Definition of Common peroneal nerve dysfunction:

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

Causes, incidence, and risk factors:

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.