Evidence of subclinical brain influence in clinically complete spinal cord injury: discomplete SCI

Abstract

Previous studies of the neurocontrol of movement in spinal cord injury (SCI) subjects revealed that even those without volitional movement may retain some degree of preservation of distal brain influence. We previously defined a discomplete lesion as one which is clinically complete but which is accompanied by neurophysiological evidence of residual brain influence on spinal cord function below the lesion. In order to document the nature and extent of such neurocontrol, we recorded surface EMGs from multiple muscle groups to study patterns of motor unit activity in response to tendon vibration, activation of muscles below the lesion by reinforcement maneuvers above the lesion and by voluntary suppression of plantar withdrawal reflexes. We analyzed data from this brain motor control assessment (BMCA) procedure in order to describe the frequency of occurrence and characteristics of residual control in discomplete SCI subjects, comparing with findings in (clinically and neurophysiologically) complete and in (clinically and neurophysiologically) incomplete SCI subjects. From a group of 139 SCI subjects seen for management of spasticity, 88 had clinically complete lesions. Of these, 74 (84%) were discomplete as defined by responses to the above maneuvers. The selection of management and intervention strategies, whether physiological, pharmacological, behavioral or surgical, should give consideration to the high likelihood that clinically complete subjects may be neurophysiologically incomplete.