Clinical Neurophysiological Assessment of Residual Motor Control in Post-Spinal Cord Injury Paralysis

Abstract

Objective. This study was designed to characterize the rudimentary residual lower-limb motor control that can exist in clinically paralyzed spinal-cord-injured individuals. Methods. Sixty-seven paralyzed spinal-cord-injured subjects were studied using surface electromyography recorded from muscles of the lower limbs and analyzed for responses to a rigidly administered protocol of reinforcement maneuvers, voluntary movement attempts, vibration, or the ability to volitionally suppress withdrawal evoked by plantar surface stimulation. Results. Markers for the subclinical discomplete motor syndrome were found in 64% of the subjects. The tonic vibration response was recorded in 37%, volitional plantar surface stimulation response suppression in 27%, and reinforcement maneuver responses in 6% of the subjects. Three subjects, 4%, produced reliable but very low amplitude surface electromyography during the voluntary movement segment of the protocol. Surface electromyography recorded during passive leg movement was related to Ashworth scores as was the tonic vibration response marker (P < 0.05). Conclusions. Multimuscle surface electromyography patterns recorded during a rigidly administered protocol of motor tasks can be used to differentiate between clinically paralyzed spinal-cord-injured individuals using subclinical motor output to identify the translesional neural connections that remain available for intervention testing and treatment planning after spinal cord injury.