Muscular Echovariation: A New Biomarker in Amyotrophic Lateral Sclerosis

Abstract

The purpose of the work described here was to assess the characteristics of echovariation in amyotrophic lateral sclerosis (ALS) compared with other muscle ultrasonography parameters. Twenty-six ALS patients (8 women, mean age 58.9 y, standard deviation 12.02 y) and 26 healthy controls (17 women, mean age 59.6 y, standard deviation 6.41 y) were included in this observational study. They underwent bilateral and transverse ultrasound of the biceps/brachialis, forearm flexor group, quadriceps femoris and tibialis anterior. Muscular thickness, echo-intensity and echovariation were analyzed. Muscles affected by ALS had increased echo-intensity, decreased thickness and decreased echovariation. Echovariation in all muscles except the quadriceps femoris strongly correlated with muscle strength (explained variance between 21.8% in the biceps/brachialis and 37.5% in the tibialis anterior) and the ALS Functional Rating Scale Revised score (explained variance between 26% in the biceps/brachialis and 36.7% in the forearm flexor group). Echovariation is an easy-to-obtain quantitative muscle ultrasonography parameter that could distinguish ALS patients from healthy controls more accurately than previous described biomarkers.

Keywords: Amyotrophic lateral sclerosis; Clinical neurology examination; Observational study; Ultrasound.