Clinical neurophysiology of focal spinal cord injury

A focal spinal cord injury produces a host of electrophysiologic abnormalities, most of which reflect either local spinal cord destruction or the functional disconnection of rostral and caudal portions. Routine electromyographic and nerve conduction studies are most useful to investigate the deficits that result from local cord damage and have demonstrated that the injury zone most often extends at least 3 to 4 myotomes. Electromyographic studies of muscles innervated by more caudal myotomes have also shown abnormalities, but the extent to which these reflect primary changes of spinal cord injury is uncertain. Electrophysiologic studies of spinal cord function caudal to the site of injury have shown alterations in autonomic output, as well as changes in the level of excitability of reflex pathways. These changes may provide insight into the mechanisms that underlie the development of spasticity.