Etiology of spastic foot drop among 16 patients undergoing electrodiagnostic studies: patient series

BACKGROUND: Differentiating foot drop due to upper motor neuron (UMN) lesions from that due to lower motor neuron lesions is crucial to avoid unnecessary surgery or surgery at the wrong location. Electrodiagnostic (EDX) studies are useful in evaluating patients with spastic foot drop (SFD). OBSERVATIONS: Among 16 patients with SFD, the cause was cervical myelopathy in 5 patients (31%), cerebrovascular accident in 3 (18%), hereditary spastic paraplegia in 2 (12%), multiple sclerosis in 2 (12%), chronic cerebral small vessel disease in 2 (12%), intracranial meningioma in 1 (6%), and diffuse brain injury in 1 (6%). Twelve patients (75%) had weakness of a single leg, whereas 2 others (12%) had bilateral weakness. Eleven patients (69%) had difficulty walking. The deep tendon reflexes of the legs were hyperactive in 15 patients (94%), with an extensor plantar response in 9 patients (56%). Twelve patients (75%) had normal motor and sensory conduction, 11 of whom had no denervation changes of the legs. LESSONS: This study is intended to raise awareness among surgeons about the clinical features of SFD. EDX studies are valuable in ruling out peripheral causes of foot drop, which encourages diagnostic investigation into a UMN source for the foot drop.