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.

Keywords:

• Amyotrophic lateral sclerosis
• ultrasound
• M-mode
• bulbar
• upper motor neuron

Declaration of interest

Y. Noto is a recipient of International Federation of Clinical Neurophysiology Research Scholarship and the Nakabayashi Trust for ALS Research. K. Shibuya and JM Matamala are recipients of International Federation of Clinical Neurophysiology Research Scholarship. M. C. Kiernan serves as an editor-in-chief of Journal of Neurology, Neurosurgery, and Psychiatry and as an editorial board member of Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration. N. Simon reports no disclosures.

This work was supported by funding to Forefront, a collaborative research group dedicated to the study of motor neuron disease and frontotemporal dementia from The National Health and Medical Research Council of Australia (NHMRC) programme grant (#1037746) and International Federation of Clinical Neurophysiology Research Scholarship.