Lumbosacral nerve root avulsion: report of a case and review of the literature.

The 14th myelographically demonstrated case of lumbosacral nerve root avulsion is presented with a summary of the previously reported cases. In most cases lumbosacral nerve root avulsion is associated with pelvic fractures and sacroiliac dislocation, which cause a stretching force to be applied to the nerves of the lumbar and sacral plexuses, and in turn to the nerve roots intradurally. This force causes nerve root avulsion in the intradural course of the nerve root. The myelographic defect is a pseudomeningocele or diverticulum-like outpouching created by the tearing of the arachnoid covering of the nerve roots. Myelography clearly indicates nerve root avulsion and surgical exploration is not indicated.