Endoscopic Management of Posterior Fossa Arachnoid Cysts

Background: Posterior fossa arachnoid cysts constitute 10-11% of all intracranial arachnoid cysts and are considered to be the second most common after middle fossa arachnoid cysts. Their diagnosis, indications of surgical intervention and mode of surgical management are still points of debate. Objective: We report our experience in the management of posterior fossa arachnoid cysts using neuroendoscopic techniques. Our work aims to assess the efficacy and safety of endoscopic fenestration as a minimally invasive technique for the management of such cysts. Patients Methods: We retrospectively reviewed thirteen cases of posterior fossa arachnoid cysts managed by endoscopic cyst fenestration at the Department of Neurosurgery, Mansoura University Hospital during the period from January 2000 through March 2014. We reviewed clinical data, radiological images, operative details and postoperative clinical and radiological follow up. Results: Our study included eight female and five male parents ranging in age from10 months to 25 years (mean=60 month). Arachnoid cysts were located in the vermis, cisterna magna and foramen magnum regions in six patients, the cerebellopontine angle in three patients, the cerebellar hemisphers in two patients and supracerebellar location in two patients. Endoscopic cyst fenestration was the primary procedure in all cases. Mean postoperative followup was 34 months (range 6-118 months). Follow-up imaging studies showed complete remission or reduction of the cyst size in eleven pa􀆟ents (84.6%) while the cyst remained unchanged in only two parents (15.4%). The overall clinical improvement was attained in 77% of our parents with no mortality or major postoperative morbidity. Two patients required repeat surgery; one for insertion of cystoperitoneal shunt in a patient with foramen magnum residual cyst and the other was endoscopic third ventriculuostomy to release persistent supratentorial hydrocephalus. Conclusion: Endoscopic fenestration of posterior fossa arachnoid cyst is an effective and safe treatment option that carries minimal morbidity. It should be considered as a first line treatment for symptomatic posterior fossa arachnoid cysts, while cystoperitoneal shunt remains a salvage procedure after failure of endoscopic fenestration.