Computed tomography of a post traumatic spinal arachnoid cyst.

A case of post-traumatic arachnoid spinal cyst with haemorrhagic contents is presented. CT findings were indistinguishable from those of epidural or subdural haematomas. The use of CT myelography permits a more accurate diagnosis by localizing the lesion into one of the three spaces. In our case, bleeding into a preexisting arachnoid cyst was thought to occur, but we cannot exclude a newly formed cyst of traumatic origin.