Lumbar Disc Herniation

Anatomy

The lumbar spine is composed of five bones called vertebrae that stack on one another to form a portion of the spinal column in the low back.  The vertebrae are separated by discs, flat round structures that absorb mechanical forces and serve to decrease the friction associated with movement of the spine. 

The Problem

Discs are composed of a tough, flexible fibrous outer rim and a soft, jelly-like inner core with high water content.  With aging, the water content of the discs gradually decreases and the discs become thinner and more brittle.  Fraying of the outer fibrous rim can also occur to weaken the disc.  (See Degenerative Disc Disorder)

General wear and tear, increased strain or trauma to the low back can cause the jelly-like core to push against the outer rim of the disc.  A disc herniation results when the core of the disc begins to push through the outer rim.  This process occurs to varying degrees.  The core substance can remain attached to the core as it herniates, or a portion can break off from the core as it pushes out through the outer wall.  In most cases, the herniation occurs to the rear of the disc and spine.

The pressure of the core substance against the outer wall can result in low back pain.  Once the herniation has occurred, the displaced core material can press on spinal nerves nearby.  Substances can also leak out of the injured disc to cause irritation of surrounding spinal nerves.

Diagnosis

Mechanical pressure on spinal nerves can produce numbness, tingling, pain of the leg in a predictable manner that is based on the specific spinal nerve that has been affected.  (See Lumbar Radiculopathy)   Detecting changes in muscle strength and muscle stretch reflexes on physical examination can tell the physician a great deal about which nerves have been affected and, therefore, the general location of the disc herniation.  Imaging studies, including MRI, are often used to confirm the presence of disc herniation and the degree to which spinal nerves are being pinched.  

Treatment

Nine out of ten patients with lumbar disc herniation are successfully treated without surgery and many patients treated in this way get better within two months of the start of symptoms.  The primary goals of treatment are to speed the recovery process and to educate patients about methods to prevent further episodes.

A variety of medications can be helpful in relieving inflammation or muscle and nerve pain.  Exercises can help the body reduce the herniated portion of the disc and can treat muscle spasm and changes in posture or alignment that can occur following the herniation.

Epidural steroid injections treat pain and nerve root inflammation in an anatomically precise way.  (See Lumbar Epidural Steroid Injection and Lumbar Transforaminal Epidural Steroid Injection)

Prolonged bedrest should be avoided, as it may lead to a variety of secondary problems, such as muscle weakness, blood clots or kidney stones.