AIM: To report neurological and radiological features, surgical management, and mid-term outcomes of patients with chronic subdural hematoma (CSDH) associated with ipsilateral arachnoid cyst (AC) of the middle fossa.

MATERIAL and METHODS: A total of 453 patients with CSDH were treated at our clinic between August 2004 and August 2012. Of these patients, 15 had ipsilateral AC in the middle fossa. A single burr hole craniostomy was performed to drain the hematoma. The AC was left intact in 14 patients, and one patient had no surgical intervention. The follow-up period ranged from 13 to 88 months (mean 43.07 ± 23.23 months).

RESULTS: The patients with AC associated CSDH were found to be younger than the patients with CSDH alone, and the mean age of 58 patients was 13.15 ± 13.17 years, while it was 11 ± 14.22 years in the other patients. Eleven patients had experienced head trauma at 21?50 days before admission. Hematoma evacuation through a single burr hole with closed-system subdural drainage performed at 2?4 days after surgery improved the symptoms in all patients. Two patients developed subdural fluid collection, which was treated by subduroperitoneal shunt placement.

CONCLUSION: Greater prevalence of ACs in patients with CSDHs has been reported in the literature. We recommend the drainage of the hematoma via a single craniostomy and to leave the AC intact as the first choice of treatment if the associated AC is a Galassi type I or II. Additional subduroperitoneal shunting may be performed in patients with Galassi type III cyst.