Symptoms and Causes

The origin of the pain is often unknown, and imaging studies may fail to determine its cause. Disk disease, spinal arthritis, and muscle spasms are the most common diagnoses. Other problems can also cause back pain, however.

Muscle and Ligament Injuries/Lumbar Strain

Strain and injury to the muscles and ligaments supporting the back are the major causes of low back pain. The pain is typically more spread out in the muscles next to the spine, and may be associated with spasms in those muscles. The pain may move to the buttocks but rarely any farther down the leg.

Sciatica

The sciatic nerve is a large nerve that starts in the lower back.

• It forms near the spine and is made up from branches of the roots of the lumbar spinal nerves.
• It travels through the pelvis and then deep into each buttock.
• It then travels down each leg. It is the longest and widest single nerve in the body.

Sciatica is not a diagnosis but a description of symptoms. Anything that places pressure on one or more of the lumbar nerve roots can cause pain in parts or all of the sciatic nerve. A herniated disk, spinal stenosis, degenerative disc disease, spondylolisthesis, or other abnormalities of vertebrae can all cause pressure on the sciatic nerve.

Some cases of sciatica pain may occur when a muscle located deep in the buttocks pinches the sciatic nerve. This muscle is called the piriformis. The resulting condition is called piriformis syndrome. Piriformis syndrome usually develops after an injury. It is sometimes difficult to diagnose.

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Review Date: 04/07/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)