Spinal extradural arachnoid cysts: clinical, radiological, and surgical features.

Extradural arachnoid cysts in the spine are rare and are seldom a cause of spinal cord compression. They are thought to arise from congenital defects in the dura mater, and they almost always communicate with the intrathecal subarachnoid space through a small defect in the dura. The mainstay of treatment in patients with neurological symptoms is surgical removal of the cyst together with ligation of the communicating pedicle and closure of the dural defect. In the present paper the authors review the literature and discuss the clinical and pathological features, mechanisms of pathogenesis, neuroimaging characteristics, and surgical management of spinal extradural arachnoid cysts. The surgical technique for removal of these lesions is illustrated in a patient with a large thoracolumbar spinal extradural arachnoid cyst causing neurogenic claudication.