A comparative study of peripheral nerve MRI and ultrasound in MMN and ALS

Introduction: Differentiating multifocal motor neuropathy (MMN) from amyotrophic lateral sclerosis (ALS) is important, as MMN is a difficult, but treatable disorder. Methods: We studied peripheral nerve imaging techniques in differentiating MMN from ALS by measuring the cross-sectional area (CSA) of the median and ulnar nerves in the forearms using high resolution ultrasound (HRUS) and magnetic resonance imaging (MRI). Results: HRUS CSA values of the median nerve in the forearm (P =0.002) and the ulnar nerve distal to the sulcus (P =0.009) were significantly enlarged in patients with MMN. There was a positive correlation between CSA as measured with HRUS and MRI (Spearman rho 0.60, P<0.001). Conclusion: Peripheral nerve imaging is a potentially powerful technique to distinguish MMN from ALS. This article is protected by copyright. All rights reserved.