O21 Peak ratio and motor unit potential analyses in detection of chronic neurogenic changes in amyotrophic lateral sclerosis

Abstract

Objectives Peak ratio analysis is a quantitative way of analyzing interference pattern by turns-amplitude analysis. We aimed in this study to compare the sensitivities of peak ratio analysis and quantitative motor unit potential (MUP) analysis in detecting chronic neurogenic changes in amyotrophic lateral sclerosis (ALS). Methods Twenty-two patients (1 definite, 7 probable, and 9 possible ALS according to Awaji criteria as reference standard, and 5 progressive muscular atrophy) were prospectively included. Quantitative MUP and peak ratio analyses were done in 22 biceps brachialis (BB), 22 tibialis anterior (TA) and 18 abductor pollicis brevis (APB) muscles on the least affected side. Results were compared to laboratory controls. The sensitivity of MUP duration and peak ratio was compared using the McNemar chi-square test. Results Peak ratio analysis was more frequently abnormal than MUP analysis in BB (59% vs. 23%), and TA (59% vs. 18%) muscles ( p Discussion Peak ratio analysis sampled at stronger effort detected more frequently chronic neurogenic changes than MUP analysis recruited at weak effort. Conclusions Peak ratio analysis may provide earlier detection of chronic neurogenic changes, thereby facilitating earlier diagnosis of ALS. Significance Peak ratio analysis which is available in commercial EMG machines should be considered in the electrodiagnostic investigation of ALS.