Endoscopic aqueductal stent placement for the treatment of a trapped fourth ventricle.

OBJECT: Endoscopic aqueductal stent therapy has evolved into an important technique in the treatment of a trapped fourth ventricle (TFV). The authors analyzed five cases of symptomatic TFV treated by endoscopic aqueductal stent therapy and, on the basis of intraoperative findings, discuss aspects of TFV formation.

METHODS: Patients' ages ranged from 2 to 17 years (mean 9.2 years). Two patients underwent endoscopy via a coronal bur hole approach and three via a small suboccipital craniectomy. The mean follow-up period was 30 months (range 24-38 months). In four cases, a membrane occluding the orifice of the aqueduct and covering part of the walls of the ventricle was observed. Despite slit ventricles in four cases, there was no intraoperative evidence of aqueduct wall collapse. All procedures were successful, and all patients experienced positive outcomes. In one patient, Parinaud syndrome, rotatory nystagmus, and abducent nerve palsy developed postoperatively; these deficits resolved after a preexisting supratentorial shunt was upgraded. There were no cases of aqueduct reocclusion during the follow-up period.

CONCLUSIONS: Aqueductal stent therapy is an effective method of TFV treatment. Because it prevents aqueduct reocclusion by chronic inflammatory processes in postinflammatory hydrocephalus, it has been shown to be more efficient than aqueductoplasty alone and to be an important alternative to the placement of a fourth ventricle shunt. Intraventricular processes leading to membrane formation play an important role in occlusion of the cerebral aqueduct orifices and final isolation of the fourth ventricle in postinflammatory hydrocephalus.