Spinal arachnoid cysts - our experience and review of literature

Arachnoid cysts are discrete pockets of CSF or CSF-like fluid found adjacent to normal CSF spaces, either spinal or cranial. Spinal arachnoid cysts (SAC) are most commonly extradural, however intradural or perineural are also described.

All patients admitted to our center and surgically treated with a diagnosis of SAC, were included in the study. The results were analyzed in terms of the clinical symptoms, location of cyst, surgical procedure performed and outcome following surgery.

Eleven patients were operated for SAC during the study period and the mean age at surgery was 32.9 ± 20.8 years. Male to female ratio was 2.7:1 in our series. Common presenting complaints were lower limb weakness and pain. The median duration of symptoms before surgery was nine months (mean 21 ± 28 months). Ten patients had extradural cysts while one had intradural cyst. Extradural cysts were managed by laminoplasty and excision of the cyst, except for one patient in whom the SAC extended from C3 to L2 and marsupialization of the cyst was done. The only patient with intradural cyst underwent cyst fenestration. One patient had two communications and both were closed. In our series, at the time of last follow up two patients became completely free of symptoms, while other five reported substantial improvement in their symptoms. Operative complications were noted in two patients.

Formation and expansion of SAC is not completely understood. Myelography, CT myelography and cinematic MRI can demonstrate the location of the communication site between the spinal subarachnoid space and the cyst cavity. The usual management of SAC is excision of the cyst with closure of the dural defect in extradural cysts, while in case of intradural cysts, especially the ones located anterior to the cord, fenestration of the cyst is usually performed.