Print This PageSciatica Causes
Sciatica refers to a set of symptoms that are usually caused by a problem in the lower back called a radiculopathy - when a nerve root that connects to the sciatic nerve is compressed or irritated. The six most common problems that can cause sciatica and sciatica-type symptoms include:
Lumbar herniated disc. A herniated disc occurs when the soft inner core of the disc (nucleus pulposus) leaks out, or “herniates”, through the fibrous outer core (annulus) of the disc and irritates the contiguous nerve root as it exits the spine. In general, it is thought that a sudden twisting motion or injury can lead to an eventual disc herniation and sciatica.However, most discs weaken over time due to repetitive stress and the final result is a herniation. A herniated disc is sometimes referred to as a slipped disk, ruptured disk, bulging disc, protruding disc, or a pinched nerve, and sciatica is the most common symptom of a lumbar herniated disc.
- For more herniated disc information and treatment options, see Lumbar disc herniation
Lumbar spinal stenosis. This condition commonly causes sciatica due to a narrowing of the spinal canal. Spinal stenosis is relatively common in adults over age 60. Lumbar spinal stenosis is related to natural aging in the spine, and typically results from a combination of one or more of the following: enlarged facet joints, overgrowth of soft tissue, and a bulging disc placing pressure on the nerve roots as they exit the spine and causing sciatica pain.
- For more spinal stenosis information and treatment options, see Definitive Guide to Lumbar Spinal Stenosis
Article continues belowDegenerative disc disease. While disc degeneration is a natural process that occurs with aging, for some people one or more degenerated discs in the lower back can also irritate a nerve root and cause sciatica. Degenerative disc disease is diagnosed when a weakened disc results in excessive micro-motion at the corresponding spinal level, and inflammatory proteins from inside the disc become exposed and irritate the area (including the nerve roots).
- For more degenerative disc disease information and treatment options, see Degenerative disc disease
Some less common causes of sciatica include the following:Isthmic spondylolisthesis. This condition occurs when a small stress fracture allows one vertebral body to slip forward on another vertebral body (e.g. the L5 vertebra slips over the S1 vertebra). With a combination of disc space collapse, the fracture, and the vertebral body slipping forward, the L5 nerve can get pinched as it exits the spine and cause sciatica.
- For more isthmic spondylolisthesis information and treatment options, see Isthmic spondylolisthesis
Piriformis syndrome. The sciatic nerve can also get irritated as it runs under the piriformis muscle in the rear. If the piriformis muscle irritates or pinches a nerve root that comprises the sciatic nerve, it can cause sciatica-type pain. This is not a true radiculopathy (the clinical definition of sciatica), but the leg pain can feel the same as sciatica caused by a nerve irritation.
- For more piriformis syndrome information and treatment options, see Piriformis syndrome—another irritation to the sciatic nerve
Sacroiliac joint dysfunction. Irritation of the sacroiliac joint at the bottom of the spine can also irritate the L5 nerve, which lies on top of the sacroiliac joint, and can cause sciatica-type pain. This is not a true radiculopathy, but the leg pain can feel the same as sciatica caused by a nerve irritation.
For more sacroiliac joint dysfunction information and treatment options, see Sacroiliac Joint Dysfunction
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Pregnancy. The changes that the body goes through during pregnancy, including weight gain, a shift on one's center of gravity, and hormonal changes, can cause sciatica during pregnancy.
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Scar tissue. If scar tissue is affecting the nerve root, it can cause sciatica.
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Muscle strain. In some cases, inflammation related to a muscle strain can put pressure on a nerve root and cause sciatica.
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Spinal tumor. In rare cases, a spinal tumor can impinge on a nerve root in the lower back and cause sciatica symptoms.
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Infection. While rare, an infection that occurs in the low back can affect the nerve root and cause sciatica.
It is important to know the underlying clinical diagnosis of the cause of sciatica, as treatments will often differ depending on the cause. For example, specific sciatica exercises, which are almost always a part of a sciatica treatment program, will be different depending on underlying cause of the sciatica symptoms.
