The Slit Ventricle Syndrome

Slit ventricle syndrome: Historical considerations, diagnosis, pathophysiology, and treatment review

After the introduction of shunt treatment for the management of childhood hydrocephalus, a wide variety of complications related to this treatment modality have been recognized. The entity of slit ventricle syndrome (alternatively, symptomatic ventricular coaptation) is one of them, is frequently encountered in the pediatric population and its symptom complex resembles that of shunt failure. We conducted research on PubMed^®, MEDLINE^®, and Web of Science^®, using the keywords: “slit ventricles,” “slit ventricle syndrome,” “SVS” and “ventricular coaptation.” The aim of our review was to trace the advances made through the past decades, concerning our knowledge about the clinical characteristics, pathophysiology, and treatment options of this entity. The discrepancy among researchers about the offending etiology and the optimum treatment algorithm of this entity, as well as the necessity of an updated concept regarding shunt over drainage is analyzed. The multiple treatment modalities proposed and pathophysiologic mechanisms implicated for the treatment of slit ventricle syndrome illustrate the complexity of this entity. Consequently, the issue requires more detailed evaluation. In this review, we comment on all the main facets related to shunt over drainage and the resultant slit ventricle syndrome.

Aesthetic Cranial Vault Expansion in a Child With Slit Ventricle Syndrome and Eumorphic Face

Ventricular shunting procedures represent the classical surgical treatment for hydrocephalus. Slit ventricle syndrome (SVS) with craniocerebral disproportion (CCD) and secondary craniosynostosis (SCS) is a well-known but uncommon complication following cerebrospinal fluid (CSF) shunting in children. Its general management includes shunt upgrade or revision, placement of anti-siphon devices, lumbo-peritoneal shunting, and endoscopic third ventriculostomy. Cranial expansion is generally considered a major procedure and is indicated when less invasive treatments fail. In these cases, SVS and associated SCS have been usually managed through anterior cranial vault expansion. This procedure aims to decrease the risk of further shunt revisions and to improve neurologic symptoms, but it takes the disadvantage of considerable iatrogenic alterations of the facial proportions. The authors report a case of a 6-year old boy with SVS and SCS, who maintained eumorphic face and was treated by an innovative post-coronal vault expansion ensuring a wide volume increase while avoiding any change of facial conformation.

Endoscopy in the treatment of slit ventricle syndrome

The present study aimed to investigate the efficacy of endoscopy in the treatment of post-shunt placement for slit ventricle syndrome (SVS). Endoscopic surgery was performed on 18 patients with SVS between October 2004 and December 2012. Sex, age, causes of the hydrocephalus, ventricular size and imaging data were collected and analyzed. All patients were divided into two groups according to ventricular size and underwent endoscopic surgeries, including endoscopic third ventriculostomy (ETV), endoscopic aqueductoplasty and cystocisternostomy. All treated patients were observed postoperatively for a period of 2 to 3 weeks, and outpatient follow-up was subsequently scheduled for >12 months. Clinical results, including catheter adherence, shunt removal and complications, were analyzed during the follow-up period. The success rate of endoscopic surgery was indicated to be 82.7%. Syndromes caused by aqueductal stenosis in 15 patients who underwent ETV were relieved; however, syndromes in the 3 patients with cerebral cysticercosis, suprasellar arachnoid cysts, pinea larea glioma and communicating hydrocephalus, respectively, were not relieved and underwent shunt placement again. Brain parenchyma, choroid plexus and ependymal tissue were the predominant causes for catheter obstruction and the obstruction rate was indicated to be 77.8% (14/18). Complications, such as pseudobulbar paralysis, infection and intraventricular hemorrhage arose in 3 patients. The present study indicates that endoscopic treatments are effective and ETV may be considered as a recommended option in the treatment of post-shunt placement SVS in hydrocephalus patients.

Does optic nerve sheath diameter on MRI decrease with clinically improved pediatric hydrocephalus?

INTRODUCTION

Serial change in ventricular size is recognized as an imperfect indicator of ongoing hydrocephalus in children. Potentially, other radiographic features may be useful in determining the success of hydrocephalus interventions. In this study, optic nerve sheath diameter (ONSD), optic nerve tortuosity, and optic disk bulging were assessed as indicators of hydrocephalus control in children who underwent endoscopic third ventriculostomy (ETV) or posterior fossa tumor resection.

METHODS

Sixteen children underwent ETV or tumor resection for treatment of hydrocephalus. T2-weighted axial magnetic resonance images of the orbit were obtained, and the ONSD was measured posterior to the optic globe, pre- and post-intervention. Evidence of optic disk bulging and optic nerve tortuosity was also assessed. Ventricular size was estimated using the frontal and occipital horn ratio (FOR).

RESULTS

There was a significant reduction in the ONSD post-ETV (n = 9) and after tumor resection (n = 7). Average preoperative ONSD was 6.21 versus 5.71 mm postoperatively (p = 0.0017).There was also an 88% (p = 0.011) and 60% (p = 0.23) reduction in optic disk bulging and tortuosity, respectively. The FOR normalized in the tumor resection group but not the ETV group. After intervention, all patients showed improvement in signs and symptoms of hydrocephalus.

CONCLUSION

In our study population, ONSD decreased in response to measures to reduce hydrocephalus. Optic disk bulging also appears to resolve. Serial reduction in ONSD, and optic disk bulging may be indicators of improved hydrocephalus following pediatric neurosurgical interventions.

EARLY EXPERIENCE FROM THE APPLICATION OF A NONINVASIVE MAGNETIC RESONANCE IMAGING-BASED MEASUREMENT OF INTRACRANIAL PRESSURE IN HYDROCEPHALUS

OBJECTIVE

The decision for surgical intervention in hydrocephalic patients presenting with symptoms suggesting raised intracranial pressure (ICP) is challenging because radiographic ventricular size often lacks the specificity to predict abnormal ICP. An early assessment of the potential clinical usefulness of a noninvasive magnetic resonance imaging-based measurement of ICP (MR-ICP) in symptomatic hydrocephalic patients is reported.

METHODS

Twenty-seven symptomatic hydrocephalic patients (18 with shunts and 9 without shunts) underwent brain magnetic resonance imaging-based studies that included measurements of cerebrospinal fluid and blood flows to and from the cranial vault, from which measurements of ICP were derived using a previously described algorithm. The predictive values of the MR-ICP measurement were determined on the basis of whether or not the patient underwent a surgical treatment of a shunt placement or shunt revision within a 3-month period after the magnetic resonance imaging-based study.

RESULTS

MR-ICP values in these patients spanned a much wider range than in healthy control subjects. However, the majority of the patients (20 out of 26 patients) had MR-ICP values within the normal range. The short-term follow-up of patients who had normal MR-ICP measurement reveals that only one of the 20 patients required surgery. Consequently, the MR-ICP measurement has a strong negative predictive value (95% for all patients and 100% for patients without a shunt).

CONCLUSION

A finding of a normal MR-ICP value in hydrocephalic patients presenting with symptoms suggestive of abnormal ICP is a strong predictor for resolution of symptoms or stable outcome without surgical intervention.

CSF shunt failure with stable normal ventricular size

OBJECTIVE

The purpose of this study was to review the clinical features of a group of patients in whom ventricular enlargement was not a manifestation of prolonged CSF shunt obstruction.

RESULTS

Twelve patients who had prolonged symptoms consistent with CSF shunt failure and stable normal ventricular size were demonstrated at the time of surgery to have obstruction of their CSF shunts.

CONCLUSION

Ventricular enlargement is a common but not sine qua non indicator of CSF shunt failure, even after weeks or months of elevated intracranial pressure, and therefore cannot be relied upon for the diagnosis of CSF shunt failure. Although an increase in ventricular size is usually seen relatively early in the course of shunt malfunction, stable normal ventricular size in patients with symptoms and signs that are consistent with shunt failure can delay the diagnosis with potentially serious adverse consequences.

Short-term dexamethasone treatment for symptomatic slit ventricle syndrome

OBJECTIVE

The objective was to report our positive experience of using dexamethasone to treat 13 patients with symptomatic slit ventricle syndrome (SVS).

METHODS

Thirteen SVS patients who received dexamethasone during acute episodes were studied. The etiology for hydrocephalus was prematurity and intraventricular hemorrhage in 9 patients and neonatal meningitis, chorioamnionitis, Dandy-Walker variant, and congenital in 1 case each. The shunt was inserted at 1.8+/-1.0 months of age and SVS was diagnosed at 4.9+/-3.2 years of age.

RESULTS

All patients reported relief and shorter duration of symptoms with dexamethasone. Surgical intervention was decided upon and carried out within 11+/-8 months of SVS diagnosis in 9 out of 13 patients. The other 4 are being monitored and continue to receive dexamethasone when needed.

CONCLUSIONS

Dexamethasone appears to be a useful treatment in acutely increased intracranial pressure caused by SVS. It can provide temporary relief during the decision-making process of whether and when to perform surgery.

Periventricular rigidity in long-term shunt-treated hydrocephalus

OBJECT

The failure of ventricles to enlarge after acute shunt malfunction in long-term shunt-dependent patients is generally attributed to the presence of periventricular rigidity resulting from gliosis. The aim of this study was to test the hypothesis that periventricular rigidity is present in these patients.

METHODS

Fifteen pediatric patients who presented with acute shunt malfunction were studied; slit ventricles were detected in all of these patients. Pressure measurements were recorded simultaneously in both the ventricle and the brain parenchyma during shunt revision and then repeated after bolus infusion of fluid into the ventricle. The mean intraventricular pressure (IVP) at presentation was 24.1 mm Hg (standard deviation 10 mm Hg). The mean baseline IVP after drainage of cerebrospinal fluid but prior to the infusion was 7.5 +/- 4.3 mm Hg. There was no significant difference in the increase in the IVP and the intraparenchymal pressure (IPP) after bolus infusion into the ventricle (3.6 +/- 2.4 mm Hg and 3.3 +/- 2.1 mm Hg, respectively; p = 0.39). The mean pressure volume index was 24.1 ml (standard error of the mean 4.6 ml).

CONCLUSIONS

The profile of the changes in IVP and IPP indicates that the periventricular wall does not restrict ventricular enlargement following shunt malfunction in long-term shunt-dependent patients.