Effects of deep brain stimulation in the subthalamic nucleus or globus pallidus internus on step initiation in Parkinson disease: laboratory investigation. Low-frequency Versus High-frequency Subthalamic Nucleus Deep Brain Stimulation on Postural Control and Gait in Parkinson's Disease: A Quantitative Study Deep brain stimulation of the subthalamic nucleus in Parkinson's disease. Improved asymmetry of gait in Parkinson's disease with DBS: gait and postural instability in Parkinson's disease treated with bilateral deep brain stimulation in the subthalamic nucleus. Effects of bilateral subthalamic stimulation on gait kinematics and kinetics in Parkinson’s disease Quantitative assessments of the effect of bilateral subthalamic stimulation on multiple aspects of sensorimotor function for patients with Parkinson's disease. Effects of bilateral pallidal or subthalamic stimulation on gait in advanced Parkinson's disease. Is gait speed a valid measure to predict community ambulation in patients with Parkinson's disease? Bilateral stimulation of the caudal zona incerta nucleus for tremor control Quantitative Normative Gait Data in a Large Cohort of Ambulatory Persons with Parkinson’s Disease Effect of bilateral subthalamic nucleus stimulation on gait in Parkinson's disease. Measuring gait and gait-related activities in Parkinson's patients own home environment: a reliability, responsiveness and feasibility study. Effect of L-dopa and Subthalamic Nucleus stimulation on arm and leg swing during gait in Parkinson's Disease Gait analysis in patients with advanced Parkinson disease: different or additive effects on gait induced by levodopa and chronic STN stimulation Unilateral and Bilateral Subthalamic Nucleus Stimulation in Parkinson's Disease: Effects on EMG Signals of Lower Limb Muscles During Walking Effects of subthalamic nucleus stimulation and levodopa treatment on gait abnormalities in Parkinson disease. A closer look at unilateral versus bilateral deep brain stimulation: results of the National Institutes of Health COMPARE cohort. Identifying clinical measures that most accurately reflect the progression of disability in Parkinson disease. Comparative effects of unilateral and bilateral subthalamic nucleus deep brain stimulation Physical performance measures in the clinical setting. Effect of bilateral subthalamic nucleus stimulation on parkinsonian gait Modulation of gait coordination by subthalamic stimulation improves freezing of gait. Unilateral stimulation of the subthalamic nucleus in Parkinson disease: a double-blind 12-month evaluation study. Bilateral Effects of Unilateral Subthalamic Nucleus Deep Brain Stimulation in Advanced Parkinson’s Disease Deep brain stimulation effects on gait variability in Parkinson's disease.
OBJECT Difficulty with step initiation , called " start hesitation , " is related to gait bradykinesia and is an early hallmark of gait freezing in Parkinson disease ( PD ) . Authors of this study investigated the effects of deep brain stimulation ( DBS ) and levodopa on step initiation before and 6 months after DBS surgery in 29 patients with PD who were r and omized to either the bilateral subthalamic nucleus ( STN ) or globus pallidus internus ( GPi ) as the DBS site . METHODS The authors measured the amplitude and duration of anticipatory postural adjustments ( APAs ) , the feed-forward postural preparation that precedes the onset of voluntary step initiation , based on center-of-pressure displacements on a force plate . They also measured the length and velocity of the first step using a motion analysis system to study kinematics . Some of the patients ( 22 ) were from a large , multicenter , double-blind clinical trial , and all patients in the study ( 29 , PD-DBS group ) were r and omized to  DBS in either the bilateral STN ( 15 patients ) or bilateral GPi ( 14 patients ) . Differences in step initiation were investigated in 2 conditions before surgery ( off/on levodopa ) and in 4 conditions after surgery ( off/on levodopa combined with off/on DBS ) . Twenty-eight elderly healthy control volunteers ( CTRL group ) were also tested , and 9 control volunteers with PD who met the criteria for DBS ( PD-C group ) were tested at baseline and 6 months later . RESULTS Patients in the PD-DBS group had smaller amplitudes and longer duration s of APAs compared with those in the 28 healthy control volunteers in all conditions . Before surgery , APAs improved with levodopa . After surgery , the APAs were significantly worse than in the best-treatment state before surgery ( DOPA condition ) , and responsiveness to levodopa decreased . No differences in APAs were detected between the STN and GPi groups . A comparison with PD control volunteers who did not undergo DBS surgery confirmed that a deterioration in step preparation was not related to disease progression . Step length and velocity were smaller in the PD-DBS group than in controls in all conditions . Before surgery , levodopa improved the length and velocity of the first step . Both step length and velocity were unchanged in the best-treatment state before surgery ( DOPA condition ) as compared with after surgery ( DBS+DOPA ) , with only step velocity in the STN group getting worse after surgery . CONCLUSIONS Six months of DBS in the STN or GPi impaired anticipatory postural preparation for step initiation , the opposite effect as with levodopa . Deep brain stimulation disrupted postural preparation more than step execution , suggesting independent motor pathways for preparation and execution of gait . Although turning the stimulators on after surgery combined with levodopa benefited the postural preparation to step , a comparison of pre- and postsurgery conditions suggests that either the surgery itself or 6 months of continuous stimulation may lead to an alteration of circuits or plastic changes that impair step initiation BACKGROUND High frequency stimulation ( HFS ) of the subthalamic nucleus ( STN-DBS ) has been shown to have little impact on postural control and gait improvements in Parkinson 's disease ( PD ) . There is a lack of consensus and quantitative evidence to suggest that stimulating STN at a lower frequency ( LFS ) as compared to HFS will be superior in improving symptoms . OBJECTIVE /HYPOTHESIS To determine if postural control and gait characteristics of persons with PD improve at an LFS ( 60 Hz ) compared to HFS ( > 100 Hz ) . We hypothesized that persons with PD would perform better on postural control and gait measures at LFS . METHODS Nineteen participants with bilateral STN-DBS underwent UPDRS , static and dynamic postural control using gait initiation , and gait evaluations in three stimulation conditions ( baseline voltage stable across conditions : OFF , LFS of 60 Hz , and HFS of > 100 Hz ) . Additionally 10/19 participants were also stimulated at 30 Hz and 60 Hz and at higher voltages . A one-way ANOVA was performed to compare the conditions . RESULTS Total UPDRS-III score , step length and velocity during gait initiation , and gait speed significantly improved during 60 Hz and > 100 Hz conditions when compared to the OFF condition ( P < 0.05 ) . There were no significant differences between 60 Hz and > 100 Hz conditions . Using LFS at higher voltage showed no improvement over > 100 Hz condition . CONCLUSIONS The positive effects of both LFS and HFS on postural control and gait were similar and clinical changes were relatively small . LFS may not help improve postural control , and gait particularly for persons with PD who do not develop gait-related disorders after HFS OBJECTIVE To evaluate the effects of bilateral deep brain stimulation in the subthalamic nucleus for symptomatic relief of advanced idiopathic Parkinson 's disease .  DESIGN Prospect i ve cohort study . SETTING Patients were assessed and received medical treatment at the Kingston Centre , Southern Health , Melbourne . Surgery took place at Melbourne Neuroscience Centre , The Royal Melbourne Hospital . Both are tertiary public institutions . SUBJECTS 14 patients with Parkinson 's disease with intact cognition and difficult to manage motor symptoms who were referred to Kingston Centre between 1996 and 2000 and were eligible for surgical intervention . INTERVENTIONS All patients were assessed both after 12 hours ' withdrawal from and while taking their levodopa medication on two occasions before surgery . Further assessment s were carried out one , three , six and 12 months after surgery . MAIN OUTCOME MEASURES The Unified Parkinson 's Disease Rating Scale motor exam and gait parameters , such as stride length and velocity , were compared at six months after surgery with neither stimulation nor medication , with stimulation only , with medication only , and with stimulation and medication . RESULTS Stimulators were explanted in one patient after intracranial haemorrhage and relocated to the thalamus in a second . Extraneous factors prevented two patients from attending at six-month follow-up . Motor performance improved significantly with stimulation alone in the 10 remaining patients . Further significant gains were seen with stimulation and medication combined , with an apparent reduction in side-effects such as dyskinesia . CONCLUSIONS Bilateral deep brain stimulation of the subthalamic nucleus significantly improves motor performance in advanced Parkinson 's disease , despite a rather high complication rate Postural instability is a sign of progression of Parkinson 's disease ( PD ) and often resistant to levodopa treatment . To explore the effect of bilateral deep brain stimulation ( DBS ) of the subthalamic nucleus ( STN ) on postural stability and gait , full body gait analyses were performed without medication , OFF and ON DBS in eight PD patients and 12 healthy age-matched controls . DBS setting was changed at least 3 hours before gait analysis . To describe asymmetry most and least affected sides ( MAS and LAS ) were rated with the Unified Parkinson 's Disease Rating Scale , motor part and quantitative gait analysis with the Vicon 612 gait analysis system . Stride length and gait velocity but not cadence improved ON DBS . The distances between the heel markers and center of mass ( COM ) were asymmetric and reduced OFF DBS . STN DBS  increased the distances significantly and reduced asymmetry . The improvement in heel to COM distance was larger on the MAS compared with the LAS . OFF DBS knee momentum asymmetry was inversed so that LAS was more impaired than MAS . ON DBS asymmetry improved . PD patients OFF  DBS place the heel too close to COM . The most affected body side has the most impaired swing and the result is a smaller knee moment on the opposite and least affected body side and an asymmetric gait pattern with disturbed balance OFF STN DBS . The asymmetry OFF DBS improved ON DBS . We suggest that DBS facilitates symmetric gait and thereby improves balance during gait Abstract .Subthalamic nucleus ( STN ) stimulation , a recent surgical approach to Parkinson ’s disease ( PD ) , has been shown to be effective in relieving motor symptoms . The present study carried out a full body gait analysis , during overground walking , on ten PD patients with bilaterally implanted STN stimulation devices .  Walking performance was analyzed on the same day , in four conditions ( Stim Off – Med Off , Stim On – Med Off , Stim Off – Med On , Stim On – Med On ) . The results showed that , on average , STN stimulation alone ( S+M− ) and l -dopa alone ( S-M+ ) , significantly increased gait speed , stride length and the lower limb joint Range of Motion ( ROM ) with respect to the basal condition ( S−M− ) ; also cadence was found to play a role in velocity increase , particularly when l -dopa was administered . Both treatments improved pelvis and trunk kinematics , and power production at the ankle and hip joints . The combination of the two treatments ( S+M+ ) produced an additional effect on gait speed , stride length , ROM of knee and ankle joints , pelvis obliquity and trunk inclination . Given the additive and synergistic effects , it can be hypothesized that the two treatments have different mechanisms of action . Our results confirm the findings of earlier studies that employed treadmill walking Deep brain stimulation ( DBS ) of the subthalamic nucleus ( STN ) is effective for the treatment of advanced Parkinson 's disease . Most studies have evaluated the effectiveness of DBS of the STN using clinical motor scores or simple timed tests of motor function . There have been few studies that quantitatively assessed the outcome of STN DBS using multiple testing paradigms . In the current study , 11 patients who had bilateral STN DBS  were quantitatively evaluated under four conditions using gait , postural control , and gait initiation . The four conditions included the medication on/stimulation on ( M_on/S_on ) , medication on/stimulation off ( M_on/S_off ) , medication off/stimulation on ( M_off/S_on ) , and medication off/stimulation off ( M_off/S_off ) conditions . DBS of the STN significantly increased walking speed with and without levodopa , but had no influence on the cadence . The addition of levodopa had a minimal additional effect on walking speed . The effect of STN DBS on gait initiation approached the significant level . The mean values of lateral body sway during quiet st and ing increased moderately with medication and /or DBS , but the changes were not statistically significant . Future studies need to determine whether or not there is a potential negative effect of STN DBS on the postural control Bilateral high-frequency stimulation of the internal globus pallidus ( GPi ) and the subthalamic nucleus ( STN ) both alleviate akinesia , rigidity , and tremor in idiopathic Parkinson 's disease . To test the specific effect of these procedures on gait , we used quantitative gait analysis in addition to relevant subscores of the Unified Parkinson 's Disease Rating Scale in a group of 10 patients with advanced Parkinson 's disease treated by GPi stimulation and eight patients treated by STN stimulation .  Patients were assessed before and 3 months after surgery . Thirty age-matched healthy subjects served as controls . The non-r and om selection allowed a descriptive but no direct statistical comparison of the respective procedure . Gait analysis showed significant stimulation-induced improvements of spatiotemporal gait and step parameters in both patient groups . Moreover , the effects on step length and cadence suggested a differential effect of both basal ganglia targets . Hence , the increase in gait velocity in the STN group was almost exclusively due to a significant increase in step length , while in the GPi group statistically non-significant increases in both step length and cadence contributed OBJECTIVE To investigate the predictive value of gait speed for community walking in Parkinson 's disease and to develop a multivariate prediction model for community walking . DESIGN Data from baseline assessment s in a r and omized clinical trial were used . SUBJECTS A total of 153 patients with Parkinson 's disease were included . METHODS  Community walking  was evaluated using the mobility domain of the Nottingham extended activities of daily living index ( NEAI ) . Patients who scored 3 points on item 1 ( " Did you walk around outside ? " ) and item 5 ( " Did you cross roads ? " ) were considered community walkers .  Gait speed was measured with the 6-m or 10-m timed walking test . Age , gender , marital status , disease duration , disease severity , motor impairment , balance , freezing of gait , fear of falling , previous falls , cognitive function , executive function , fatigue , anxiety and depression were investigated for their contribution to the multivariate model . RESULTS Seventy patients ( 46 % ) were classified as community walkers . A gait speed of 0.88 m/s correctly predicted 70 % of patients as community walkers . The multivariate model , including gait speed and fear of falling , correctly predicted 78 % of patients as community walkers . CONCLUSION Timed walking tests are valid measurements to predict community walking in Parkinson 's disease . However , evaluation of community walking should include an assessment of fear of falling Introduction : The ventrolateral ( VL ) nucleus of the thalamus is the commonly chosen target for deep brain stimulation ( DBS ) to alleviate tremor . However , it has a poor efficacy in alleviating proximal tremor and patients may develop tolerance to the action component of tremor . We performed bilateral stimulation of the caudal or motor part of the zona incerta nucleus ( cZI ) to determine its safety and efficacy in alleviating tremor . Methods : 5 patients with parkinsonian tremor and 13 with a range of tremors ( Holmes ( HT ) , cerebellar ( CT ) , essential ( ET ) , multiple sclerosis ( MS ) and dystonic tremor ( DT ) ) affecting both the proximal and distal body parts underwent MRI guided , bilateral cZI DBS . Tremor was assessed by the Fahn – Tolosa – Marin ( FTM ) tremor scale at baseline and at a mean follow-up of 12 months . Results : Resting PD tremor improved by 94.8 % and postural tremor by 88.2 % . The total tremor score improved by 75.9 % in 6 patients with ET . HT improved by 70.2 % , proximal CT by 60.4 % and proximal MS tremor by 57.2 % in the total tremor rating score . In the single patient with DT , there was improvement in both the dystonia and the tremor . Patients required low voltages of high-frequency stimulation and did not develop tolerance to it . Stimulation-related side effects were transient . Conclusion This prospect i ve study shows that the cZI may be an alternative target for the treatment of tremor with DBS . In contrast to bilateral DBS of the VL nucleus , it improves all components of tremor affecting both the distal and proximal limbs as well as the axial musculature Background Gait performance is widely evaluated to assess health status in older adult population s. While several investigators have presented normative values for spatiotemporal gait parameters drawn from older adult population s , the literature has been void of large-scale cohort studies , which are needed in order to provide quantitative , normative gait data in persons with Parkinson ’s disease . The aim of this investigation was to provide reference values for clinical ly important gait characteristics in a large sample of ambulatory persons with Parkinson ’s disease to aid both clinicians and research ers in their evaluations and treatments of gait impairment . Methodology /Principal Findings  Gait performance  was collected in 310 individuals with idiopathic Parkinson ’s disease as they walked across a pressure sensitive walkway . Fourteen quantitative gait parameters were measured and evaluated with respect to Hoehn and Yahr disease staging and gender . Disease duration and age were controlled for in all analyses . Individuals with the greatest Parkinson ’s disability walked significantly slower with shorter steps and stride lengths than the mild and moderately affected groups . Further , the most affected patients spent more time with both feet on the ground , and walked with a wider base of support than the moderately disabled patients . No differences were detected between the mild and moderate disability groups on any of the gait parameters evaluated . Conclusions / Significance Reference values for 14 gait parameters in a large cohort of ambulatory patients with Parkinson ’s disease are provided and these may be highly useful for assessing and interpreting an individual ’s gait dysfunction . It is important for clinicians and research ers to appreciate the lack of change in quantitative parameters as PD patients move from mild to moderate gait impairment The fundamental disturbance of the parkinsonian gait is the reduction in walking velocity . This is mainly due to reduction in stride length , while cadence ( steps/min ) is slightly enhanced . Treatment with L-dopa increases stride length while cadence is unchanged . Chronic stimulation of the thalamus has no effect on Parkinsonian gait . The efficacy of electrical stimulation of the subthalamic nucleus ( STN ) on gait in advanced Parkinson 's disease has been clearly demonstrated clinical ly . The aim of the present study was to quantify the changes in gait measures induced by STN stimulation and L-dopa and to assess possible differential or additive effects . Eight Parkinson 's disease patients ( mean + /- SD age 48.1 + /- 7.3 years ) with chronic bilateral STN stimulation ( mean duration of disease 13.3 + /- 2.4 years , mean stimulation time 15.4 + /- 10.6 months ) and 12 age-matched controls were investigated . Subjects walked on a special treadmill with a closed-loop ultrasound control system that used the subject 's position to adjust treadmill speed continuously for the actual walking velocity . In an appropriate crossover design , spatiotemporal gait measures and leg joint angle movements were assessed for at least 120 stride cycles in four treatment conditions : with and without stimulation and with and without a suprathreshold dose of L-dopa . With STN stimulation , there were increases of almost threefold in mean walking velocity ( from 0.35 to 0.96 m/s ) and stride length ( from 0.34 to 0.99 m ) . Cadence remained constant . The range of motion of the major leg joints also increased . L-Dopa alone had a slightly weaker effect , with an increase in walking velocity to 0.94 m/s and in stride length to 0.92 m at a similar cadence . These increased values were in the range of those for healthy age-matched subjects performing the same task . The combination of both treatments further increased the mean walking velocity to 1.19 m/s and stride length to 1.20 m at an unchanged cadence . However , not all patients receiving STN stimulation improved further when they also received L-dopa . These results demonstrate that chronic bilateral STN stimulation , like treatment with L-dopa , improves walking velocity by increasing stride length without changing cadence .  STN stimulation almost exclusively affects mechanisms involved in the control of spatial gait measures rather than rhythmicity . The gait measures obtained with STN stimulation alone are in the range of control subjects The aim of this study was to assess reliability , responsiveness and feasibility of gait and gait related tests in the home of patients with Parkinson 's disease ( PD ) . The Unified Parkinson 's Disease Rating Scale , a timed walking test , the Timed Get Up and Go test the Berg Balance Scale and the Functional Reach test  were applied by three independent observers on 26 PD patients . Moderate to high Intraclass Correlation Coefficients were found , ranging from 0.74 to 0.88 and 0.64 to 0.87 for the intra- and inter-observer reliability , respectively . All test showed Reliable Change Indexes under 11 % and the whole test battery was applicable within 30 min The effects of subthalamic nucleus ( STN ) stimulation and L-dopa administration on the arm and leg swing movements associated with overground walking were studied in a group of patients with idiopathic Parkinson 's disease ( PD ) . Ten patients undergoing deep brain stimulation and twenty controls were tested using 3D kinematic motion analysis . Parkinsonian patients under basal conditions walked more slowly and with reduced arm and leg swing compared to controls . Moreover , they displayed significant impairments of the normal interlimb coordination . Both STN stimulation and L-dopa increased the walking speed and the amplitude of arm and leg swing movements . Additional improvements of the coordination between upper and lower limb were documented by reductions of the phase-shift between arm and ipsilateral leg motion , with displacement toward the control range ( perfect counterphase ) . STN stimulation alone and L-dopa alone produced similar effects on the variables analyzed . The combination of the two treatments , instead , yielded additive effects on the gait speed and a slight increase of the upper and lower limb range of motion , in the absence of further improvements in the inter-segmental coordination . Moreover , whereas the increased arm swing could be accounted by the sole adoption of a higher gait speed , both the increment of the leg movement amplitude and the decreased interlimb phase shift appeared to imply an additional effect , possibly related to the treatment . These results may suggest that differential supraspinal controls operate on the neural networks subserving upper and lower limb motion during human walking Summary .The aim of our study was to observe the effects on gait parameters induced by STN stimulation and levodopa medication in patients with advanced Parkinson ’s disease in order to determine different or additive effects . Therefore we examined 12 patients with advanced Parkinson disease after bilateral implantation of DBS into the STN .  We assessed the motor score of the UPDRS and quantitative gait analysis under 4 treatment conditions : with and without stimulation as well as with and without levodopa . The mean improvement of the UPDRS motor score was almost the same with levodopa and DBS . Combining both therapies we saw a further improvement of the motor score . Gait parameters of patients with PD treated either with levodopa or STN stimulation were greatly improved . A significant difference between levodopa and STN stimulation could only be shown for the parameters velocity and step length . These parameters improved more with levodopa than with stimulation . The combination of both therapeutic methods showed the best results on the UPDRS motor score and gait parameters The effects of subthalamic nucleus ( STN ) stimulation on the spatio-temporal organization of locomotor comm and s directed to lower limb muscles were studied in subjects with idiopathic Parkinson 's Disease ( PD ) by recording the EMG activity produced during steady-state walking in representative thigh ( rectus femoris , RF , and semimembranosus , SM ) and leg ( gastrocnemius medialis , GAM , and tibialis anterior , TA ) muscles , under four experimental conditions : basal stimulation off , unilateral ( right and left ) stimulation on , and bilateral stimulation on . Locomotor profiles of all of the muscles tested were found to be substantially affected by STN stimulation , either in terms of restoration/enhancement of the main activity bursts or normalization of recruitment timing thereof . Responses showed relatively higher statistical significance in the distal groups ( GAM and TA ) and , within them , for the EMG components called into action over the ground-contact ( ankle dorsiflexors ) and midstance ( ankle plantarflexors ) phases of the stride cycle . In line with data obtained from clinical rating , unilateral stimulation produced less consistent EMG changes compared with bilateral stimulation . However , at variance with clinical effects , which prevailed on the side of the body contralateral to stimulation , EMG responses to unilateral stimulation were usually symmetrical . Results indicate that the impact of STN stimulation on locomotor activation of lower limb muscles in PD is characterized by : 1 ) substantial effects exhibiting differential topographical ( distal versus proximal ) and stride-phase ( stance versus swing ) consistency and 2 ) absence of the lateralized actions typically observed for the clinical signs of the disease . Interaction with the activity of functionally different executive systems might account for the observed pattern of responsiveness BACKGROUND Stimulation of the subthalamic nucleus is proposed for the treatment of patients presenting with severe Parkinson disease . The effect on gait is not clearly established . OBJECTIVES To evaluate objective ly the influence of bilateral subthalamic nucleus stimulation on gait in Parkinson disease and to compare it with the effects of levodopa treatment . METHODS Ten patients underwent bilateral subthalamic nucleus stimulation .  The preoperative and postoperative ( 3 months after surgery ) clinical gait disturbances , as well as spatial and temporal gait parameters , were analyzed in off and on-drug conditions . The gait analysis was performed using a video motion analysis system ( optoelectronic VICON system ; Oxford Metrics , Oxford , Engl and ) . RESULTS In the off condition , there was an improvement after surgery for the total motor score and the gait subscore . In the on-drug condition , there was an improvement in levodopa-induced dyskinesias and the motor score , whereas the gait subscore was unchanged . For the gait parameters measured by the video motion analysis system system , there was also an improvement in the off condition and to a lesser extent in the on-drug condition . CONCLUSIONS Our method allowed exact quantification of the benefit of surgery on gait parameters . Compared with the levodopa treatment , the effect of stimulation on gait kinematic parameters seems to be qualitatively similar but quantitatively different with a lower benefit on gait velocity and stride length . Concerning the pathophysiology of gait troubles in Parkinson disease , the deficit in control of stride length would be the fundamental deficit . The study underlines the possible role of the subthalamic nucleus on the stride length regulation OBJECT In this paper , the authors ' aim was to examine reasons underpinning decisions to undergo , or alternatively forgo , a second-sided deep brain stimulation ( DBS ) implantation in patients with Parkinson disease ( PD ) . METHODS Fifty-two patients with Parkinson disease ( PD ) were r and omized to receive DBS to the subthalamic nucleus or globus pallidus internus ( GPi ) as part of the COMPARE trial . Forty-four patients had complete data sets . All patients were offered a choice at 6 months after unilateral implantation whether to receive a contralateral DBS implant .  All patients had advanced PD . The mean patient age was 59.8 years ( range 43 - 76 years ) , and the mean duration of disease was 12.2 years ( range 5 - 21 years ) . The mean baseline Unified Parkinson 's Disease Rating Scale (UPDRS)-III motor score was 42.7 . The main outcome measures used in this study were the UPDRS-III Motor Scale and the UPDRS-IV Dyskinesia Scale . RESULTS Twenty-one ( 48 % ) of the 44 patients in the cohort did not undergo bilateral implantation and have been successfully treated for an average of 3.5 years ; of these , 14 ( 67 % ) had a GPi target . The most common reason for adding a second side was inadequacy to address motor symptoms . Patient satisfaction with motor outcomes after unilateral DBS implantation was the most common reason for not undergoing bilateral implantation . Those who chose a second DBS procedure had significantly higher baseline UPDRS-III motor and ipsilateral UPDRS-III scores , and a significantly lower asymmetrical index . The logistic regression analysis revealed that the odds of proceeding to  bilateral DBS was 5.2 times higher for STN than for GPi DBS . For every 1 % increase in asymmetry , the odds of bilateral DBS decreased [ corrected ] by 0.96 . CONCLUSIONS Unilateral DBS is an effective treatment for a subset of patients with PD . Baseline asymmetry is an important factor in the effectiveness and decision-making process between unilateral and bilateral DBS .  Patients with GPi DBS in this cohort were more likely to choose to remain with unilateral implantation INTRODUCTION The temporal relationship between disease and disability progression in Parkinson disease ( PD ) is not well understood . Our objective was to describe the natural , multidimensional trajectory of disability in persons with PD over a two-year period . METHODS We conducted a multi-center , prospect i ve cohort study involving four institutions . Data were collected at baseline and at 6-month intervals over 2 years using st and ardized clinical tests representing three World Health Organization defined disability domains : impairment , activity limitation , and participation restriction . Unadjusted mixed effects growth models characterized trajectories of disability in the three disability domains . The data set was analyzed using restricted maximum likelihood ( REML ) estimation . St and ardized estimates of change were also computed using Cohen 's d for each measure . RESULTS Of the 266 enrolled participants , we analysed data from individuals who participated in at least 3 assessment s ( n = 207 , 79 % ) .  Rates of disability progression over the 2-year period differed across domains . Moderate effects were detected for motor impairment ( d = .28 ) and walking-related activity limitation ( gait-related balance ( d = .31 ) ; gait speed ( d = .30 ) ) . Marginal effects were noted for upper extremity-related activity limitation ( d = .11 ) and health-related quality of life participation restriction ( d = .08 ) . CONCLUSIONS The natural trajectory of walking-related activity limitation was the most potent indicator of evolving disability , suggesting that routine assessment of walking and periodic rehabilitation is likely to be warranted for many persons with PD . Natural trajectories of disability provide important comparison data for future intervention studies Objective : To compare the effects of unilateral subthalamic nucleus ( STN ) deep brain stimulation ( DBS ) with bilateral STN DBS in advanced PD . Methods : Our initial 10 consecutive patients with medication-refractory motor fluctuations and levodopa-induced dyskinesias undergoing chronic bilateral STN DBS  underwent a st and ardized evaluation of unilateral and bilateral STN DBS in the medication-off state 6 to 18 months after electrode implantation . Results : Bilateral STN DBS improved the mean total Unified Parkinson ’s Disease Rating Scale motor score by 54 % , whereas unilateral stimulation improved motor scores only 23 % . Unilateral STN DBS improved postural stability and gait 14 % , other axial motor features 19 % , and overall parkinsonism in limbs contralateral to stimulation by 46 % , including an 86 % improvement in contralateral tremor . However , bilateral STN DBS result ed in greater improvement in each of these domains , including limb function , i.e. , the reduction in scores from the limbs on one side was greater with bilateral than with unilateral stimulation of the contralateral STN . Conclusions : Bilateral STN DBS improves parkinsonism considerably more than unilateral STN DBS ; bilateral simultaneous electrode implantation may be the most appropriate surgical option for patients with significant bilateral disability . Unilateral STN DBS results in moderate improvement in all aspects of off-period parkinsonism and improves tremor as much as is typically reported with DBS of the ventral intermedius nucleus of the thalamus ( Vim ) . For this reason , STN DBS may be a more appropriate choice than Vim DBS or thalamotomy for parkinsonian tremor . Some patients with highly asymmetric tremor-dominant PD might be appropriately treated with unilateral instead of bilateral STN DBS OBJECTIVES To assess the ability of gait speed alone and a three-item lower extremity performance battery to predict 12-month rates of hospitalization , decline in health , and decline in function in primary care setting s serving older adults . DESIGN Prospect i ve cohort study . SETTING Primary care programs of a Medicare health maintenance organization ( HMO ) and Veterans Affairs ( VA ) system . PARTICIPANTS Four hundred eighty-seven persons aged 65 and older . MEASUREMENTS  Lower extremity performance Established Population for Epidemiologic Studies of the Elderly ( EPESE ) battery including  gait speed , chair st and s , and t and em balance tests ; demographics ; health care use ; health status ; functional status ; probability of repeated admission scale ( Pra ) ; and primary physician 's hospitalization risk estimate . RESULTS Veterans had poorer health and higher use than HMO members . Gait speed alone and the EPESE battery predicted hospitalization ; 41 % ( 21/51 ) of slow walkers ( gait speed < 0.6 m/s ) were hospitalized at least once , compared with 26 % ( 70/266 ) of intermediate walkers ( 0.6 - 1.0 m/s ) and 11 % ( 15/136 ) of fast walkers ( > 1.0 m/s ) ( P < .0001 ) . The relationship was stronger in the HMO than in the VA . Both performance measures remained independent predictors after accounting for Pra . The EPESE battery was superior to gait speed when both Pra and primary physician 's risk estimate were included . Both performance measures predicted decline in function and health status in both health systems . Performance measures , alone or in combination with self-report measures , were more able to predict outcomes than self-report alone . CONCLUSION Gait speed and a physical performance battery are brief , quantitative estimates of future risk for hospitalization and decline in health and function in clinical population s of older adults . Physical performance measures might serve as easily accessible " vital signs " to screen older adults in clinical setting Abstract Clinical reports show that bilateral subthalamic nucleus ( STN ) stimulation is effective in improving parkinsonian gait .  Quantitative analysis of the efficacy of STN stimulation on gait is of interest and can be carried out using a commercially available stride analyser . Ten parkinsonian patients ( 5 men , 5 women ) with a mean age of 55.8 , SD 9.6 years were included in our study . They had a mean duration of Parkinson 's disease ( PD ) of 13.3 , SD 4.5 years and a motor examination score ( part III of the Unified Parkinson 's Disease Rating Scale ) ( UPDRS ) of 43 , SD 13 in off-stimulation off-drug condition . All the patients had bilateral chronic STN stimulation which had started from 3 to 36 months before the study . Patients were evaluated in off-drug and on-drug conditions both with and without stimulation . We analysed the principal gait measures : velocity , cadence , stride length , gait cycle , duration of single and double limb support . The clinical parkinsonian signs were evaluated with the part III of the UPDRS . In the off-drug condition , STN stimulation significantly ( p < 0.05 ) improved velocity and stride length . The effect was similar to that of levodopa . When STN stimulation was switched on at the best of the levodopa induced effect , no further improvement was observed . The UPDRS motor score was significantly ( p < 0.001 ) decreased after both stimulation and levodopa . In conclusion ,  STN stimulation is effective on parkinsonian gait The effect of subthalamic deep brain stimulation on gait coordination and freezing of gait in patients with Parkinson 's disease is incompletely understood . The purpose of this study was to investigate the extent to which modulation of symmetry and coordination between legs by subthalamic deep brain stimulation alters the frequency and duration of freezing of gait in patients with Parkinson 's disease . We recruited 13 post-subthalamic deep brain stimulation patients with Parkinson 's disease with off freezing of gait and evaluated them in the following 4 conditions : subthalamic deep brain stimulation on ( ON ) and stimulation off ( OFF ) , 50 % reduction of stimulation voltage for the leg with shorter step length ( worse side reduction ) and for the leg with longer step length ( better side reduction ) . Gait analysis was performed on a treadmill and recorded by an optoelectronic analysis system . We measured frequency and duration of freezing of gait episodes . Bilateral coordination of gait was assessed by the Phase Coordination Index , quantifying the ability to generate antiphase stepping . From the OFF to the ON state , freezing of gait improved in frequency ( 2.0 ± 0.4 to 1.4 ± 0.5 episodes ) and duration ( 12.2 ± 2.6 to 2.6 ± 0.8 seconds ; P = .005 ) . Compared with the ON state , only better side reduction further reduced freezing of gait frequency ( 0.2 ± 0.2 ) and duration of episodes ( 0.2 ± 0.2 seconds ; P = .03 ) ; worse side reduction did not change frequency ( 1.3 ± 0.4 ) but increased freezing of gait duration ( 5.2 ± 2.1 seconds ) . The better side reduction-associated improvements were accompanied by normalization of gait coordination , as measured by phase coordination index ( 16.5 % ± 6.0 % ) , which was significantly lower than in the other 3 conditions . Reduction of stimulation voltage in the side contralateral to the leg with longer step length improves frequency and duration of freezing of gait through normalization of gait symmetry and coordination in subthalamic deep brain stimulation  patients with Parkinson 's disease . This identifies poor leg coordination as a risk factor for causing freezing of gait OBJECT Bilateral deep brain stimulation ( DBS ) of the subthalamic nucleus ( STN ) has been established as an effective treatment for  Parkinson disease ( PD ) . Nevertheless , bilateral surgical procedures can be associated with frequent and severe complications . The aim in the present study was to assess the safety and efficacy of unilateral STN stimulation , and the need for a second procedure . METHODS Twelve patients with PD underwent unilateral DBS of the STN  and were followed up for 12 months . Patients were assessed at baseline and at each visit in a double-blind fashion by analyzing the Unified PD Rating Scale ( UPDRS ) , ambulation speed , and home diaries . Levodopa-off/stimulation-on UPDRS motor scores were improved by 26 + /- 8 % ( p < 0.05 , mean + /- st and ard deviation [ SD ] ) compared with the baseline levodopa-off score ; there was a 50 % improvement in contralateral features , a 17 % improvement ipsilaterally , and a 36 % improvement in axial features . The mean ambulation speed increased by 83 + /- 44 % ( p < 0.01 , mean + /- SD ) . The medication-on time with dyskinesias was significantly reduced ( p < 0.01 ) and the daily levodopa dose was reduced by 19 + /- 6 % ( p < 0.05 , mean + /- SD ) . There were no clinical ly significant side effects . CONCLUSIONS Unilateral DBS of the STN is safe and well tolerated , and may provide sufficient benefit so that additional surgery is not required To investigate the bilateral effects of unilateral subthalamic nucleus deep brain stimulation ( STN-DBS ) , we prospect ively studied 9 consecutive advanced Parkinson ’s disease ( PD ) patients ( 2 men and 7 women ) who underwent unilateral STN-DBS .  Patients were evaluated preoperatively and at 3 and 6 months postoperatively with and without dopaminergic medications ( ‘ on ’ and ‘ off ’ medication , respectively ) . Postoperatively , patients were assessed with and without stimulation . We found that , when compared with baseline , the ‘ off ’ medication scores of the Unified Parkinson ’s Disease Rating Scale motor part ( UPDRS III ) and activities of daily living ( UPDRS II ) were improved by 37 % ( p = 0.028 ) and 50 % ( p = 0.046 ) at 6 months after surgery , respectively . Stimulation while ‘ off ’ medication improved the total UPDRS score by 42 % ( p = 0.028 ) at 6 months . At 6 months after surgery , the subscore of UPDRS III of body parts contralateral to the DBS implantation had improved by 48 % ( p = 0.028 ) , and the ipsilateral subscore of UPDRS III and the axial subscore of UPDRS III had improved by 20 % ( p = 0.027 ) and 39 % ( p = 0.028 ) , respectively . Daily dosage of levodopa was reduced by 15 % at 6 months . No patient exhibited permanent side effects . These findings indicate that unilateral STN-DBS may be a reasonable surgical procedure for selected PD patients who have markedly asymmetric parkinsonism The effects of subthalamic nucleus ( STN ) deep brain stimulation ( DBS ) on fall risk in patients with Parkinson 's disease ( PD ) currently remain unclear . Although several gait parameters , such as gait speed , have shown improvement with DBS , some studies have reported an increased fall risk following DBS . The purpose of this study was to examine the effect of bilateral DBS on gait variability , a marker of fall risk . The gait of 13 patients with idiopathic PD was analyzed to determine the influence of DBS , levodopa and both therapies together . Following treatment with both levodopa and STN DBS , subjects displayed improved gait speed , reduced gait variability ( enhanced stability ) , and lower Unified Parkinson 's Disease Rating Scale ( UPDRS ) scores . Although UPDRS scores improved with STN DBS alone , parallel improvements were not seen for gait variability . These findings suggest that different mechanisms may contribute to performance on UPDRS motor testing and gait stability in response to DBS
In Parkinson ’s disease ( PD ) , slow gait speed is significantly related to clinical ratings of disease severity , impaired performance of daily activities , as well as increased overall disability .
Conducting a meta- analysis on gait speed is an objective and quantitative technique to summarize the effectiveness of DBS and to determine the effect sizes for future studies .
We conducted a systematic review and meta- analysis that analyzed the effects of deep brain stimulation ( DBS ) surgery on gait speed in patients with PD to gain fundamental insight into the nature of therapeutic effectiveness .