The Sensitivity of Quantitative Sonographic Assessment of Muscle Thickness for Amyotrophic Lateral Sclerosis Diagnosis

Abstract

Purpose: In the current proof-of-concept study, we aimed to examine the sensitivities and specificities of previously reported normal values for muscle ultrasound thickness in amyotrophic lateral sclerosis.Methods: Muscle ultrasound was performed in 65 healthy control subjects and 91 amyotrophic lateral sclerosis patients using a standardized assessment of eight relaxed muscles and four contracted muscles. Normal values for muscle thickness were determined as values above the 5th percentile stratified by age and gender using the weighted average method. Sensitivity for amyotrophic lateral sclerosis diagnosis was determined for muscles with and without the addition of muscle contraction.Results: Amyotrophic lateral sclerosis patients showed reduced muscle sum thickness both in relaxed and in contracted states compared with control subjects. Muscle ultrasound of muscles with and without contraction showed excellent diagnostic accuracy for differentiating amyotrophic lateral sclerosis patients from control subjects (area under curve ¼ 0.96, sensitivity: 93%-95%, specificity: 84-87). Muscle ultrasound sensitivity was lower within 6 months of symptom onset (83%) compared with longer disease duration (.92%).Conclusions: Quantitative sonographic assessment of muscle thickness can be complementary in the diagnosis of amyotrophic lateral sclerosis with excellent accuracy for differentiating patients from healthy subjects, and might be useful in other neuromuscular disorders, although additional studies are required.

Quantitative sonographic assessment of muscle thickness and fasciculations distribution is a sensitive tool for neuromuscular disorders

“…In addition, muscle thickness was assessed in 4 maximally contracted muscles (biceps brachii, APB, quadriceps, and tibialis anterior) [ 16 ]. Reduced relaxed or contracted muscle thickness was determined as lower than the 5 th percentile in healthy controls, stratified by age and gender [ 11 ]. Fasciculations were recorded during a time interval of 15 seconds, therefore detecting mainly muscles with a fasciculation frequency ≥ 4 per minute.…”

“…Normal values for muscle thickness stratified by gender were previously determined, as well as the frequency of fasciculations in healthy controls [ 10 ]. Subsequently, normal values for muscle thickness were further stratified by age, and normal values for contracted muscle thickness were determined as well [ 11 ].…”

“…We hypothesized that neuromuscular US may be used as a point of care study complementary to the neurological examination, providing an objective biomarker for diagnosing and following patients with neuromuscular disorders, with a potential to increase the sensitivity and the accuracy of the neurological diagnosis. In order to support this assumption, we aimed to determine in this current proof of concept study, the sensitivity and specificity of quantitative sonographic assessment of muscle thickness and the presence of fasciculations for diagnosing various neuromuscular disorders, using our previously determined normal values [ 10 , 11 ].…”