Tracking motor neuron loss in a set of six muscles in XXXX using the Motor Unit Number Index (MUNIX): a 15-month longitudinal multicentre trial.

@entity1 @entity746
BACKGROUND: Motor Unit Number Index (MUNIX) is a novel neurophysiological measure that provides an index of the number of functional lower motor neurons in a given muscle. So far its performance across centres in @entity1 with @entity746 ( @entity746 ) has not been investigated. OBJECTIVE: To perform longitudinal MUNIX recordings in a set of muscles in a multicentre setting in order to evaluate its value as a marker of disease progression. METHODS: Three centres applied MUNIX in 51 @entity746 @entity1 over 15   months. Six different muscles (abductor pollicis brevis, abductor digiti minimi, biceps brachii, tibialis anterior, extensor dig. brevis, abductor hallucis) were measured every 3   months on the less affected side. The decline between MUNIX and ALSFRS-R was compared. RESULTS: 31 @entity1 reached month 12. For all @entity1 , ALSFRS-R declined at a rate of 2.3%/month. Using the total score of all muscles, MUNIX declined significantly faster by 3.2%/month (p <=0.02). MUNIX in individual muscles declined between 2.4% and 4.2%, which differed from ASLFRS-R decline starting from month 3 (p <=0.05 to 0.002). Subgroups with bulbar, lower and upper limb onset showed different decline rates of ALSFRS-R between 1.9% and 2.8%/month, while MUNIX total scores showed similar decline rates over all subgroups. Mean intraclass correlation coefficient for MUNIX intra-rater reliability was 0.89 and for inter-rater reliability 0.80. CONCLUSION: MUNIX is a reliable electrophysiological biomarker to track lower motor neuron loss in @entity746 .
