Identifying Spinal Lesion Site from Surface EMG Grid Recordings

Human spinal cord injuries (SCI) disrupt the pathways between the brain and spinal cord, resulting in substantial impairment and loss of function. We recorded surface electromyogram signals (sEMG) using grids of electrodes (8 × 8) applied on Biceps Brachii and Triceps Brachii muscles. We aimed to identify dysfunctional muscle activation in individuals with incomplete injuries of the cervical cord. We recorded sEMG and force from one SCI individual (Chronic, C5-C7, ASIA score D) and from a neurologically intact person during the generation of an isometric sinusoidal force trajectory (15s elbow flexion + 15s elbow extension). We found that the SCI subject was not able to follow the target force during elbow extension as precisely as in elbow flexion. Failure in tracking force was quantified using the root mean squared error between the target and generated forces. Our data suggest that C7 was the most affected spinal segment while the anatomical level had been diagnosed C5-C7. These data show the potential use of sEMG grid recording for localizing the motor lesion level within the spinal cord. Additional confirmatory studies are necessary to validate our results.