Understanding Lumbar Disc Herniations

Article written by Mark A. Knaub, MD

Spinal intervertebral discs lie between two adjacent vertebral bodies and act as a cushion or shock absorber for the spine. They are responsible for distributing the forces that travel through the entire spine. The intervertebral discs also function as a stabilizer by helping to control normal motion between two adjacent vertebrae. As discs begin to wear out, they loose their ability to perform these functions. Disc herniations, or ruptures, occur when the inner, "jelly-like" nucleus pulposus bulges or ruptures through the weakened outer layers (annulus) of the disc.

Although almost all people experience degenerative (arthritic) changes in the low back, not all of these changes lead to a disc herniation. Disc herniations in the low back may be due to trauma, such as lifting a heavy object or repetitive twisting or bending motions, such as golfing. Often times a disc may herniate with no injury at all; patients often state they just "woke up with the pain"

Symptoms of lumbar disc herniation include both low back pain and leg pain. Patients can also present with numbness, weakness and/or tingling in one or both of the legs. In extreme cases, a large disc herniation can compress nerves to the bowel and bladder, leading to incontinence. The low back pain is likely caused by irritation of nerve fibers located around the disc itself. Pain or numbness and tingling radiating down the leg, commonly referred to as radiculopathy, stems from irritation and compression of the nerves that exit the spine in the lumbar region and travel to the lower extremities.

Various diagnostic tests are typically utilized to assist in the diagnosis of a lumbar disc herniation. Plain x-rays of the low back are taken to rule out other potential sources of the sciatica, but do not allow for actual visualization of the herniated disc. Direct visualization of the disc herniation is usually accomplished with a radiographic test called magnetic resonance imaging (MRI).

Most herniated discs will heal with rest and medications. A short period of decreased activity in combination with various medications will result in relief of both back and leg pain in a vast majority of patients. Physical therapy may be beneficial in those patients in whom symptoms do not subside within the first few weeks. Occasionally, injections of anti-inflammatory medications around the inflamed nerves (epidural steroids) are necessary to control symptoms. If leg pain fails to respond to conservative treatments, surgery may be necessary to remove the herniated portion of the disc that is putting pressure on the nerve. The goal of surgery is to remove the pressure from the nerve and therefore relieve leg pain. Complete recovery from such a procedure generally takes from one to three months.