Intradural migration of sequestrated disc fragment during decompression of cauda equina.

We report the case of a man who underwent urgent surgery to relieve compression of the cauda equina caused by a large L4/5 disc protrusion. A post-operative but not pre-operative MRI scan showed appearances suggestive of intradural migration of a disc fragment, confirmed at re-operation. We believe that this event happened during the first operation and not before it.