Reliability of surface EMG as an assessment tool for trunk activity and potential to determine neurorecovery in SCI.

ABSTRACT

STUDY DESIGN: Reliability and validity study. OBJECTIVE: This study investigates the responsiveness and reliability of the brain motor control assessment (BMCA) as a standardized neurophysiological assessment tool to (i) characterize trunk neural activity in neurologically-intact controls; (ii) measure and quantify neurorecovery of trunk after spinal cord injury (SCI). SETTING: Kessler Foundation Research Center, West Orange, NJ. METHODS: A standardized BMCA protocol was performed to measure surface electromyography (sEMG) recordings for seven bilateral trunk muscles on 15 able-bodied controls during six maneuvers (inhalation, exhalation, neck flexion, jendrassik, unilateral grip). Additionally, sEMG recordings were analyzed for one chronic SCI individual before electrical stimulation (ES), after ES of the lower extremities while supine, and after active stand training using body-weight support with bilateral ES. sEMG recordings were collected on bilateral erector spinae, internal and external obliques, upper and middle trapezius, biceps and triceps. For each maneuver a voluntary response index was calculated incorporating the magnitude of sEMG signal and a similarity index (SI), which quantifies the distribution of activity across all muscles. RESULTS: Among all maneuvers, the SI presented reproducible assessment of trunk-motor function within (ICC 0.860-0.997) and among (P⩾0.22) able-bodied individuals. In addition, potential changes were measured in a chronic SCI individual after undergoing two intensive ES protocols. CONCLUSION: The BMCA provides reproducible characterization of trunk activity in able-bodied individuals, lending credence for its use in neurophysiological assessment of motor control. Additionally, the BMCA as an assessment tool to measure neurorecovery in an individual with chronic SCI after intense ES interventions was demonstrated.