Nerve ultrasound in the differentiation of multifocal motor neuropathy (MMN) and amyotrophic lateral sclerosis with predominant lower motor neuron disease (ALS/LMND)

The objective of the study was to investigate nerve ultrasound (US) in comparison to nerve conduction studies (NCS) for differential diagnosis of amyotrophic lateral sclerosis with predominant lower motoneuron disease (ALS/LMND) and multifocal motor neuropathy (MMN). A single-center, prospective, examiner-blinded cross-sectional diagnostic study in two cohorts was carried out. Cohort I: convenience sample of subjects diagnosed with ALS/LMND or MMN (minimal diagnostic criteria: possible ALS (revised EL-Escorial criteria), possible MMN (European Federation of Neurosciences guidelines). Cohort II: consecutive subjects with suspected diagnosis of either ALS/LMND or MMN. Diagnostic US and NCS models were developed based on ROC analysis of 28 different US and 32 different NCS values measured in cohort I. Main outcome criterion was sensitivity/specificity of these models between ALS/LMND and MMN in cohort II. Cohort I consisted of 16 patients with ALS/LMND and 8 patients with MMN. For cohort II, 30 patients were recruited, 8 with ALS/LMND, 5 with MMN, and 17 with other diseases. In cohort I, the three best US measures showed higher mean ± SD areas under the curve than the respective NCS measures (0.99 ± 0.01 vs. 0.79 ± 0.03, p