If a damaged disk bulges, flattens and presses out of place between your vertebrae, the disk can press on nearby nerves. A flattened disk may also cause two vertebrae to press together, which can pinch or put pressure on the nerve, or a bone spur may grow as an extension of a vertebral bone, which can similarly put pressure on the sciatic nerve.

Other causes include spinal stenosis (narrowing of the spinal canal) or spasms in a muscle (the piriformis muscle in the buttocks) that the sciatic nerve passes through. Sciatica usually causes pain and muscle spasms that extend down the leg. Burning, tingling, or numbness can also occur.