Peroneal Nerve Dysfunction

Common peroneal nerve dysfunction is a disorder caused by damage to the peroneal nerve, characterized by loss of movement of sensation in the foot or leg.

Causes
The peroneal nerve is a branching of the sciatic nerve, which supplies movement and sensation to the lower leg, foot and toes. This condition can affect people of any age. It is located behind the knee.

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 muscle control, loss of muscle tone, and eventual loss of muscle mass because of lack of nervous simulation 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 let
• Habitual leg crossing
• Regularly wearing high boots
• Pressure to the knee from positions during deep sleep, coma, or surgery

Symptoms

• Decreased sensation, numbness or tingling at the top of the foot
• Weakness of the ankles or feet
• Walking Abnormalities
• "Slapping" gait (walking pattern)
• Foot drop (unable to hold foot horizontal)
• Toes drag while walking

Tests
Usually, an EMG (a test of electrical activity in muscles) is ordered. If lumbar spine pathology is suspected, and MRI is sometimes ordered.

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

Prognosis
The outcome depends on the underlying cause. Successful treatment of the underlying cause may resolve the
dysfunction. Resolution may take several months until the nerve can grow back.

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

This handout utilized information in part from an article at www.ADAM.com, which was reviewed before placement on that site by: Jacqueline A. Hart, M.D., Newton-Wellesley Hospital, Newton, MA., and Senior Medical Editor, A.D.A.M., Inc. Previously reviewed by Elaine T. Kiriakopoulos, M.D., MSc, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard University, Boston, MA. Review provided by VeriMed Healthcare Network (7/28/2002). www.ADAM.com

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