Dynamic muscle ultrasound identifies upper motor neuron involvement in amyotrophic lateral sclerosis

Abstract

Objective: The aim of the present study was to elucidate the pattern of change in bulbar muscles using ultrasound in patients diagnosed with amyotrophic lateral sclerosis (ALS). Methods: Changes in the mylohyoid and geniohyoid muscle complex (mylohyoid-geniohyoid-muscle-complex) thickness were recorded while swallowing 5 ml of water using M-mode ultrasound in 30 ALS patients compared to 20 healthy controls. The ratio of mylohyoid-geniohyoid-muscle-complex thickness as determined by the maximum thickness of mylohyoid-geniohyoid-muscle-complex during swallowing divided by thickness at rest, was compared between ALS patients and controls, with the correlation between thickness ratio, echogenicity and clinical parameters assessed. Results: Overall, the thickness ratio in ALS patients was 1.39 ± 0.23 (mean ± SD) compared to 1.55 ± 0.17 in controls (p < 0.05). In sub-analysis, the thickness ratio was significantly decreased in ALS patients with bulbar-onset disease compared to those with limb-onset disease (p < 0.01) and controls (p < 0.01). Thickness ratio negatively correlated with the severity of upper motor neuron involvement in the bulbar region (p < 0.05). Conclusions: Bulbar muscle ultrasound represents a novel method to detect impaired mobility and thereby provides an objective assessment of upper motor neuron involvement in the bulbar region of ALS patients.