Not only cross-sectional area: Echogenicity matters in nerve ultrasound studies of patients with motor multifocal neuropathy

Nerve ultrasound (n-US) supports the diagnosis of multifocal motor neuropathy (MMN), though most studies focus on nerve enlargement (NE) and its distribution. This study explored nerve echotexture using ultrahigh-frequency ultrasound (UH-FUS) in 13 MMN patients (mean age 61.9 years, disease duration 147 ± 105 months). NE was detected in 77%, preferentially involving median nerve, yet conduction blocks corresponded to NE in only 15%. Notably, 92% showed mixed/hyperechoic echotexture, including three patients with normal CSA, suggesting microstructural remodeling beyond swelling. No hypoechoic nerves were observed, consistent with limited acute inflammation. Combining echogenicity with NE assessment may improve n-US sensitivity, especially in atypical MMN.