Fasciculation Intensity and Disease Progression in Amyotrophic Lateral Sclerosis

Objective: To investigate the association between the frequency and intensity of fasciculations with clinical measures of disease progression in amyotrophic lateral sclerosis (ALS).

Methods: Twenty-four consecutive patients with ALS underwent clinical review and neuromuscular ultrasound assessment to detect intensity of fasciculations. Results were correlated with clinical markers of disease severity, as measured by the ALS Functional Rating Scale-revised (ALSFRS-R) and rate of disease progression (ΔFS), in addition to assessment of cortical motor function.

Results: Disease duration negatively correlated (R = -0.530, p < 0.01) with fasciculation intensity, while the ΔFS positively correlated with the fasciculation number (R = 0.626, p < 0.01). In terms of potential central contributions to ectopic impulse generation, patients were classified into cohorts based on their fasciculation intensity and short interval intracortical inhibition (SICI). ΔFS was significantly higher in patients with established hyperexcitability (low SICI) with high fasciculation intensity compared to those patients with minimal SICI change.

Conclusions: Fasciculation intensity appears linked to disease progression and separately to markers of cortical dysfunction, specifically the advent of cortical hyperexcitability.

Significance: Assessment of the intensity of patient fasciculations is a noninvasive approach that may provide further insight disease pathophysiology in ALS.