LAUSR

BACKGROUND Manual muscle testing is a mainstay of strength assessment despite not having been compared to intraoperative electrical stimulation of peripheral nerves. METHODS Intraoperative electrical stimulation served as the reference standard in evaluating predictive accuracy of the Active Movement Scale (AMS) and the Medical Research Council (MRC) scale. Retrospective consecutive sampling of all patients with AFM who underwent exploration or nerve transfer at a pediatric multidisciplinary brachial plexus and peripheral nerve center March 2016 - July 2020 were included. The nonparametric area under the curve (AUC) was calculated. Optimal cutoff score (Youden's J) and diagnostic accuracy values were reported. AMS and MRC were directly compared for predictive superiority. RESULTS 181 upper extremity nerves (73 donor nerve candidates, 108 recipient nerve candidates) were tested intraoperatively from 40 children (mean age 7.9 years, SD: 4.9). The scales performed similarly (p=.953) in classifying suitable donor nerves with satisfactory accuracy (AUCAMS: 71.5%, AUCMRC: 70.7%; optimal cutoff: AMS >5, MRC >2). The scales performed similarly (p=.688) in classifying suitable recipient nerves with good accuracy (AUCAMS: 92.1%, AUCMRC: 94.9%; optimal cutoff: AMS ≤3, MRC ≤1). CONCLUSIONS Manual muscle testing is an accurate, non-invasive means of identifying donor and recipient nerves for transfer in children with acute flaccid myelitis. The utility of these results is in minimizing unexpected findings in the operating room and aiding in the development of contingency plans. Further research may extend these findings to test the validity manual muscle testing as outcome measures of the success of nerve transfer.