Diagnosis of perineurial arachnoid cysts using computed tomography: technical and clinical considerations.

Perineurial arachnoid cysts are often multiple lesions that are usually found in the lumbosacral area. These cysts may cause compression of surrounding structures. Examination of the first, second and third sacral nerves should be performed on patients with prolonged symptoms of a herniated disc or cauda equina syndrome. Three cases are presented for which computed tomography provided accurate, noninvasive diagnosis. Perineurial cysts are often associated with asymptomatic herniated disc; thus, surgery on the disc with an underlying symptomatic cyst may result in a failed back syndrome.