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

Objective 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. Methods 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 neurological examination. We used multiple linear
regression analysis to identify factors that correlated with worse
outcome. Results We found that age of diagnosis (45.2 vs. 48.6 years,
p<0.02) significantly increased between 2007 and 2015-2016, whereas
diagnostic delay decreased with 15 months. Seven out of ten outcome
measures deteriorated over time (all p<0.01). Patients who had a
lower MRC sum score and absence of one or more reflexes at the baseline
visit showed a greater functional loss at follow up (p=0.007 and p=0.016).
Conclusions 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 significantly deteriorated
over time. Lower MRC sum score and absence of reflexes predicted a more
progressive disease course. Classification of evidence This study provides
Class II evidence that lower MRC sum score and the absence of reflexes
predict a more progressive disease course in patients with MMN.