Femoral nerve dysfunction is a condition involving impaired movement or sensations in the leg (a form of peripheral neuropathy ), caused by damage to the femoral nerve.

Alternative Names

Neuropathy - femoral nerve

Causes, incidence, and risk factors

The femoral nerve is located in the leg and supplies the muscles that assist the leg in straightening. It supplies sensation to the front of the thigh and part of the lower leg. Dysfunction of a single nerve group such as the femoral nerve is classed as mononeuropathy . Mononeuropathy implies a local cause of the nerve damage, although systemic disorders may occasionally cause isolated nerve damage (such as occurs with mononeuritis multiplex ). The usual causes are direct trauma, prolonged pressure on the nerve, and compression of the nerve by nearby body structures or pathologic structures (such as a tumor ). Entrapment involves pressure on the nerve where it passes through a narrow structure. The damage includes destruction of the myelin sheath of the nerve or destruction of part of the nerve cell (the axon). This damage slows or prevents conduction of impulses through the nerve. The femoral nerve can be injured as a result of pelvic fractures . It may be injured during procedures involving catheterization of the femoral artery. It can be affected by systemic diseases causing polyneuropathy (damage to multiple nerves) such as diabetes mellitus or polyarteritis nodosa . It can be damaged by pressure from lesions such as tumor, abscess , or internal bleeding into the pelvis or abdomen. One relatively common risk factor is a prolonged "lithotomy" position, where the patient lies on his back with his thighs and legs flexed, during surgery or diagnostic procedures. In some cases, no detectable cause can be identified. Mechanical factors, such as pressure, may be complicated by ischemia (lack of oxygen from decreased blood flow) in the area.

Signs and tests

A neuromuscular examination of the legs indicates femoral nerve dysfunction. There may be weakness on extension of the knee or flexion of the hips. Sensation changes are located in the lateral and anterior thigh and medial calf. The knee jerk reflex may be abnormal. There may be atrophy (loss of muscle mass) of the quadriceps muscles of the anterior (front) thigh. Tests that reveal femoral nerve dysfunction may include:

Treatment

Treatment is aimed at maximizing mobility and independence. The cause should be identified and treated as appropriate. In some cases, no treatment is required and recovery is spontaneous. If there is no history of trauma to the area, conservative treatment is indicated by sudden onset, minimal sensation changes and no difficulty in movement, and no evidence on testing of degeneration of the nerve axon. Corticosteroids injected into the area may reduce swelling and pressure on the nerve in some cases. Over-the-counter or prescription analgesics may be needed to control pain ( neuralgia ). Various other medications may reduce the stabbing pains that some people experience, including phenytoin, carbamazepine, gabapentin or tricyclic antidepressants such as amitriptyline. Whenever possible, medication use should be avoided or minimized to reduce the risk of side effects. Surgical removal of lesions that press on the nerve may benefit some cases. Physical therapy exercises may be appropriate for some people to maintain muscle strength. Orthopedic assistance may maximize the ability to walk. This may include the use of braces, splints , or other appliances. Vocational counseling, occupational therapy, occupational changes, job retraining, or similar interventions may be recommended.

Expectations (prognosis)

If the cause of the femoral nerve dysfunction can be identified and successfully treated, there is a possibility of full recovery. In some cases, there may be partial or complete loss of movement or sensation resulting in various extent of disability. Nerve pain may be quite uncomfortable and persist for a prolonged period of time. Trauma to the femoral area may also involve trauma to the femoral artery, which can cause fatal hemorrhage.

Complications

A complication is a recurrent or an unnoticed injury to the leg.

Calling your health care provider

Call your health care provider if symptoms of femoral nerve dysfunction develop.

Prevention

The prevention is variable depending on the cause of the nerve damage.