Clinical outcomes in multifocal motor neuropathy: A combined cross-sectional and follow-up study.

Abstract

To assess the clinical course of multifocal motor neuropathy (MMN) in a large cohort of patients and to identify predictive factors of a progressive disease course. Between May 2015 and February 2016, we collected clinical data from 100 patients with MMN, of whom 60 had participated in a nationwide cross-sectional cohort study in 2007. We documented clinical characteristics using standardized questionnaires and performed a standardized neurologic examination. We used multiple linear regression analysis to identify factors that correlated with worse outcome. We found that age at diagnosis (45.2 vs 48.6 years, <i>p</i> < 0.02) was significantly increased between 2007 and 2015-2016, whereas diagnostic delay decreased by 15 months. Seven out of 10 outcome measures deteriorated over time (all <i>p</i> < 0.01). Patients who had a lower Medical Research Council (MRC) sumscore and absence of 1 or more reflexes at the baseline visit showed a greater functional loss at follow-up (<i>p</i> = 0.007 and <i>p</i> = 0.016). Our study shows that MMN is a progressive disease. Although 87% of patients received maintenance treatment, muscle strength, reflexes, vibration sense, and the Self-Evaluation Scale score significantly deteriorated over time. Lower MRC sumscore and absence of reflexes predicted a more progressive disease course. This study provides Class II evidence that lower MRC sumscore and the absence of reflexes predict a more progressive disease course in patients with MMN.