The disks in your spine, called intervertebral disks, are thin, oblong structures that serve as cushions between the bones of your back (vertebrae). Each disk is made of a soft gel core surrounded by a tough, fibrous outer shell. This structure allows the disk to be firm enough to maintain the space between the vertebrae, but soft enough to compress when the spine flexes during bending, leaning and turning sideways.
In some people, mostly middle-aged adults, a disk's tough outer shell develops an area of weakness or a small tear. When this happens, part of the disk's soft inner core can bulge out of its normal position (herniate), producing a condition called a herniated disk. If the herniated disk presses on nerves in the nearby spinal canal, this can cause variety of nerve-related symptoms, including pain, numbness and muscle weakness. In the most severe cases, a herniated disk can compress nerves that control the bowel and bladder, causing urinary incontinence and loss of bowel control.
Scientists do not fully understand why disks herniate. Most theories attribute this condition to a combination of the following factors:
There are three distinct areas of the vertebral column where a herniated disk may occur:
Herniated disks are most common in the lumbar region. Herniated disks are relatively rare in the thoracic region, where they account for only 1 in every 200 to 400 disk herniations.
The first symptom of a herniated disk is usually back pain in the area of the affected disk. Some researchers believe this pain is a signal that a disk's tough outer shell has been injured or weakened, not necessarily that the inner core has herniated. If the inner core does herniate and press on a nearby nerve, the resulting symptoms vary depending on the location of the herniated disk:
Your health care professional will review your medical history, including any history of fever, cancer, steroid use or recent back injuries. Your doctor then will ask you specific questions about your pain:
After reviewing your medical history and symptoms, your doctor will do a thorough physical examination to rule out other illnesses that can cause back pain, such as cancer or a bone infection of the vertebrae.
This general physical exam will be followed by a more detailed examination of your back, during which your doctor will look for differences between your right and left sides, muscle spasms, abnormal curvature, limitation of movement, lack of flexibility, areas of numbness, and areas of tenderness. Your doctor's findings will help to rule out other types of back problems that can cause similar symptoms.
If you have symptoms of lumbar disk herniation, your doctor may ask you to do specific maneuvers, such as walking on your toes, walking on your heels, squatting and standing, and flexing your ankle against resistance. Your doctor will want to do a straight leg-raising test. You will lie on your back with your legs straight. While you relax, your doctor slowly raises each leg individually to determine the angle where your leg pain begins. Your doctor will do a neurological examination, looking for changes in your reflexes, as well as for any evidence of muscle weakness or decreased sensation.
Spinal X-rays, a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan may be recommended if your initial diagnosis is not clear, if your symptoms persist or worsen after several weeks of treatment, or if you are considering surgery. Because imaging tests, such as MRI or a CT scan, may show disk abnormalities even in people without symptoms, the results must be interpreted carefully. It is common to find abnormalities that have no effect on symptoms. Your doctor also may recommend an electromyography, a test that analyzes muscle and nerve function to identify sites of nerve compression or irritation.
In most people, back pain gradually improves within four to six weeks of treatment.
In many cases, it is not possible to prevent a herniated disk. However, if you have suffered from a herniated disk in the past, you may be able to decrease your chances of it happening again by:
In most cases, a herniated disk (with or without sciatica) will respond to conservative treatment. This may include limited bed rest (generally no more than a day or two); warm baths; heating pads; and medications, such as aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) or muscle relaxants. Some doctors prescribe oral corticosteroids, although the benefits of this treatment are uncertain.
Because prolonged inactivity can promote deconditioning, your doctor may suggest that you start an exercise regimen early. Even if you begin your treatment with one to two days of bed rest, you may still be asked to complete two or three 20-minute periods of walking each day. After one to two weeks, you usually can begin a more strenuous program of daily aerobic exercises (walking, biking, swimming) and physical therapy. Other types of conservative treatment that have been helpful to some people include ultrasound, massage and acupuncture.
When these more conservative measures don't work, epidural steroid injections may be helpful. This involves the careful injection of a long-acting steroid and an anesthetic into the space near the spinal cord and compressed nerves. These injections are guided by X-rays or CT scanning so that the needle can be placed precisely in the proper location. If you have lost bowel or bladder control, if you have evidence of progressive nerve damage, or if you have unrelenting pain that persists despite weeks of conservative treatment, more aggressive treatment may be needed, including surgery. In most cases, this means removing the disk (diskectomy), which may require major surgery. Increasingly, though, a less invasive operation is done in which the herniated disk is removed through a hollow tube inserted through a tiny incision.
Call your health care professional immediately if you develop severe back pain, especially if you also have pain or numbness in your arms or legs or if you lose control of your bowels or bladder.
About 60% of people respond to conservative therapy within 1 week, and 90% to 98% respond within 6 weeks. Surgical intervention has a high success rate when MRI or CT shows that the cause of the symptoms can be corrected.
National Institute of Arthritis and Musculoskeletal and Skin Diseases
National Insitutes of Health
1 AMS Circle
Bethesda, MD 20892-3675
American Academy of Orthopaedic Surgeons (AAOS)
6300 North River Road
Rosemont, IL 60018-4262
North American Spine Society
7075 Veterans Blvd.
Burr Ridge, IL 60527
American Physical Therapy Association
1111 North Fairfax St.
Alexandria, VA 22314-1488
P.O. Box 7669
Atlanta, GA 30357-0669