Injury or pressure affecting the sciatic nerve is called sciatica. It is a symptom of another medical problem which must be treated in order to relieve the sciatica.
The sciatic nerve is the longest nerve of the body, running from the lower spine down the back of the leg. It controls the activity of muscles in the lower leg and the back of the knee. It's the origin of sensation in the back part of the thigh, some of the lower leg, and the bottom of the foot.
Sciatica can be the result of a slipped, or a herniated, disk in the spine, tumors, or pelvic injury. It may be caused by a pain disorder in the buttocks called piriformis syndrome.
Piriformis syndrome occurs when the piriformis muscle constricts or spasms. This can put unpleasant pressure on the sciatic nerve.
Sciatica can be caused by lumbar spinal stenosis or spondylolisthesis.
Lumbar spinal stenosis is a narrowing in the upper or lower area of your spine. Sciatica is the result when the narrowing is in the lower spine.
Spondylolisthesis may result from degenerative disk disease, when a vertebra has slipped forward over another vertebra. The sciatic nerve can be pinched by the bone that is out of place.
Sciatica pain can run the gamut from a mild ache or tingling in the lumbar region (lower part) of the spine, to a severe burning sensation that makes it impossible for the sufferer to move. It may be experienced as an electric shock or a sudden jolt. Sensations may also be felt as numbness or muscle weakness.
Usually sciatica will only affect one side at a time, often becoming more painful at night. Pain can be worsened by standing or sitting for too long.
Coughing, laughing or sneezing can increase the pain. Bending backwards or walking even a short distance can increase the pain, particularly if the sufferer has spinal stenosis.
Sciatica resulting from cauda equina syndrome may cause loss of control of bladder or bowel. Cauda equina syndrome is a serious condition that should be treated immediately by a doctor. This is a rare condition, but one to be dealt with as quickly as possible.