Ultra High-Frequency Ultrasound of Median Nerve Fascicles at the Wrist in Amyotrophic Lateral Sclerosis: An Exploratory Study.

Purpose: High-frequency ultrasound (HFUS) of muscle and nerve has the potential to be a reliable, responsive, and informative biomarker of disease progression for individuals with amyotrophic lateral sclerosis (ALS). High-frequency ultrasound is not able to visualize median nerve fascicles to the same extent as ultra-high-frequency ultrasound (UHFUS). Evaluating the number and size of fascicles within a nerve may facilitate a better understanding of nerve diseases. This exploratory study aims to image median nerve fascicles at the wrist in individuals with ALS using UHFUS and compare these findings with those from previously observed controls.

Methods: Fifteen individuals with ALS underwent sonographic examination of the median nerves on each upper limb using UHFUS with a 48-MHz linear array transducer. Fascicle count and density in each examined nerve were determined by a single rater. Demographic and sonographic data from 20 previously studied controls were compared.

Results: In individuals with ALS, the average fascicle number was 22.4 (SD 5.2) and average fascicle density 1.7 (SD 0.5). There was no significant difference in fascicle counts between individuals with ALS and controls.

Conclusions: Fascicular quantification using UHFUS is possible in individuals with ALS. Given the lack of appreciable difference between fascicle counts in individuals with ALS and controls, UHFUS of the median nerve at the wrist may not be a responsive biomarker for ALS disease progression.