CNV has been shown to display significant increases after administration of levodopa in patients with Parkinson's disease, suggesting a role for the central dopaminergic system in its generation (Oishi et al., 1995).

Although electrophysiological methods objectively reflect motor and sensory dysfunctions, they are still used rather rarely in the clinical evaluation of PD. We carried out systematic and detailed research of surface EMG characteristics in PD patients in comparison with agematched healthy subjects, paying the special attention on the correlation associations between EMG parameters and subitems of the Unified Parkinson's Disease Rating Scale (UPDRS). Amplitude and spectral features, statistics of distribution, fractal dynamics of the EMG signals were investigated. Separate research was dedicated to the study of EMG characteristics of clinically healthy kinsmen of the patients suffering from PD in order to detect latent symptoms of extrapyramidal insufficiency that can be considered genetic determinants of the risk of development of the above disease. Since the question of the relationship the early and late phases of CNV with the mechanisms controlling motor functions in PD has received inadequate study we conducted such research in patients with this disease. With the purpose of evaluation of the brain inhibitory processes in PD patients the study of cortical evoked potentials upon paired-click auditory stimulation was performed. The results of these investigations are presented below.

## **2. Surface electromyography**

Surface EMG is a simple and noninvasive method that permits to estimate the severity of symptomatology in patients and also may help to exposure of the hidden manifestations of the disturbed muscles activity on the presymptomatic stage of the neurodegenerative process (Kryzhanovsky et al., 2002; Lukhanina et al., 2010). In PD patients the EMG characteristics of the tonic and phasic shoulder muscle activities at rest, during voluntary contraction and under tonic muscle strain were studied. In kinsmen of the patients, suffering from PD, EMGs in the resting state and under conditions of two functional tests (retention of load and retention of arms in the elevated and outstretched state) were recorded.

#### **2.1 Amplitude and spectral analysis of EMGs in patients with Parkinson's disease**

One of the informative EMG sign of extrapyramidal insufficiency appears to be the resting EMG amplitude values that reflect the muscle ability for relaxation. Spectral analysis of resting EMGs is used for assessing the burst muscle discharges with a frequency of 4-8 Hz reflecting parkinsonian tremor. Amplitude values of the EMGs recorded during the voluntary muscle contraction serve to calculate the phasic activation coefficient. This coefficient clearly reflects the competitive relationships between the tonic and phasic processes. Study of the reflex agonist/antagonist muscle involvement under tonic strain is valid for establishing coordinating muscle relationships.

#### **2.1.1 Methods**

28 Diagnostics and Rehabilitation of Parkinson's Disease

studies of the central mechanisms underlying the organization of motor function and its impairments increasingly involve analysis of endogenous cortical event-related potentials, a set of potentials which includes contingent negative variation (CNV). The CNV extent depends on the level of attention, motivation, and volitional effort (Deecke, 2001). The magnitude of this potential is known to decrease in diseases accompanied by motor disorders, including PD (Aotsuka et al., 1996; Pulvenmuller et al., 1996). CNV has been shown to display significant increases after administration of levodopa in patients with Parkinson's disease, suggesting a role for the central dopaminergic system in its generation

Although electrophysiological methods objectively reflect motor and sensory dysfunctions, they are still used rather rarely in the clinical evaluation of PD. We carried out systematic and detailed research of surface EMG characteristics in PD patients in comparison with agematched healthy subjects, paying the special attention on the correlation associations between EMG parameters and subitems of the Unified Parkinson's Disease Rating Scale (UPDRS). Amplitude and spectral features, statistics of distribution, fractal dynamics of the EMG signals were investigated. Separate research was dedicated to the study of EMG characteristics of clinically healthy kinsmen of the patients suffering from PD in order to detect latent symptoms of extrapyramidal insufficiency that can be considered genetic determinants of the risk of development of the above disease. Since the question of the relationship the early and late phases of CNV with the mechanisms controlling motor functions in PD has received inadequate study we conducted such research in patients with this disease. With the purpose of evaluation of the brain inhibitory processes in PD patients the study of cortical evoked potentials upon paired-click auditory stimulation was

Surface EMG is a simple and noninvasive method that permits to estimate the severity of symptomatology in patients and also may help to exposure of the hidden manifestations of the disturbed muscles activity on the presymptomatic stage of the neurodegenerative process (Kryzhanovsky et al., 2002; Lukhanina et al., 2010). In PD patients the EMG characteristics of the tonic and phasic shoulder muscle activities at rest, during voluntary contraction and under tonic muscle strain were studied. In kinsmen of the patients, suffering from PD, EMGs in the resting state and under conditions of two functional tests (retention of load and retention of arms in the elevated and outstretched state) were

**2.1 Amplitude and spectral analysis of EMGs in patients with Parkinson's disease**  One of the informative EMG sign of extrapyramidal insufficiency appears to be the resting EMG amplitude values that reflect the muscle ability for relaxation. Spectral analysis of resting EMGs is used for assessing the burst muscle discharges with a frequency of 4-8 Hz reflecting parkinsonian tremor. Amplitude values of the EMGs recorded during the voluntary muscle contraction serve to calculate the phasic activation coefficient. This coefficient clearly reflects the competitive relationships between the tonic and phasic processes. Study of the reflex agonist/antagonist muscle involvement under tonic strain is

performed. The results of these investigations are presented below.

valid for establishing coordinating muscle relationships.

**2. Surface electromyography**

recorded.

(Oishi et al., 1995).

Studies were performed in two groups: 48 patients with PD, 1.5-3.5 Hoehn-Yahr scale (23 men and 25 women, mean ± SE age 62.2 1.6, range 49-75 years) and 42 age-matched healthy controls (20 men and 22 women, mean ± SE age 65.8 ± 1.43, range 58-74 years). All of them were right-handed persons. The study patients, who regularly underwent treatment at the Parkinson's Disease Centre of Institute of Gerontology, gave their written informed consent to participate in this investigation. They had 4-13-year history of an idiopathic PD and received an antiparkinsonian medication (an individual dose 0.250-12g of levodopa/carbidopa, daily). All patients were studied in the OFF state. For the quantitative evaluation of levodopa therapy 20 patients (in which the clinical "ON-OFF" phenomenon was verified) were studied also in the ON state, one hour after an intake of the single individual dose of levodopa/carbidopa. The motor activity of PD patients was evaluated in ON state, according to sections II-III of the UPDRS.

For each subject, we recorded the surface EMG from the flexors and extensors (mm. biceps and triceps brachii) of the right and left arms. The subject lay on his back, with the arms lying on the horizontal surface. The EMGs were recorded using four bipolar skin electrodes (0.5x1.0 cm) with an interelectrode distance constant of 1.5 cm. Bioelectrical potentials were amplified with a band pass of 10 Hz - 10 kHz. The amplified analogue signals were fed to a computer, which digitized them at a sampling rate of 1000 Hz and then stored the data for further measurements. The time of each recording was 10 sec. EMG recordings were made:

In resting EMG recordings, the average and maximal EMG amplitudes were calculated to evaluate the muscle ability for relaxation. An artefact-free section on the EMG record was selected by the experimenter. The single EMG wave amplitude was defined as the difference between the values of upper and lower peaks. The oscillations with no less than 2 V amplitude were considered. The resting average EMG amplitude was calculated based on minimum 100 measurements. The maximum amplitude value was calculated on the same EMG section. The amplitude distribution histograms were constructed.

The resting EMG recordings were also used for assessing the burst muscle discharges For this purpose, the Fourier spectrum diagrams for the low frequency area were constructed. In doing this, part of the data with negative EMG amplitude meanings were discarded. Data with the positive EMG amplitude meanings underwent a Butterworth digital sinus low pass filtering with a band pass of 0-20 Hz As a result, the envelope of EMG amplitude was formed, which then served as the data array for fast Fourier transformation. The data for each lead were divided into several successive sections, each containing 512 points, which underwent the fast Fourier transformation. The obtained spectra were averaged, and the envelope of EMG amplitude frequency with a maximal power was determined (Fig 1). The statistical significance of the frequency peak was determined by means of constructing the 95% confidential intervals (M 2 S.D).

Diagnosis of Parkinson's Disease by Electrophysiological Methods 31

average EMG amplitude values for mm. biceps and triceps brachii varied across the subjects within 3-12 V and the maximal amplitude values within 4-34 V. For the whole group of healthy subjects, mean ± SE average amplitude did not exceed 5.9 ± 0.2 V and mean ± SE

Table 1. Resting EMG amplitudes of shoulder muscles in healthy controls and patients with Parkinson's disease. Notes: values are Mean Standard Error; n - number of subjects in each

There were no statistical differences in EMG amplitude values between men and women. A significant positive correlation (p<0.05) was found for the resting activities of the antagonist muscles of the upper extremities in the age-matched healthy subjects (Table 2). The use of the envelope EMG construction technique demonstrated the presence of rhythmic burst muscle discharges in those cases where they were badly visualized on the EMG. Low amplitude burst discharges were occasionally identified in healthy subjects with the help of this technique (Fig 2, Control 2)**.** Of EMG recordings taken from flexors and extensors on both sides in 42 persons of the control group, 11 recordings (6.5%) made in eight subjects displayed the burst discharges, with a mean ± SE frequency of 6.1 ± 0.3 Hz. The maximal amplitude of burst

Healthy controls PD patients, OFF state PD patients, ON state

0.42\*\* 0.40\*\* 0.27 0.33\* - 0.26 0.32\*

In the group of PD patients, we observed a significant increase in the resting EMG amplitudes, which was ascribed to muscle relaxation disturbances. The mean average amplitude values for various study muscles, estimated for a whole PD group, were 2-3 times

Table 2. Correlation coefficients between average EMG amplitudes of the antagonist shoulder muscles (mm. biceps and triceps brachii) at rest in healthy controls and PD

less impaired side

more impaired side

less impaired side

group; \*, \*\*\* significant difference compared to healthy controls according to Mann-

discharges in control subjects did not exceed 11-18 V (mean ± SE = 14.3 ± 1.1 V).

more impaired side

patients. \* significant correlation, p< 0.05; \*\* is . p< 0.01.

5.30.8 5.50.7 5.90.2 5.40.8

12.52.1 12,82.3 11.91.3 12.32.1

Healthy controls (n = 42) PD patients (n = 48)

19.53.8 \*\*\* 21.47.4 \*\*\* 13.11.7 \* 12.53.1

74.017.9 \*\*\* 73.815.6 \*\*\* 60.17.4 61.912.0

maximal amplitude was no more 12.8 ± 2.3 V (Table 1).

m. biceps dexter m. biceps sinister m. triceps dexter m. triceps sinister

m. biceps dexter m. biceps sinister m. triceps dexter m. triceps sinister

Whitney test, p< 0.05 and p< 0.001, respectively.

right side left side

Average EMG amplitude (V)

Maximal EMG amplitude (V)

The EMG recordings made during the voluntary m. biceps brachii contraction served to calculate the phasic activation coefficient (PhAC), from a formula :

$$\text{PhAC} = \text{(AVCa-ARa)} / \text{AVCa} \tag{1}$$

where AVCa is the average EMG amplitude on a section with most marked changes in the muscle activity under voluntary contraction, and ARa is the average amplitude of resting EMG. In the conditions of low tonic muscle activity at rest the phasic muscle activation during voluntary movement is facilitated and the PhAC value is close to 1. On the contrary, when the resting tonic activity increases, the PhAC falls.

Fig. 1. The spectrogram of the power of EMG envelope frequency with 95% confidence intervals (A) and the corresponding resting EMG pattern of m. biceps brachii in a patient with Parkinson's disease (B). Peak deviation on the spectrogram reflects the frequency of the rhythmic burst muscle discharges.

The functional test with weight holding served for study of the reflex agonist and antagonist involvement during tonic muscle strain. We calculated the coefficients of reflex involvement of the muscles of the opposite arm, which characterized "distant" synergies. The coefficients of reflex involvement, respectively for the m. biceps brachii and m. triceps brachii of the opposite upper limb were obtained by calculation of the ratio of the mean amplitude recorded from the m. biceps (or triceps) on the resting side and mean amplitude recorded from the m. biceps on the side of retention of a load; the latter value was taken as 100%. In the norm, the value should not exceed 15%. An increase in this index is indicative of abnormal intensification of muscle coordinative interactions; if the coefficient of reflex involvement value exceeds 50%, such a disorder is qualified as gross.

Statistical analysis of the obtained data was performed using Statistic 8 software. Dispersion analysis ANOVA and a non-parametric two-tailed Mann-Whitney criterion were used in the course of comparison of the values observed in the different groups of the tested persons. Data obtained from the same patients before and after Levodopa treatment were compared using two-tailed paired t-test. The nonparametric Spearman test was used to evaluate possible correlation between above EMG parameters and subitems of UPDRS. Differences were considered to be significant at *Р* < 0.05.

#### **2.1.2 Results and discussion**

In the group of age-matched healthy subjects, the EMG amplitude of the shoulder flexors and extensors during muscle relaxation showed low values (Fig 2, Controls 1, 2). The

The EMG recordings made during the voluntary m. biceps brachii contraction served to

where AVCa is the average EMG amplitude on a section with most marked changes in the muscle activity under voluntary contraction, and ARa is the average amplitude of resting EMG. In the conditions of low tonic muscle activity at rest the phasic muscle activation during voluntary movement is facilitated and the PhAC value is close to 1. On the contrary,

Fig. 1. The spectrogram of the power of EMG envelope frequency with 95% confidence intervals (A) and the corresponding resting EMG pattern of m. biceps brachii in a patient with Parkinson's disease (B). Peak deviation on the spectrogram reflects the frequency of the

involvement value exceeds 50%, such a disorder is qualified as gross.

The functional test with weight holding served for study of the reflex agonist and antagonist involvement during tonic muscle strain. We calculated the coefficients of reflex involvement of the muscles of the opposite arm, which characterized "distant" synergies. The coefficients of reflex involvement, respectively for the m. biceps brachii and m. triceps brachii of the opposite upper limb were obtained by calculation of the ratio of the mean amplitude recorded from the m. biceps (or triceps) on the resting side and mean amplitude recorded from the m. biceps on the side of retention of a load; the latter value was taken as 100%. In the norm, the value should not exceed 15%. An increase in this index is indicative of abnormal intensification of muscle coordinative interactions; if the coefficient of reflex

Statistical analysis of the obtained data was performed using Statistic 8 software. Dispersion analysis ANOVA and a non-parametric two-tailed Mann-Whitney criterion were used in the course of comparison of the values observed in the different groups of the tested persons. Data obtained from the same patients before and after Levodopa treatment were compared using two-tailed paired t-test. The nonparametric Spearman test was used to evaluate possible correlation between above EMG parameters and subitems of UPDRS. Differences

In the group of age-matched healthy subjects, the EMG amplitude of the shoulder flexors and extensors during muscle relaxation showed low values (Fig 2, Controls 1, 2). The

PhAC = (AVCa-ARa)/AVCa (1)

calculate the phasic activation coefficient (PhAC), from a formula :

when the resting tonic activity increases, the PhAC falls.

rhythmic burst muscle discharges.

were considered to be significant at *Р* < 0.05.

**2.1.2 Results and discussion**

average EMG amplitude values for mm. biceps and triceps brachii varied across the subjects within 3-12 V and the maximal amplitude values within 4-34 V. For the whole group of healthy subjects, mean ± SE average amplitude did not exceed 5.9 ± 0.2 V and mean ± SE maximal amplitude was no more 12.8 ± 2.3 V (Table 1).

Table 1. Resting EMG amplitudes of shoulder muscles in healthy controls and patients with Parkinson's disease. Notes: values are Mean Standard Error; n - number of subjects in each group; \*, \*\*\* significant difference compared to healthy controls according to Mann-Whitney test, p< 0.05 and p< 0.001, respectively.

There were no statistical differences in EMG amplitude values between men and women. A significant positive correlation (p<0.05) was found for the resting activities of the antagonist muscles of the upper extremities in the age-matched healthy subjects (Table 2). The use of the envelope EMG construction technique demonstrated the presence of rhythmic burst muscle discharges in those cases where they were badly visualized on the EMG. Low amplitude burst discharges were occasionally identified in healthy subjects with the help of this technique (Fig 2, Control 2)**.** Of EMG recordings taken from flexors and extensors on both sides in 42 persons of the control group, 11 recordings (6.5%) made in eight subjects displayed the burst discharges, with a mean ± SE frequency of 6.1 ± 0.3 Hz. The maximal amplitude of burst discharges in control subjects did not exceed 11-18 V (mean ± SE = 14.3 ± 1.1 V).

Table 2. Correlation coefficients between average EMG amplitudes of the antagonist shoulder muscles (mm. biceps and triceps brachii) at rest in healthy controls and PD patients. \* significant correlation, p< 0.05; \*\* is . p< 0.01.

In the group of PD patients, we observed a significant increase in the resting EMG amplitudes, which was ascribed to muscle relaxation disturbances. The mean average amplitude values for various study muscles, estimated for a whole PD group, were 2-3 times

Diagnosis of Parkinson's Disease by Electrophysiological Methods 33

Of interest is the fact that PD patients did not show a significant correlation between resting activities of the antagonist mm. biceps and triceps brachii on the dominant side, as has been true in the cases of the right and left sides in healthy subjects (Table 2). On the EMGs taken from PD patients with the akinetic-rigid-trembling form of the disease burst muscle discharges occurred as a rule with a frequency of 4-8 Hz. The mean ± SE frequency of the burst discharges was 5.2 ± 0.2 Hz. They had high amplitude (Fig.3). The maximal amplitude of burst discharges varied from 30 to 508 V (mean ± SE = 89.8 ± 15.6 V). Of special note, no significant correlation was found between resting EMG amplitude values and the

When comparing the data in OFF-state and ON-state, we observed a noticeable decrease in amplitude values. Mean ± SE average EMG amplitude of different muscles decreased to 8.2 ± 1.9 – 12.3 ± 5.1 V and mean ± SE maximal amplitude decreased to 20.1± 5.3 – 32.1± 7.1 V In this respect, the amplitude histograms made for the same patient during both states were

Fig. 4. The decrease of resting EMG amplitude values (calculated from peak to peak) of m. biceps brachii in a PD patient after intake of single dose of levodopa/carbidopa. OFF: the histograms of distribution of EMG amplitude values during the off-medication state; ON :

But the treatment with levodopa did not result in the normalization of correlations between resting activities of the antagonist shoulder muscles (Table 2). Following a single dose of levodopa/carbidopa the number of cases displaying burst discharges with a frequency of 4- 8 Hz decreased. In some patients the rhythmic discharges disappeared, as is shown in Figure 5, top records. In the other patients who displayed discharges after a dose of

EMGs recorded during the performance of voluntary arm bending were found to differ considerably in healthy subjects and PD patients. In the healthy subjects, we clearly distinguished an onset of muscle phasic activation on the EMG (Fig. 6, Control). Means ± SE of average EMG amplitude of the mm. biceps brachii during their voluntary contraction was 49 ± 8 V from the right and 44 ± 2 V from the left, the maximal amplitude – 189 ± 31 V and 137 ± 30 V, respectively. In view of the low resting EMG amplitude value in healthy subjects, the coefficient of phasic activation in most cases was equal to 0.7-0.9; mean ± SE

In contrast, in the PD patients it was often difficult to locate a site on the EMG at which the muscle phasic activation started because of increased resting tonic muscle activity and a very delayed rise in EMG amplitude after the delivery of a command to move (Fig. 6, PD). During peak voluntary flexor contraction, some patients showed a noticeable reduction of

levodopa, an increase occurred in the discharges frequency (Fig. 5, lower records).

one hour after drug intake. The bin of histograms is 4 V.

occurrence of burst muscle discharges.

very illustrative (Fig.4).

was 0.77 ± 0.04.

greater compared to control values, and the mean maximal amplitude values were approximately 5-6 times greater (Table 1). In some patients, average amplitude from a more impaired side reached 44-123 V and maximal amplitude - 210-508 V

Fig. 2. The spectrograms of the power of EMG envelope frequency with 95% confidence intervals (A) and the corresponding resting EMG patterns of m. biceps brachii (B) in healthy controls (Control 1 and 2) Peak deviation on the spectrogram reflects the frequency of the rhythmic burst muscle discharges. Control 1: the absence of the burst muscle activity. Control 2: low amplitude burst muscle discharges with a frequency of 4 Hz in a healthy control subject.

Fig. 3. Typical examples of EMGs registered in the resting state from three patients with the akinetic-rigid trembling form of Parkinson's disease (three upper records) and a patient with the akinetic-rigid form of this disease (low record).

greater compared to control values, and the mean maximal amplitude values were approximately 5-6 times greater (Table 1). In some patients, average amplitude from a more

Fig. 2. The spectrograms of the power of EMG envelope frequency with 95% confidence intervals (A) and the corresponding resting EMG patterns of m. biceps brachii (B) in healthy controls (Control 1 and 2) Peak deviation on the spectrogram reflects the frequency of the rhythmic burst muscle discharges. Control 1: the absence of the burst muscle activity. Control 2: low amplitude burst muscle discharges with a frequency of 4 Hz in a healthy

Fig. 3. Typical examples of EMGs registered in the resting state from three patients with the akinetic-rigid trembling form of Parkinson's disease (three upper records) and a patient

with the akinetic-rigid form of this disease (low record).

control subject.

impaired side reached 44-123 V and maximal amplitude - 210-508 V

Of interest is the fact that PD patients did not show a significant correlation between resting activities of the antagonist mm. biceps and triceps brachii on the dominant side, as has been true in the cases of the right and left sides in healthy subjects (Table 2). On the EMGs taken from PD patients with the akinetic-rigid-trembling form of the disease burst muscle discharges occurred as a rule with a frequency of 4-8 Hz. The mean ± SE frequency of the burst discharges was 5.2 ± 0.2 Hz. They had high amplitude (Fig.3). The maximal amplitude of burst discharges varied from 30 to 508 V (mean ± SE = 89.8 ± 15.6 V). Of special note, no significant correlation was found between resting EMG amplitude values and the occurrence of burst muscle discharges.

When comparing the data in OFF-state and ON-state, we observed a noticeable decrease in amplitude values. Mean ± SE average EMG amplitude of different muscles decreased to 8.2 ± 1.9 – 12.3 ± 5.1 V and mean ± SE maximal amplitude decreased to 20.1± 5.3 – 32.1± 7.1 V In this respect, the amplitude histograms made for the same patient during both states were very illustrative (Fig.4).

Fig. 4. The decrease of resting EMG amplitude values (calculated from peak to peak) of m. biceps brachii in a PD patient after intake of single dose of levodopa/carbidopa. OFF: the histograms of distribution of EMG amplitude values during the off-medication state; ON : one hour after drug intake. The bin of histograms is 4 V.

But the treatment with levodopa did not result in the normalization of correlations between resting activities of the antagonist shoulder muscles (Table 2). Following a single dose of levodopa/carbidopa the number of cases displaying burst discharges with a frequency of 4- 8 Hz decreased. In some patients the rhythmic discharges disappeared, as is shown in Figure 5, top records. In the other patients who displayed discharges after a dose of levodopa, an increase occurred in the discharges frequency (Fig. 5, lower records).

EMGs recorded during the performance of voluntary arm bending were found to differ considerably in healthy subjects and PD patients. In the healthy subjects, we clearly distinguished an onset of muscle phasic activation on the EMG (Fig. 6, Control). Means ± SE of average EMG amplitude of the mm. biceps brachii during their voluntary contraction was 49 ± 8 V from the right and 44 ± 2 V from the left, the maximal amplitude – 189 ± 31 V and 137 ± 30 V, respectively. In view of the low resting EMG amplitude value in healthy subjects, the coefficient of phasic activation in most cases was equal to 0.7-0.9; mean ± SE was 0.77 ± 0.04.

In contrast, in the PD patients it was often difficult to locate a site on the EMG at which the muscle phasic activation started because of increased resting tonic muscle activity and a very delayed rise in EMG amplitude after the delivery of a command to move (Fig. 6, PD). During peak voluntary flexor contraction, some patients showed a noticeable reduction of

Diagnosis of Parkinson's Disease by Electrophysiological Methods 35

Fig. 6. The phasic activation of m. biceps brachii dexter during voluntary movement in healthy control and off-medication patient with Parkinson's disease. Two sections of native EMGs in a healthy 64-year old subject (Control) and in a 53-year old patient (PD). The vertical thick lines designate the moment of experimenter's command. The horizontal lines over EMGs designate the periods, at which the amplitude measurements of maximal muscular activity during voluntary contractions (AVC) were taken. The resting EMG

The described quantitative EMG parameters added fundamentally to the clinical motor characteristics of PD patients and correlated selectively with definite UPDRS subitems. Thus, the most significant increases in the resting average and maximal EMG amplitude and decreases in the coefficient of phasic activation were observed in patients whose part III UPDRS scores exceeded 50. At the same time, the greatest involvement of the reciprocal muscles during the functional test was noted in patients with high part II UPDRS scores on the upper extremity daily activity. These patients also, had the greatest dyskinesia (disability) scores. We established the following statistically significant correlations (see Table 3). The resting muscle amplitudes from the more affected side correlated positively with the upper extremity rigidity and general motor scores. We found negative correlations between the phasic activation coefficient of m. biceps brachii from the more affected side and the upper extremity rigidity and general motor scores. The antagonist muscle involvement during the tonic strain holding a weight correlated positively with the handwriting, cutting food, dressing score and dyskinesia (disability) score. Levodopa intake did not influence essentially on the correlations between the reflex muscle involvement and

We found the present computer EMG analysis to be a sensitive tool for the objective evaluation of PD symptoms and to quantify the efficacy of levodopa therapy. One of the most useful EMG signs of extrapyramidal insufficiency appears to be the resting EMG amplitude value. In PD, the resting EMGs in the OFF state were characterized by the splashes of high muscle activity in contrast to the flat EMGs seen in age-matched healthy subjects. The average resting EMG amplitude was 2-3 times and the maximal amplitude was 5-6 times greater in PD patients than in the control group. Of interest are our data indicating the statistically significant correlation between levels of resting activity in the antagonist muscles (m. biceps and triceps brachii) in healthy subjects and the lack of such a correlation in PD patients on the most affected side. These findings appear to be an objective EMG

amplitudes (AR) were measured during 5 s prior to command presentation.

UPDRS scores.

Fig. 5. Changes in the rhythmic (4-7 Hz) burst muscle discharges in patients with Parkinson's disease after the intake of an individual single dose of levodopa/carbidopa. The spectrograms of the power of EMG envelope frequency in two patients in an off-medication state (OFF) and one hour after drug intake (ON). After the drug intake, burst muscle discharges disappeared in one patient, while their frequency somewhat increased in another patient. For other notes see Fig. 1.

EMG amplitude, while other patients had the same meanings as healthy subjects. The coefficient of phasic activation of a voluntarily contracting mm biceps brachii in PD patients was generally decreased to 0.1-0.6 and, sometimes (when amplitude values at rest exceeded those that were observed during phasic activation), even had negative values; mean ± SE was 0.42 ± 0.08. The magnitude of the phasic activation decrease showed a distinct dependence on the side which was most affected. Reduction of the coefficient of phasic activation in the OFF patient group compared to healthy individuals was statistically significant (p<0.01).

Disturbance of coordinative muscle interactions was one more typical feature of the EMG recorded in Parkinson's patients. This was manifested in increased reflex involvement of the muscles of the opposite arm (distant synergy) at tonic tension of the m. biceps brachii at one of the sides within the period of retention of a load. In this group, the mean values of the coefficients of reflex involvement for the m. biceps brachii and m. triceps brachii of the opposite side exceeded 50%. As was already mentioned, these phenomena should be considered a gross disturbance of coordinative interactions. In control group the mean values of the coefficients of reflex involvement were 20-26%.

The dose of levodopa/carbidopa in PD patients produced a decrease in resting muscle activity parallel to an increase, more often, to normal values (0.8-0.9) of the coefficient of phasic activation during voluntary contraction of flexors. With regard to the reflex activation of the agonist and antagonist muscles during weight holding, a noticeable reduction of the coefficients of reflex involvement was only observed in some of the patients who took levodopa/carbidopa treatment. In seven patients, after medication even more marked enhancement developed in the agonist or antagonist muscles, and was registered during the performance of the functional test.

Fig. 5. Changes in the rhythmic (4-7 Hz) burst muscle discharges in patients with

patient. For other notes see Fig. 1.

significant (p<0.01).

Parkinson's disease after the intake of an individual single dose of levodopa/carbidopa. The spectrograms of the power of EMG envelope frequency in two patients in an off-medication state (OFF) and one hour after drug intake (ON). After the drug intake, burst muscle

discharges disappeared in one patient, while their frequency somewhat increased in another

EMG amplitude, while other patients had the same meanings as healthy subjects. The coefficient of phasic activation of a voluntarily contracting mm biceps brachii in PD patients was generally decreased to 0.1-0.6 and, sometimes (when amplitude values at rest exceeded those that were observed during phasic activation), even had negative values; mean ± SE was 0.42 ± 0.08. The magnitude of the phasic activation decrease showed a distinct dependence on the side which was most affected. Reduction of the coefficient of phasic activation in the OFF patient group compared to healthy individuals was statistically

Disturbance of coordinative muscle interactions was one more typical feature of the EMG recorded in Parkinson's patients. This was manifested in increased reflex involvement of the muscles of the opposite arm (distant synergy) at tonic tension of the m. biceps brachii at one of the sides within the period of retention of a load. In this group, the mean values of the coefficients of reflex involvement for the m. biceps brachii and m. triceps brachii of the opposite side exceeded 50%. As was already mentioned, these phenomena should be considered a gross disturbance of coordinative interactions. In control group the mean

The dose of levodopa/carbidopa in PD patients produced a decrease in resting muscle activity parallel to an increase, more often, to normal values (0.8-0.9) of the coefficient of phasic activation during voluntary contraction of flexors. With regard to the reflex activation of the agonist and antagonist muscles during weight holding, a noticeable reduction of the coefficients of reflex involvement was only observed in some of the patients who took levodopa/carbidopa treatment. In seven patients, after medication even more marked enhancement developed in the agonist or antagonist muscles, and was registered

values of the coefficients of reflex involvement were 20-26%.

during the performance of the functional test.

Fig. 6. The phasic activation of m. biceps brachii dexter during voluntary movement in healthy control and off-medication patient with Parkinson's disease. Two sections of native EMGs in a healthy 64-year old subject (Control) and in a 53-year old patient (PD). The vertical thick lines designate the moment of experimenter's command. The horizontal lines over EMGs designate the periods, at which the amplitude measurements of maximal muscular activity during voluntary contractions (AVC) were taken. The resting EMG amplitudes (AR) were measured during 5 s prior to command presentation.

The described quantitative EMG parameters added fundamentally to the clinical motor characteristics of PD patients and correlated selectively with definite UPDRS subitems. Thus, the most significant increases in the resting average and maximal EMG amplitude and decreases in the coefficient of phasic activation were observed in patients whose part III UPDRS scores exceeded 50. At the same time, the greatest involvement of the reciprocal muscles during the functional test was noted in patients with high part II UPDRS scores on the upper extremity daily activity. These patients also, had the greatest dyskinesia (disability) scores. We established the following statistically significant correlations (see Table 3). The resting muscle amplitudes from the more affected side correlated positively with the upper extremity rigidity and general motor scores. We found negative correlations between the phasic activation coefficient of m. biceps brachii from the more affected side and the upper extremity rigidity and general motor scores. The antagonist muscle involvement during the tonic strain holding a weight correlated positively with the handwriting, cutting food, dressing score and dyskinesia (disability) score. Levodopa intake did not influence essentially on the correlations between the reflex muscle involvement and UPDRS scores.

We found the present computer EMG analysis to be a sensitive tool for the objective evaluation of PD symptoms and to quantify the efficacy of levodopa therapy. One of the most useful EMG signs of extrapyramidal insufficiency appears to be the resting EMG amplitude value. In PD, the resting EMGs in the OFF state were characterized by the splashes of high muscle activity in contrast to the flat EMGs seen in age-matched healthy subjects. The average resting EMG amplitude was 2-3 times and the maximal amplitude was 5-6 times greater in PD patients than in the control group. Of interest are our data indicating the statistically significant correlation between levels of resting activity in the antagonist muscles (m. biceps and triceps brachii) in healthy subjects and the lack of such a correlation in PD patients on the most affected side. These findings appear to be an objective EMG

Diagnosis of Parkinson's Disease by Electrophysiological Methods 37

norm, and, in addition, a decrease in the active contraction amplitudes occurred in some of the patients. As a consequence, the phasic activation coefficient of the voluntarily contracting m. biceps brachii of the patients was generally reduced to 0.1-0.6 and even had negative values, while in healthy subjects the value of the phasic activation coefficient was in most cases 0.7-0.9. Our study data suggest that phasic activation coefficients represent a sufficiently informative index that may be used to quantify phasic muscle activity in PD. Involvement of the agonist and antagonist muscles appeared to be useful for establishing coorditating muscle relationships. We demonstrated significantly (p<0.05) greater activation of the agonist and antagonist muscles during m. biceps brachii tonic strain in PD patients compared to age-matched healthy subjects. The present findings confirm the results of other investigators who consider this fact to be a consequence of increased excitation in the motor

When examining the action of an individual dose of levodopa/carbidopa in PD patients with ON-OFF phenomenon, we observed distinct positive drug effects in the following EMG parameters: average and maximal EMG amplitudes at rest; the number of cases with registered rhythmic burst muscle discharges of 4-8 Hz; value of the phasic activation coefficient during voluntary muscle contraction. However, levodopa therapy didn't appear to be effective in terms of the normalization of coordinating agonist - antagonist muscle relationships, either at rest and during holding a weight. In some of patients on levodopa/carbidopa, we even observed an enhancement of the activation of agonist and antagonist muscles during above functional test. We believe that such an increased coactivation of the agonist and antagonist muscles is an objective indicator of risk for developing levodopa-induced dyskinesia in PD patients. According to the literature data, the latter is the result of hypersensitivity of the dopamine receptors in the nigrostriatal system or of a disturbed balance between the degrees of activation of D1 and D2 dopamine

The histograms of distribution of EMG amplitude values at rest are informative characteristic of muscle activity (Meigal, 2009). The histogram sharpness and statistical EMG parameters, such as range, variance and kurtosis reflect the magnitude of bioelectrical

Fig. 7. Example of the histogram of resting EMG amplitudes distribution in healthy subject. An artifact-free EMG recordings (no less than 10 seconds in duration) from the flexors and extensors (mm. biceps and triceps brachii), registered in 33 patients with PD and 24 age-

centers, caused by dopaminergic control failure (Kryzhanovsky et al, 2002).

**2.2 Statistics of EMG distribution in patients with Parkinson's disease**

muscle signals and the level of motor unit synchronization.

receptors (Jenner, 1994).

manifestation of the disorganisation of the brain's neuronal excitatory-inhibitory processes and the loss of functional balance between the structures which regulate muscle tone, all of which are due to a neostriatal dopamine deficit (DeLong, 1990).

Table 3. Significant correlations of EMG indices with the UPDRS scores studied in 20 PD patients in which the clinical "ON-OFF" phenomenon was verified. Data on the EMG indices and the upper extremity rigidity score for a more impaired side are presented. \*- p<0.05; \*\* p<0.01; "ns "- not statistically significant (p0.05).

A distinguishing feature of the bioelectrical muscle activity at rest in PD patients was the presence of burst muscle discharges with a rhythm of 4-8 Hz. It should be noted that no significant correlation was found between resting EMG amplitude value and the occurrence of burst muscle discharges. This fact is consistent with the viewpoint that muscle rigidity and tremor at PD do not constitute symptoms which influence one another, and that different pathophysiological mechanisms underlie their origin (Furukawa et al., 1991; Otsuka et al., 1996).

The brain systems, regulating the tonic and phasic muscle activities, were shown to be antagonistically interrelated: the activation of the phasic processes is accompanied by an inhibition of the tonic impulses and, vice versa, the enhancement of tonic impulsation hampers the phasic activity (Houk, 1979). In PD, due to an increased tonic muscle activity at rest, increment in EMG amplitude during phasic activation was reduced relative to the

manifestation of the disorganisation of the brain's neuronal excitatory-inhibitory processes and the loss of functional balance between the structures which regulate muscle tone, all of

> Motor score (points 18-31)

Handwriting, cutting food, dressing score (points 8-10)

0.51 \* 0.50 \* ns ns

ns 0.67 \*\* ns ns

ns -0.64 \*\* ns ns

ns ns 0.55 \* 0.52\*

ns ns 0.52 \* ns

ns ns 0.57 \*\* 0.48\*

ns ns 0.53 \* 0.51\*

Table 3. Significant correlations of EMG indices with the UPDRS scores studied in 20 PD patients in which the clinical "ON-OFF" phenomenon was verified. Data on the EMG indices and the upper extremity rigidity score for a more impaired side are presented. \*- p<0.05; \*\* -

A distinguishing feature of the bioelectrical muscle activity at rest in PD patients was the presence of burst muscle discharges with a rhythm of 4-8 Hz. It should be noted that no significant correlation was found between resting EMG amplitude value and the occurrence of burst muscle discharges. This fact is consistent with the viewpoint that muscle rigidity and tremor at PD do not constitute symptoms which influence one another, and that different pathophysiological mechanisms underlie their origin (Furukawa et al., 1991;

The brain systems, regulating the tonic and phasic muscle activities, were shown to be antagonistically interrelated: the activation of the phasic processes is accompanied by an inhibition of the tonic impulses and, vice versa, the enhancement of tonic impulsation hampers the phasic activity (Houk, 1979). In PD, due to an increased tonic muscle activity at rest, increment in EMG amplitude during phasic activation was reduced relative to the

Dyskinesia (disability) score (point 33)

which are due to a neostriatal dopamine deficit (DeLong, 1990).

Upper extremity rigidity score (point 22)

EMG indices

of m. biceps at rest

Phasic activation coefficient of m .biceps during voluntary contraction

involvement under tonic strain of m. biceps of the opposite arm

Otsuka et al., 1996).

Average amplitude

M. biceps

M. triceps involvement under tonic strain of m. biceps of the opposite arm

norm, and, in addition, a decrease in the active contraction amplitudes occurred in some of the patients. As a consequence, the phasic activation coefficient of the voluntarily contracting m. biceps brachii of the patients was generally reduced to 0.1-0.6 and even had negative values, while in healthy subjects the value of the phasic activation coefficient was in most cases 0.7-0.9. Our study data suggest that phasic activation coefficients represent a sufficiently informative index that may be used to quantify phasic muscle activity in PD.

Involvement of the agonist and antagonist muscles appeared to be useful for establishing coorditating muscle relationships. We demonstrated significantly (p<0.05) greater activation of the agonist and antagonist muscles during m. biceps brachii tonic strain in PD patients compared to age-matched healthy subjects. The present findings confirm the results of other investigators who consider this fact to be a consequence of increased excitation in the motor centers, caused by dopaminergic control failure (Kryzhanovsky et al, 2002).

When examining the action of an individual dose of levodopa/carbidopa in PD patients with ON-OFF phenomenon, we observed distinct positive drug effects in the following EMG parameters: average and maximal EMG amplitudes at rest; the number of cases with registered rhythmic burst muscle discharges of 4-8 Hz; value of the phasic activation coefficient during voluntary muscle contraction. However, levodopa therapy didn't appear to be effective in terms of the normalization of coordinating agonist - antagonist muscle relationships, either at rest and during holding a weight. In some of patients on levodopa/carbidopa, we even observed an enhancement of the activation of agonist and antagonist muscles during above functional test. We believe that such an increased coactivation of the agonist and antagonist muscles is an objective indicator of risk for developing levodopa-induced dyskinesia in PD patients. According to the literature data, the latter is the result of hypersensitivity of the dopamine receptors in the nigrostriatal system or of a disturbed balance between the degrees of activation of D1 and D2 dopamine receptors (Jenner, 1994).

#### **2.2 Statistics of EMG distribution in patients with Parkinson's disease**

The histograms of distribution of EMG amplitude values at rest are informative characteristic of muscle activity (Meigal, 2009). The histogram sharpness and statistical EMG parameters, such as range, variance and kurtosis reflect the magnitude of bioelectrical muscle signals and the level of motor unit synchronization.

Fig. 7. Example of the histogram of resting EMG amplitudes distribution in healthy subject.

An artifact-free EMG recordings (no less than 10 seconds in duration) from the flexors and extensors (mm. biceps and triceps brachii), registered in 33 patients with PD and 24 age-

Diagnosis of Parkinson's Disease by Electrophysiological Methods 39

Patients with the akinetic-rigid-trembling form of PD had the highest values of the EMG statistical parameters. The histograms of EMG amplitude distribution had a sharp peak (fig. 8, B). In some patients of this PD group range reached 382 V, variance – 951 and kurtosis – 13 (table 4). Correlation analyses revealed statistically significant connection of kurtosis with scores of the point 20 of UPDRS, estimating intensity of tremor of the hand, on which EMG was registered. A coefficient of nonparametric Spearman rank-order correlation between these indices was 0.46 (p<0.01). This fact is in accordance with the point of view (Meigal, 2009) that kurtosis well reflects synchronization of motor units responsible for the origin of

Fractal analysis is a new method for biomedical signal processing. Nonlinear analysis techniques are necessary to understand the complexity of the EMG. Study of fractal dynamics of EMG data is based on detrended fluctuation analysis and calculation of Hurst exponent. The Hurst exponent is used as a measure of the long term memory of time series,

Fractal dynamics of EMG signals was studied in 33 patients with akinetic-rigid-trembling form of PD (mean ± SE age 62.1 2.6, range 48-77 years), 30 age-matched healthy subjects ( mean ± SE age 65.4 ± 1.9, range 57-78 years) and 20 persons of middle age ( mean ± SE age 48.3 ± 1.49, range 45-58 years). EMGs were recorded from m. biceps brachii at the side, where morbid affection was more expressed, at rest no less than 10 seconds in duration. The rescaled range was calculated for time series. The first step was calculation of the mean. Then mean-adjusted series were created and the cumulative deviate series were calculated

> 1 () ( ) *k i*

Where *z* is the mean and *z(i)* is the value from time series. Then the row of values *y (k), k = 1,…N* was divided into the segments of length *n,* and within the limits of each segment the equalization of stright, approximating the sequence of *y(k),* was defined by least squares method. It is considered that approximation of *yn (k )* is the local trend. Further a standard

Dependence *lg F(lg n)* was further built, the angle of slope of approximating line was

We identified three different patterns of surface EMG signals according to fractal dimension (Fig 9, 10): with one, two and three scaling regions, every of which is characteristic by own local exponent. In healthy subjects, the fractal dimension with two exponents was most frequently observed, in 60% among persons of middle age and in 50% among elderly individuals. One exponent was observed in 20% in both groups of healthy subjects and three exponents – in 20% and 30% in middle age and elderly, respectively. In patients with akineticrigid-trembling form of PD the fractal dimension of surface EMG signals with three exponents

determined and the value of Hurst index was estimated (Stanley et al., 1999).

was most characteristic (64%). One exponent did not occur in PD patients (Fig. 11).

(2)

<sup>1</sup> <sup>2</sup> ( ) [( ( ) ( )] *Fn yk y k <sup>n</sup> <sup>N</sup>* (3)

*i y k zz*

**2.3 Fractal dynamics of EMGs in patients with Parkinson's disease**

i.e., the autocorrelation of the time series. (Talebinejad et al., 2010).

burst muscle discharges.

from the formula:

deviation was created from the formula:

matched healthy subjects at rest, were analyzed by the computer programs "Origin 8" and "Statistic 8". EMG in healthy subjects was characterized by low amplitude, flat symmetric histogram (fig. 7) and small values of range, variance and kurtosis (table 4). Range did not exceed 20 V, variance – 7 and kurtosis – 0.4. In patients with the akinetic-rigid form of the disease, the amplitude of EMG signals was considerably increased because of impossibility of entire muscle relaxation. The mean values of EMG statistical parameters, estimated for this PD group, were significantly (p<0.001) augmented as compared to control. In some patients range amounted to 66 V, variance – 56 and kurtosis – 1.4 (table 4).

Fig. 8. Examples of the histograms of resting EMG amplitudes distribution in a patient with akinetic-rigid form of Parkinson's disease (A) and a patient with akinetic-rigid- trembling form of this disease (B).

Table 4. Statistical characteristics of EMG in patients with Parkinson's disease and agematched healthy subjects. EMG characteristics in patients were taken at the side where morbid affection was more expressed; in healthy persons such characteristics were taken at the side where higher values were observed. \*\* p <0.01, \*\*\* p <0.001 compared to control group. n is number of subjects in each group. In brackets the range of indices in different tested persons is presented.

matched healthy subjects at rest, were analyzed by the computer programs "Origin 8" and "Statistic 8". EMG in healthy subjects was characterized by low amplitude, flat symmetric histogram (fig. 7) and small values of range, variance and kurtosis (table 4). Range did not exceed 20 V, variance – 7 and kurtosis – 0.4. In patients with the akinetic-rigid form of the disease, the amplitude of EMG signals was considerably increased because of impossibility of entire muscle relaxation. The mean values of EMG statistical parameters, estimated for this PD group, were significantly (p<0.001) augmented as compared to control. In some

Fig. 8. Examples of the histograms of resting EMG amplitudes distribution in a patient with akinetic-rigid form of Parkinson's disease (A) and a patient with akinetic-rigid- trembling

> 112.75 ± 16.80 \*\*\* (24.48 – 381.62)

36.81 ± 3.96 \*\*\* (21.16 – 66.18)

11.18 ± 0.71 (7.08 – 16.46)

Table 4. Statistical characteristics of EMG in patients with Parkinson's disease and agematched healthy subjects. EMG characteristics in patients were taken at the side where morbid affection was more expressed; in healthy persons such characteristics were taken at the side where higher values were observed. \*\* p <0.01, \*\*\* p <0.001 compared to control group. n is number of subjects in each group. In brackets the range of indices in different

Statistical parameters Range (V) Variance Kurtosis

> 147.20 ± 44.38 \*\* (6.91 – 950.63)

20.26 ± 4.26 \*\*\* (7.89 – 56.16)

2.30 ± 0.31 (0.70 – 5.14) 4.32 ± 0.51 \*\*\* (1.04 – 12.98)

0.58 ± 0.14 \*\*\* (0.07 – 1.40)

patients range amounted to 66 V, variance – 56 and kurtosis – 1.4 (table 4).

form of this disease (B).

Groups of the tested

Patients with akineticrigid-trembling form of the

form of the disease

Control group of agematched healthy subjects

tested persons is presented.

Patients with akinetic-rigid

persons

disease n=20

n=13

n=24

Patients with the akinetic-rigid-trembling form of PD had the highest values of the EMG statistical parameters. The histograms of EMG amplitude distribution had a sharp peak (fig. 8, B). In some patients of this PD group range reached 382 V, variance – 951 and kurtosis – 13 (table 4). Correlation analyses revealed statistically significant connection of kurtosis with scores of the point 20 of UPDRS, estimating intensity of tremor of the hand, on which EMG was registered. A coefficient of nonparametric Spearman rank-order correlation between these indices was 0.46 (p<0.01). This fact is in accordance with the point of view (Meigal, 2009) that kurtosis well reflects synchronization of motor units responsible for the origin of burst muscle discharges.

#### **2.3 Fractal dynamics of EMGs in patients with Parkinson's disease**

Fractal analysis is a new method for biomedical signal processing. Nonlinear analysis techniques are necessary to understand the complexity of the EMG. Study of fractal dynamics of EMG data is based on detrended fluctuation analysis and calculation of Hurst exponent. The Hurst exponent is used as a measure of the long term memory of time series, i.e., the autocorrelation of the time series. (Talebinejad et al., 2010).

Fractal dynamics of EMG signals was studied in 33 patients with akinetic-rigid-trembling form of PD (mean ± SE age 62.1 2.6, range 48-77 years), 30 age-matched healthy subjects ( mean ± SE age 65.4 ± 1.9, range 57-78 years) and 20 persons of middle age ( mean ± SE age 48.3 ± 1.49, range 45-58 years). EMGs were recorded from m. biceps brachii at the side, where morbid affection was more expressed, at rest no less than 10 seconds in duration.

The rescaled range was calculated for time series. The first step was calculation of the mean. Then mean-adjusted series were created and the cumulative deviate series were calculated from the formula:

$$y(k) = \sum\_{i=1}^{k} (z\_i - \overline{z}) \tag{2}$$

Where *z* is the mean and *z(i)* is the value from time series. Then the row of values *y (k), k = 1,…N* was divided into the segments of length *n,* and within the limits of each segment the equalization of stright, approximating the sequence of *y(k),* was defined by least squares method. It is considered that approximation of *yn (k )* is the local trend. Further a standard deviation was created from the formula:

$$F(n) = \sqrt{\frac{1}{N} [(y(k) - y\_n(k))^2]} \tag{3}$$

Dependence *lg F(lg n)* was further built, the angle of slope of approximating line was determined and the value of Hurst index was estimated (Stanley et al., 1999).

We identified three different patterns of surface EMG signals according to fractal dimension (Fig 9, 10): with one, two and three scaling regions, every of which is characteristic by own local exponent. In healthy subjects, the fractal dimension with two exponents was most frequently observed, in 60% among persons of middle age and in 50% among elderly individuals. One exponent was observed in 20% in both groups of healthy subjects and three exponents – in 20% and 30% in middle age and elderly, respectively. In patients with akineticrigid-trembling form of PD the fractal dimension of surface EMG signals with three exponents was most characteristic (64%). One exponent did not occur in PD patients (Fig. 11).

Diagnosis of Parkinson's Disease by Electrophysiological Methods 41

significantly (p<0.001) differed from same value in elderly subjects (2.7 ± 0.5). Negative

Fig. 11. Comparison of the incidence of different patterns of surface EMG signals fractal dimension (with one, two or three Hurst exponents) in persons of middle age (control 1),

Overall, the present investigation has demonstrated the following distinctive features of surface EMG signals fractal dimension in patients with akinetic-rigid-trembling form of PD: 1) correlation behavior of the resting EMG time series in patients was more complex compared to healthy subjects and often suggested three scaling regions; 2) the value of Hurst exponent was significantly lower in patients, its value may descend to 0.1 - 0.2 that indicates a time series with negative autocorrelation (e.g. a decrease between values will probably be followed by an increase); 3) considerable degradation of short and longer range correlation properties, that, perhaps, is associated with the loss of integrated physiological

**2.4 EMG characteristics of clinically healthy kinsmen of the patients with Parkinson's**

According to modern concepts, the genetic factor plays a considerable role in the development of Parkinson's disease. Modifications in several genetic loci responsible for the development of this disease have been identified. The considerable role of the genetic factor for the propensity to Parkinson's disease has been confirmed by the data of epidemiological studies. The frequency of development of this disease in kinsmen of Parkinsonian patients is two to seven times higher than that in persons of the control groups (Elbaz et al., 1999). Symptoms of functional insufficiency of the extrapyramidal system can be identified very early, namely several decades prior to possible onset of the development of the clinical form of Parkinson's disease (Berg et al., 2002). Prevention or deceleration of the development of this disease can be provided by the detection of the early, presymptomatic stage of the neurodegenerative process and identification of informative "biomarkers" of PD (Illarioshkin, 2008). We studied surface EMG in clinically healthy kinsmen of the patients

elderly subjects (control 2) and patients with Parkinson's disease (PD).

responsiveness at this disease (Goldberger et al., 2002).

**disease**

correlation between H1 and H3 (r = -0.67, p<0.01) was revealed in PD patients.

Fig. 9. Patterns of fractal dimension of the surface EMG signals with one and two exponents. Thick line is general exponent, thin lines are local exponents. H is general Hurst index; H1, H2, H3 are values of local Hurst indices.

Fig. 10. Pattern of fractal dimension of the surface EMG signals with three exponents. Thick line is general exponent, thin lines are local exponents. H is general Hurst index; H1, H2, H3 are values of local Hurst indices.

Another difference concerned the value of general Hurst index (H). In persons of middle age mean value of H was 0.47 ± 0.02 (range 0.32 – 0.71) and in elderly – 0.44 ± 0.02 (range 0.33 – 0.57). In PD patients mean value of H was significantly (p<0.01) lower as compared to elderly subjects – 0.31 ± 0.03 (range 0.09 – 0.49). In PD patients, the value of Hurst index of the third scaling region (H3) in patterns with three exponents also significantly differed from H3 in healthy subjects. H3 was 0.30 ± 0.06 in middle-aged persons, 0.39 ± 0.05 in elderly and 0.14 ± 0.05 in patients with PD (p<0.05). It is of interest that the tendency to negative correlation between H and motor scores of part III UPDRS was observed in patients with PD (r = -0.35, p =0.05).

Our data showed essential alterations in short and more long-range EMG correlation properties in patients with akinetic-rigid-trembling form of PD. The mean value of H1/H3 in patterns with three exponents in the group of PD patients came up to 27.2 ± 9.5 that

Fig. 9. Patterns of fractal dimension of the surface EMG signals with one and two exponents. Thick line is general exponent, thin lines are local exponents. H is general Hurst index; H1,

Fig. 10. Pattern of fractal dimension of the surface EMG signals with three exponents. Thick line is general exponent, thin lines are local exponents. H is general Hurst index; H1, H2, H3

Another difference concerned the value of general Hurst index (H). In persons of middle age mean value of H was 0.47 ± 0.02 (range 0.32 – 0.71) and in elderly – 0.44 ± 0.02 (range 0.33 – 0.57). In PD patients mean value of H was significantly (p<0.01) lower as compared to elderly subjects – 0.31 ± 0.03 (range 0.09 – 0.49). In PD patients, the value of Hurst index of the third scaling region (H3) in patterns with three exponents also significantly differed from H3 in healthy subjects. H3 was 0.30 ± 0.06 in middle-aged persons, 0.39 ± 0.05 in elderly and 0.14 ± 0.05 in patients with PD (p<0.05). It is of interest that the tendency to negative correlation between H and motor scores of part III UPDRS was observed in

Our data showed essential alterations in short and more long-range EMG correlation properties in patients with akinetic-rigid-trembling form of PD. The mean value of H1/H3 in patterns with three exponents in the group of PD patients came up to 27.2 ± 9.5 that

H2, H3 are values of local Hurst indices.

are values of local Hurst indices.

patients with PD (r = -0.35, p =0.05).

significantly (p<0.001) differed from same value in elderly subjects (2.7 ± 0.5). Negative correlation between H1 and H3 (r = -0.67, p<0.01) was revealed in PD patients.

Fig. 11. Comparison of the incidence of different patterns of surface EMG signals fractal dimension (with one, two or three Hurst exponents) in persons of middle age (control 1), elderly subjects (control 2) and patients with Parkinson's disease (PD).

Overall, the present investigation has demonstrated the following distinctive features of surface EMG signals fractal dimension in patients with akinetic-rigid-trembling form of PD: 1) correlation behavior of the resting EMG time series in patients was more complex compared to healthy subjects and often suggested three scaling regions; 2) the value of Hurst exponent was significantly lower in patients, its value may descend to 0.1 - 0.2 that indicates a time series with negative autocorrelation (e.g. a decrease between values will probably be followed by an increase); 3) considerable degradation of short and longer range correlation properties, that, perhaps, is associated with the loss of integrated physiological responsiveness at this disease (Goldberger et al., 2002).

#### **2.4 EMG characteristics of clinically healthy kinsmen of the patients with Parkinson's disease**

According to modern concepts, the genetic factor plays a considerable role in the development of Parkinson's disease. Modifications in several genetic loci responsible for the development of this disease have been identified. The considerable role of the genetic factor for the propensity to Parkinson's disease has been confirmed by the data of epidemiological studies. The frequency of development of this disease in kinsmen of Parkinsonian patients is two to seven times higher than that in persons of the control groups (Elbaz et al., 1999). Symptoms of functional insufficiency of the extrapyramidal system can be identified very early, namely several decades prior to possible onset of the development of the clinical form of Parkinson's disease (Berg et al., 2002). Prevention or deceleration of the development of this disease can be provided by the detection of the early, presymptomatic stage of the neurodegenerative process and identification of informative "biomarkers" of PD (Illarioshkin, 2008). We studied surface EMG in clinically healthy kinsmen of the patients

Diagnosis of Parkinson's Disease by Electrophysiological Methods 43

Fig. 12. Types of burst-like muscle discharges with frequency 6, 8 and 10 Hz recorded in

Statistical parameters Number of tested persons

Variance [8.08 – 13.55] 5 (14 %)

Kurtosis [0.67; 0.70] 2 (5 %)

Total 16 (43 %)

Table 5. Incidence of resting EMG statistical parameters, going out outside a norm, in kinsmen of patients with Parkinson's disease. In square brackets the range of indices in

The data obtained in our work agree with findings of other authors who emphasized that data obtained using EMG techniques are of a high informative value in the diagnostics of subclinical manifestations of weakening of the supraspinal control (Robichaud et al., 2009), and that the genetic factor responsible for the propensity for development of the extrapyramidal insufficiency is rather important (Elbaz et al., 1999; Illarioshkin, 2002). A single common pathogenetic factor, namely conformational modifications of some cellular proteins at a post-translational stage of their synthesis, underlies most neurodegenerative diseases, including PD. Due to the existence of powerful compensatory and detoxication

9 (24 %)

three kinsmen of patients suffering from Parkinson's disease.

Range [22.46 – 113.61 V] Variance [8.23 – 112.32] Kurtosis [0.43 – 16.30]

Range [24.22 – 28.33 V]

different persons is presented.

suffering from PD in order to detect latent symptoms of extrapyramidal insufficiency that can be considered genetic determinants of the risk of development of the above disease. The task of our study included estimation of the frequency of occurrence of muscle activity disorders in kinsmen of the patients, characterization of correlations between the appearance symptoms of extrapyramidal insufficiency and age of the tested persons, and formulation of recommendations for individuals belonging, from the aspect of risk of development of PD, to a risk group.

We examined two groups of persons. The first group consisted of 37 clinically healthy kinsmen/kinswomen of patients suffering from PD (children, brothers, and sisters; 22 women and 15 men aged 30 to 56; mean age 45.6 ± 1.5 years). The second group (control) included 30 healthy young and middle-aged persons (19 women and 11 men; age nearly corresponding to that of persons of the first group , i.e., from 34 to 58 years, mean age 46.9 ± 2.2 years. All examined persons gave informed consent to be involved in the study. We recorded surface EMG at rest using superficial bipolar electrodes fixed on the flexor and extensor of the elbow joint (m. biceps brachii and m. triceps brachii, respectively); an electroneuromyograph NeuroMPF (Russia) was used. The detailed description of method is presented in section 2.1.1.

In 9 (24%) clinically healthy kinsmen of PD patients symptoms of functional insufficiency of the extrapyramidal system were evident. They demonstrated the mean amplitude value of 5.4-12.4 V, maximal amplitude value of 25-93 V, and the mean power of EMG oscillations reached 0.85- 1.8 mV/sec. In control group the mean amplitude value varied from 3.4 to 5.0 V, maximal amplitude varied from 5.6 to 20.6 V and the mean power of EMG oscillations did not exceed 0.02-0.71 mV/sec. Higher values of the intensity of electrical muscle activity in kinsmen of PD patients positively correlated with their age; it should be noted that, in this respect, age older than 45 years can be considered to be critical. The number of elder (older than 45 years) subjects with values of the mean power of EMG oscillations higher than the mean value of this parameter in persons of control group exceeded significantly the number of elder persons with low values of the mean power of EMG oscillations (p < 0.05, χ<sup>2</sup> criterion). The correlation coefficient between the age of the tested persons and the value of mean power of EMG oscillations was 0.40 (p < 0.05).

In 6 (16%) kinsmen of PD patients short burst-like discharges consisting of two to three oscillations generated with a frequency of 5-10 Hz were observed within the resting EMG (Fig. 12). As a rule, the amplitude of these potentials did not exceed 52 V.

For more detailed investigation we used statistics of EMG distribution, namely such parameters as range, variance and kurtosis. Range and variance reflect the extent of bioelectrical muscle signals. Kurtosis characterizes motor unit synchronization. We supposed that statistical methods might appear effective for exposure of pathological signs of muscle activity. In control group of healthy middle-aged persons the extreme value of resting EMG amplitude range was 20 V, variance – 7 and kurtosis – 0.4. The parameters of range, variance and kurtosis were considered going out outside a norm, if they exceeded the extreme values of these indices in the control group. We found 16 (43 %) kinsmen of patients with PD, who had high statistical parameters of EMG signals. In 14 kinsmen (38 %) range and variance were augmented compared to the extreme values of these indices in the control group. In 11 kinsmen (29 %) kurtosis had higher values than normal, presumably, reflecting enhanced synchronization in activity of motor units (Table 5).

suffering from PD in order to detect latent symptoms of extrapyramidal insufficiency that can be considered genetic determinants of the risk of development of the above disease. The task of our study included estimation of the frequency of occurrence of muscle activity disorders in kinsmen of the patients, characterization of correlations between the appearance symptoms of extrapyramidal insufficiency and age of the tested persons, and formulation of recommendations for individuals belonging, from the aspect of risk of

We examined two groups of persons. The first group consisted of 37 clinically healthy kinsmen/kinswomen of patients suffering from PD (children, brothers, and sisters; 22 women and 15 men aged 30 to 56; mean age 45.6 ± 1.5 years). The second group (control) included 30 healthy young and middle-aged persons (19 women and 11 men; age nearly corresponding to that of persons of the first group , i.e., from 34 to 58 years, mean age 46.9 ± 2.2 years. All examined persons gave informed consent to be involved in the study. We recorded surface EMG at rest using superficial bipolar electrodes fixed on the flexor and extensor of the elbow joint (m. biceps brachii and m. triceps brachii, respectively); an electroneuromyograph NeuroMPF (Russia) was used. The detailed description of method is

In 9 (24%) clinically healthy kinsmen of PD patients symptoms of functional insufficiency of the extrapyramidal system were evident. They demonstrated the mean amplitude value of 5.4-12.4 V, maximal amplitude value of 25-93 V, and the mean power of EMG oscillations reached 0.85- 1.8 mV/sec. In control group the mean amplitude value varied from 3.4 to 5.0 V, maximal amplitude varied from 5.6 to 20.6 V and the mean power of EMG oscillations did not exceed 0.02-0.71 mV/sec. Higher values of the intensity of electrical muscle activity in kinsmen of PD patients positively correlated with their age; it should be noted that, in this respect, age older than 45 years can be considered to be critical. The number of elder (older than 45 years) subjects with values of the mean power of EMG oscillations higher than the mean value of this parameter in persons of control group exceeded significantly the number of elder persons with low values of the mean power of EMG oscillations (p < 0.05, χ<sup>2</sup> criterion). The correlation coefficient between the age of the tested persons and the value of

In 6 (16%) kinsmen of PD patients short burst-like discharges consisting of two to three oscillations generated with a frequency of 5-10 Hz were observed within the resting EMG