Herniated nucleus pulposus (slipped disk)

Alternative names
Lumbar radiculopathy; Cervical radiculopathy; Herniated intervertebral disk; Prolapsed intervertebral disk; Slipped disk; Ruptured disk

Definition
Herniated nucleus pulposus, or slipped disk, is a condition in which part or all of the soft, gelatinous central portion of an intervertebral disk (the nucleus pulposus) is forced through a weakened part of the disk. This results in back pain and leg pain (lumbar herniation) or neck pain and arm pain (cervical herniation) due to nerve root irritation.

Causes, incidence, and risk factors

The bones of the spinal column, or vertebrae, run down the back connecting the skull to the pelvis. These bones protect nerves as they exit the brain and travel down the back and then to the entire body.

The spinal column is divided into several segments - the cervical spine (the neck), the thoracic spine (the part of the back behind the chest), the lumbar spine (lower back), and sacral spine (the part connected to the pelvis that does not move).

The spinal vertebrae are separated by cartilage disks filled with a gelatinous substance, which provide cushioning to the spinal column. These disks may herniate (move out of place) or rupture from trauma or strain, especially if degenerative changes have occurred in the disk.

Radiculopathy refers to any disease affecting the spinal nerve roots. A herniated disk is one cause (but not the only cause) of radiculopathy (sciatica).

Most herniation takes place in the lumbar area of the spine. Lumbar disk herniation occurs 15 times more often than cervical (neck) disk herniation, and it is one of the most common causes of lower back pain. The cervical disks are affected 8% of the time and the upper-to-mid-back (thoracic) disks only 1 to 2% of the time.

Nerve roots (large nerves that branch out from the spinal cord) may become compressed resulting in neurological symptoms, such as sensory or motor changes.

Disk herniation occurs more frequently in middle aged and older men, especially those involved in strenuous physical activity. Other risk factors include any congenital conditions that affect the size of the lumbar spinal canal.

Symptoms

Symptoms OF HERNIATED LUMBAR DISK

     
  • severe low back pain  
  • pain radiating to the buttocks, legs, and feet  
  • pain made worse with coughing, straining, or laughing  
  • tingling or numbness in legs or feet  
  • muscle weakness or atrophy in later stages  
  • muscle spasm

Symptoms OF HERNIATED CERVICAL DISK

     
  • neck pain, especially in the back and sides  
  • deep pain near or over the shoulder blades on the affected side  
  • pain radiating to the shoulder, upper arm, forearm, and rarely the hand, fingers or chest  
  • pain made worse with coughing, straining, or laughing  
  • increased pain when bending the neck or turning head to the side  
  • spasm of the neck muscles  
  • arm muscle weakness

Signs and tests

A physical examination and history of pain may be sufficient to diagnose the disorder. A neurological examination will be performed to evaluate muscle reflexes, sensation, and muscle strength. Often, examination of the spine will reveal a decrease in the spinal curvature in the affected area.

Straight-leg-raising test that reveals leg pain is diagnostic of a herniated lumbar disk.

A “foraminal compression test of Spurling” will be performed to diagnose cervical radiculopathy. This is performed by bending the head forward and to the sides while downward pressure is applied to the top of the head. Increased pain or numbness during this test is usually indicative of cervical radiculopathy.

DIAGNOSTIC TESTS

     
  • A spine X-ray may be performed to rule out other causes of back or neck pain. However, it is not possible to diagnosis herniated disk by spinal X-ray alone.  
  • A spine MRI and/or spine CT will show spinal canal compression by the herniated disk.  
  • A myelogram may be performed to define the size and location of disk herniation.  
  • An EMG may be performed to determine the exact nerve root(s) that is (are) involved.  
  • A nerve conduction velocity test may also be performed.

Treatment

The mainstay of treatment for herniated disks is an initial period of rest with pain and anti-inflammatory medications, followed by physical therapy. Under this regimen, over 95% of people will recover and return to their normal activities. A small percentage of people do need to go on and have further treatment which may include steroid injections or surgery.

MEDICATIONS

For people with an acute herniated disk caused by some sort of trauma (like a car accident or lifting a very heavy object) and immediately followed by severe pain in the back and leg, narcotic pain relievers and non-steroidal anti-inflammatory medications (NSAIDs) will be prescribed.

If there is also an element of back spasm, anti-spasm drugs, also called muscle relaxants, are usually given. On rare occasions, steroids may be administered either by pill or directly into the blood with an intervenous line (IV).

Long-term pain control is usually limited to NSAIDs, but occasionally narcotics are used as well (if the pain does not respond to NSAIDs).

For people unable to do physical therapy because of pain, steroid injections into the back in the area of the herniation can be very helpful in controlling pain for several months. This allows a vigorous therapy program to be initiated which will usually control pain for the long-term.

LIFESTYE MODIFICATIONS

Any extra weight being carried by an individual, especially weight up front in the abdomen, will worsen any back pain syndrome. A program of diet and exercise is crucial to improving back pain in overweight patients.

Physical therapy is another crucial treatment for nearly everyone with lumbar disk disease. Therapists will instruct you how to properly lift, dress, walk, and perform other activities.

They will also work on strengthening the muscles of the abdomen and lower back to help support the spine. Flexibility of the spine and legs is the third aspect of most therapy programs.

Some practitioners recommend the use of back braces to help support the spine. However, overuse of these devices can weaken the abdominal and back muscles leading to a worsening of the problem. Weight belts can be helpful in preventing injuries in those whose work requires lifting of heavy objects.

A soft cervical collar may be prescribed for people with cervical radiculopathy. The collar helps reduce the pain and muscle spasms by limiting neck movements. A rigid neck collar may occasionally be necessary to eliminate weight bearing on the cervical spine in people with severe pain and muscle spasms.

SURGERY

For the few patients whose symptoms persist despite the above interventions, surgery may be a good option to control pain.

Diskectomy is performed to remove a protruding disk under general anesthesia. The hospital stay is short, about 2-3 days. You will be encouraged to walk the first day after surgery to reduce the risk of blood clots.

Complete recovery takes several weeks. If more than one disk needs to be taken out or if there are other problems in the back besides a herniated disk, more extensive surgery may be needed. This may require a much longer recovery period.

Other surgical options include micro diskectomy, a procedure removing fragments of nucleated disk through a very small incision with X-ray guidance and chemo nucleosis.

Chemonucleolysis involves the injection of an enzyme (called chymopapain) into the herniated disk to dissolve the protruding gelatinous substance. This procedure may be an alternative to diskectomy in certain situations.

Expectations (prognosis)

Most people will improve with conservative treatment. A small percentage may continue to have chronic back pain even after treatment. People who injure themselves on the job tend not to do as well as those without such injuries.

It may take several months to a year or more to resume all activities without pain or strain to the back. Certain occupations that involve heavy lifting or back strain may need modification to avoid recurrent back injury.

Complications

     
  • chronic back pain  
  • permanent spinal cord injury (very rare)       o loss of movement or sensation in the legs or feet       o loss of bowel and bladder function

Calling your health care provider

Call your health care provider if persistent, severe back pain develops, especially if there is any numbness or loss of movement.

Prevention

Safe work and play practices, proper lifting techniques, and weight control may help to prevent back injury in some people.

Johns Hopkins patient information

Last revised: December 2, 2012
by Arthur A. Poghosian, M.D.

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