Herniated Intervertebral Discs

What is it?

Intervertebral discs herniate. They do not slip.  A herniation occurs when the inner jelly of the disc (nucleus pulposus) escapes from the trilayer outer fibrous tissue layer (annulus fibrosus) that encases it.  A disc protrusion, or bulging, occurs when the escaped gel remains inside the outermost wall of the restraining annulus.  A disc herniation or extrusion happens when the gel escapes entirely and enters the spinal canal.  Disc herniation occurs most commonly in people aged 30 to 40 years.  Gel causes pain when contacting spinal nerves.  Locations for this contact include the spinal canal or the neural foramina through which smaller nerves pass that branch off from the spinal canal.  When the gel comes into contact with nerves, the body considers the gel a foreign substance and tries to remove it by sending an inflammatory response consisting of cells and enzymes that dissolve it. Unfortunately, the inflammatory response causes irritation in the spinal nerve causing pain and numbness in the area supplied by that nerve.

The most common locations for herniation are at the 3 lowest levels of the lumbar spine, lumbar 3 through sacral 1 but any intervertebral disc can herniate. The discs at the lower end of the spine carry a greater portion of the weight of the upper body.  Each spinal nerve travels to a specific part of the body supplying impulses for muscle and sensory function.   A disc herniation irritating the L5 nerve root will cause number in the lower leg affecting the big toe, weakness in lifting up on the toes (foot drop) but no loss of reflexes in the lower leg.  Irritation to the S1 nerve root is associated with numbness on the bottom of the foot and the 4th and 5th toes, weakness walking on the heel, and loss of the ankle reflex on that side.

Symptoms

The symptoms of a herniated disc may be an episode of very acute low back pain that resolves with the subsequent development of leg pain in the distribution of the nerve compressed by the herniated disc.  The pain is more intense with sitting, coughing, driving, or having a bowel movement, which increases pressure within the disc.  Radiculopathy (irritation of a specific nerve root) is associated with pins and needle sensation or numbness in the leg.  More intense involvement is associated with muscle weakness.

Diagnosis

A diagnosis of a herniated disc is confirmed with findings on an MRI scan of the appropriate level of the spine, the neck (cervical spine) for arm symptoms and low back (lumbar spine) for leg symptoms.

Treatment

After a diagnosis of a herniated disc is made, is spine surgery necessary?  ABSOLUTELY NOT!  The vast majority of herniated discs resorb spontaneously without the need for surgery.  Surgery is required for progressive muscle weakness, loss of bladder or rectal function, or uncontrollable pain.  Although it may take months, the gel from the disc herniation is resorbed and the nerve can return to normal functioning.

The non-surgical therapy of herniated discs may include a number of options.  The most important is gradual movement.  Movement allows for better healing, so trying to stay out of bed is important. Movement allows the spine to heal while avoiding the loss of muscle strength associated with prolonged bed rest.

Medication: Drug therapy can include anti-inflammatories, analgesics and/or muscle relaxants.  These medicines can reduce inflammation irritating the nerve.  Muscle relaxants reduce muscle contractions that are counterproductive to improved movement.  Analgesics – non-opioid and opioids- are indicated to decrease pain to improve healing.

Epidural injections anti-inflammatory medicine can be injected directly into a herniated disc in order to reduce swelling and inflammation. Corticosteroids are more commonly injected and the medicine targets the specific area of nerve inflammation.  As many as three injections can be given over a 6 week period to resolve the pain associated with an acute disc herniation.

Surgery for a herniated disc is needed in a very small number of individuals approximately 1 in 20.  The primary reasons for surgery are persistent pain that is resistant to pain therapy and significant muscle weakness resulting in an abnormal gait, usually a foot drop.

A number of different surgical techniques may be used for the removal of the portion of disc compressing the spinal nerve causing the symptoms.  The gold standard is open discectomy.  A 3inch incision is needed to visualize the protruding portion of the disc compressing a spinal nerve.  Only the proportion of the disc protruding is removed.

Other surgical techniques for disc removal include microdiscectomy, percutaneous discectomy, and laser surgery.  Each of these techniques uses a much smaller incision to gain access to the spine.  Currently when given a choice, open discectomy is the preferred technique with a greater success rate.

Prevention of a disc herniation is based on factors that are only partially in one’s control.  Having good discs to start with can be very helpful.  That is genetic background with a family history lacking any disc herniation events.  Good techniques in lifting can help prevent excessive force placed on the spine.  No specific nutritional or dietary interventions are particularly helpful.

Lifestyle Changes and Management Tips:  Sitting is the new smoking.   Getting up from a chair on a regular basis is a way to maintain spine health.  Do not start smoking if you have not smoked, and stop if you do.  Maintaining a regular exercise program including core strengthening is useful.  Also maintaining a good weight is another way to minimize back pain. 

Reference: Heal Your Back: Your Complete Prescription for Preventing, Treating, and Eliminating Back Pain

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