The sciatic nerve is the longest nerve in your body. It runs from the bottom of your spinal cord in your lower back to your buttock and hip area and down the back of each leg. The term “sciatica” refers to pain that radiates along the path of this nerve from your back down your buttock and leg.
Sciatica is a symptom of another problem involving compression or inflammation of the nerve, possibly from a herniated disk or arthritis. Depending on the cause, acute sciatic pain can be considerably uncomfortable.
However, conservative care such as chiropractic, massage and physical therapy, pain management and/or acupuncture may significantly reduce the intensity and length of time you suffer with this condition.
Signs & Symptoms
Pain that radiates from your lower (lumbar) spine to your buttock and down the back of your leg is the hallmark of sciatica. You may feel the discomfort almost anywhere along the nerve pathway, but it's especially likely to follow a path from your low back to your buttock and the back of your thigh and calf.
The pain can vary widely, from a mild ache to a sharp, burning sensation or excruciating discomfort. Sometimes it may feel like a jolt or electric shock. It may be worse when you cough or sneeze, and prolonged sitting also can aggravate symptoms. Usually only one lower extremity is affected.
- Pain. It's especially likely to occur along a path from your low back to your buttock and the back of your thigh and calf.
- Numbness or muscle weakness along the nerve pathway in your leg or foot. In some cases, you may have pain in one part of your leg and numbness in another.
- Tingling or a pins-and-needles feeling, often in your toes or part of your foot.
- A loss of bladder or bowel control. This is a sign of cauda equina syndrome, a rare but serious condition that requires emergency care. If you experience either of these symptoms, seek medical help immediately.
Your sciatic nerve controls many of the muscles in your lower legs and provides feeling to your thighs, legs and feet. Sciatica frequently occurs when a nerve root is compressed in your lower (lumbar) spine often as a result of a herniated disk in your lower back. Disks are pads of cartilage that separate the bones (vertebrae) in your spine. They keep your spine flexible and act as shock absorbers to cushion the vertebrae when you move.
As you grow older, the disks may start to deteriorate, becoming drier, flatter and more brittle. Eventually, the tough, fibrous outer covering of the disk may develop tiny tears, causing the jelly-like substance in the disk's center to seep out (herniation or rupture). The herniated disk may then press on a nerve root, causing pain in your back, leg or both. You may also experience numbness, tingling or weakness in your buttock, leg or foot.
Although a herniated disk is a common cause of sciatic nerve pain, other conditions also can put pressure on your sciatic nerve, including:
- Lumbar spinal stenosis. Your spinal cord is a bundle of nerves that extends the length of your spine. It's housed inside a channel (spinal canal) within the vertebrae. Nerves branch off the spinal cord, providing communication between your brain and the rest of your body. In spinal stenosis, one or more areas in the spinal canal narrow, putting pressure on the spinal cord or on the roots of the nerves branching off of the spinal cord. When the narrowing occurs in the lower spine, the lumbar and sacral nerve roots may be affected.
- Spondylolisthesis. This condition, often the result of degenerative disk disease or stress fracture of the pars interarticularis, occurs when one vertebra slips slightly forward over another vertebra. The displaced bone may pinch the sciatic nerve where it leaves your spine.
- Piriformis syndrome. The piriformis muscle is a hip rotator muscle that runs directly above the sciatic nerve in the buttock; this muscle starts at your lower spine and connects to each thighbone (femur). Piriformis syndrome occurs when the muscle becomes tight or goes into spasms, putting pressure on the sciatic nerve. The pain may radiate down the back of your thigh but doesn't extend below the knee, distinguishing it from a herniated disk. Prolonged sitting, car accidents and falls also can contribute to piriformis syndrome.
- Spinal and sciatic nerve tumors can also compress the cord itself or the nerve roots.
- Trauma. A car accident, fall or blow to your spine can injure the lumbar or sacral nerve roots.