Peripheral neurophysiology of acute distal spinal cord infarction

F-wave abnormalities, in the presence of normal distal motor nerve conduction, most often are the first indicators of proximal peripheral nerve dysfunction in demyelinating polyradiculoneuropathies. However, a 15-year-old female—who developed lumbosacral spinal cord infarction with paraplegia, sensory loss, and incontinence beginning 15 hours after a fall—studied electrophysiologically at 2 days postparaplegia manifested absent lower-extremity f-waves and H-reflexes and normal compound muscle action potentials and distal motor and sensory conduction velocities. Subsequent evaluations demonstrated permanent loss of compound muscle action potentials, f-waves, and H-reflexes and prominent acute denervation in paralyzed lower-extremity muscles. Thus early f-wave and H-reflex loss can also occur in spinal cord disease, thereby representing the first evidence of motoneuron destruction.