Neuropathy - sciatic nerve; Sciatic nerve dysfunction

Sciatica occurs when there is damage to the sciatic nerve, located in the back of the leg. This nerve controls the muscles of the back of the knee and lower leg and provides sensation to the back of the thigh, part of the lower leg and the sole of the foot. Incomplete damage to the sciatic nerve may appear identical to damage to one of the branches of the sciatic nerve (tibial nerve dysfunction or common peroneal nerve dysfunction).

Common causes of sciatica include:

• Degenerative disc disease
• Pelvic injury or fracture
• Piriformis syndrome (a pain disorder involving the narrow piriformis muscle in the buttocks)
• Slipped disk
• Spinal stenosis
• Tumors

Sciatica pain can vary widely. It may feel like a mild tingling, dull ache, or a burning sensation. In some cases, the pain is severe enough to make a person unable to move.

The pain most often occurs on one side. Some people have sharp pain in one part of the leg or hip and numbness in other parts. The sensations may also be felt on the back of the calf or on the sole of the foot. The affected leg may feel weak.

The pain often starts slowly. Sciatica pain may get worse:

• After standing or sitting
• At night
• When sneezing, coughing, or laughing
• When bending backwards or walking more than a few yards, especially if caused by spinal stenosis

Sciatica might be revealed by a neuromuscular examination of the legs by a physician. There may be weakness of knee bending or foot movement, or difficulty bending the foot inward or down. Reflexes may be abnormal, with weak or absent ankle-jerk reflex. Pain down the leg can be reproduced by lifting the leg straight up off the examining table.

Tests are guided by the suspected cause of the dysfunction, as suggested by the history, symptoms, and pattern of symptom development. They may include various blood tests, x-rays, MRIs, or other tests and procedures.

Treatment is aimed at maximizing mobility and independence. The cause of the nerve dysfunction should be identified and treated as appropriate. In some cases, no treatment is required and recovery is spontaneous.

Conservative treatment is usually appropriate if there was sudden onset, minimal sensation changes, no difficulty in movement, no history of trauma to the area, and no evidence of degeneration of the nerve axon.

Surgical removal of lesions that press on the nerve, such as a herniated disk, may relieve symptoms. In cases of severe injury to the nerve, such as laceration, recovery may be not possible or may be limited.

Injections can be used to reduce inflammation around the nerve. Over-the-counter or prescription analgesics may be needed to control nerve pain.

Various other medications may reduce the stabbing pains that some people experience, including phenytoin, carbamazepine, or tricyclic antidepressants such as amitriptyline. Steroids may help with nerve inflammation related to a herniated disk. Whenever possible, their use should be avoided or minimized to reduce the risk of medication side effects.

Physical therapy exercises may be appropriate for some people to maintain muscle strength. The use of braces, splints, orthopedic shoes, or other appliances may help compensate for lost or impaired function. Vocational counseling, occupational therapy, occupational changes, job retraining, or similar interventions may be recommended.

If the cause of the sciatic nerve dysfunction can be identified and successfully treated, full recovery is possible. The extent of disability varies from no disability to partial or complete loss of movement or sensation. Nerve pain may be severe and persist for a prolonged period of time.

• Partial or complete loss of leg movement
• Partial or complete loss of sensation in the leg
• Recurrent or unnoticed injury to the leg
• Side effects of medications

Call your health care provider if you have symptoms of this disorder. Nerve pain is very difficult to treat. If you have ongoing problems with pain, you may want to see a neurologist or pain specialist to ensure that you have access to the widest range of treatment options.

Also call your health care provider if persistent, severe back pain develops, especially if you have any numbness, loss of movement, weakness, or bowel or bladder changes.

Prevention varies depending on the cause of the nerve damage. Avoid prolonged sitting or lying with pressure on the buttocks.

Clarke JA, van Tulder MW, Blomberg SE, et al. Traction for low-back pain with or without sciatica. Cochrane Database Syst Rev. 2007;(2):CD003010.

Chou R, Qaseem A, et al. Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society. Ann Intern Med. 2007;147(7):478-491.