Arachnoid cysts represent benign cysts that occur in the cerebrospinal axis in relation to the arachnoid membrane and do not communicate with the ventricular system. They usually contain clear, colorless fluid that is most likely normal cerebrospinal fluid.
Most are developmental anomalies. Arachnoid cysts often are an incidental finding on imaging, and usually, patients are asymptomatic even if the cyst is quite large. The most commonly associated clinical features are headache, bulging, and seizures, with focal neurologic signs occurring less frequently.
The surgical placement of a shunt may be required to decompress (remove pressure from) the cyst..
Untreated, arachnoid cysts may cause permanent severe neurological damage due to the progressive expansion of the cyst(s)or hemorrhage (bleeding). With treatment most individuals with arachnoid cysts do well.
Drainage by needle aspiration or burr hole. While these procedures are relatively simple, there is a high incidence of recurrence.