Sciatica is pain, numbness, weakness, or tingling in the leg caused by pressure or injury to the sciatic nerve, which runs from the lower back through the buttocks and down each leg. Causes Sciatica occurs when the sciatic nerve or the nerve roots that form it are compressed, irritated, or inflamed. ▪Herniated disk: A slipped disk can put pressure on a nerve root. ▪Spinal stenosis: A narrowing of the spinal canal. ▪Piriformis syndrome: Compression of the sciatic nerve by the piriformis muscle in the buttock. ▪Other causes: Spondylolisthesis, bone spurs, pelvic injuries, or, rarely, tumors can also cause sciatica. Symptoms ▪Intense, shooting pain from the lower back through the buttock and down the back of the leg. ▪Numbness or tingling in the leg. ▪Weakness in the leg muscles. ▪Pain that may be worse with sitting, bending, coughing, or sneezing.