Pathophysiology of Foot Drop: Central vs Peripheral Etiologies
Foot drop is not a standalone disease; it is a profound clinical manifestation indicating weakness or paralysis of the ankle dorsiflexor muscles, primarily the tibialis anterior, extensor hallucis longus, and extensor digitorum longus. Inability to lift the foot during the swing phase of gait leads to toe drag, predisposing the patient to tripping and severe domestic falls.
Bidaya clinicians categorize foot drop into two distinct neurological mechanisms requiring opposing therapeutic approaches:
1. Central (Upper Motor Neuron) Foot Drop: Originating from an ischemic stroke, traumatic brain injury, or Multiple Sclerosis. Characterized by antagonistic calf muscle spasticity (gastrocnemius and soleus hypertonia), forcing the foot into an equinovarus (downward and inward) posture. Therapy requires spasticity inhibition alongside dorsiflexor facilitation.
2. Peripheral (Lower Motor Neuron) Foot Drop: Originating from common peroneal nerve (fibular nerve) entrapment at the fibular head, surgical trauma, or severe L5 lumbar nerve root compression. Characterized by flaccid paresis, loss of ankle reflexes, and cutaneous sensory numbness over the dorsal foot. Therapy focuses on nerve regeneration support and muscle preservation.
