Sciatic nerve injuries are caused by pressure on or irritation of the sciatic nerve, which runs from the lower back, through the buttock, and down the leg. Sciatica is characterized by lower back, buttock, and leg pain along the path of the sciatic nerve, which can last for weeks or months and may be accompanied by weakness, numbness, or tingling along the sciatic nerve. The most common sciatic nerve injuries are a result of disc problems, such as a herniated disc or degenerative disc disease. Other common causes of sciatica include spinal stenosis, isthmic spondylolisthesis, and piriformis syndrome.
Herniated discs are the primary cause of sciatic nerve injuries. When the soft inner portion of a spinal disc ruptures and leaks, the fluid can irritate the sciatic nerve as it pushes out through the outer portion of the disc. This condition is also referred to as a slipped disc, bulged disc, or ruptured disc. Most herniated discs do not happen suddenly. Repetitive movements and stress on the disc eventually causes it to rupture.
Degenerative disc disease is a condition that can lead to sciatic nerve injuries, and irritation from increased movement of the disc due to wear and tear. Spinal discs naturally wear and deteriorate with age, but people diagnosed with degenerative disc disease suffer from one or more discs in the lower back that wear down faster than normal. Their positioning in the lower areas of the spine make it more likely that they will irritate the sciatic nerve than people with disc problems in the upper spine or neck areas.
Spinal stenosis, a condition typically found in elderly adults, is characterized by a narrowing of the spinal canal. As the space between the spinal discs decreases as a result of stenosis, the discs may bulge and press on the sciatic nerve. Stenosis can also lead to additional soft tissue growth around the spine, which may irritate the sciatic nerve.
Isthmic spondylolisthesis can lead to a pinched sciatic nerve. Small fractures in the vertebrae that go undetected and untreated can eventually cause the affected vertebra to slip out of place. This compresses the space for the disc, which can pinch and injure the sciatic nerve.
Piriformis syndrome can lead to sciatic nerve injuries when the piriformis muscle in the buttock tightens and pinches against the sciatic nerve. The piriformis muscle runs from the lower spine to the thigh. Spasms can result from overuse, injury, or hip problems, triggering pressure on the sciatic nerve, which results in buttock and leg pain or numbness.