Isolated Fourth Ventricle: To Shunt or Stent

Of the various management options for isolated fourth ventricle (IFV), fourth ventriculoperitoneal shunts (FVPS) and aqueductal stents (AST) have been the most favored. Though effective, FVPS are often difficult to place and have higher complication rates than conventional ventricular shunts.

To assess the efficacy of AST in IFV and compare the outcome with FVPS.

Twenty-five patients surgically treated for IFV were analyzed. In all, a preoperative magnetic resonance imaging assessed the extent of aqueductal obstruction. Patients with an identified short-segment aqueductal stenosis were considered for AST placement; those with long-segment aqueductal obstruction underwent FVPS.

Of the 25, 12 were symptomatic, while 13 were asymptomatic (progressive dilation of IFV in 9, persistent dilation with distortion of the brain stem in 4). In 3 with normal ventricles, the ventricles had to be dilated by externalizing the shunt before placing the stent. Nineteen underwent AST placement, whereas in 6 FVPS was performed. Sixteen patients underwent a simultaneous cerebrospinal fluid diversion procedure and fourth ventricular decompression. At follow-up (mean: 45 mo), stent migration was observed in 2 patients. In the FVPS group, 1 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.

Both FVPS and AST are effective in managing IFV. The extent of aqueductal obstruction and degree of ventriculomegaly are often the deciding factors in choosing the management option.