Lumbar radiculopathy, or radiating nerve pain going down a leg, occurs in up to 40% of the population at some time during their life. Typically, the pain originates from a compressed nerve in the lumbar spine although, uncommonly, nerves can be compressed elsewhere in the buttock. The nerves most commonly compressed in the lumbar spine (L4, L5, and S1) join to create the sciatic nerve going down the back of the thigh. The L1, L2, and L3 nerves are less commonly compressed; they join to create the femoral nerve that travels down the front of the thigh. The pain can range from mild throbbing to severe ache that leads to difficulty walking.
The most common cause of pain radiating down the leg is a disc herniation pressing upon a spinal nerve. A disc herniation can come about during trauma or may occur suddenly without any clear cause. Foraminal stenosis, or narrowing of the foramen (hole) that the nerve exits the spine through, can also cause radiating leg pain. Foraminal stenosis usually results from bone spurs and a bulging disc that develops gradually.
Most disc herniations improve spontaneously because the disc resorbs. About 50% of patients feel improvement within one month, and 80-90% of patients will have their symptoms spontaneously resolve within three months. As a result, the first treatment option is observation. Other options include medicines. Non-steroidal anti-inflammatories (ibuprofen, naproxen, etc.), oral steroids (prednisone), and nerve medicines (Neurontin, Lyrica) can sometimes help minimize pain as the disc resorbs. Epidural steroid injections under x-ray guidance frequently decrease the inflammation of the nerve and the pain that results. Physical therapy has little role when the cause of lumbar radiculopathy is a disc herniation because exercise cannot relieve pressure on the nerve but can provide benefit when foraminal stenosis is causing the leg pain.
When more conservative approaches fail, or there is progressive leg weakness or severe pain, surgery should be considered. The operation, typically a lumbar microdiscectomy, relieves leg pain in about 85% of patients. Patients can leave the same day or after an overnight stay. Over 80% of patients see a significant immediate improvement in symptoms immediately after the surgery.