Foot drop is a deficit in turning the ankle and toes upward. Conditions leading to foot drop may be neurologic, muscular or anatomic in origin, often with significant overlap.
Foot drop is characterized by steppage gait. When the person with foot drop walks, the foot slaps down onto the floor. To compensate for the toe drop, the patient must raise the thigh excessively, as if walking upstairs.
Patients with painful disorders of sensation (dysesthesia) of the soles of the feet may have a similar gait, but do not have foot drop. Because of the extreme pain evoked by even the slightest pressure on the feet, the patient walks as if walking barefoot on hot sand.
Pathophysiology
The causes of foot-drop, as for all causes of neurological lesions should be approached using a localization focussed approach before etiologies are considered.
Treated systematically, possible lesion sites causing foot drop include (going from peripheral to central)
If the L5 nerve root is involved the most common cause is a herniated disc.
Treatment
The underlying disorder must be treated. For example, if a spinal disc herniation in the low back is impinging on the nerve that goes to the leg and causing symptoms of foot drop, then the herniated disc should be treated.
Ankles can be stabilized by lightweight orthoses, available in molded plastics as well as softer materials that use elastic properties to prevent foot drop. Additionally, shoes can be fit with springs to prevent foot drop while walking. Regular exercise is usually prescribed.
The latest treatments include stimulation of the peroneal nerve that lifts the foot when you step. Many stroke and multiple sclerosis patients with foot drop have had success with it.
References
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Diseases of the musculoskeletal system and connective tissue (M, 710-739)