INJURY ZONE DENERVATION IN TRAUMATIC QUADRIPLEGIA IN HUMANS

In order to obtain an electrophysiological characterization of the inj ury zone in traumatic quadriplegia, we performed electromyography and nerve conduction studies on the upper limbs of 15 patients with cervic al cord trauma, Evidence of significant axonal loss was found in multi ple myotomes of all patients, In most cases, the level of the most sev ere denervation, as determined by the absence or diminution of the com pound motor action potential and the density of fibrillation potential s, was 2-5 spinal segments below the clinically and radiologically def ined injury levels. In patients with injuries, the rostral extent of w hich is at C5 or higher, the most obvious clinical and electromyograph ic denervation was seen in the intrinsic hand muscles (C8/T1), with co mplete loss of C8/T1 motor axons in a subset of these patients, Our re sults document that spinal cord trauma can cause loss of motor axons i n regions several segments caudal to the rostral level of injury. This finding may have implications for the pathophysiology of secondary in jury, for recovery potential, and for the design of rehabilitation str ategies. (C) 1996 John Wiley & Sons, Inc.