The sciatic nerve is the longest nerve in the human body and supplies the lower extremities with sensory and The sciatic nerve is the longest nerve in the human body and supplies the lower extremities with sensory motor function. Nerve roots extend from the spinal cord in the lower back (lumbar region) and bundle in the hip area to form the massive nerve, which then runs down the back of the legs, with branches extending to the toes. The term "sciatica" is often used to describe pain, numbness, or muscle weakness along the path of the sciatic nerve. Although sciatica is common, the term is often misused and misunderstood.
Contrary to popular belief, sciatic pain is rarely caused by a problem with the sciatic nerve itself. Rather, sciatica is a set of symptoms, which include pain in the lower back, buttock, hip, leg, and foot. Pain can be accompanied by numbness, tingling, and muscle weakness, which may become more severe during certain activities such as standing up from a chair, coughing, or sneezing. Sciatica, not a diagnosis in and of itself, is simply an indication of a number of possible conditions or disorders. Although considerably uncomfortable, sciatic pain is usually benign and often goes away on its own in four-to-eight weeks.
Because the term sciatica refers to only the symptoms themselves, it is most important to diagnose the underlying problem. Although two people may experience similar sciatic pain, they may suffer from two very different conditions and require two very different treatments. The most common causes of sciatic pain are nerve impingement and bursitis in the hip. A physician will conduct a full evaluation to determine what is causing the pain, often performing an MRI to visualize the anatomy of the affected area and to rule out more serious conditions of the spine.
Nerve impingement describes a "pinch" or obstruction of the nerve by some anatomical force. There are two common causes of nerve impingement that can result in sciatic pain: a herniated disc and Piriformis syndrome.
Herniated lumbar discs can cause severe pain, affecting a person's ability to perform everyday tasks. Discs are spongy pads that separate the vertebrae in your spine. Ideally, they keep your spine flexible and act as shock absorbers to cushion the vertebrae when you move. But after years of wear and tear or following an injury, the gel-like center of a disk, called the nucleus, may be forced into or through the disc's tough outer lining. This protrusion may press directly on the nerve roots that extend from that part of the spine. Nerve roots may also become inflamed or irritated by chemicals from the disc's nucleus. Because most herniated discs occur in the lower spine, the nerve roots affected are those that bundle in the hip to create the sciatic nerve.
A herniated disc is often indicated by sciatic pain that radiates into the calf and ankle. It may also cause numbness in the foot and weakness of the foot and ankle. A sharp and intense pain may result from coughing or sneezing. Not all herniated discs require surgery; at least 50 percent will resolve on their own in four-to-eight weeks. Non-operative treatments consist of anti-inflammatory medications, physical therapy, cortisone injections, or rest from strenuous physical activity. If surgery is required, a microdiscectomy may be performed to remove herniated disc material through a small incision. A microdiscectomy is generally performed as an outpatient procedure.
In addition to disc herniation, nerve impingement to the sciatic nerve can also be caused by muscle structures of the pelvis. One example of this is Piriformis syndrome, which occurs when the sciatic nerve is aggravated by the , located behind the hip joint. The sciatic nerve runs under (and sometimes through) the piriformis muscle as the nerve exits the pelvis. If the muscle or tendon is anatomically abnormal, overused, or injured, the sciatic nerve is susceptible to irritation.
Deep buttock pain that travels down the back of one leg is common among patients with Piriformis syndrome. Patients may also experience increased pain while sitting. Anti-inflammatory medications, physical therapy, or rest from intense activity will usually ease the pain of Piriformis syndrome. Muscle injections may be recommended for more intense pain or pain that is not alleviated by more conservative treatments. Surgery is not usually indicated for Piriformis syndrome.
Hip bursitis is another common cause of lower extremity pain. Bursae are small, jelly-like sacs that serve as cushions between bone and overlying soft tissue. Bursae are located throughout the body, with a fairly large one covering the outside of the bony point of the hip, called the . Irritation from overuse or injury can cause a bursa to become inflamed and painful, resulting in bursitis. Trochanteric bursitis, or inflammation of the bursa around the greater trochanter, is common and is often caused by the repetitive stress of running, cycling, stair climbing or standing for long periods of time, or from a fall onto the hip.
Pain from hip bursitis is concentrated at the boney point of the hip and can be tender to the touch. The pain usually extends from the hip to the outside of the thigh area and gets worse at night, when lying on the affected hip, getting up in the morning, or rising from a chair. Generally, surgery is not indicated for bursitis. Rest from activities that irritate the bursa, anti-inflammatory medications, and physical therapy are often recommended for patients with hip bursitis. If symptoms persist, cortisone injections may be given to reduce the inflammation of the bursa.
However painful, sciatica is usually harmless and resolves on its own with time. Rarely is sciatic pain the result of a more serious condition like a tumor. Signs to seek immediate medical attention include sudden, severe pain in your low back or leg; severe numbness or muscle weakness in one or both legs; pain that follows a violent injury, such as a traffic accident; or trouble controlling bowel or bladder functions. If mild to moderate pain lasts longer than a few weeks, it is important to see your physician to evaluate the underlying cause. When in doubt, or in pain, consult your doctor. There is no reason to be limited by the pain of sciatica.
Kipp Kennedy, MD, specializes in spinal, arthroscopic, and joint replacement surgery at The Orthopaedic Institute in Florida. He may be reached at 888-860-7050, www.toi-health.com.
