Somatosensory evoked potentials in acute spinal cord injury: prognostic value.

The somatosensory evoked potential is absent in patients with complete motor and sensory loss below the level of spinal cord injury. When spinal cord injury is incomplete, these alterations in potential may be elicited from stimulation of a nerve entering the cord below the level of injury. The presence of such potentials soon after injury, or their early return, and progressive normalization of the wave form are sensitive early indications of favorable prognosis. Indeed, recovery of the somatosensory evoked potentials frequently precedes major clinical improvement and may occur in advance of clinical recovery or posterior column function.