Objective: Our surgical results of middle fossa arachnoid cysts are presented, and advantages and disadvantages of cystoperitoneal shunting are discussed.
Methods: Seventy-seven patients with middle fossa arachnoid cysts, including 20 cases of asymptomatic cyst, were treated by cystoperitoneal shunting. In cases associated with subdural hematoma, the cystoperitoneal shunt was preceded by irrigation of the hematoma. Follow-up periods ranged from 8 months to 16 years (mean, 7.7 yr).
Results: In all cases, postoperative computed tomography and magnetic resonance imaging revealed subsequent expansion of the surrounding brain, concomitant with either the disappearance of or a marked decrease in the size of the cyst. Patients who initially presented with headaches, hemiparesis, choked discs, and diplopia were cured postoperatively. Head enlargement presented preoperatively did not progress after shunting. Mental retardation and behavior problems, however, remained unchanged postoperatively, even though the cyst had disappeared. One cystoperitoneal shunt became infected, and shunt malfunction developed in eight patients. Four of the eight patients presented acute signs and symptoms of intracranial hypertension when the shunt malfunctioned, although the concurrent increase in cyst size was slight and ventriculomegaly was not seen. The observed condition in these four patients could be considered shunt dependency.
Conclusion: Cystoperitoneal shunting is a valid method of achieving obliteration of the cyst and clinical improvement and seems to feature low operative risk and few complications. It should be noted, however, that some patients experience shunt dependency after cystoperitoneal shunting.