title: Clinical features of Japanese patients with inclusion body myositis.
abstract: BACKGROUND
  The incidence of sporadic inclusion body myositis (sIBM) has been much lower in Japanese than in Western populations. Because of a few reports on Asian populations, it is unclear whether the clinical characteristics of sIBM are identical in Caucasian and Japanese patients.
  
  
  METHODS
  We compared 18 patients with sIBM, divided into 3 groups by age-of-onset, with previous cohort studies. We calculated the ΔIBM functional rating scale/time duration (ΔIBMFRS/Δtime) as an index of functional disability progression. Patients' electrophysiology was analyzed in relation to their clinical characteristics.
  
  
  RESULTS
  The cohort was 83.3% male and showed uniform initial muscle weakness in the lower and/or upper limbs. An older age-at-onset was associated with a more rapid progression, and patients with a longer duration frequently showed F-wave abnormalities and findings of chronic denervation.
  
  
  CONCLUSIONS
  The clinical characteristics of sIBM were relatively homogeneous beyond the ethnic differences. Aging might be a synergistic factor for the progression of sIBM pathology.
authors.affiliation: Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hori
authors.affiliation: Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan. Electronic address: y-stsh@kumamoto-u.ac.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamashita
authors.affiliation: Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Nozomu
authors.initials: N
authors.lastname: Tawara
authors.affiliation: Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Tomoo
authors.initials: T
authors.lastname: Hirahara
authors.affiliation: Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Kawakami
authors.affiliation: Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Tomo
authors.initials: T
authors.lastname: Nishikami
authors.affiliation: Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Maeda
authors.affiliation: Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Ando
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D044466:Asian People; D015331:Cohort Studies; D018450:Disease Progression; D005121:Extremities / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000209:etiology / Q000503:physiopathology*; D018979:Myositis, Inclusion Body / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D012720:Severity of Illness Index
keywords: Chronic denervation; Clinical characteristics; F-wave abnormality; Japanese cases; Motor neuron disease; Sporadic inclusion body myositis