Science News: Improving Muscle Grade Accuracy With EMG
Published April 17, 2025
Science News
Submitted by: Oksana Sayko, MD
Edited by: Nakul Katyal, MD
Citation: Lee SJ, Yoo J, Park S, Shin JC. Concordance between needle electromyography and manual muscle test findings for muscles with motor grades 0 and 1. PM R. 2024;16(3):210-218. doi:10.1002/pmrj.13032
Summary: When it is difficult to determine whether a muscle is grade 0 or 1, manual muscle test (MMT) accuracy can be further improved by using needle electromyography (EMG) as a supplementary and confirmatory examination tool.
The researcher鈥檚 goal was to evaluate concordance between needle EMG and MMT findings for key muscles with motor grades 0 and 1 on the International Standards of Neurological Classification of Spinal Cord Injury (ISNCSCI) examination, and to potentially improve the prognosis for grade 0 muscles with proven muscle activity based on needle EMG findings.
This was a retrospective study conducted in an inpatient tertiary rehabilitation facility.
A total of 107 patients with new spinal cord injury (SCI) admitted for rehabilitation (n = 1218 key muscles, grades 0 or 1). Motor grade changes for 23 patients were also analyzed at their readmission (mean time to readmission from initial discharge 86.2 卤 43.6) for 256 ISNCSCI key muscles.
Inter-rater reliability between MMTs and needle EMG was analyzed using Cohen鈥檚 kappa coefficient (魏). A Mantel Haenszel linear-by-linear association chi-square test was used to determine whether the presence of motor unit action potentials (MUAPs) in muscles graded 0 on the initial MMT at admission was associated with MMT grades at discharge and readmission.
Moderate-to-substantial agreement between needle EMG and MMT findings was observed (魏 = 0.671, p < .01). Concerning key upper and lower extremity muscles, moderate and substantial agreement was identified, respectively. The lowest agreement was noted for C6 muscles. During follow up, 68.8% of muscles with proven MUAPs showed improved motor grades.
At initial assessment, distinguishing between motor grades 0 and 1 is imperative because motor grade 1 muscles are more likely to have a better prognosis for improvement. Moderate-to-substantial agreement was observed between MMT and needle EMG findings. The MMT is a reliable method of muscle grading, yet needle EMG may be of value in certain clinical situations to evaluate for the presence of MUAPs when evaluating motor function.
Comments: This is an interesting study that proves correlation between the MMT and muscle assessment with needle EMG, supports the reliability of MMT.