What is a Herniated Disc?

Herniation of the nucleus pulposus (HNP) occurs when the nucleus pulposus (gel-like substance) breaks through the anulus fibrosus (tire-like structure) of an intervertebral disc (spinal shock absorber).

A herniated disc occurs most often in the lumbar region of the spine especially at the L4-L5 and L5-S1 levels (L = Lumbar, S = Sacral). This is because the lumbar spine carries most of the body's weight. People between the ages of 30 and 50 appear to be vulnerable because the elasticity and water content of the nucleus decreases with age.

The progression to an actual HNP varies from slow to sudden onset of symptoms. There are four stages: (1) disc protrusion (2) prolapsed disc (3) disc extrusion (4) sequestered disc. Stages 1 and 2 are referred to as incomplete, where 3 and 4 are complete herniations. Pain resulting from herniation may be combined with a radiculopathy, which means neurological deficit. The deficit may include sensory changes (i.e. tingling, numbness) and/or motor changes (i.e. weakness, reflex loss). These changes are caused by nerve compression created by pressure from interior disc material.

The extremities affected are dependent upon the vertebral level at which the HNP occurred. Consider the following examples:

Cervical - Pain in the neck, shoulders, and arms

Thoracic - Pain radiates into the chest

Lumbar - Pain extends into the buttocks, thighs, legs

Cauda Equina Syndrome occurs from a central disc herniation and is serious requiring immediate surgical intervention. The symptoms include bilateral leg pain, loss of perianal sensation (anus), paralysis of the bladder, and weakness of the anal sphincter.

Diagnosis of a Herniated Disc

The spine is examined with the patient laying down and standing. Due to muscle spasm, a loss of normal spinal curvature may be noted. Radicular pain (inflammation of a spinal nerve) may increase when pressure is applied to the affected spinal level.

A Lasegue test, also known as Straight-leg Raising Test, is performed. The patient lies down, the knee is extended, and the hip is flexed. If pain is aggravated or produced, it is an indication the lower lumbosacral nerve roots are inflamed.

Other neurological tests are performed to determine loss of sensation and/or motor function. Abnormal reflexes are noted as these changes may indicate the location of the herniation.

Radiographs are helpful, but Computed Axial Tomography (CAT) or Magnetic Resonance Imaging (MRI) provides more detail. The MRI is the best method enabling the physician to see the soft spinal tissues unseen in a conventional x-ray.

Facts and Tips about Herniated Discs

Herniated Discs Animation Video Transcript

The backbone, or spinal column, consists of a series of bones called vertebrae, that connect the skull to the pelvis. The vertebrae are separated and cushioned by discs, which are filled with a jelly-like substance that acts as a shock absorber between each vertebrae.

Nestled inside a channel running from the brain to the base of the spine is the spinal cord. From the spinal cord, nerves branch out to the arms, legs and other parts of the body. It is through the spinal cord and connecting nerves that the brain sends signals to the body allowing movement and all body functions.

Trauma or injury to the back can cause the cushioning discs to rupture or to protrude (herniate) from the spinal column; the disc then presses on the branching nerves.

Pressure on a nerve can be painful, and because these nerves travel to other parts of the body, pain, tingling or numbness can be felt in other parts of the body.

Treatment of a ruptured disc depends on the severity of the injury..