Association of posttraumatic spinal arachnoid cyst and syringomyelia.

A patient developed a painful progressive paraparesis following trauma. Metrizamide myelography revealed an arachnoid cyst. A delayed metrizamide computed tomography scan of the area confirmed the cyst and demonstrated a syrinx at that level that was not appreciated on the myelogram. The association of these two lesions after trauma are perhaps more common than appreciated and the importance of a computed tomography scan of the abnormal area on myelography is emphasized.