Spinal arachnoid cysts

Arachnoid cysts are benign cerebrospinal fluid filled cavities which can occur anywhere along the nervous system. Spinal arachnoid cysts (SAC) account for 1-3% of all benign spinal space-occupying lesions and can be extradural, intradural-extramedullary, intramedullary, or perineural. Seen commonly in the adult population and in the thoracic region, their etiopathogenesis is uncertain and multiple hypothesis have been postulated. SAC is often incidental but maybe produce symptoms by compression of the spinal cord or by traction over the nerve roots. Magnetic resonance imaging is the diagnostic modality of choice, and computed tomography myelography may assist to identify the exact site of leak in select cases. Small or asymptomatic cysts may be observed, but there is still some debate regarding the best treatment strategy for symptomatic ones. Surgery is indicated in symptomatic patients, but in the absence of large clinical series the optimal surgical strategy remains unclear. The main goal of surgery is to drain the cyst, relieve the pressure, and prevent re accumulation. Surgical techniques employed include total/partial cyst removal, marsupialization, fenestration, ligation of the communication site, shunting, or a combination of these techniques. Motor and gait symptoms show good improvement but there is a definite risk of recurrence especially in those patients where the cyst wall could not be removed completely or the site of leak could not be closed properly. This short review provides an overview on the etiopathogenesis, clinical presentation, and management of this unique pathology.