Japanese Multifocal Motor Neuropathy Study Group

Japanese, Japan

Japanese Multifocal Motor Neuropathy Study Group

Japanese, Japan

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Miyashiro A.,Tokushima University | Matsui N.,Tokushima University | Shimatani Y.,Tokushima University | Nodera H.,Tokushima University | And 15 more authors.
Muscle and Nerve | Year: 2014

Introduction: Our objective was to do an epidemiologic survey of patients with multifocal motor neuropathy (MMN) in comparison with those with amyotrophic lateral sclerosis (ALS) in Japan. Methods: In this retrospective study, we examined 46 patients with MMN and 1,051 patients with ALS from major neuromuscular centers in Japan from 2005 to 2009. Diagnosis was based on the European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) and the revised El Escorial criteria. The efficacy of intravenous immunoglobulin (IVIg) was also taken into consideration in the diagnosis of MMN. Results: The ratio of MMN to ALS patients (0-0.10) varied among the centers, but mostly converged to 0.05. The prevalence was estimated to be 0.29 MMN patients and 6.63 ALS patients per 100,000 population. Conclusions: The frequency of MMN patients was around 1 out of 20 ALS patients, and MMN was possibly underdiagnosed in some centers. © 2013 Wiley Periodicals, Inc.


Matsui N.,Tokushima University | Miyashiro A.,Tokushima University | Shimatani Y.,Tokushima University | Nodera H.,Tokushima University | And 15 more authors.
Clinical and Experimental Neuroimmunology | Year: 2013

Objective We carried out a retrospective study to define clinical features in a large series of patients with multifocal motor neuropathy (MMN) and to assess the diagnostic spectrum of MMN. Methods The study consisted of 46 patients with MMN between 2005 and 2009 from 19 major neuromuscular centers in Japan. The 2006 European Federation of Neurological Societies (EFNS)/Peripheral Nerve Society (PNS) criteria (hereafter, original criteria) and the efficacy of intravenous immunoglobulin (IVIg) therapy were taken into consideration in the diagnosis of MMN. The main parameters were clinical features and electrophysiological findings. The Japanese MMN Study Group designed a set of recommended criteria to reduce the frequency of underdiagnosis. Furthermore, we verified the diagnostic spectrum of MMN using both the original criteria and the recommended criteria. Results Clinical features were similar to those of previous studies. A total of 25 of the 46 patients (54.3%) showed conduction block (CB); that is, nearly half of the patients did not satisfy the original criteria. The Japanese MMN Study Group included findings indicative of focal demyelination, namely, activity-dependent CB and asymmetric abnormality of F-waves in the electrophysiological test, in the recommended criteria. By doing so, the diagnostic sensitivity of the recommended criteria was increased by 17.4% compared with that of the original criteria. Conclusions The recommended criteria designed by the Japanese MMN Study Group showed higher diagnostic sensitivity than the original criteria, but no significant difference was found between them. A prospective study using the recommended criteria might reduce the frequency of underdiagnosis in patients with MMN. © 2013 Japanese Society for Neuroimmunology.

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