Anterior cervical arachnoid cyst simulating syringomyelia: a case with preceding posterior arachnoid cysts.

An arachnoid cyst lying anterior to the cervical cord at level C6-7 was found in a 28-year-old woman believed to have syringomyelia. This diagnosis was based both on previous findings at laminectomy and on computerized tomography. The diagnosis of arachnoid cyst was suspected because of clinical features atypical for classical syringomyelia and a history of arachnoid cysts found during childhood. Air myelography demonstrated an extramedullary intradural mass anteriorly that proved to be an arachnoid cyst. Drainage and subtotal resection resulted in marked clinical improvement. This case illustrates the need for reevaluation when a patient with "known" syringomyelia presents an atypical clinical picture. Anterior cervical arachnoid cyst, which may accompany or succeed posterior arachnoid cysts, should be considered.