sciatica

pain radiating from the buttock into the thigh, calf, and occasionally the foot. Although it is in the distribution of the sciatic nerve, sciatica is rarely due to disease of this nerve. Pain felt down the back and lateral aspect of the thigh, leg, and foot is often caused by degeneration or displacement of an intervertebral disc (see prolapsed intervertebral disc), which encroaches upon and irritates a lower lumbar or an upper sacral spinal nerve root. The onset may be sudden, brought on by an awkward lifting or twisting movement that causes a tear in the fibrous coat of the disc, or more gradual, from progressive narrowing secondary to degenerative changes in the disc. The back is often stiff and painful and there may be numbness and weakness in the leg. Bed rest will often relieve the pain but surgical treatment is occasionally necessary (see laminectomy, discectomy, microdiscectomy).