O25 Motor unit number estimation methods compared to quantitative motor unit potential analysis in amyotrophic lateral sclerosis

Abstract

Objectives To compare the sensitivity of MUNE methods to quantitative motor unit potential (MUP) analysis in amyotrophic lateral sclerosis (ALS). Methods Twenty-four patients (1 definite, 11 probable and 8 possible ALS according to awaji criteria as reference standard, and 4 progressive muscular atrophy) were included. Patients were evaluated by revised ALS functional rating scale (ALSFRS-R). In all patients, quantitative MUP analysis and three MUNE methods; MScanFit MUNA (MScan), multiple point stimulation MUNE (MPS), and Motor Unit Number Index (MUNIX) were done in abductor pollicis brevis (APB). MUNE results were compared to 20 age-matched healthy controls and EMG to laboratory controls. The sensitivity of each methods was compared using McNemar chi-square test. MUNE values and MUP parameters were correlated to ALSFRS-R by regression analysis. Results MScan (70%) and MPS (61%) more frequently showed abnormality than MUP duration (35%) whereas only MScan was more often abnormal than MUP amplitude (39%) ( p r = 0.42, p = 0.03) but not MPS ( r = 31), MUNIX ( r = 35), MUP duration ( r = 0.19) or amplitude ( r = 0.09). Discussion MUP analysis gives information about reinnervation, but not about loss of motor units. Therefore MUNE methods may be preferable in ALS electrodiagnosis. Conclusions MUNE methods, particularly MScan, had higher sensitivities than MUP analysis in detection of abnormality in APB and were correlated better to ALSFRS-R. Significance MScan is a promising novel method which should be considered in diagnosis and monitoring disease progression in ALS.