Figure. Dr. Anant M. Shenoy
Q What causes “foot drop”?
DR. ANANT M. SHENOY RESPONDS:
A With foot drop, people have difficulty lifting the foot at the ankle due to weakness or muscle paralysis. It can occur in one or both feet. People typically experience pain, weakness, or numbness in the affected foot. A person may not initially identify the weakness but instead notice that they are tripping more or dragging their feet as they walk.
Foot drop indicates an underlying neurological, muscular, or anatomical problem. There are multiple causes: neurodegenerative disorders, such as multiple sclerosis (MS), cerebral palsy, and stroke; motor neuron disorders, such as polio, amyotrophic lateral sclerosis (ALS), and some forms of spinal muscular atrophy; peripheral nerve disorders; muscular disorders; certain genetic neurological conditions; and injury to the nerve roots. Depending on the cause, foot drop can either be temporary or permanent.
Because there are many possible causes of foot drop, it is important to be evaluated by a neurologist. The neurologist will use your description of symptoms, family history, and an examination to help narrow the list of possible causes. In addition, the neurologist will likely order diagnostic tests including MRI, blood work, and electrodiagnostic studies, which measure the speed and degree of electrical activity in muscles, to help make the diagnosis. The two most common electrodiagnostic studies are electromyography and nerve conduction studies. Depending on the cause of the foot drop, treatment may be available. In every case, a rehabilitation consult with a physical therapist will be recommended to aid in gait training and ankle bracing to help with functionality.
Anant M. Shenoy, M.D.
Assistant professor of neurology at Boston University School of Medicine in Boston, MA.