Aging, injuries, and being overweight can cause a herniated disk.
When herniated disks cause pain, it can be slight to debilitating.
Imaging tests are done to make the diagnosis.
People can reduce their risk of a herniated disk by exercising, strengthening their muscles, and maintaining a healthy weight.
Treatment includes measures to relieve pain and sometimes surgery.
The spine (spinal column) consists of back bones (vertebrae). There are shock-absorbing disks between each of the vertebrae. The disks have a tough, outer layer of fibrocartilage and a soft, jelly-like interior called the nucleus.
If a disk is suddenly squeezed by the vertebrae above and below it (as when lifting a heavy object), the outer layer may tear (rupture), causing pain. The interior of the disk can squeeze through the tear in the covering, so that part of the interior bulges out (herniates). This bulge can compress, irritate, and even damage the spinal nerve root or sometimes the spinal cord (see also Compression of the Spinal Cord). A ruptured or herniated disk in the low back commonly causes low back pain and sciatica. It can cause neck pain if the rupture or herniation affects a disk that is in the neck (called a herniated cervical disk).
More than 80% of herniated disks occur in the lower back. They are most common among people aged 30 to 50 years. Between these ages, the covering weakens. The jelly-like interior, which is under high pressure, may squeeze through a tear or a weakened spot in the covering and bulge out. After age 50, the interior of the disk begins to harden, making herniation less likely.
A disk may herniate because of a sudden, traumatic injury or repeated minor injuries. Being overweight or lifting heavy objects, particularly lifting incorrectly, increases the risk.
A Herniated Disk
Often, herniated disks, even ones that appear obviously bulging or herniated on imaging tests such as magnetic resonance imaging (MRI) or computed tomography (CT), cause no symptoms. Herniated disks that do not cause symptoms are more common as people age. However, herniated disks may cause slight to debilitating pain. Movement often intensifies the pain, and the pain is worsened by coughing, sneezing, straining, or leaning forward.
Where the pain occurs depends on which disk is herniated and which spinal nerve root is affected. The pain may be felt along the pathway of the nerve compressed by the herniated disk. For example, a herniated disk in the low back commonly causes sciatica—pain along the sciatic nerve, down the back of the leg. A herniated disk in the neck causes neck pain that often extends down the arm, sometimes to the hand. Pain that starts in one place but travels to another, usually along the path of a nerve, is called radiating pain.
A herniated disk can also cause numbness and muscle weakness. If pressure on the nerve root is great, a leg may be paralyzed. Rarely, the disk can put pressure on the spinal cord itself, possibly causing weakness or paralysis of both legs. If the cauda equina (the bundle of nerves extending from the bottom of the cord in the lower back) is affected, control of bladder and bowels can be lost. If these serious symptoms develop, medical attention is required immediately.
Magnetic resonance imaging (MRI) or computed tomography (CT) are imaging tests that are done to identify the cause and determine the location of a herniated disk. Rarely, another imaging test called CT myelography is done when doctors need more detail of the spinal cord and surrounding bone than MRI or CT alone can provide.
Tests of the nerves and muscles (electrodiagnostic tests), such as nerve conduction studies and electromyography, may help identify the affected spinal nerve root.
It is not always possible to prevent a herniated disc, but there are ways to reduce the risk of developing one:
Regular exercise is an effective way to reduce the risk of developing a herniated disc. Aerobic exercise and specific muscle-strengthening and stretching exercises can help.
Aerobic exercise, such as swimming and walking, improves general fitness and generally strengthens muscles.
Specific exercises to strengthen and stretch the muscles in the abdomen, buttocks, and back (the core muscles) can help stabilize the spine and decrease strain on the disks that cushion the spine and the ligaments that hold it in place.
Muscle-strengthening exercises include pelvic tilts and abdominal curls. Stretching exercises include the knee-to-chest stretch. Stretching exercises can increase back pain in some people and therefore should be done carefully. As a general rule, any exercise that causes or increases back pain should be stopped. Exercises should be repeated until the muscles feel mildly but not completely fatigued. Breathing during each exercise is important. People who have back pain should consult a doctor before beginning to exercise.
Exercises to Prevent Low Back Pain
Exercise can also help people maintain a desirable weight because being overweight increases the stress on a disk.
Maintaining good posture when standing, sitting, and sleeping reduces stress on the back. Slouching should be avoided. Chair seats can be adjusted to a height that allows the feet to be flat on the floor, with the knees bent up slightly and the lower back flat against the back of the chair. If a chair does not support the lower back, a pillow can be used behind the lower back. Sitting with the feet on the floor rather than with the legs crossed is advised. People should avoid standing or sitting for long periods. If prolonged standing or sitting is unavoidable, changing positions frequently may reduce stress on the back.
Learning to lift correctly helps prevent back injury. The hips should be aligned with the shoulders (that is, not rotated to one side or the other). People should not bend over with their legs nearly straight and reach out with their arms to pick up an object. Instead, they should bend at the hips and knees. Bending this way keeps the back straighter and brings the arms down to the object with the elbows at the side. Then, keeping the object close to the body, they lift the object by straightening their legs. This way, the legs, not the back, lift the object. Lifting an object over the head or twisting while lifting increases the risk of back injury.
Because a herniated disk shrinks over time, symptoms tend to lessen regardless of treatment. Most people recover without any treatment, usually within 3 months, but often much faster.
Applying cold (such as ice packs) or heat (such as a heating pad) or using over-the-counter analgesics (such as acetaminophen and nonsteroidal anti-inflammatory drugs [NSAIDs]) may help relieve the pain. If symptoms are not relieved with analgesics, doctors may give corticosteroids taken by mouth or injected into the epidural space (between the spine and the outer layer of tissue covering the spinal cord).
Sleeping in a comfortable position on a medium mattress is recommended. People who sleep on their back can place a pillow under their knees. People who sleep on their side should use a pillow to support their head in a neutral position (not tilted down toward the bed or up toward the ceiling). They should place another pillow between their knees with their hips and knees bent slightly if that relieves their back pain.
If a herniated disk is causing relentless or chronic sciatica, weakness, loss of sensation, or loss of bladder and bowel control (cauda equina syndrome), surgical removal of the bulging part of the disk (diskectomy) and sometimes part of the vertebra (lumbar laminectomy) may be necessary. A general anesthetic is usually required. The hospital stay is usually 1 or 2 days. Often, microsurgical techniques, with a small incision and regional spinal anesthesia (which numbs only a specific part of the body), can be used to remove the herniated portion of the disk. Hospitalization for this procedure is usually not required. After either procedure, most people can resume all of their activities in 6 weeks to 3 months. Surgery tends to result in faster recovery than treatment without surgery. However, after about a year or two, people treated with or without surgery have about the same degree of recovery.
In 10 to 20% of people who have surgery for sciatica due to a herniated disk, another disk ruptures.