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Sciatic nerve dysfunction is a condition in which the sciatic nerve conducts impulses abnormally. The sciatic nerve is the main nerve of the leg. Abnormalities of this nerve can impair movement and/or sensation.
What is going on in the body?
The sciatic nerve runs through the leg and is the largest nerve in the body. It attaches to the hip joint and some of the thigh muscles. It also attaches to the knee and ankle joints, all the muscles of the lower leg, and the foot. When dysfunction of the nerve occurs, any of these areas may be affected. Many conditions ranging from disc problem in the back to alcohol abuse can cause sciatic nerve dysfunction.
What are the signs and symptoms of the condition?
Symptoms may involve sensation, movement, or both. Examples of symptoms include:
Many conditions, such as a ruptured disc in the back, will have both movement and sensation symptoms.
- pain, which often involves the lower back and may travel to the back of the thigh and calf
- numbness, burning, or tingling in the leg
- decreased ability to move the foot and toes in certain directions
- decreased ability to flex the knee
What are the causes and risks of the condition?
The sciatic nerve can be damaged by many different conditions, including:
The primary risks of this condition are permanent muscle weakness, long-term sensation problems, and pain. Other risks are related to the underlying cause.
- a bulging or ruptured disc in the lower back, the most common cause. Improper lifting techniques or heavy labour increase the risk of a disc problem.
- trauma, such as a gunshot wound or hip fracture
- compression of the nerve by nearby bones, such as the vertebrae of the spine
- decreased blood supply to the nerve
- damage from toxic agents, such as lead poisoning or alcoholism
- surgery or other medical procedures that accidentally damage the nerve
What can be done to prevent the condition?
Proper lifting techniques can help reduce the risk of disc problems. Good general health practices, such as diabetes therapy, regular exercise, maintenance of a normal weight, and avoidance of smoking and alcohol, can also prevent some cases. Many cases cannot be prevented.
How is the condition diagnosed?
The history and physical examination usually make a doctor suspect a sciatic nerve problem. Depending on the suspected cause of the problem, he doctor may order diagnostic tests, such as:
What are the long-term effects of the condition?
Sciatic nerve dysfunction may result in permanent muscle weakness and long-term abnormal sensations. Chronic or constant pain is also a possible long-term effect. Other long-term effects depend on the underlying cause.
What are the risks to others?
There are no risks to others.
What are the treatments for the condition?
Treatment is based on the cause, often a conservative approach to treatment is all that may be required. In some cases while it is important to relieve the symptoms, it is more important to treat the underlying cause. For example, surgery may be advised in cases of a disc or bone problem in the back and trauma. Medications may be prescribed to improve blood sugar control and help treat the nerve dysfunction if diabetes is the cause. In some cases, such as toxin exposure or any delayed treatment, nerve function cannot be restored.
What are the side effects of the treatments?
All surgery carries a risk of bleeding, infection and allergic reactions to the anaesthesia medication. The medications used for those with diabetes-related nerve problems may cause drowsiness and other side effects. This depends on the specific medication used. Gastric upset from NSAIDs and side-effects from analgesics should also be watched for.
What happens after treatment for the condition?
This depends on the underlying cause. If the cause is reversible and is treated, no further treatment may be required. A person can often return to normal activities in these cases, such as after disc or spine surgery. Treatment may be prolonged if the underlying cause cannot be fixed.
How is the condition monitored?
A person should be monitored if toxic causes, such as alcohol or lead, have been identified so that further exposure can be avoided. A person recovering from ruptured discs should follow proper body mechanics. If medical causes such as diabetes or poor blood supply played a role, proper treatment and follow-up for these conditions is needed.
Author: John A.K. Davies, MD
Reviewer: eknowhow Medical Review Panel
Editor: Dr John Hearne
Last Updated: 6/09/2004
Potential conflict of interest information for reviewers available on request