Sciatica (lumbar radiculopathy)

Sciatica is pain that comes from a nerve. That nerve is the sciatic nerve, and the problem can be in the nerve itself or in one of its lumbosacral roots, which are where the nerves come out of the lower part of the spine. Along with the pain, there can be paresthesias, which are abnormal sensations in the skin, like tingling.

The sciatic nerve is the largest nerve in the body. It forms where the nerve roots from L4 through S3 come together; those labels tell you at what level of the spine each root comes out. Picture a thick cable that starts at the lower spine: no matter where along the way it gets damaged, you feel it in the area the cable reaches. And what damages it most often is inflammation, which irritates the nerve.

The most common cause is in the intervertebral discs, the cushions that sit between the vertebrae of the lower back. A disc can be herniated, when part of it slips out of place, or bulging, when it pushes outward. And sciatica pain gets worse with certain movements: bending forward at the lower back, twisting, bending down, or coughing.