Sciatic nerve pain, or sciatica, occurs when at least one of the five nerve roots in the lower back are compressed. There are several different lumbar disorders that can lead to compression of the sciatic nerve. Anything that irritates or compresses the sciatic nerve or sciatic nerve root will cause pain.
The sciatic nerve begins at the back of the pelvis and runs under the buttock and down into each leg. It is made of five sets of nerve roots from the lumbar spine. Pain often occurs when a disc rupture or abnormal bone growth in the lumbar spine compresses the nerve roots. Symptoms of nerve compression are radiating leg pain, chronic or sharp pain on one side of the buttocks, as well as a numbness, burning, and tingling sensation in the leg.
A common cause of sciatic nerve pain is lumbar bulging. Lumbar bulging is swelling of a lumbar spine disc. The outer shell of the disc remains intact, and the gel-like nucleus is contained within the disc. The swelling disc can apply pressure to the nerve root and result in sciatic pain.
A herniated disc is similar to lumbar bulging and also causes sciatic nerve pain. The herniated disc occurs when the fluid inside the lumbar spine disc expands out of the disc shell. This fluid can cause nerve compression. The fluid also contains a chemical that causes sciatic nerve irritation.
Sciatic nerve pain can occur during pregnancy. The expanding uterus will sometimes irritate or compress the sciatic nerve tissue. Pressure placed on the lumbar spine caused by the added weight may also lead to compression and therefore sciatic nerve pain.
Lumbar spinal stenosis is a common cause of sciatic nerve pain in the elderly population. This disorder occurs when the sciatic nerve roots are compressed in the narrow passageways, called neural foramina, in the hips between the bones and ligaments. The sciatic nerve roots use these passageways to travel from the lumbar to the legs. It is not uncommon for them to become clogged or blocked with age.
Sciatic nerve pain is also associated with displaced or slipped lumbar vertebrae. This condition is called spondylolisthesis. Sometimes spondylolisthesis is present at birth and develops during childhood. Physical stress, such as weight lifting, trauma, or spinal degeneration, are also causes of lumbar vertebrae slippage.
Sciatic nerve pain can also come from blunt force trauma to the lumbar region. An outside object can hit and compress the sciatic nerve or nerve root. Bone fragments can break loose from an injury and cause nerve compression. Injuries from sports or vehicle accidents are often associated with sciatic nerve pain.
Another cause of sciatic pain is a disorder called piriformis syndrome. Pirformis syndrome is caused by muscle spasms in the pirformis muscle, which runs directly above the sciatic nerve. When the muscle spasms, it irritates the nerve.