ARACHNOID CYSTS OF THE CEREBELLOPONTINE ANGLE - DIAGNOSIS AND SURGERY

OBJECTIVE: The optimal surgical management of arachnoid cysts remains controversial. The cerebellopontine angle (CPA) is a rare location for arachnoid cysts, and only 28 cases of arachnoid cysts occurring in th e CPA have been reported in the literature. We discuss the diagnosis, radiographic imaging, and surgical management of CPA arachnoid cysts. METHODS: Five patients (three male and two female patients) with a mea n age of 5.6 years have been operated on at our institution since 1980 . Magnetic resonance imaging allows for the accurate diagnosis of thes e arachnoid cysts, which can present with only discrete symptoms, such as headache or ataxia. All five arachnoid cysts compressed the cerebe llum or brain stem. One patient had associated hydrocephalus. Three pa tients presented with refractory headaches associated with nausea and vomiting. The remaining two patients presented with cerebellar signs. No patient had an initial cranial neuropathy. RESULTS: All patients un derwent a retrosigmoid suboccipital craniotomy and microsurgical resec tion and fenestration of the cyst walls. One patient underwent two pro cedures. A cystoperitoneal shunt was inserted at the first operation. After the shunting procedure, the patient's condition deteriorated; ho wever, after the microsurgical resection and fenestration, his symptom s improved. With a mean 5.2-year follow-up, there has been no evidence of clinical or radiographic recurrence. CONCLUSION: Although CPA arac hnoid cysts represent a small number of total arachnoid cysts, the CPA is the second most common location for arachnoid cysts to occur. CPA cysts are congenital lesions found in children who present with subtle signs or symptoms. The definitive treatment for these arachnoid cysts is a retrosigmoid suboccipital craniotomy and microsurgical resection and fenestration of the cyst walls.