title: Are multifocal motor neuropathy patients underdiagnosed? An epidemiological survey in Japan.
abstract: BACKGROUND
  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.
authors.forename: Ai
authors.initials: A
authors.lastname: Miyashiro
authors.forename: Naoko
authors.initials: N
authors.lastname: Matsui
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Shimatani
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nodera
authors.forename: Yuishin
authors.initials: Y
authors.lastname: Izumi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kuwabara
authors.forename: Tomihiro
authors.initials: T
authors.lastname: Imai
authors.forename: Masayuki
authors.initials: M
authors.lastname: Baba
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Komori
authors.forename: Masahiro
authors.initials: M
authors.lastname: Sonoo
authors.forename: Takahiro
authors.initials: T
authors.lastname: Mezaki
authors.forename: Jun
authors.initials: J
authors.lastname: Kawamata
authors.forename: Takefumi
authors.initials: T
authors.lastname: Hitomi
authors.forename: Jun
authors.initials: J
authors.lastname: Kawamata
authors.forename: Takefumi
authors.initials: T
authors.lastname: Hitomi
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kohara
authors.forename: Kimiyoshi
authors.initials: K
authors.lastname: Arimura
authors.forename: Shuji
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Kokichi
authors.initials: K
authors.lastname: Arisawa
authors.forename: Susumu
authors.initials: S
authors.lastname: Kusunoki
authors.forename: Ryuji
authors.initials: R
authors.lastname: Kaji
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000453:epidemiology*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006761:Hospitals; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis* / Q000453:epidemiology*; D012189:Retrospective Studies; D055815:Young Adult