Common peroneal nerve dysfunction

Causes and Risks:
Common peroneal nerve dysfunction is a peripheral neuropathy (damage to nerves not including the brain or spinal cord). It may occur in a person of any age. The peroneal nerve is a branching of the sciatic nerve. It supplies movement and sensation to the lower leg, foot, and toes.

Involvement of a single nerve, such as the common peroneal nerve, is classed as mononeuropathy . Mononeuropathy implies a local cause of the nerve damage, although systemic conditions may cause isolated nerve injuries (such as occurs with mononeuritis multiplex ). Damage to the nerve causes destruction (degeneration) of the covering of the nerve cells ( myelin sheath), or degeneration of the entire nerve cell. There is a loss of muscle control, loss of muscle tone, and eventual loss of muscle mass because of lack of nervous stimulation to the muscles.

Common causes of damage to the peroneal nerve include trauma or injury to the knee, fracture of the fibula bone of the lower leg, tight plaster cast (or other long-term constriction) of the lower leg, habitual leg crossing , chronic wearing of high boots, pressure to the knee from positions during deep sleep or coma , and other conditions that place pressure on the back of the knee. The common peroneal nerve may also be injured during knee surgery. Another risk is a very thin or emaciated body build. Systemic conditions such as diabetic neuropathy or polyarteritis nodosa may cause damage to the common peroneal nerve. Charcot-Marie-Tooth disease is an inherited disorder that affects all nerves, with peroneal nerve dysfunction apparent early in the disorder.

Prevention:
Avoid prolonged pressure to the back of the knee. Injuries to the leg or knee should be treated promptly. If there is a cast, splint, dressing, or other possible constriction of the lower leg, any tight feeling or numbness of the area should be brought to the attention of a health care provider.

Symptoms:



Signs and Tests:
Examination of the legs may show a loss of muscle control of the legs and feet. Atrophy of the muscles of the foot or leg may be present. There is difficulty with dorsiflexion (lifting up the foot and toes) and with eversion (toe-out movements).

Muscle biopsy or a nerve biopsy may confirm the disorder, but they are rarely necessary.

Tests of nerve activity include:

Other tests are guided by the suspected cause of the nerve dysfunction, as suggested by the patients history, symptoms, and pattern of symptom development. They may include various blood tests, X-rays, scans, or other tests and procedures.

Treatment:
Treatment is aimed at maximizing mobility and independence. The cause should be corrected, if possible, to reduce further damage.

If there is no history of trauma to the area, and the condition developed suddenly with minimal sensation changes and no difficulty in movement, and no test evidence of nerve axon degeneration, then a conservation treatment plan will probably be recommended. Corticosteroids injected into the area may reduce swelling and pressure on the nerve in some cases. Surgery may be required if the disorder is persistent or symptoms are worsening, if there is difficulty with movement, or if there is evidence on testing that the nerve axon is degenerating. Surgical decompression of the area may reduce symptoms if the disorder is caused by entrapment of the nerve. Surgical removal of tumors (or other conditions) that press on the nerve may benefit some other cases.

control of symptoms:
Over-the-counter or prescription analgesics may be needed to control pain ( neuralgia ). Other medications may be used to reduce the stabbing pains that some people experience, including phenytoin, carbamazepine or tricyclic antidepressants such as amitriptyline. Whenever possible, medication use should be avoided or minimized to reduce the risk of side effects.

Physical therapy exercises may be appropriate for some people to maintain muscle strength.

Orthopedic assistance may maximize the ability to walk and prevents contractures . This may include use of braces, splints , orthopedic shoes, or other equipment.

Vocational counseling, occupational therapy, or similar intervention may be recommended to help maximize mobility and independence.

Prognosis:
Common peroneal nerve dysfunction may cause eventual disability. The nerve pain may be quite uncomfortable. The disorder does not usually shorten the expected life span.

Complications:



Call Your Healthcare Provider:
Call your health care provider if symptoms indicate common peroneal nerve dysfunction may be present.