RESUMO
INTRODUCTION: The aim of this study was to estimate jitter parameters in the orbicularis oculi muscle using a concentric needle electrode (CNE) in patients with myasthenia gravis (MG) and to determine its diagnostic accuracy for jitter analysis (CNEMG-jitter). METHODS: CNEMG-jitter was performed in 20 healthy subjects and 33 MG patients using the voluntary contraction technique. Receiver operating characteristic (ROC) curves were constructed to determine cut-off points with the best sensitivity/specificity combination for jitter analysis. RESULTS: CNEMG-jitter yielded high positivity rates for ocular MG (92.3%) and generalized MG (100%). The ROC curve cut-off point that provided the highest sensitivity without false positives was 24.7 µs for mean jitter and 33.1 µs for the 18th highest value. Sensitivity was 93.9% for both parameters. Diagnostic accuracy of CNEMG-jitter was > 96%. CONCLUSIONS: CNEMG-jitter yielded high sensitivity and specificity rates. Our reference values were lower than previously published values, possibly due to less technical variation between the different recordings. Muscle Nerve 55: 190-194, 2017.