Diagnosis

Foot drop is usually diagnosed during a physical exam. Your doctor will watch you walk and check your leg muscles for weakness. He or she may also check for numbness on your shin and on the top of your foot and toes.

Imaging tests

Foot drop is sometimes caused by an overgrowth of bone in the spinal canal or by a tumor or cyst pressing on the nerve in the knee or spine. Imaging tests can help pinpoint these types of problems.

• X-rays. Plain X-rays use a low level of radiation to visualize a soft tissue mass or a bone lesion that might be causing your symptoms.
• Ultrasound. This technology, which uses sound waves to create images of internal structures, can check for cysts or tumors on the nerve or show swelling on the nerve from compression.
• CT scan. This combines X-ray images taken from many different angles to form cross-sectional views of structures within the body.
• Magnetic resonance imaging (MRI). This test uses radio waves and a strong magnetic field to create detailed images. MRI is particularly useful in visualizing soft tissue lesions that may be compressing a nerve.

Nerve tests

Electromyography (EMG) and nerve conduction studies measure electrical activity in the muscles and nerves. These tests can be uncomfortable, but they're useful in determining the location of the damage along the affected nerve.