Partial cauda equina compromise: result of sacral stenosis.

Although partial or complete cauda equina compromise due to lumbar stenosis is a recognized entity, cauda equina compromise due to sacral stenosis is extremely uncommon. We present a patient with a three-week history of right thigh and buttock pain who developed right scrotal and buttock numbness, urinary retention, and difficulty with bowel evacuation. The patient had diminished sensation to right buttock and anus pinprick with decreased anal sphincter tone and absent bulbocavernosus reflex. Lumbosacral spine films revealed only minimal degenerative changes, while lumbar myelogram showed L4-L5 and L5-S1 ventral extradural defects. Only a drop of pantopaque descended caudally below the level of the L5-S1 interspace. Operatively, significant stenosis and thickening of the posterior sacrum with compromise of the lower sacral nerve roots was noted. Bilateral sacral laminectomy was performed and the symptoms resolved postoperatively. This case illustrates an unusual clinical entity: partial cauda equina compromise due to sacral stenosis.