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

Signs 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:

• EMG (electromyography, a test of electrical activity in muscles)
• Nerve conduction tests
• MRI to look for compressive lesion along nerve

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.