Biofeedback effect on electromyography responses in patients with spinal cord injury.

OBJECTIVE To determine if electromyography (EMG) biofeedback procedures using an operant conditioning paradigm could significantly increase voluntary EMG responses from the triceps muscles of long term cervical spinal cord injured individuals. DESIGN Intervention study with before-after trial measurement with each subject as its own control. SETTING University outpatient clinic. PARTICIPANTS One hundred individuals with cervical spinal cord injuries C6 or higher that were greater than 1-year duration, and who had less than normal strength and recordable EMG activity from the triceps, and who had reached a plateau in return of function. The first 100 individuals meeting this criteria who presented sequentially for EMG testing and biofeedback were included. No subjects were deleted from the sample. INTERVENTION Muscle strength and surface EMG recording during attempts at elbow extension were obtained. The EMG pretest data were derived from the highest average recorded voluntary EMG response from the triceps during elbow extension. One 45-minute treatment session of EMG biofeedback for the triceps in an operant conditioning paradigm was provided for each of the 100 subjects. Seventy-five subjects received an average of 3 additional biofeedback treatment sessions. The posttest EMG data were derived from EMG measurements of the triceps during attempts at elbow extension from the 45-minute biofeedback treatment session and from the last additional biofeedback treatment session in a similar manner to the pretest procedures. MAIN OUTCOME MEASURES A significant increase in EMG activity occurred from the triceps (p < or = .001) after one biofeedback treatment session and further significant increases in EMG activity occurred after additional biofeedback treatment sessions (p < or = .001). Initial muscle strength and initial EMG levels were not determining factors for response to the biofeedback. CONCLUSIONS The results suggest the efficacy of biofeedback for increasing voluntary EMG responses in long term spinal cord injury patients.