Somatosensory evoked potentials and Hoffmann reflex in acute spinal cord lesions; physiopathological and prognostic aspects

Twenty-four patients with recent and acute spinal cord lesions were examined. The somatosensory cerebral evoked potential (SEP) following stimulation of the peroneus communis nerve tested spinal conduction, whereas the H reflex showed spinal excitability belowe the lesion. After complete spinal cord section, the SEP was always abolished and the H reflex was absent in most cases tested in the first 24 hours. Into other patients, the recruitment curve and the recovery cycle of the H reflex displayed some abnormalities which progressively disappeared. With partial lesions, SEP could occasionally be altered. Some abnormalities of the H reflex recovery cycle, of the same type as those seen in the late stage of complete sections, were also observed. These data give nre information on the physiopathology of spinal shock; they lead to the distinction of several evolutionary stages after acute spinal lesions and also have prognostic disgnificance.