Fasciculations demonstrate daytime consistency in amyotrophic lateral sclerosis.

BACKGROUND: Fasciculations represent early neuronal hyperexcitability in amyotrophic lateral sclerosis (ALS). To aid calibration as a disease biomarker, we set out to characterise the daytime variability of fasciculation firing. METHODS: Fasciculation awareness scores were compiled from 19 ALS patients. Additionally, ten ALS patients prospectively underwent high-density surface EMG (HDSEMG) recordings from biceps and gastrocnemius at three time-points during a single day. RESULTS: Daytime fasciculation awareness scores were low (mean=0.28 muscle groups), demonstrating significant variability (coefficient of variation=303%). Biceps HDSEMG recordings were highly consistent for fasciculation potential frequency (intra-class correlation coefficient [ICC] = 95%, n=19) and the inter-quartile range of fasciculation potential amplitude (ICC = 95%, n=19). These parameters exhibited robustness to observed fluctuations in data quality parameters. Gastrocnemius demonstrated more modest levels of consistency overall (44-62%, n=20). DISCUSSION: There was remarkable daytime consistency of fasciculation firing in the biceps of ALS patients, despite sparse and intermittent awareness amongst patient accounts. This article is protected by copyright. All rights reserved.