Introduction: Of various management options for isolated fourth ventricle (IFV), fourth ventricular shunts (FVPS) and aqueductal stents (AST) have been the most favored. Though effective, 4th ventricular shunts are often difficult to place and are reported to have higher complication rates than conventional ventricular shunts.
Methods: 22 patients (3mos – 28yrs) who were surgically treated for IFV over a 10 year period were analysed. In all, the extent of aqueductal obstruction was assessed by a preoperative MRI. Patients with an identified short segment aqueductal stenosis were considered for AST placement while those with long segment aqueductal obstruction underwent FVPS. FVPS were placed either by a transcerebellar or trans-foramen Magendie route while the stents were placed by a transventricular route.
Results: Of the 22, 12 were symptomatic while 10 were asymptomatic (progressive dilation of IFV in 6, persistent dilation with distortion of the brain stem in 4). 15 had preexisting lateral ventricle shunts. In 2 with normal ventricles, the ventricles had to be gradually dilated by externalizing the shunt before placing the stent.
16 underwent AST placement while in 6 FVPS was performed. Seven patients underwent a simultaneous CSF diversion procedure (Endoscopic third ventriculostomy or ventricular shunt) and 4th ventricular decompression.
Mean follow up was 37 months (AST: 30 mos, FVPS: 53 mos). At follow up, stent migration was observed in one. In the FVPS group, one had 2 shunt revisions while another developed reversible cranial nerve paresis. Though a reduction of the IFV was observed with both procedures, the extent of reduction was more with FVPS.
Conclusions: Both FVPS and AST are effective in managing IFV. Extent of aqueductal obstruction and degree of ventriculomegaly is often the deciding factor in choosing the management option.In patients with functioning ventricular shunts, gradual ventricular dilation can be performed prior to placement of stent.
Patient Care: With the proposed management protocol we can identify the candidates who can be managed with endoscopic aqueductal stent placement thus potentially avoiding placing a fourth ventricular shunt.
Learning Objectives: 1. Describe the importance of identifying isolated fourth ventricle in patients with hydrocephalus.
2. Discuss, in small groups the ideal candidates for aqueductal stenting and fourth ventricular shunts
3. Identify and formulate an effective management protocol for patients with IFV.