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Common peroneal nerve dysfunction

Definition

Common peroneal nerve dysfunction is damage to the peroneal nerve leading to loss of movement or sensation in the foot and leg.

Alternative Names

Neuropathy - common peroneal nerve; Peroneal nerve injury; Peroneal nerve palsy

Causes

The peroneal nerve is a branch of the sciatic nerve, which supplies movement and sensation to the lower leg, foot and toes. Common peroneal nerve dysfunction is a type of peripheral neuropathy (damage to nerves outside the brain or spinal cord). This condition can affect people of any age.

Dysfunction of a single nerve, such as the common peroneal nerve, is called a mononeuropathy. Mononeuropathy implies there is a local cause of the nerve damage, although certain bodywide conditions may also cause isolated nerve injuries.

Damage to the nerve destroys the covering of the nerve cells (the myelin sheath) or causes degeneration of the entire nerve cell. There is a loss of sensation, muscle control, 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 the following:

  • Trauma or injury to the knee
  • Fracture of the fibula (a bone of the lower leg)
  • Use of a tight plaster cast (or other long-term constriction) of the lower leg
  • Habitual leg crossing
  • Regularly wearing high boots
  • Pressure to the knee from positions during deep sleep or coma
  • Injury during knee surgery.

People who are extremely thin or emaciated (for example, from anorexia nervosa) have a higher-than-normal risk of common peroneal nerve injury. Conditions such as diabetic neuropathy or polyarteritis nodosa, as well as exposure to certain toxins, can also 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.

Symptoms

  • Decreased sensation, numbness or tingling in the top of the foot or the outer part of the upper or lower leg
  • Weakness of the ankles or feet
  • Walking abnormalities
  • "Slapping" gait (walking pattern in which each step taken makes a slapping noise)
  • Foot drop (unable to hold foot horizontal)
  • Toes drag while walking

Exams and Tests

Examination of the legs may show a loss of muscle control over the legs (usually the lower legs) and feet. The foot or leg muscles may atrophy (lose mass). 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 determined by the suspected cause of the nerve dysfunction, based on the person's 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. Any illness or other source of inflammation that is causing the neuropathy should be treated.

If there is no history of trauma to the area, the condition developed suddenly with minimal sensation changes and no difficulty in movement, and there is no test evidence of nerve axon degeneration, then a conservative 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 pressure on the nerve. Surgical removal of tumors or other conditions that press on the nerve may be of benefit.

CONTROLLING SYMPTOMS

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

If pain is severe, a pain specialist should be consulted so that all options for pain treatment are explored.

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.

Outlook (Prognosis)

The outcome depends on the underlying cause. Successful treatment of the underlying cause may resolve the dysfunction, although it may take several months for the nerve to grow back.

Alternately, if nerve damage is severe, disability may be permanent. The nerve pain may be quite uncomfortable. This disorder does NOT usually shorten the person's expected life span.

Possible Complications

When to Contact a Medical Professional

Call your health care provider if you have symptoms that indicate common peroneal nerve dysfunction.

Prevention

Avoid prolonged pressure to the back or side of the knee. Injuries to the leg or knee should be treated promptly.

If a cast, splint, dressing, or other possible constriction of the lower leg causes a tight feeling or numbness, notify your health care provider.

References

King JC. Peroneal neuropathy. In: Frontera WR, Silver JK, Rizzo TD, eds. Essentials of Physical Medicine and Rehabilitation: Musculoskeletal disoders, pain and rehabilitation.. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2008: chap 66.


Review Date: 8/29/2009
Reviewed By: Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital; David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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