Quinn & Pople (1992) in their study confirmed increased pulsatility index in the cases of malfunction of ventriculoperitoneal shunt in children with hydrocephalus. After revision surgery the pulsatility index decreased. The change of the dilatation of cerebral ventricles

The relationship between intracranial pressure and Doppler parameters of cerebral arteries is of a complex nature. Many extracranial and intracranial factors may influence the cerebral

The relationship between increased resistive index and increased intracranial pressure in preterm infants with posthaemorrhagic hydrocephalus was first described by Bada et al.

The changes of resistive index of anterior cerebral artery in newborns with hydrocephalus was assessed by Hill & Volpe (1982). In 9 from 11 cases with raised intracranial pressure, the dilatation of cerebral ventricles was presented. In all cases the resistive index was increased. The significant decrease of resistive index after the successful drainage procedure was

The study of Fisher & Livingstone (1989) showed increased pulsatility index, significantly decreased end-diastolic blood flow velocity and slight decrease of peak systolic blood flow velocity in anterior cerebral circulation (anterior cerebral artery, middle cerebral artery, internal carotid artery) in pediatric hydrocephalus. The values of Doppler parameters after the drainage procedure with functional internal drainage system were normal. The dilatation of cerebral ventricles (except the width of third ventricle) persisted also after the drainage procedure. There was found no corelation between the size of cerebral ventricles and peak systolic blood flow velocity. The relationship between end-diastolic blood flow velocity and the size of cerebral ventricles was intraindividual. Pulsatility index showed the highest level of corelation with the size of cerebral ventricles. The width of third ventricle seems to be the most sensitive morphological parameter of intracranial volume changes. Anterior cerebral artery and middle cerebral artery are the most sensitive cerebral vessels to the intracranial dynamics (Aaslid, 1984; Fisher & Livingstone, 1989). Also the studies of another authors confirmed the significant increase of pulsatility index of cerebral vessels before the drainage operation and significant decrease of pulsatility index after the drainage

Nishimaki et al. (1990) were interested in the changes of resistive index of anterior cerebral artery and basilar artery in children with hydrocephalus. There was increased resistive index of both arteries before the drainage procedure. The successful drainage operation led to the significant decrease of resistive index of anterior cerebral artery and basilar artery. The decrease of resistive index of anterior cerebral artery was significantly higher than decrease of resistive index of basilar artery. Normal values of resistive index of anterior cerebral artery in children are lower than the values of resistive index of basilar artery. The difference between the haemodynamic changes of anterior cerebral artery and basilar artery can be caused by the anatomical localisation of vessels. The anterior cerebral artery has close relationship to the lateral cerebral ventricles and third ventricle, basilar artery is localised in pontine cistern. In most cases of pediatric hydrocephalus, the progressive dilatation of lateral cerebral ventricles and third ventricle is greater than the dilatation of fourth ventricle. Therefore authors suggest, that the enlargement of cerebral ventricles in hydrocephalus affects more haemodynamic parameters of the anterior cerebral artery than basilar artery. Quinn & Pople (1992) in their study confirmed increased pulsatility index in the cases of malfunction of ventriculoperitoneal shunt in children with hydrocephalus. After revision surgery the pulsatility index decreased. The change of the dilatation of cerebral ventricles

procedure (Jindal & Mahapatra, 1998; Nadvi et al., 1994).

blood flow.

detected.

(Bada et al., 1982).

was detected only in 10 from 32 patients with malfunction of ventriculoperitoneal shunt. In spite of stable dilatation of cerebral ventricles, there were presented clinical signs of intracranial hypertension and an increase of pulsatility index before the revision surgery.

Goh et al. (1991) studied the corelation between resistive index of cerebral arteries and intracranial pressure in newborns and children with hydrocephalus. There was found good intraindividual corelation between the resistive index and intracranial pressure in newborns, whereas in older children the corelation between resistive index and intracranial pressure was good in generally. The differences between age groups are probably caused by highly individual volume-pressure compensation mechanisms in newborns in different stages of hydrocephalus and different compliance of neonatal head (biomechanical and fibroelastic properties of bones, sutures and soft tissue of head). The intracranial dynamics in older children is more uniform, therefore the corelation of resistive index of cerebral arteries and intracranial pressure is generally good. There was found significant decrease of resistive index and increase of end-diastolic blood flow velocity after the drainage procedure in all age groups, but only in newborns was detected moderate increase of peak systolic blood flow velocity and mean blood flow velocity. The same haemodynamic Doppler changes of cerebral vessels were found in the cases of shunt malfunction and after the successful revision surgery.

Goh et al. (1995) in their study confirmed, that there was no increase of resistive index of cerebral vessels in newborns with hydrocephalus in the cases of stable dilatation of cerebral ventricles. The results of the study suggest, that the increase of resistive index of cerebral arteries is caused by raised intracranial pressure and not by enlargement of cerebral ventricles alone.

In spite of detection of increased values of resistive index of cerebral vessels there was found also altered CO2 cerebral vasoreactivity in children with hydrocephalus with the need of drainage procedure. After the insertion of shunt or revision surgery for shunt malfunction, the improvement of CO2 cerebral vasoreactivity was confirmed (De Oliveira & Machado, 2003).

Vajda et al. (1999) found the significant decrease of pulsatility index of middle cerebral artery in children with obstructive hydrocephalus after successful endoscopic third ventriculostomy in relationship to the preoperative value. The function of ventriculostomy was confirmed by the detection of cerebrospinal fluid flow by means of magnetic resonance imaging. The clinical symptomatology improved in 17 from 22 patients. There was found no corelation between the pulsatility index and the age and sex of children. The results of this study show the role of transcranial Doppler sonography in the indirect assessment of the function of endoscopic third ventriculostomy in the early postoperative period.

Cosan et al. (2000) analysed the haemodynamic changes of cerebral circulation in neonatal rats with progressive communicating hydrocephalus by means of transcranial Doppler ultrasonography. There was confirmed, than in the acute phase of hydrocephalus, the dilatation of cerebral ventricles was not accompanied by the alteration of Doppler parameters of cerebral vessels (the value of pulsatility index was normal). During the progression of communicating hydrocephalus an increase of the size of cerebral ventricles and an increase of pulsatility index occured. The enlargement of cerebral ventricles alone in the initial phase of communicating neonatal hydrocephalus did not lead to the changes of

Transcranial Doppler Ultrasonography in the Management of Neonatal Hydrocephalus 143

and incoherent. The reason for this discrepancy can be the use of different type of sonographic equipment, method of sonographic examination, heterogenity of the group of premature newborns (gestational age, weight, extracranial factors, medication, number of

Perlman & Volpe (1982) analysed the Doppler parameters of anterior cerebral artery in 32 premature newborns with intraventricular haemorrhage. The gestational age of premature newborns was in the range from 26 to 34 weeks. There was found no corelation between intraventricular haemorrhage and resistive index of anterior cerebral artery. In 29 cases, the intraventricular haemorrhage was not accompanied by the decrease of cerebral blood flow velocity. There was no corelation betwen the time of the onset of intraventricular haemorrhage and the value of resistive index. In 9 cases with pneumothorax, the significant decrease of resistive index was detected. Another authors described increased value of resistive index (more than 0,90) of cerebral arteries in premature newborns with

Van Bel et al. (1988) analysed the Doppler parameters of anterior cerebral artery in 10 premature newborns with posthaemorrhagic hydrocephalus. There was found a significantly increased pulsatility index and peak systolic blood flow velocity before the drainage procedure. After the drainage procedure, a significant decrease of pulsatility index and peak systolic blood flow velocity was detected. The values of postoperative pulsatility index were normal. There were found no significant changes of end-diastolic blood flow velocity and mean blood flow velocity before and after the drainage procedure. The increase of pulsatility index before the surgery was caused by an increase of peak systolic blood flow velocity. The reason for the earliest indication of drainage procedure was the reduction of the damage of cerebral circulation. The indication criterion included the progressive dilatation of cerebral ventricles with increased size more than 97th percentil. The same results were published by Alvisi et al. (1985). Authors suggest, that the increase of peak systolic blood flow velocity before the drainage procedure is caused by the dislocation and compression of anterior cerebral artery by enlarged cerebral ventricles. The transport of cerebrospinal fluid into the white matter also causes the loss of transmural pressure gradient

The frequency and timing of intermitent drainage of cerebrospinal fluid in newborns with posthaemorrhagic hydrocephalus is still the topic of discussion. One of the aims of intermitent drainage of cerebrospinal fluid is the prevention of negative influence of raised

Kempley & Gamsu (1993) assessed the changes of intracranial pressure and Doppler parameters of anterior cerebral artery in the group of 6 newborns with posthaemorrhagic hydrocephalus before and after the drainage of cerebrospinal fluid (23 drainage procedures). There was found significant decrease of intracranial pressure after the derivation of cerebrospinal fluid. The decrease of intracranial pressure was accompanied by an increase of mean blood flow velocity and decrease of pulsatility index. The results of the study suggest, that the derivation of cerebrospinal fluid in newborns with posthaemorrhagic hydrocephalus leads to the significant improvement of haemodynamic parameters of cerebral circulation. Authors recommend, that the alteration of Doppler parameters of cerebral vessels should be taken in the consideration in the indication and timing of

patients) and different indication for drainage procedure.

(Alvisi et al., 1985; Weller & Shulman, 1972; Wozniak et al., 1975).

drainage procedure in newborns with posthaemorrhagic hydrocephalus.

intracranial pressure on cerebral circulation.

intraventricular haemorrhage.

pulsatility index of cerebral vessels. The alteration of Doppler parameters of cerebral vessels (increased pulsatility index, decreased end-diastolic blood flow velocity) occured in the phase of progression with increased intracranial pressure. In this phase, the cerebral circulation is more affected by increased intracranial pressure than by the dilatation of cerebral ventricles. The raised intracranial pressure leads to the compression of brain capillaries and increase of vascular resistance of cerebral arteries with increased pulsatility index (Cosan et al., 2000; Seibert et al., 1989). In the chronic phase of hydrocephalus, the enlargement of cerebral ventricles and haemodynamic changes of cerebral circulation are accompanied by several pathologic changes (Del Bigio, 1993).

Taylor et al. (1994) analysed the anterior fontanelle compressive test as a part of the examination of newborns with altered intracranial compliance by means of transcranial Doppler sonography. Basal and compressive values of resistive index of middle cerebral artery were measured. The basal resistive index in the preterm newborns and term newborns with altered intracranial compliance was significantly higher than in healthy term newborns. There was only a minimal change of basal resistive index during the anterior compressive test in healthy preterm and term newborns. In newborns with altered intracranial compliance, the value of resistive index during the compressive test was increased. In newborns with hydrocephalus with increased intracranial pressure, increased values of basal resistive index were detected. After the drainage procedure, the haemodynamic response on anterior fontanelle compression was improved.

In another study Taylor et al. (1996) assessed the haemodynamic response of anterior cerebral artery on anterior fontanelle compression in newborns with hydrocephalus. The results suggest, that the significant increase of resistive index was found in newborns with increased intracranial pressure with the need of drainage procedure.

Also the study of another authors confirmed increased basal and compressive values of resistive index of anterior cerebral artery in children with hydrocephalus in the cases of increased intracranial pressure. After the successful drainage procedure, the significant decrease of basal and compressive values of resistive index was found. The borderline value of basal resistive index of anterior cerebral artery was defined as 0,70, for positive anterior compressive test as 0,90 or increase of basal resistive index more than 25% (Westra et al., 1998).

Gera et al. (2002) were interested in the assessment of Doppler parameters of anterior cerebral artery in newborns and children with hydrocephalus in relationship to the need of drainage procedure. There was found a significant increase of basal and compressive resistive index in patients with the need of drainage operation. After the drainage procedure, the significant decrease of basal and compressive resistive index was detected. The results of the study suggest significant increase of intracranial compliance after the drainage procedure. There was no significant change of head circumference after surgery. The importance of the assessment of resistive index of anterior cerebral artery in newborns and children with hydrocephalus in relationship to the need of drainage procedure was defined: basal resistive index – sensitivity 72,5%, specificity 80%, diagnostic accuracy 75%, false negativity 25%, compressive resistive index – sensitivity 75%, specificity 100%, diagnostic accuracy 83,3%, false negativity 25%.

The asessment of Doppler parameters of cerebral vessels in premature newborns with hydrocephalus is still disputable. The results of published studies are sometimes different

pulsatility index of cerebral vessels. The alteration of Doppler parameters of cerebral vessels (increased pulsatility index, decreased end-diastolic blood flow velocity) occured in the phase of progression with increased intracranial pressure. In this phase, the cerebral circulation is more affected by increased intracranial pressure than by the dilatation of cerebral ventricles. The raised intracranial pressure leads to the compression of brain capillaries and increase of vascular resistance of cerebral arteries with increased pulsatility index (Cosan et al., 2000; Seibert et al., 1989). In the chronic phase of hydrocephalus, the enlargement of cerebral ventricles and haemodynamic changes of cerebral circulation are

Taylor et al. (1994) analysed the anterior fontanelle compressive test as a part of the examination of newborns with altered intracranial compliance by means of transcranial Doppler sonography. Basal and compressive values of resistive index of middle cerebral artery were measured. The basal resistive index in the preterm newborns and term newborns with altered intracranial compliance was significantly higher than in healthy term newborns. There was only a minimal change of basal resistive index during the anterior compressive test in healthy preterm and term newborns. In newborns with altered intracranial compliance, the value of resistive index during the compressive test was increased. In newborns with hydrocephalus with increased intracranial pressure, increased values of basal resistive index were detected. After the drainage procedure, the

In another study Taylor et al. (1996) assessed the haemodynamic response of anterior cerebral artery on anterior fontanelle compression in newborns with hydrocephalus. The results suggest, that the significant increase of resistive index was found in newborns with

Also the study of another authors confirmed increased basal and compressive values of resistive index of anterior cerebral artery in children with hydrocephalus in the cases of increased intracranial pressure. After the successful drainage procedure, the significant decrease of basal and compressive values of resistive index was found. The borderline value of basal resistive index of anterior cerebral artery was defined as 0,70, for positive anterior compressive test as 0,90 or increase of basal resistive index more than 25% (Westra et al., 1998). Gera et al. (2002) were interested in the assessment of Doppler parameters of anterior cerebral artery in newborns and children with hydrocephalus in relationship to the need of drainage procedure. There was found a significant increase of basal and compressive resistive index in patients with the need of drainage operation. After the drainage procedure, the significant decrease of basal and compressive resistive index was detected. The results of the study suggest significant increase of intracranial compliance after the drainage procedure. There was no significant change of head circumference after surgery. The importance of the assessment of resistive index of anterior cerebral artery in newborns and children with hydrocephalus in relationship to the need of drainage procedure was defined: basal resistive index – sensitivity 72,5%, specificity 80%, diagnostic accuracy 75%, false negativity 25%, compressive resistive index – sensitivity 75%, specificity 100%,

The asessment of Doppler parameters of cerebral vessels in premature newborns with hydrocephalus is still disputable. The results of published studies are sometimes different

accompanied by several pathologic changes (Del Bigio, 1993).

haemodynamic response on anterior fontanelle compression was improved.

increased intracranial pressure with the need of drainage procedure.

diagnostic accuracy 83,3%, false negativity 25%.

and incoherent. The reason for this discrepancy can be the use of different type of sonographic equipment, method of sonographic examination, heterogenity of the group of premature newborns (gestational age, weight, extracranial factors, medication, number of patients) and different indication for drainage procedure.

Perlman & Volpe (1982) analysed the Doppler parameters of anterior cerebral artery in 32 premature newborns with intraventricular haemorrhage. The gestational age of premature newborns was in the range from 26 to 34 weeks. There was found no corelation between intraventricular haemorrhage and resistive index of anterior cerebral artery. In 29 cases, the intraventricular haemorrhage was not accompanied by the decrease of cerebral blood flow velocity. There was no corelation betwen the time of the onset of intraventricular haemorrhage and the value of resistive index. In 9 cases with pneumothorax, the significant decrease of resistive index was detected. Another authors described increased value of resistive index (more than 0,90) of cerebral arteries in premature newborns with intraventricular haemorrhage.

Van Bel et al. (1988) analysed the Doppler parameters of anterior cerebral artery in 10 premature newborns with posthaemorrhagic hydrocephalus. There was found a significantly increased pulsatility index and peak systolic blood flow velocity before the drainage procedure. After the drainage procedure, a significant decrease of pulsatility index and peak systolic blood flow velocity was detected. The values of postoperative pulsatility index were normal. There were found no significant changes of end-diastolic blood flow velocity and mean blood flow velocity before and after the drainage procedure. The increase of pulsatility index before the surgery was caused by an increase of peak systolic blood flow velocity. The reason for the earliest indication of drainage procedure was the reduction of the damage of cerebral circulation. The indication criterion included the progressive dilatation of cerebral ventricles with increased size more than 97th percentil. The same results were published by Alvisi et al. (1985). Authors suggest, that the increase of peak systolic blood flow velocity before the drainage procedure is caused by the dislocation and compression of anterior cerebral artery by enlarged cerebral ventricles. The transport of cerebrospinal fluid into the white matter also causes the loss of transmural pressure gradient (Alvisi et al., 1985; Weller & Shulman, 1972; Wozniak et al., 1975).

The frequency and timing of intermitent drainage of cerebrospinal fluid in newborns with posthaemorrhagic hydrocephalus is still the topic of discussion. One of the aims of intermitent drainage of cerebrospinal fluid is the prevention of negative influence of raised intracranial pressure on cerebral circulation.

Kempley & Gamsu (1993) assessed the changes of intracranial pressure and Doppler parameters of anterior cerebral artery in the group of 6 newborns with posthaemorrhagic hydrocephalus before and after the drainage of cerebrospinal fluid (23 drainage procedures). There was found significant decrease of intracranial pressure after the derivation of cerebrospinal fluid. The decrease of intracranial pressure was accompanied by an increase of mean blood flow velocity and decrease of pulsatility index. The results of the study suggest, that the derivation of cerebrospinal fluid in newborns with posthaemorrhagic hydrocephalus leads to the significant improvement of haemodynamic parameters of cerebral circulation. Authors recommend, that the alteration of Doppler parameters of cerebral vessels should be taken in the consideration in the indication and timing of drainage procedure in newborns with posthaemorrhagic hydrocephalus.

Transcranial Doppler Ultrasonography in the Management of Neonatal Hydrocephalus 145

Fig. 4. Basal Doppler parameters of pericallosal artery in preterm newborn with

posthaemorrhagic hydrocephalus before the drainage procedure: decreased end-diastolic blood flow velocity, increased resistive index, increased pulsatility index (figure – authors)

Fig. 5. Positive anterior fontanelle compressive test, compressive Doppler parameters of pericallosal artery in preterm newborn with posthaemorrhagic hydrocephalus before the

drainage procedure -reverse end-diastolic blood flow (figure – authors)

Also the results of the study by Nishimaki et al. (2004) confirmed an increase of resistive index of anterior cerebral artery before the drainage procedure in newborns with posthaemorrhagic hydrocephalus. The drainage procedure, lumbar punction or punction of subcutaneous reservoir, with the aspiration of cerebrospinal fluid (5-10 ml/kg) led to the significant decrease of resistive index.

Maertzdorf et al. (2002) analysed the Doppler parameters of anterior cerebral artery and middle cerebral artery in premature newborns with posthaemorrhagic hydrocephalus. The authors performed repeated aspiration of cerebrospinal fluid from the subcutaneous reservoir. The increased resistive index and decreased end-diastolic blood flow velocity was confirmed in the cases of increased intracranial pressure (≥ 6cm H2O) before the aspiration of cerebrospinal fluid. After the derivation of cerebrospinal fluid with a decrease of intracranial pressure (≤ 6cm H2O), a significant increase of end-diastolic blood flow velocity and decrease of resistive index was found. There was no significant change of peak systolic blood flow velocity after the drainage procedure. The results of the study suggest a good intraindividual corelation between the resistive index of anterior cerebral artery and middle cerebral artery and intracranial pressure in premature newborns with posthaemorrhagic hydrocephalus.

The qualitative indices of Doppler waveform (resistive index, pulsatility index) have certain disadvantages. Both indices are influenced by the heart rate and have a broad range of reference values, especially in children. Hanlo et al. (1995a) presented a hydrodynamic model, which showed the effects of raised intracranial pressure on the cerebral circulation. The authors defined a new Doppler index, the trans-systolic time, reflecting specific changes in the Doppler waveform induced by changes in the intracranial pressure.

Leliefeld et al. (2009) analysed the relationship between the trans-systolic time of Doppler waveform of middle cerebral artery and intracranial pressure in infants with hydrocephalus.

There was found significant decrease of the intracranial pressure after the drainage procedure (p<0.005), accompanied by the significant increase of trans-systolic time (p<0.005), significant decrease of pulsatility index (p<0.05) and significant decrease of resistive index (p<0.05). Trans-systolic time has a strong correlation with the intracranial pressure (p<0.005). Trans-systolic time reflects the relative changes in the cerebral blood flow velocity caused by intracranial dynamics changes. The results of the study suggest, that the trans-systolic time has a closer relation to intracranial pressure than the pulsatility index and the resistive index.

The changes of Doppler parameters of pericallosal artery before and after the drainage procedure in preterm newborn with posthaemorrhagic hydrocephalus are shown in Figures 4-7.

Transcranial Doppler ultrasonography plays an important role in the management of newborn with hydrocephalus. Is widely used because of it´s noninvasivity, repeatability and the possibility of bedside examination. The clinical applications of transcranial Doppler ultrasonography in the management of neonatal hydrocephalus include:

Also the results of the study by Nishimaki et al. (2004) confirmed an increase of resistive index of anterior cerebral artery before the drainage procedure in newborns with posthaemorrhagic hydrocephalus. The drainage procedure, lumbar punction or punction of subcutaneous reservoir, with the aspiration of cerebrospinal fluid (5-10 ml/kg) led to the

Maertzdorf et al. (2002) analysed the Doppler parameters of anterior cerebral artery and middle cerebral artery in premature newborns with posthaemorrhagic hydrocephalus. The authors performed repeated aspiration of cerebrospinal fluid from the subcutaneous reservoir. The increased resistive index and decreased end-diastolic blood flow velocity was confirmed in the cases of increased intracranial pressure (≥ 6cm H2O) before the aspiration of cerebrospinal fluid. After the derivation of cerebrospinal fluid with a decrease of intracranial pressure (≤ 6cm H2O), a significant increase of end-diastolic blood flow velocity and decrease of resistive index was found. There was no significant change of peak systolic blood flow velocity after the drainage procedure. The results of the study suggest a good intraindividual corelation between the resistive index of anterior cerebral artery and middle cerebral artery and intracranial pressure in premature newborns with posthaemorrhagic

The qualitative indices of Doppler waveform (resistive index, pulsatility index) have certain disadvantages. Both indices are influenced by the heart rate and have a broad range of reference values, especially in children. Hanlo et al. (1995a) presented a hydrodynamic model, which showed the effects of raised intracranial pressure on the cerebral circulation. The authors defined a new Doppler index, the trans-systolic time, reflecting specific changes

Leliefeld et al. (2009) analysed the relationship between the trans-systolic time of Doppler waveform of middle cerebral artery and intracranial pressure in infants with hydrocephalus. There was found significant decrease of the intracranial pressure after the drainage procedure (p<0.005), accompanied by the significant increase of trans-systolic time (p<0.005), significant decrease of pulsatility index (p<0.05) and significant decrease of resistive index (p<0.05). Trans-systolic time has a strong correlation with the intracranial pressure (p<0.005). Trans-systolic time reflects the relative changes in the cerebral blood flow velocity caused by intracranial dynamics changes. The results of the study suggest, that the trans-systolic time has a closer relation to intracranial pressure than the pulsatility index

The changes of Doppler parameters of pericallosal artery before and after the drainage procedure in preterm newborn with posthaemorrhagic hydrocephalus are shown in Figures

Transcranial Doppler ultrasonography plays an important role in the management of newborn with hydrocephalus. Is widely used because of it´s noninvasivity, repeatability and the possibility of bedside examination. The clinical applications of transcranial Doppler

in the Doppler waveform induced by changes in the intracranial pressure.

ultrasonography in the management of neonatal hydrocephalus include:

significant decrease of resistive index.

hydrocephalus.

and the resistive index.

4-7.

Fig. 4. Basal Doppler parameters of pericallosal artery in preterm newborn with posthaemorrhagic hydrocephalus before the drainage procedure: decreased end-diastolic blood flow velocity, increased resistive index, increased pulsatility index (figure – authors)

Fig. 5. Positive anterior fontanelle compressive test, compressive Doppler parameters of pericallosal artery in preterm newborn with posthaemorrhagic hydrocephalus before the drainage procedure -reverse end-diastolic blood flow (figure – authors)

Transcranial Doppler Ultrasonography in the Management of Neonatal Hydrocephalus 147

Increased intracranial pressure in progressive neonatal hydrocephalus leads to the alteration of cerebral circulation (decreased cerebral blood flow, hypoperfusion and ischaemia). Transcranial color coded Doppler sonography provides a noninvasive method of monitoring of the blood flow velocities in cerebral vessels. In generall, there is a good corelation between the increase of intracranial pressure and changes in Doppler curve parameters. Before the drainage procedure there was confirmed increased basal and compressive values of resistive index and pulsatility index of cerebral arteries. After the successful drainage procedure, the significant decrease of basal and compressive values of

The published studies and clinical experiences confirm, that transcranial Doppler ultrasonography can be routinely used as a noninvasive method for the monitoring of cerebral circulation, indirect monitoring of intracranial pressure and compliance with good clinical applications in the indication of drainage procedure or the monitoring of the function of drainage systems and endoscopic third ventriculostomy in newborns with

This work was supported by project "Center of Excellence of Perinatology Research (CEPV

Aaslid, R., Hubert, P., & Nornes, H. (1984). Evaluation of cerebrovascular spasm with

Aaslid, R., Markwalder, TM., & Nornes, H. (1982). Noninvasive transcranial Doppler

Alvisi C., Cerisoli M., Giulioni M., Monari P., Salvioli GP., Sandri F., Lippi C., Bovicelli L., &

Ausina, A., Baquena, M., Nadal, M., Manrique, S., Ferrer, A., Sahuquillo, J., & Garnacho, A.

transcranial Doppler ultrasound. *J Neurosurg,* Vol. 60, No. 1, (January 1984), pp. 37-

ultrasound recording of flow velocity in basal cerebral arteries. *J Neurosurg,*Vol. 57,

Pilu G. (1985). Evaluation of cerebral blood flow changes by transfontanelle Doppler ultrasound in infantile hydrocephalus. *Childs Nerv Syst*, Vol. 1, No. 5,

(1998). Cerebral haemodynamic changes during sustained hypocapnia in severe

II)", ITMS code:<PHONE_NUMBER>6, which is co-financed by EU sources.

No. 6, (December 1982), pp. 769-774

(November 1985), pp. 244-247

cerebrospinal fluid), endoscopic third ventriculostomy

surgery of the shunt with malfunction

resistive index and pulsatility index was found.

ventriculostomy

**4. Conclusion**

hydrocephalus.

**6. References**

41

**5. Acknowledgment**

posthaemorrhagic hydrocephalus (frequency and the volume of derivated

Fig. 6. Basal Doppler parameters of pericallosal artery in preterm newborn with posthaemorrhagic hydrocephalus after the drainage procedure: increased end-diastolic blood flow velocity, decreased resistive index, decreased pulsatility index (figure – authors)

Fig. 7. Negative anterior fontanelle compressive test, compressive Doppler parameters of pericallosal artery in preterm newborn with posthaemorrhagic hydrocephalus after the drainage procedure (figure – authors)

posthaemorrhagic hydrocephalus (frequency and the volume of derivated cerebrospinal fluid), endoscopic third ventriculostomy

### **4. Conclusion**

146 Hydrocephalus

Fig. 6. Basal Doppler parameters of pericallosal artery in preterm newborn with posthaemorrhagic hydrocephalus after the drainage procedure: increased end-diastolic blood flow velocity, decreased resistive index, decreased pulsatility index (figure – authors)

Fig. 7. Negative anterior fontanelle compressive test, compressive Doppler parameters of pericallosal artery in preterm newborn with posthaemorrhagic hydrocephalus after the

drainage procedure (figure – authors)

Increased intracranial pressure in progressive neonatal hydrocephalus leads to the alteration of cerebral circulation (decreased cerebral blood flow, hypoperfusion and ischaemia). Transcranial color coded Doppler sonography provides a noninvasive method of monitoring of the blood flow velocities in cerebral vessels. In generall, there is a good corelation between the increase of intracranial pressure and changes in Doppler curve parameters. Before the drainage procedure there was confirmed increased basal and compressive values of resistive index and pulsatility index of cerebral arteries. After the successful drainage procedure, the significant decrease of basal and compressive values of resistive index and pulsatility index was found.

The published studies and clinical experiences confirm, that transcranial Doppler ultrasonography can be routinely used as a noninvasive method for the monitoring of cerebral circulation, indirect monitoring of intracranial pressure and compliance with good clinical applications in the indication of drainage procedure or the monitoring of the function of drainage systems and endoscopic third ventriculostomy in newborns with hydrocephalus.

#### **5. Acknowledgment**

This work was supported by project "Center of Excellence of Perinatology Research (CEPV II)", ITMS code:<PHONE_NUMBER>6, which is co-financed by EU sources.

#### **6. References**

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**10**

Yasuo Aihara

*Japan*

**Novel Method for Controlling Cerebrospinal**

**Fluid Flow and Intracranial Pressure by**

*Department of Neurosurgery, Tokyo Women's Medical University, Tokyo,*

In general, cerebrospinal fluid (CSF) shunt valves control the intracranial pressure rather than fluid flow or other aspects. 1-4 There are various kinds of shunt valves including fixed pressure and programmable valves. Fixed pressure valves usually have low, medium or high pressure settings. The choice of valve pressure is based on preoperative intracranial

Programmable valves with or without anti-siphon devices were subsequently developed. 9-16 CSF flow is regulated by adjusting the pressure via a magnetically-controlled valve. However, CSF dynamics are complicated because production and absorption rates of CSF may vary in any given patient. Consequently, the existing shunt systems cannot correspond to each of these situations. With regard to intracranial pressure; treatment *in vivo* involves not only setting the shunt's valve pressure but also taking into consideration the CSF flow rate; which is a very important parameter.17, 18. Even with anti-siphon devices attached to some valves, despite their advantages, there is still no perfect valve system in neurosurgery as devices with these attachments still fail to adequately control pressure requirements as well as CSF flow rates at the same time. Practically, we sometimes experience a patient with

To overcome the difficulties of the existing shunt valve systems in achieving adequate CSF pressure and flow control, we contrived a novel tandem shunt valve system. We performed *in vitro* experiments using a manometer, and report the first clinical application of the novel

An *in vitro* system with a manometer was built to measure pressure and flow rates of water in open and closed systems using the Codman (Codman; Johnson & Johnson Co., Raynham) Hakim programmable valve (CHPV) and the STRATA programmable valve (Medtronic, Inc, Minneapolis) as shown in figures 1 and 2, respectively. Single (Fig. 1a and Fig. 2a) and two single shunt valves (Fig. 1b and Fig. 2b) connected in series (the tandem shunt system) were

pressure, clinical course, cerebral ventricle size, age, and the lifestyle of the patient.5-8

over-drainage problem even using an anti-siphon device.

connected to the manometer to check the pressure.

tandem shunt system in humans.

**2. Material and methods**

**1. Introduction**

**Use of a Tandem Shunt-Valve System**

### **Novel Method for Controlling Cerebrospinal Fluid Flow and Intracranial Pressure by Use of a Tandem Shunt-Valve System**

Yasuo Aihara *Department of Neurosurgery, Tokyo Women's Medical University, Tokyo, Japan*

#### **1. Introduction**

152 Hydrocephalus

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EO. (1991). Response of cerebral blood volume to change in arterial carbon dioxide tension in preterm and term infants. *Pediatr Res,* Vol. 29, No. 6, (June 1991), pp. 553In general, cerebrospinal fluid (CSF) shunt valves control the intracranial pressure rather than fluid flow or other aspects. 1-4 There are various kinds of shunt valves including fixed pressure and programmable valves. Fixed pressure valves usually have low, medium or high pressure settings. The choice of valve pressure is based on preoperative intracranial pressure, clinical course, cerebral ventricle size, age, and the lifestyle of the patient.5-8

Programmable valves with or without anti-siphon devices were subsequently developed. 9-16 CSF flow is regulated by adjusting the pressure via a magnetically-controlled valve. However, CSF dynamics are complicated because production and absorption rates of CSF may vary in any given patient. Consequently, the existing shunt systems cannot correspond to each of these situations. With regard to intracranial pressure; treatment *in vivo* involves not only setting the shunt's valve pressure but also taking into consideration the CSF flow rate; which is a very important parameter.17, 18. Even with anti-siphon devices attached to some valves, despite their advantages, there is still no perfect valve system in neurosurgery as devices with these attachments still fail to adequately control pressure requirements as well as CSF flow rates at the same time. Practically, we sometimes experience a patient with over-drainage problem even using an anti-siphon device.

To overcome the difficulties of the existing shunt valve systems in achieving adequate CSF pressure and flow control, we contrived a novel tandem shunt valve system. We performed *in vitro* experiments using a manometer, and report the first clinical application of the novel tandem shunt system in humans.

#### **2. Material and methods**

An *in vitro* system with a manometer was built to measure pressure and flow rates of water in open and closed systems using the Codman (Codman; Johnson & Johnson Co., Raynham) Hakim programmable valve (CHPV) and the STRATA programmable valve (Medtronic, Inc, Minneapolis) as shown in figures 1 and 2, respectively. Single (Fig. 1a and Fig. 2a) and two single shunt valves (Fig. 1b and Fig. 2b) connected in series (the tandem shunt system) were connected to the manometer to check the pressure.

Novel Shunt Therapy for Hydrocephalus 155

Top (2a): Manometer connected to the single shunt valve with a scale on the opposite end to measure

Bottom (2b): the inclusion of another STRATA shunt valve connected in series was the only change

end to measure the volume of water as seen in figure 2. In our single valve open system experiment the manometer was set to 400 mmH2O and the STRATA valve used had 5 programmable settings (0.5, 1.0, 1.5, 2.0, and 2.5). These are referred to as performance levels (PL) by STRATA and we took manometer readings at each PL. An electric flow meter was also used to measure the volume of water every 30 seconds for each PL. The same measurements for the open tandem shunt valve system (Fig. 2b) were also taken but for different combinations of PLs. This experiment helped us illustrate the effects of a tandem

Fig. 2. *In Vitro* Open system with STRATA programmable valves (Medtronic, Inc,

volume of water over time.

shunt valve system in hydrocephalus cases.

made to the system.

Minneapolis)

Top (1a): single shunt valve setup with clamp to close the system. Bottom (2b): closed setup with two shunt valves connected in series (tandem shunt valve system) with clamp to close the system.

Fig. 1. *In Vitro* closed system with Codman (Codman; Johnson & Johnson Co., Raynham) Hakim programmable valves (CHPV)

#### **2.1 In vitro closed system with water bath (Fig. 1)**

In the closed single shunt valve system experiment, as shown in figure 1a, we measured the pressure in the original bath to be 400 mmH2O with a closed valve (V1). We conducted 3 changes to V1, the valve pressure of the CHPV, and took 5 measurements each at V1=50, V1=100 and V1=200. Figure 1b shows the setup in a closed tandem shunt valve system. If we set V1=50 and V2=50, the total pressure setting of the valves (V) is V1 + V2 = 100. Other combinations of V1 and V2 were taken and six are reported below.

#### **2.2 In vitro open system with manometer (Fig. 2)**

An open system represents the real world environment. Unlike figure 1a and figure 1b, figure 2 does not have a clamp at the endpoint to keep the system closed. In our experiment we have the STRATA valve directly connected to the manometer and a scale at the other

Top (1a): single shunt valve setup with clamp to close the system.

**2.1 In vitro closed system with water bath (Fig. 1)**

**2.2 In vitro open system with manometer (Fig. 2)**

combinations of V1 and V2 were taken and six are reported below.

clamp to close the system.

Hakim programmable valves (CHPV)

Bottom (2b): closed setup with two shunt valves connected in series (tandem shunt valve system) with

Fig. 1. *In Vitro* closed system with Codman (Codman; Johnson & Johnson Co., Raynham)

In the closed single shunt valve system experiment, as shown in figure 1a, we measured the pressure in the original bath to be 400 mmH2O with a closed valve (V1). We conducted 3 changes to V1, the valve pressure of the CHPV, and took 5 measurements each at V1=50, V1=100 and V1=200. Figure 1b shows the setup in a closed tandem shunt valve system. If we set V1=50 and V2=50, the total pressure setting of the valves (V) is V1 + V2 = 100. Other

An open system represents the real world environment. Unlike figure 1a and figure 1b, figure 2 does not have a clamp at the endpoint to keep the system closed. In our experiment we have the STRATA valve directly connected to the manometer and a scale at the other

Top (2a): Manometer connected to the single shunt valve with a scale on the opposite end to measure volume of water over time.

Bottom (2b): the inclusion of another STRATA shunt valve connected in series was the only change made to the system.

Fig. 2. *In Vitro* Open system with STRATA programmable valves (Medtronic, Inc, Minneapolis)

end to measure the volume of water as seen in figure 2. In our single valve open system experiment the manometer was set to 400 mmH2O and the STRATA valve used had 5 programmable settings (0.5, 1.0, 1.5, 2.0, and 2.5). These are referred to as performance levels (PL) by STRATA and we took manometer readings at each PL. An electric flow meter was also used to measure the volume of water every 30 seconds for each PL. The same measurements for the open tandem shunt valve system (Fig. 2b) were also taken but for different combinations of PLs. This experiment helped us illustrate the effects of a tandem shunt valve system in hydrocephalus cases.

#### **3. Results**

#### **3.1 In vitro closed system with water bath**

In the single shunt valve system experiment, when V1 was adjusted to 50, the final measurement in the manometer equaled around 350 mmH2O (Fig. 3a). When V1=100, the final manometer reading was around 300 mmH2O. Subsequently a V1 adjustment of 200 resulted in a final manometer reading of around 200 mmH2O. Based on these results, we can conclude that the original water bath pressure = V1 pressure value + final manometer value (M1) as shown in figure 3a, where the average results of 5 measurements at (V1=50, 100 and 200) were taken. In the closed tandem shunt valve system experiment, when the final manometer reading was 300 mmH2O, the sum of V1 + V2 always equaled around 100. We conducted further experiments that measured five manometer readings at different combinations of V1 and V2 such that (V1 + V2 = 100, 150, 200, 250, 300 and 400) and averaged the results as summarized in figure 3b. Based on our experiment, the final manometer pressure is the original water bath pressure minus (V1+V2). This principal holds for any value of V1 and V2. In conclusion, when two valves (Fig. 1b) are connected in series, regardless of whether one is higher than the other, their sum will always behave in the same way as the one valve in the closed system as shown in figure 1a.

#### **3.2 In vitro open system with manometer**

In an open system, at any value of V1, the manometer represents the same value as V1. At PL of 0.5 on the STRATA valve the final manometer reading was approximately 30mmH2O after we had allowed the system to run for some time. Subsequent PL settings were measured and their final pressure manometer readings are as follow: 1.0≅40 mmH2O; 1.5≅100 mmH2O, 2.0≅170 mmH2O, and 2.5≅200 mmH2O as seen in the legend of figure 4. Figure 4 also shows the calculated flow rate (ml/min) curve over time. At the highest PL setting of 2.5 we achieved a lower flow rate as expected.

Figure 2b shows two valves connected in series in an open system (tandem system). In our tandem valve open system experiment we varied V1 and V2 and measured the final manometer readings for each combination and a summarized table of results is shown in Table 1. Interestingly, in the tandem system, the final pressure was almost equal to the highest pressure setting of one of the valves in the system. In a single valve system the flow rate changed depending on the valve pressure (Fig. 4). On the other hand, the flow rate in the tandem system depends on the total pressure of each shunt valve setting (Fig. 5). Furthermore, based on our experiments, we concluded that in an open system, along with reducing the flow rate, we discovered that we could control pressure because the final pressure reading on the manometer was always equal to the highest pressure value of either V1 or V2.

We assessed all combinations of tandem shunt valve pressures. The result was that the flow rate depended on the total valve pressure in the system (Fig. 5). Of considerable significance in table 1 is the experiment with STRATA performance level (1.0 + 1.0) and STRATA performance level (2.0). We would expect the final manometer pressure to be the same for these two experiments (because the PL totals are the same) but they are actually 50 mmH20 and 170 mmH20, respectively. There are two significant points here 1) flow rate and 2) final Novel Shunt Therapy for Hydrocephalus 157

(a)

(b) Demonstrating that the original water bath pressure = V1 pressure + final manometer reading (M1). With two valves connected in series, the following relationship continues to exist: original water bath

Fig. 3. (a) Single shunt valve experiment results for the closed system (b) Tandem shunt

pressure = (V1 pressure + V2 pressure) + final manometer reading (M1).

valve experiment results for the closed system

In the single shunt valve system experiment, when V1 was adjusted to 50, the final measurement in the manometer equaled around 350 mmH2O (Fig. 3a). When V1=100, the final manometer reading was around 300 mmH2O. Subsequently a V1 adjustment of 200 resulted in a final manometer reading of around 200 mmH2O. Based on these results, we can conclude that the original water bath pressure = V1 pressure value + final manometer value (M1) as shown in figure 3a, where the average results of 5 measurements at (V1=50, 100 and 200) were taken. In the closed tandem shunt valve system experiment, when the final manometer reading was 300 mmH2O, the sum of V1 + V2 always equaled around 100. We conducted further experiments that measured five manometer readings at different combinations of V1 and V2 such that (V1 + V2 = 100, 150, 200, 250, 300 and 400) and averaged the results as summarized in figure 3b. Based on our experiment, the final manometer pressure is the original water bath pressure minus (V1+V2). This principal holds for any value of V1 and V2. In conclusion, when two valves (Fig. 1b) are connected in series, regardless of whether one is higher than the other, their sum will always behave in the same

In an open system, at any value of V1, the manometer represents the same value as V1. At PL of 0.5 on the STRATA valve the final manometer reading was approximately 30mmH2O after we had allowed the system to run for some time. Subsequent PL settings were measured and their final pressure manometer readings are as follow: 1.0≅40 mmH2O; 1.5≅100 mmH2O, 2.0≅170 mmH2O, and 2.5≅200 mmH2O as seen in the legend of figure 4. Figure 4 also shows the calculated flow rate (ml/min) curve over time. At the highest PL

Figure 2b shows two valves connected in series in an open system (tandem system). In our tandem valve open system experiment we varied V1 and V2 and measured the final manometer readings for each combination and a summarized table of results is shown in Table 1. Interestingly, in the tandem system, the final pressure was almost equal to the highest pressure setting of one of the valves in the system. In a single valve system the flow rate changed depending on the valve pressure (Fig. 4). On the other hand, the flow rate in the tandem system depends on the total pressure of each shunt valve setting (Fig. 5). Furthermore, based on our experiments, we concluded that in an open system, along with reducing the flow rate, we discovered that we could control pressure because the final pressure reading on the manometer was always equal to the highest pressure value of either

We assessed all combinations of tandem shunt valve pressures. The result was that the flow rate depended on the total valve pressure in the system (Fig. 5). Of considerable significance in table 1 is the experiment with STRATA performance level (1.0 + 1.0) and STRATA performance level (2.0). We would expect the final manometer pressure to be the same for these two experiments (because the PL totals are the same) but they are actually 50 mmH20 and 170 mmH20, respectively. There are two significant points here 1) flow rate and 2) final

**3. Results**

V1 or V2.

**3.1 In vitro closed system with water bath**

**3.2 In vitro open system with manometer**

way as the one valve in the closed system as shown in figure 1a.

setting of 2.5 we achieved a lower flow rate as expected.

Demonstrating that the original water bath pressure = V1 pressure + final manometer reading (M1). With two valves connected in series, the following relationship continues to exist: original water bath pressure = (V1 pressure + V2 pressure) + final manometer reading (M1).

Fig. 3. (a) Single shunt valve experiment results for the closed system (b) Tandem shunt valve experiment results for the closed system

Novel Shunt Therapy for Hydrocephalus 159

pressure. From figure 5, if we compare the rate of decrease between the two experiments we find that the curves follow similar flow rates, which indicates that even at different pressures we can control the flow rate. In fact, at PL (1.0 + 1.0), the final pressure of 50 mmH20 is quite similar to that of a single valve with PL (1.0), where pressure is 40 mmH20 as shown in table 1, but exhibits flow rates similar to PL (2.0). Similarly compare the experiments where

performance level (2.0 + 0.5) with performance level (2.5) and the same property exist.

When the total performance levels are the same, the flow rates are similar. However, flow rates can

In conclusion, we can decrease flow rate without a major change in pressure using a tandem shunt valve system. After obtaining these *in vitro* results, we implemented tandem shunt valve systems in two shunt cases where problems associated with shunt implants such as

A 6-year-old girl with a malignant glioma underwent bilateral ventricle-peritoneal (V-P) shunt (CHPV) for obstructive hydrocephalus. Although the patient's intracranial pressure was controlled by the shunt system (valve pressure was 150 mmH2O), hydrocephalus developed during chemotherapy and radiotherapy. The lateral ventricle size and abdominal circumference increased due to a peritoneal fluid collection caused by tumor tissue dissemination through the V-P shunt tract. The shunt valve pressure was adjusted from 150 to 180 mmH2O to solve this over-drainage problem. However this caused acute

Fig. 5. Tandem shunt valve experiment results for the open system

slit like ventricle and or intractable hydrocephalus were present.

decrease while maintaining final pressures.

**Case 1**

Each performance level setting on the STRATA valve corresponds to a final pressure reading as shown in the legend. Flow rate depends on shunt valve pressure setting.

Table 1. Results comparing the Single shunt valve with Tandem shunt valve in the Open system. In the tandem system, with V1 at 1.0 and V2 at 1.0 the final pressure (50 mmH2O) is always close to the final pressure (40 mmH2O) when V1 is at 1.0 in a single valve system.

Each performance level setting on the STRATA valve corresponds to a final pressure reading as shown

Table 1. Results comparing the Single shunt valve with Tandem shunt valve in the Open system. In the tandem system, with V1 at 1.0 and V2 at 1.0 the final pressure (50 mmH2O) is always close to the final pressure (40 mmH2O) when V1 is at 1.0 in a single valve system.

in the legend. Flow rate depends on shunt valve pressure setting.

Fig. 4. Single shunt valve experiment results for the open system

pressure. From figure 5, if we compare the rate of decrease between the two experiments we find that the curves follow similar flow rates, which indicates that even at different pressures we can control the flow rate. In fact, at PL (1.0 + 1.0), the final pressure of 50 mmH20 is quite similar to that of a single valve with PL (1.0), where pressure is 40 mmH20 as shown in table 1, but exhibits flow rates similar to PL (2.0). Similarly compare the experiments where performance level (2.0 + 0.5) with performance level (2.5) and the same property exist.

When the total performance levels are the same, the flow rates are similar. However, flow rates can decrease while maintaining final pressures.

Fig. 5. Tandem shunt valve experiment results for the open system

In conclusion, we can decrease flow rate without a major change in pressure using a tandem shunt valve system. After obtaining these *in vitro* results, we implemented tandem shunt valve systems in two shunt cases where problems associated with shunt implants such as slit like ventricle and or intractable hydrocephalus were present.

#### **Case 1**

A 6-year-old girl with a malignant glioma underwent bilateral ventricle-peritoneal (V-P) shunt (CHPV) for obstructive hydrocephalus. Although the patient's intracranial pressure was controlled by the shunt system (valve pressure was 150 mmH2O), hydrocephalus developed during chemotherapy and radiotherapy. The lateral ventricle size and abdominal circumference increased due to a peritoneal fluid collection caused by tumor tissue dissemination through the V-P shunt tract. The shunt valve pressure was adjusted from 150 to 180 mmH2O to solve this over-drainage problem. However this caused acute

Novel Shunt Therapy for Hydrocephalus 161

Intra-ventricular cerebrospinal fluid, shunt valve opening pressure, and intra-abdominal pressure are, through common use in neurosurgery and convention, called ICP, valve pressure and abdominal pressure, respectively. If we also consider the tube connecting the head to the abdominal, a difference of water pressure is present, conventionally referred to as hydrostatic pressure. If we assume (ICP + hydrostatic pressure) – (valve pressure + abdominal pressure) = 0, then this simplifies to ICP = (valve pressure + abdominal pressure)

The difference in pressure causes fluid flow, however, other parameters to consider include the coefficient of viscosity caused by protein in the CSF, resistance between inner wall shunt tube and CSF flow (tube diameter), the positioning of the shunt valve (forehead or back of the head) and the intra-abdominal tube length and so on. All these parameters contribute to complicated flow dynamics, but a simpler approach is to only use pressures to help us describe fluid flow in a shunt system. In our *in vitro* experiment, we kept all other parameters the same and only changed pressure via valve settings and in the tandem shunt valve system, an additional shunt valve. This tandem system allowed us to precisely control the pressure and flow rate. Until now, CSF flow rate was always the result of the shunt's valve pressure but there has been no study to control the CSF flow rate and ICP individually. Our *in vitro* experiment showed that the tandem system was able to control

Intracranial pressure automatically changes when the position of the head and abdominal changes (e.g. compare heights of standing versus sleeping person); these changes cause a siphon effect, which makes it extremely difficult to control ICP with only a single shunt

Even with an anti-siphon system in place, controlling CSF flow is still difficult. However, with the tandem shunt valve system in place we were able to create a low CSF flow rate environment without increasing the intracranial pressure. In a single valve shunt system it was impossible to create such an environment while maintaining a constant ICP even with an anti-siphon system installed, because, as shown in our experiments, CSF flow is always directly related to the pressure setting at the valve. However, in the tandem valve shunt system, the most significant finding was that the final pressure was equal to the highest valve pressure of the two valves (Fig. 6). This means that in practice, this system has the possibility to control the intracranial pressure without increasing the pressure that is

Figure 6 demonstrates the mechanism behind the tandem shunt valves. It is used to show that the final pressure is equal to the highest valve pressure of the two tandem valves. M, V1 and V2 represent ICP in the human body, and the pressure settings at the shunt valve respectively. In M1 and M2 we add two walls V1 and V2 as shown in figure 6. It shows that regardless of where the highest wall is placed, the final water level at the highest wall will always be the same as the water level in column M. This demonstrates that the final

In terms of pressure management in the brain, when there are two valves present in a tandem shunt valve system, ICP pressure is controlled at the highest valve setting at the

pressure always equals the final pressures setting of either V1 or V2 (Fig 6a, b).

**4. Discussion**

system. 19-21

required by the patient.

CSF flow rate and ICP independently of each other.

hydrocephalus with deteriorating consciousness. The shunt valve pressure was decreased from 180 to 140 mmH2O. Although the ventricular size decreased and her consciousness improved, the fluid collection in the peritoneal cavity rapidly increased, which caused dyspnea due to high peritoneal pressure. We informed her parents about the two paradoxical problems that needed to be solved simultaneously, 1) finding the best V-P shunt valve pressure to prevent the hydrocephalus, and 2) reducing the amount of peritoneal fluid collection containing the brain tumor tissue and debris. To solve the opposing problems of obtaining sufficient CSF drainage to treat the hydrocephalus but not so much that it would cause peritoneal fluid collection, we tested the therapeutic possibility of the tandem shunt system by adding another adjustable valve (CHPV) with anti-siphon to the current setup. The new tandem shunt system was a connection from the lateral ventricle CHPV (1st valve) connected to the CHPV (2nd valve) with siphon guard to the peritoneal cavity. The performance level of the new tandem shunt system was adjusted to 140 mmH2O for the 1st valve and 100 mmH2O for 2nd valve. Hydrocephalus remarkably improved without peritoneal fluid collection and the patient was able to walk soon after the implant.

#### **Case 2**

A one and a half-year-old boy infected with Group B Streptococcus during pregnancy, born prematurely in July, 2007 at the gestational age of 28 weeks and weighing 1230g presented with progressive enlargement of head circumference as compared with his body size. Ultrasonography and CT scans revealed hydrocephalus caused by subependymal hemorrhage and periventricular leukomalacia. After controlling intracranial pressure using the Ommaya reservoir, a V-P shunt (Programmable STRATA non siphon control (NSC) Valve) was implanted at the age of 98 days (42 weeks gestation). The intracranial pressure was well controlled at the programmable performance valve level of 1.5. However, the performance level was changed to 2.5 (maximum pressure), because a CT scan showed slit lateral ventricles 6 months after the first shunt placement. After a temporary slight increase in size of the lateral ventricle, the patient was unable to keep a head-up position, which was judged to be a symptom of slit ventricles. Although an anti-siphon device (Delta chamber, Medtronic, Inc., Minneapolis) was added to the shunt system, which resulted in improvement of his symptoms for a month, he continued to suffer from depressed mood and loss of appetite in the head-up position. Moreover, he presented with acute hydrocephalus one day after the transient ligation of the shunt system to check the shunt system dependency. His parents were informed about the details of CSF over-drainage symptoms and the therapeutic possibility of tandem shunt valve system connection surgery. An extra adjustable STRATA NSC valve was connected to the previous shunt system. The final whole view of the tandem shunt valve system was a connection from the lateral ventricle to the STRATA NSC programmable valve (1st valve) connected to the STRATA NSC programmable valve (2nd valve) with anti-siphon system (Delta chamber) to the peritoneal cavity. The performance level of the new tandem shunt system was adjusted to 2.5 (1st valve) and 0.5 (2nd valve) but there was no remarkable change in his condition. After a few days, his second shunt valve performance level was adjusted from 0.5 to 1.0 and his general condition improved dramatically and he was able to keep head-up position over several hours.

#### **4. Discussion**

160 Hydrocephalus

hydrocephalus with deteriorating consciousness. The shunt valve pressure was decreased from 180 to 140 mmH2O. Although the ventricular size decreased and her consciousness improved, the fluid collection in the peritoneal cavity rapidly increased, which caused dyspnea due to high peritoneal pressure. We informed her parents about the two paradoxical problems that needed to be solved simultaneously, 1) finding the best V-P shunt valve pressure to prevent the hydrocephalus, and 2) reducing the amount of peritoneal fluid collection containing the brain tumor tissue and debris. To solve the opposing problems of obtaining sufficient CSF drainage to treat the hydrocephalus but not so much that it would cause peritoneal fluid collection, we tested the therapeutic possibility of the tandem shunt system by adding another adjustable valve (CHPV) with anti-siphon to the current setup. The new tandem shunt system was a connection from the lateral ventricle CHPV (1st valve) connected to the CHPV (2nd valve) with siphon guard to the peritoneal cavity. The performance level of the new tandem shunt system was adjusted to 140 mmH2O for the 1st valve and 100 mmH2O for 2nd valve. Hydrocephalus remarkably improved without

peritoneal fluid collection and the patient was able to walk soon after the implant.

A one and a half-year-old boy infected with Group B Streptococcus during pregnancy, born prematurely in July, 2007 at the gestational age of 28 weeks and weighing 1230g presented with progressive enlargement of head circumference as compared with his body size. Ultrasonography and CT scans revealed hydrocephalus caused by subependymal hemorrhage and periventricular leukomalacia. After controlling intracranial pressure using the Ommaya reservoir, a V-P shunt (Programmable STRATA non siphon control (NSC) Valve) was implanted at the age of 98 days (42 weeks gestation). The intracranial pressure was well controlled at the programmable performance valve level of 1.5. However, the performance level was changed to 2.5 (maximum pressure), because a CT scan showed slit lateral ventricles 6 months after the first shunt placement. After a temporary slight increase in size of the lateral ventricle, the patient was unable to keep a head-up position, which was judged to be a symptom of slit ventricles. Although an anti-siphon device (Delta chamber, Medtronic, Inc., Minneapolis) was added to the shunt system, which resulted in improvement of his symptoms for a month, he continued to suffer from depressed mood and loss of appetite in the head-up position. Moreover, he presented with acute hydrocephalus one day after the transient ligation of the shunt system to check the shunt system dependency. His parents were informed about the details of CSF over-drainage symptoms and the therapeutic possibility of tandem shunt valve system connection surgery. An extra adjustable STRATA NSC valve was connected to the previous shunt system. The final whole view of the tandem shunt valve system was a connection from the lateral ventricle to the STRATA NSC programmable valve (1st valve) connected to the STRATA NSC programmable valve (2nd valve) with anti-siphon system (Delta chamber) to the peritoneal cavity. The performance level of the new tandem shunt system was adjusted to 2.5 (1st valve) and 0.5 (2nd valve) but there was no remarkable change in his condition. After a few days, his second shunt valve performance level was adjusted from 0.5 to 1.0 and his general condition improved dramatically and he was able to keep head-up position over

**Case 2**

several hours.

Intra-ventricular cerebrospinal fluid, shunt valve opening pressure, and intra-abdominal pressure are, through common use in neurosurgery and convention, called ICP, valve pressure and abdominal pressure, respectively. If we also consider the tube connecting the head to the abdominal, a difference of water pressure is present, conventionally referred to as hydrostatic pressure. If we assume (ICP + hydrostatic pressure) – (valve pressure + abdominal pressure) = 0, then this simplifies to ICP = (valve pressure + abdominal pressure) - hydrostatic pressure.

The difference in pressure causes fluid flow, however, other parameters to consider include the coefficient of viscosity caused by protein in the CSF, resistance between inner wall shunt tube and CSF flow (tube diameter), the positioning of the shunt valve (forehead or back of the head) and the intra-abdominal tube length and so on. All these parameters contribute to complicated flow dynamics, but a simpler approach is to only use pressures to help us describe fluid flow in a shunt system. In our *in vitro* experiment, we kept all other parameters the same and only changed pressure via valve settings and in the tandem shunt valve system, an additional shunt valve. This tandem system allowed us to precisely control the pressure and flow rate. Until now, CSF flow rate was always the result of the shunt's valve pressure but there has been no study to control the CSF flow rate and ICP individually. Our *in vitro* experiment showed that the tandem system was able to control CSF flow rate and ICP independently of each other.

Intracranial pressure automatically changes when the position of the head and abdominal changes (e.g. compare heights of standing versus sleeping person); these changes cause a siphon effect, which makes it extremely difficult to control ICP with only a single shunt system. 19-21

Even with an anti-siphon system in place, controlling CSF flow is still difficult. However, with the tandem shunt valve system in place we were able to create a low CSF flow rate environment without increasing the intracranial pressure. In a single valve shunt system it was impossible to create such an environment while maintaining a constant ICP even with an anti-siphon system installed, because, as shown in our experiments, CSF flow is always directly related to the pressure setting at the valve. However, in the tandem valve shunt system, the most significant finding was that the final pressure was equal to the highest valve pressure of the two valves (Fig. 6). This means that in practice, this system has the possibility to control the intracranial pressure without increasing the pressure that is required by the patient.

Figure 6 demonstrates the mechanism behind the tandem shunt valves. It is used to show that the final pressure is equal to the highest valve pressure of the two tandem valves. M, V1 and V2 represent ICP in the human body, and the pressure settings at the shunt valve respectively. In M1 and M2 we add two walls V1 and V2 as shown in figure 6. It shows that regardless of where the highest wall is placed, the final water level at the highest wall will always be the same as the water level in column M. This demonstrates that the final pressure always equals the final pressures setting of either V1 or V2 (Fig 6a, b).

In terms of pressure management in the brain, when there are two valves present in a tandem shunt valve system, ICP pressure is controlled at the highest valve setting at the

Novel Shunt Therapy for Hydrocephalus 163

shunt, while CSF flow rate is controlled by adjusting the valve settings. Until now, shunted patients in a single valve system have always been treated with respect to pressure. That is, we do not attempt to control the flow rate but attempt to control the pressure setting at the valve and flow rate is just a consequence of the pressure setting at the valve; that is higher pressure, lower CSF flow and vice versa. We have shown here that we can control CSF rate

Assume a performance level of 3.0 was required of a patient in a single shunt valve system using the STRATA valve. We could only do this by using 2 STRATA valves; the first (V1) connected to another STRATA (V2) shunt valve with the following V1 + V2 patterns available: (2.5 + 0.5, 2.0 + 1.0, 1.5 + 1.5). Each of these patterns result in 1) achieve the performance level of 3.0 and 2) set up the final ICP so that it would be controlled at 2.5, 2.0, and 1.5 (the highest valve pressure of the two valves). With only a single valve, the performance level of 3.0 would not be possible because the maximum performance level is 2.5. Furthermore, we were able to control the pressure while changing the flow rate with the

While the STRATA valve has only 5 settings, the CHPV has settings from 30 to 200 at increments of 10. If we try to create a 250 environment with the CHPV, as required by the patient, it would be impossible to do so with only one valve. In a tandem system there are eight patterns available: (200 +50, 190 +60, 180 +70, 170 +80, 160 +90, 150+100, 140 +110, and 130 +120) with the CHPV shunt valve connected to another CHPV directly; creating a tandem shunt valve system. Each pattern could set up the final ICP controlled at 200, 190, 180, 170, 160, 150, 140, and 130, respectively. These results would be the same condition as the STRATA example, that is, flow rate would be adjustable while keeping ICP controlled to the highest pressure setting of either V1 or V2. Because of the different combinations available we could select the best shunt valve pressure pair depending on the condition of

With the above mechanism, the tandem shunt valve systems (performance level (2.5+1.0)) prevent intracranial pressure to increase thereby decreasing cerebrospinal fluid flow as opposed to the single valve system performance level (2.5); which is extremely significant for treating slit-like ventricle. We can prevent an increasing ICP and limit flow rate at the same time, which is especially substantial for treating cases of over drainage. Our case studies have demonstrated that this control is only possible with a tandem shunt valve

Given the associated problems that come with the usage of a single shunt, there will be a firm requirement for a shunt with tandem shunt valve properties in the future. Our mission is to assist development in this area is through the establishment of a new tandem shunt valve which contains two programmable valves in one device/chassis allowing for the best CSF flow and final ICP combination condition (Figure 7) in hydrocephalus patients. Since there have already been two successful clinical cases further studies to investigate clinical performance will only benefit hydrocephalus cases. The new tandem shunt valve system described here will provide future opportunities to achieve ICP pressure and CSF flow control in hydrocephalus and other related conditions requiring the prevention of pressure

and ICP independently in the tandem shunt valve system.

tandem shunt valve system using the STRATA valves.

system in place and not a single valve system.

fall and fluid flow management at the same time.

the patient.

Top (6a): Liquid filled column system with two walls V1 and V2. Water level at M equals water level of V2 demonstrating that final pressure equals the pressure setting at the shunt, or in this case, height of the wall. M gauges pressure in this system, and represents ICP in the body.

Bottom (6b): Liquid filled column system with two walls V1 and V2 heights reversed. Water height at the highest wall is the same as the water height at M. Regardless of the ordering of V1 or V2, the final pressure will always equal to the highest pressure setting of either V1 and or V2. In real life ICP is controlled by the height of the highest setting of the two shunts.

Fig. 6. Controlling ICP - a special mechanism of tandem shunt valves

Top (6a): Liquid filled column system with two walls V1 and V2. Water level at M equals water level of V2 demonstrating that final pressure equals the pressure setting at the shunt, or in this case, height of

Bottom (6b): Liquid filled column system with two walls V1 and V2 heights reversed. Water height at the highest wall is the same as the water height at M. Regardless of the ordering of V1 or V2, the final pressure will always equal to the highest pressure setting of either V1 and or V2. In real life ICP is

the wall. M gauges pressure in this system, and represents ICP in the body.

Fig. 6. Controlling ICP - a special mechanism of tandem shunt valves

controlled by the height of the highest setting of the two shunts.

shunt, while CSF flow rate is controlled by adjusting the valve settings. Until now, shunted patients in a single valve system have always been treated with respect to pressure. That is, we do not attempt to control the flow rate but attempt to control the pressure setting at the valve and flow rate is just a consequence of the pressure setting at the valve; that is higher pressure, lower CSF flow and vice versa. We have shown here that we can control CSF rate and ICP independently in the tandem shunt valve system.

Assume a performance level of 3.0 was required of a patient in a single shunt valve system using the STRATA valve. We could only do this by using 2 STRATA valves; the first (V1) connected to another STRATA (V2) shunt valve with the following V1 + V2 patterns available: (2.5 + 0.5, 2.0 + 1.0, 1.5 + 1.5). Each of these patterns result in 1) achieve the performance level of 3.0 and 2) set up the final ICP so that it would be controlled at 2.5, 2.0, and 1.5 (the highest valve pressure of the two valves). With only a single valve, the performance level of 3.0 would not be possible because the maximum performance level is 2.5. Furthermore, we were able to control the pressure while changing the flow rate with the tandem shunt valve system using the STRATA valves.

While the STRATA valve has only 5 settings, the CHPV has settings from 30 to 200 at increments of 10. If we try to create a 250 environment with the CHPV, as required by the patient, it would be impossible to do so with only one valve. In a tandem system there are eight patterns available: (200 +50, 190 +60, 180 +70, 170 +80, 160 +90, 150+100, 140 +110, and 130 +120) with the CHPV shunt valve connected to another CHPV directly; creating a tandem shunt valve system. Each pattern could set up the final ICP controlled at 200, 190, 180, 170, 160, 150, 140, and 130, respectively. These results would be the same condition as the STRATA example, that is, flow rate would be adjustable while keeping ICP controlled to the highest pressure setting of either V1 or V2. Because of the different combinations available we could select the best shunt valve pressure pair depending on the condition of the patient.

With the above mechanism, the tandem shunt valve systems (performance level (2.5+1.0)) prevent intracranial pressure to increase thereby decreasing cerebrospinal fluid flow as opposed to the single valve system performance level (2.5); which is extremely significant for treating slit-like ventricle. We can prevent an increasing ICP and limit flow rate at the same time, which is especially substantial for treating cases of over drainage. Our case studies have demonstrated that this control is only possible with a tandem shunt valve system in place and not a single valve system.

Given the associated problems that come with the usage of a single shunt, there will be a firm requirement for a shunt with tandem shunt valve properties in the future. Our mission is to assist development in this area is through the establishment of a new tandem shunt valve which contains two programmable valves in one device/chassis allowing for the best CSF flow and final ICP combination condition (Figure 7) in hydrocephalus patients. Since there have already been two successful clinical cases further studies to investigate clinical performance will only benefit hydrocephalus cases. The new tandem shunt valve system described here will provide future opportunities to achieve ICP pressure and CSF flow control in hydrocephalus and other related conditions requiring the prevention of pressure fall and fluid flow management at the same time.

Novel Shunt Therapy for Hydrocephalus 165

[4] Hakim, S.(1973). Hydraulic and mechanical mis-matching of valve shunts used in the

[5] Maixner, WJ. et al. (1990). Ventricular volume in infantile hydrocephalus and its

after treatment. *Apreliminary study. Pediatr Neurosurg,*16(4–5): pp. 191–196. [6] Rekate, HL. (1994). The usefulness of mathematical modeling in hydrocephalus research.

[7] Boon, AJ. et al. (1998). Dutch Normal-Pressure Hydrocephalus Study: randomized

[8] McQuarrie, IG.; Saint-Louis, L. & Scherer, PB. (1984). Treatment of normal pressure

[9] Zemack, G. et al. (2003). Clinical experience with the use of a shunt with an adjustable valve in children with hydrocephalus. *J Neurosurg,* 98(3): pp. 471–476. [10] Zemack, G. & Romner, B. (2000). Seven years of clinical experience with the

[11] Pollack, IF.; Albright, AL. & Adelson, PD. ( 1999). A randomized, controlled study of a

[12] Aschoff, A. et al. ( 1995). Overdrainage and shunt technology. A critical comparison of

[13] Trost, HA. et al. (1991). Testing the hydrocephalus shunt valve: long-term bench test

[15] Drake, JM.; da Silva, MC. & Rutka, JT. (1993). Functional obstruction of an antisiphon device by raised tissue capsule pressure. *Neurosurgery*, 32(1): pp. 137–139. [16] Lumenta, CB.; Roosen, N. & Dietrich, U. (1990). Clinical experience with a pressure-

[17] Piatt, JH Jr. (1995). Cerebrospinal fluid shunt failure: late is different from early. *Pediatr*

[18] Matsumae, M. et al. (1989). Quantification of cerebrospinal fluid shunt flow rates.

[19] Faulhauer, K. Schmitz, P. (1978). Overdrainage phenomena in shunt treated

under physiological conditions. *Eur J Pediatr Surg,* 1(Suppl 1): pp. 38–40. [14] Kestle, J. & Walker, M. (2005). A multicenter prospective cohort study of the Strata

*Neurol,*15: pp.646–653.

*Childs Nerv Syst,* 10(1): pp. 13–18.

*Neurosurgery,* 15(4): pp. 484–488.

*Neurosurg,* 92(6): pp. 941–948.

1408; discussion pp. 1408–1411.

(Suppl 2): pp. 141–145.

6(5): pp. 270–274.

360.

*Neurosurg,* 23(3): pp. 129–133.

hydrocephalus. *Acta Neurochir,* 45: pp. 89–101.

devices. *Childs Nerv Syst,* 11 (4): pp. 193–202.

treatment of hydrocephalus: the need for a servo-valve shunt. *Dev Med Child*

relationship to intracranial pressure and cerebrospinal fluid clearance before and

comparison of low- and medium-pressure shunts. *J Neurosurg,* 88(3): pp. 490–4959.

hydrocephalus with low versus medium pressure cerebrospinal fluid shunts.

programmable Codman Hakim valve: a retrospective study of 583 patients. *J*

programmable shunt valve versus a conventional valve for patients with hydrocephalus. Hakim–Medos Investigator Group. *Neurosurgery,* 45(6): pp. 1399–

programmable, hydrostatic and variableresistance valves and flow-reducing

results of various new and explanted valves. The need for model for testing valves

valve for the management of hydrocephalus in pediatric patients. *J Neurosurg*, 102

adjustable valve SOPHY in the management of hydrocephalus. *Childs Nerv Syst*,

Assessment of the programmable pressure valve. *Childs Nerv Systx*, 5(6): pp. 356–

The best combination of the CSF flow and the final ICP condition is through a tandem shunt valve containing two programmable valves. This tandem shunt valve is compact and about the same size as today's single shunt valve.

Fig. 7. The new tandem shunt valve idea model

#### **5. References**

The best combination of the CSF flow and the final ICP condition is through a tandem shunt valve containing two programmable valves. This tandem shunt valve is compact and about the same size as

[1] Barnett, GH.; Hahn, JF.& Palmer, J. (1987). Normal pressure hydrocephalus in children

[2] Black, PM. Hakim, R. & Bailey, NO. (1994). The use of the Codman-Medos

[3] Faulhauer, K. & Schmitz, P. (1978). Overdrainage phenomena in shunt treated

programmable Hakim valve in the management of patients with hydrocephalus:

today's single shunt valve.

**5. References**

Fig. 7. The new tandem shunt valve idea model

and young adults. *Neurosurgery,* 20: pp. 904–907.

illustrative cases. *Neurosurgery,* 34: pp. 1110–1113.

hydrocephalus. *Acta Neurochir* 45: pp.89–101.

**1. Introduction**

Leeds 1973).

**11**

**Complex Hydrocephalus**

*Department of Neurosurgery, Faculty of Medicine*

Hydrocephalus arising from intraventricular septations is known as complex or loculated hydrocephalus. Many synonyms for complex hydrocephalus have been used in the literature such as compartmentalized or loculated hydrocephalus. Complex hydrocephalus remains a challenging neurosurgical problem. Definitive treatment is surgical, yet the approach remains controversial. Traditional treatment consisted of shunting, often requiring the placement of multiple shunt systems and multiple revisions (Ross et al., 1994; Schultz &

Some neurosurgeons advocated stereotactic aspiration of the cysts and communication of the compartments (Mathiesen et al., 1993; Ross et al., 1994), others recommended microsurgery with lysis of intraventricular cysts. Good results are reported after using the transcortical approach (Sandberg et al., 2005) or the transcallosal approach (Nida & Haines, 1973). Early experience with neuroendoscopic management is promising. Endoscopy offers a simple means of communicating isolated cerebrospinal fluid spaces and ventricles by membrane fenestration. This can be done through the same burr hole as that for the placement of a ventricular catheter. In some cases, neuroendoscopy has led to eliminating or

Before the advancement of neuroendoscopy, microsurgery was the primary method for fenestration of intraventricular cysts. In 1972, Rhoton and Gomez reported a case of multiloculated hydrocephalus which was operated by microsurgical fenestration (Rhoton & Gomez, 1972). In their case, multiloculated hydrocephalus was converted to a univentricular system via a small corticectomy using the microsurgical technique. The hydrocephalus was

In 1982, Kleinhaus et al reported the first successful endoscopic fenestration procedure in a child who had a ventricular cyst. In their case, the bronchoscope has been used as the neuroendoscope (Kleinhaus et al., 1982). In 1986, Powers performed endoscopic fenestration of ventricular cyst using a flexible steerable endoscope and argon laser (Powers, 1986). In 1992, Powers used the same technique and performed successful fenestration in five out of

avoiding the need for shunting (EL-Ghandour, 2006, 2008).

then managed by a single shunt with good short term results.

**2. Historical perspectives**

seven patients (Powers, 1992).

Nasser M. F. El-Ghandour

*Cairo University*

*Egypt*

## **Complex Hydrocephalus**

### Nasser M. F. El-Ghandour

*Department of Neurosurgery, Faculty of Medicine Cairo University Egypt*

#### **1. Introduction**

166 Hydrocephalus

[20] Pudenz, RH. Foltz, EL. (1991). Hydrocephalus: overdrainage by ventricular shunts. A

[21] Kamiryo, T. et al. (1991). Intracranial pressure monitoring using a programmable

pressure valve and a telemetric intracranial pressure sensor in a case of slit ventricle syndrome after multiple shunt revisions. *Childs Nerv Syst,* 7(4): pp. 233–

review and recommendations. *Surg Neurol*, 35(3): pp. 200–212.

234.

Hydrocephalus arising from intraventricular septations is known as complex or loculated hydrocephalus. Many synonyms for complex hydrocephalus have been used in the literature such as compartmentalized or loculated hydrocephalus. Complex hydrocephalus remains a challenging neurosurgical problem. Definitive treatment is surgical, yet the approach remains controversial. Traditional treatment consisted of shunting, often requiring the placement of multiple shunt systems and multiple revisions (Ross et al., 1994; Schultz & Leeds 1973).

Some neurosurgeons advocated stereotactic aspiration of the cysts and communication of the compartments (Mathiesen et al., 1993; Ross et al., 1994), others recommended microsurgery with lysis of intraventricular cysts. Good results are reported after using the transcortical approach (Sandberg et al., 2005) or the transcallosal approach (Nida & Haines, 1973). Early experience with neuroendoscopic management is promising. Endoscopy offers a simple means of communicating isolated cerebrospinal fluid spaces and ventricles by membrane fenestration. This can be done through the same burr hole as that for the placement of a ventricular catheter. In some cases, neuroendoscopy has led to eliminating or avoiding the need for shunting (EL-Ghandour, 2006, 2008).

#### **2. Historical perspectives**

Before the advancement of neuroendoscopy, microsurgery was the primary method for fenestration of intraventricular cysts. In 1972, Rhoton and Gomez reported a case of multiloculated hydrocephalus which was operated by microsurgical fenestration (Rhoton & Gomez, 1972). In their case, multiloculated hydrocephalus was converted to a univentricular system via a small corticectomy using the microsurgical technique. The hydrocephalus was then managed by a single shunt with good short term results.

In 1982, Kleinhaus et al reported the first successful endoscopic fenestration procedure in a child who had a ventricular cyst. In their case, the bronchoscope has been used as the neuroendoscope (Kleinhaus et al., 1982). In 1986, Powers performed endoscopic fenestration of ventricular cyst using a flexible steerable endoscope and argon laser (Powers, 1986). In 1992, Powers used the same technique and performed successful fenestration in five out of seven patients (Powers, 1992).

Complex Hydrocephalus 169

The most common presentation of uniloculated hydrocephalus is found in the shunted patients. Inflammatory and reactive changes related to shunt catheters, bleeding, infection and scar tissue formation can lead to obstruction or occlusion at the foramen of Monro, thus providing an isolated ventricle. Congenital anatomical causes may be present as well. (Abtin

The fourth ventricle can also become isolated due to obstruction of cerebrospinal fluid at the level of the aqueduct of Sylvius and the fourth ventricle outlets, in patients in whom a shunt has already been placed for postmeningitic or posthemorrhagic hydrocephalus. The cerebrospinal fluid produced from the choroid plexus gradually accumulates, resulting in progressive dilatation of the fourth ventricle followed by compression of the brain stem and cerebellar parenchyma. A well functioning lateral ventricular shunt not only decreases the supratentorial pressure, but also reduces the pressure needed inorder to keep the aqueduct open, which occasionally leads to aqueductal collapse. Consequently, the lateral and third

Conventionally, isolated fourth ventricles have been managed by insertion of a ventriculoperitoneal shunt into the fourth ventricle or by craniotomy and microsurgical aqueductal canalization or microsurgical fenestration of the outlets of the fourth ventricle. With the advent of endoscopy in neurosurgery, isolated fourth ventricle is more often treated by endoscopic procedures such as endoscopic third ventriculostomy and aqueductal reconstruction by aqueductoplasty with or without aqueductal stenting (Mohanty, 2005).

Multiloculated hydrocephalus has many synonyms such as multilocular hydrocephalus, polycystic hydrocephalus, polycystic brain disease or intraventricular septations. The ventricular system may become trabeculated or encysted following bacterial meningitis or germinal matrix hemorrhage (Eller & Pasternak 1985; Schultz & Leeds 1973). Predisposing factors include a low birth weight, premature birth, perinatal complications and congenital central nervous system malformations (Albanese et al., 1981). In a study including 24 pediatric patients with multiloculated hydrocephalis operated by endoscopic cyst fenestration, neonatal meningitis was the most common cause (9 cases), followed by intraventricular hemorrhage (6 cases), postoperative gliosis due to previous shunt infection

In another study including 34 cases of complex hydrocephalus operated by endoscopy, among 21 cases of uniloculated hydrocephalus, 15 cases (71%) were caused by noncolloid neuroepithelial cysts, 3 cases (14%) by choroid plexus cysts, 2 cases (10%) by postoperative gliosis, and 1 case (5%) by meningitis. Among the 13 cases of multiloculated hydrocephalus included in the same study, 4 cases (31%) were caused by intraventricular hemorrhage, 4 cases (31%) by multiple neuroepithelial cysts, 3 cases (23%) by meningitis and 2 cases (15%)

Complex hydrocephalus is mainly detected in children especially neonates, without any significant variable incidence between boys and girls. The incidence of neonatal meningitis ranges from 0.13% to 0.37% in full-term infants, and from 1.36% to 2.24% in preterm infants.

ventricles become decompressed, thus leaving the fourth ventricle dilated.

(6 cases) and multiple neuroepithelial cysts (3 cases) (EL-Ghandour, 2008).

& Walker 1998).

**4.2 Multiloculated hydrocephalus**

by postoperative gliosis (Lewis et al., 1995).

**5. Incidence**

Saline torch was used for ventricular cyst fenestration by Heilman and Cohen in 1991 (Heilman & Cohen, 1991) and by Manwaring in 1992 (Manwaring 1992). In 1993, Nida and Haines reported their experience in treating 6 patients with multiloculated hydrocephalus by transcallosal fenestration of intraventricular septations with significant decrease in postoperative shunt revision rate (Nida & Haines, 1993). Lewis et al in 1995 published the first report including a group of patients with loculated hydrocephalus (21 uniloculated and 13 multiloculated) operated by endoscopy (Lewis et al., 1995).

In 2008, EL-Ghandour reported the largest group of patients with multiloculated hydrocephalus (24 pediatric patients) operated by endoscopic cyst fenestration resulting in avoiding, eliminating or simplifying the use of shunts, with significant decrease in postoperative shunt revision rate. The results reported in this study is comparable to or even much better than those obtained previously by using the microsurgical technique. However, the endoscopic procedure has the advantage of being minimally invasive (EL-Ghandour 2008).

#### **3. Classification**

Complex hydrocephalus is classified as either uniloculated or multiloculated. Uniloculated hydrocephalus means the presence of a single cyst inside the ventricular system, whether supratentorial (isolated lateral ventricle) or infratentorial (isolated fourth ventricle). Multiloculated hydrocephalus means the presence of multiple cysts or locules isolated by multiple intraventricular septations. Uniloculated hydrocephalus is generally congenital with unaffected cerebrospinal fluid pathways, whereas multiloculated hydrocephalus is generally postinfectious or postinflammatory with obliterated subarachnoid spaces.

The distinction between both types is important because their pathogenesis, success of treatment and prognosis markedly differ. Consequently, it has been concluded that the 2 divergent types of complicated hydrocephalus should not be included in a single study (El-Ghandour, 2006, 2008).

#### **4. Etiological factors**

#### **4.1 Uniloculated hydrocephalus**

Many designations for uniloculated hydrocephalus have been used such as unilateral hydrocephalus or isolated lateral ventricle. Many types of cysts can exist within the ventricular system. Uniloculated hydrocephalus occurs if the lateral ventricle becomes trapped due to obstruction of foramina of Monro by noncolloid neuroepithelial cysts such as ependymal, choroid plexus or arachnoid cysts (Abtin & Walker, 1998). Arachnoid cysts although typically extradural, can present within the ventricles, as well as choroid plexus cysts, neoplastic cysts, and parasitic cysts (hydatid and cysticercotic cysts).

It has also been described in shunted myelodysplastic children who were treated by low pressure shunt inserted in the contralateral ventricle. The ipsilateral ventricle continues to overdrain through the low pressure shunt, whereas the contralateral or the remainder of the ventricular system becomes dilated. Most of these patients remain asymptomatic and require no treatment. However, if the patient shows progressive enlargement of the lateral ventricle contralateral to the shunt and symptoms occur, further treatment is necessary. Upgrading the shunt valve pressure or simply adding shunt to the contralateral side, has been recommended (Berger et al., 1990).

Saline torch was used for ventricular cyst fenestration by Heilman and Cohen in 1991 (Heilman & Cohen, 1991) and by Manwaring in 1992 (Manwaring 1992). In 1993, Nida and Haines reported their experience in treating 6 patients with multiloculated hydrocephalus by transcallosal fenestration of intraventricular septations with significant decrease in postoperative shunt revision rate (Nida & Haines, 1993). Lewis et al in 1995 published the first report including a group of patients with loculated hydrocephalus (21 uniloculated and

In 2008, EL-Ghandour reported the largest group of patients with multiloculated hydrocephalus (24 pediatric patients) operated by endoscopic cyst fenestration resulting in avoiding, eliminating or simplifying the use of shunts, with significant decrease in postoperative shunt revision rate. The results reported in this study is comparable to or even much better than those obtained previously by using the microsurgical technique. However, the endoscopic procedure

Complex hydrocephalus is classified as either uniloculated or multiloculated. Uniloculated hydrocephalus means the presence of a single cyst inside the ventricular system, whether supratentorial (isolated lateral ventricle) or infratentorial (isolated fourth ventricle). Multiloculated hydrocephalus means the presence of multiple cysts or locules isolated by multiple intraventricular septations. Uniloculated hydrocephalus is generally congenital with unaffected cerebrospinal fluid pathways, whereas multiloculated hydrocephalus is

The distinction between both types is important because their pathogenesis, success of treatment and prognosis markedly differ. Consequently, it has been concluded that the 2 divergent types of complicated hydrocephalus should not be included in a single study (El-

Many designations for uniloculated hydrocephalus have been used such as unilateral hydrocephalus or isolated lateral ventricle. Many types of cysts can exist within the ventricular system. Uniloculated hydrocephalus occurs if the lateral ventricle becomes trapped due to obstruction of foramina of Monro by noncolloid neuroepithelial cysts such as ependymal, choroid plexus or arachnoid cysts (Abtin & Walker, 1998). Arachnoid cysts although typically extradural, can present within the ventricles, as well as choroid plexus

It has also been described in shunted myelodysplastic children who were treated by low pressure shunt inserted in the contralateral ventricle. The ipsilateral ventricle continues to overdrain through the low pressure shunt, whereas the contralateral or the remainder of the ventricular system becomes dilated. Most of these patients remain asymptomatic and require no treatment. However, if the patient shows progressive enlargement of the lateral ventricle contralateral to the shunt and symptoms occur, further treatment is necessary. Upgrading the shunt valve pressure or simply adding shunt to the contralateral side, has

cysts, neoplastic cysts, and parasitic cysts (hydatid and cysticercotic cysts).

generally postinfectious or postinflammatory with obliterated subarachnoid spaces.

13 multiloculated) operated by endoscopy (Lewis et al., 1995).

has the advantage of being minimally invasive (EL-Ghandour 2008).

**3. Classification**

Ghandour, 2006, 2008).

**4. Etiological factors**

**4.1 Uniloculated hydrocephalus**

been recommended (Berger et al., 1990).

The most common presentation of uniloculated hydrocephalus is found in the shunted patients. Inflammatory and reactive changes related to shunt catheters, bleeding, infection and scar tissue formation can lead to obstruction or occlusion at the foramen of Monro, thus providing an isolated ventricle. Congenital anatomical causes may be present as well. (Abtin & Walker 1998).

The fourth ventricle can also become isolated due to obstruction of cerebrospinal fluid at the level of the aqueduct of Sylvius and the fourth ventricle outlets, in patients in whom a shunt has already been placed for postmeningitic or posthemorrhagic hydrocephalus. The cerebrospinal fluid produced from the choroid plexus gradually accumulates, resulting in progressive dilatation of the fourth ventricle followed by compression of the brain stem and cerebellar parenchyma. A well functioning lateral ventricular shunt not only decreases the supratentorial pressure, but also reduces the pressure needed inorder to keep the aqueduct open, which occasionally leads to aqueductal collapse. Consequently, the lateral and third ventricles become decompressed, thus leaving the fourth ventricle dilated.

Conventionally, isolated fourth ventricles have been managed by insertion of a ventriculoperitoneal shunt into the fourth ventricle or by craniotomy and microsurgical aqueductal canalization or microsurgical fenestration of the outlets of the fourth ventricle. With the advent of endoscopy in neurosurgery, isolated fourth ventricle is more often treated by endoscopic procedures such as endoscopic third ventriculostomy and aqueductal reconstruction by aqueductoplasty with or without aqueductal stenting (Mohanty, 2005).

#### **4.2 Multiloculated hydrocephalus**

Multiloculated hydrocephalus has many synonyms such as multilocular hydrocephalus, polycystic hydrocephalus, polycystic brain disease or intraventricular septations. The ventricular system may become trabeculated or encysted following bacterial meningitis or germinal matrix hemorrhage (Eller & Pasternak 1985; Schultz & Leeds 1973). Predisposing factors include a low birth weight, premature birth, perinatal complications and congenital central nervous system malformations (Albanese et al., 1981). In a study including 24 pediatric patients with multiloculated hydrocephalis operated by endoscopic cyst fenestration, neonatal meningitis was the most common cause (9 cases), followed by intraventricular hemorrhage (6 cases), postoperative gliosis due to previous shunt infection (6 cases) and multiple neuroepithelial cysts (3 cases) (EL-Ghandour, 2008).

In another study including 34 cases of complex hydrocephalus operated by endoscopy, among 21 cases of uniloculated hydrocephalus, 15 cases (71%) were caused by noncolloid neuroepithelial cysts, 3 cases (14%) by choroid plexus cysts, 2 cases (10%) by postoperative gliosis, and 1 case (5%) by meningitis. Among the 13 cases of multiloculated hydrocephalus included in the same study, 4 cases (31%) were caused by intraventricular hemorrhage, 4 cases (31%) by multiple neuroepithelial cysts, 3 cases (23%) by meningitis and 2 cases (15%) by postoperative gliosis (Lewis et al., 1995).

#### **5. Incidence**

Complex hydrocephalus is mainly detected in children especially neonates, without any significant variable incidence between boys and girls. The incidence of neonatal meningitis ranges from 0.13% to 0.37% in full-term infants, and from 1.36% to 2.24% in preterm infants.

Complex Hydrocephalus 171

were treated by shunting), most of the patients were found to be seriously affected. The children reported in this study had detectable cognitive deficits, ranging from profound

In a study including 34 patients with complex hydrocephalus operated by endoscopy (21 uniloculated and 13 multiloculated), the presenting symptoms were headache in 14 cases (41.2%), developmental delay in 11 cases (32.4%), macrocephaly in 6 cases (17.6%), seizures in 5 cases (14.7%), gait ataxia in 2 cases (5.9%), and progressive hemiparesis in 2 cases (5.9%)

In another study including 24 pediatreic patients with multiloculated hydrocephalus (21 cases were infants younger than 2 years of age), operated by endoscopic cyst fenestration, all patients (100%) presented with head enlargement, 18 patients (75%) presented with developmental delay, 4 patients (16.7%) with epilepsy, and 2 patients (8.3%) with

The use of ultrasound is a well established diagnostic method for neonates and patients with open fontanel (Machado et al., 1991). It is useful in the evaluation of patients with complex hydrocephalus, often demonstrating the cyst walls and revealing any compartmentalization that has occurred. Its advantages include that it is nonradiating, noninvasive, gives a multiplanar view and patients don't require sedation. Nevertheless, it is operator-dependant and it couldn't be considered a definitive preoperative diagnostic

Plain CT scan shows disproportionate hydrocephalus, and can be used for screening of patients. However, the cysts usually have a density similar to that of cerebrospinal fluid, and the walls are usually transparent making it usually difficult to visualize the cyst walls accurately. Often CT scan shows transversely oriented septations of varying thickness and nonuniform distribution, changing the ventricular system into one of irregular contour.

Although the septations may not be visible in the early disease process, retrospective temporal review often delineates pattern of progressive compartmentalization and asymmetrical hydrocephalus. The initially documented ventricular pattern gradually becomes unrecognizable, so that ultimately the cerebral mantle encloses a large single multiloculated cavity. In advanced stages, it may be difficult to recognize the ventricles and other anatomical structures of the brain (Nida & Haines, 1993). However, CT scan is unable

Magnetic Resonance Imaging with gadolinium is considered to be the diagnostic method of choice for patients with complex hydrocephalus. Its advantages over the CT scan include the multiplanar view providing a detailed picture in three different planes (axial, coronal, sagittal), and it is more sensitive in revealing septations. The difference in protein content of

to identify communication or noncommunication between cavities.

psychomotor retardation to mild learning disability (Nida & Haines, 1993).

(Lewis et al., 1995).

hemiparesis (El-Ghandour, 2008).

**8.2 Computed tomography scan**

**8.3 Magnetic resonance imaging**

**8. Diagnostic studies**

**8.1 Ultrasound**

modality.

Hydrocephalus as a sequela of neonatal meningitis is well described, with an incidence of up to 31% (Albanese et al., 1981; Kalsbeck et al., 1980).

Only few reports exist on the rarer subgroup that develop multiloculated hydrocephalus. Many patients with bacterial meningitis also develop ventriculitis, reported as many as 92% of cases on autopsy and 100% of cases seen clinically (Albanese et al., 1981). Postmeningitic hydrocephalus is often believed to be communicating in nature due to an insult at the arachnoid granulations. Based on the pathological findings, however, components of both communicating as well as obstructive hydrocephalus may be present.

#### **6. Pathophysiology**

The pathogenesis is still unclear, but believed to be secondary to inflammatory changes and gliosis after ventriculitis, especially commom when caused by Gram-negative organisms (Kalsbeck et al., 1980). It seems that the common link between neonatal meningitis, shunt infection and intraventricular hemorrhage is the resultant ventriculitis. It is believed that the septations giving rise to multiple loculations probably represent the organization of intraventricular exudates and debris produced by ventriculitis, regardless of whether it is chemical or infectious in origin. An inflammatory response at the ependymal surface could encourage proliferation of subependymal glial tissue, upon which exudates and debris organize and serve as a nidus for the formation of septations that span the ventricles.

The septations not only alter the ventricular anatomy, but also disrupt the normal flow of cerebrospinal fluid leading to its accumulation within a loculated cavity with progressive dilatation and mass effect (Nida & Haines, 1993). Grossly, the usual findings are ventricular dilatation, and compartmentalization by membranes. The membranes appear translucent and vary in thickness. Microscopically the septations are composed of fibroglial elements with round and polymorphonuclear cells. The characteristic findings of chronic ventriculitis are frequently present, such as subependymal gliosis, small areas of denuded ependyma, and glial tufts extending through the denuded ependyma into the ventricular lumen (Schultz & Leeds, 1973).

#### **7. Clinical features**

Presenting symptoms are mainly those related to increased intracranial pressure leading to macrocephaly in infants and headache in older children. Other symptoms include seizures, gait ataxia, and hemiparesis. Developmental delay is reported to be more common in multiloculated than uniloculated cases. It has been mentioned that neurological status in this patient population is extremely poor.

Patients with multiloculated hydrocephalus are notoriously difficult to treat, and are often compromised intellectually. In a study including 33 pediatric patients who underwent craniotomies for fenestration of progressive multiloculated hydrocephalus, 29 patients (87.9%) were severely delayed or vegetative. Many patients were nonverbal or minimally verbal, nonambulatory, had significant motor deficits, had significant spasticity and experienced seizure disorders (Sandberg et al., 2005).

In a study including 10 pediatric patients with multiloculated hydrocephalus caused by neonatal meningitis, ventriculitis or intraventricular hemorrhage, who were treated surgically (6 patients underwent craniotomy and trancallosal fenestration and 4 patients

Hydrocephalus as a sequela of neonatal meningitis is well described, with an incidence of

Only few reports exist on the rarer subgroup that develop multiloculated hydrocephalus. Many patients with bacterial meningitis also develop ventriculitis, reported as many as 92% of cases on autopsy and 100% of cases seen clinically (Albanese et al., 1981). Postmeningitic hydrocephalus is often believed to be communicating in nature due to an insult at the arachnoid granulations. Based on the pathological findings, however, components of both

The pathogenesis is still unclear, but believed to be secondary to inflammatory changes and gliosis after ventriculitis, especially commom when caused by Gram-negative organisms (Kalsbeck et al., 1980). It seems that the common link between neonatal meningitis, shunt infection and intraventricular hemorrhage is the resultant ventriculitis. It is believed that the septations giving rise to multiple loculations probably represent the organization of intraventricular exudates and debris produced by ventriculitis, regardless of whether it is chemical or infectious in origin. An inflammatory response at the ependymal surface could encourage proliferation of subependymal glial tissue, upon which exudates and debris

organize and serve as a nidus for the formation of septations that span the ventricles.