title: Electrophysiological features of Hirayama disease.
abstract: BACKGROUND
  The purpose of this study was to compare the pattern of hand muscle involvement in Hirayama disease (HD) and amyotrophic lateral sclerosis (ALS).
  
  
  METHODS
  We reviewed findings of upper limb nerve conduction studies of 46 HD patients and 60 ALS patients. The findings from 54 healthy subjects were used for comparison.
  
  
  RESULTS
  In HD, the ulnar compound muscle action potential (CMAP) amplitude was more severely reduced than the median one, and the reverse pattern was observed in ALS. The mean ulnar/median (U/M) CMAP amplitude ratio was significantly lower in HD (0.64 ± 0.79) and abnormally higher in ALS (2.15 ± 1.77) compared with normal subjects (0.89 ± 0.23). An abnormally low U/M CMAP amplitude ratio (<0.6) was encountered in 34 patients with HD and in 1 with ALS. A U/M CMAP amplitude ratio ≥4.5 or absent median motor response was found only in ALS.
  
  
  CONCLUSIONS
  Our findings demonstrate different patterns of hand muscle involvement between these two diseases.
authors.affiliation: Section of Neuromuscular Disease, Department of Neurology, Chang Gung Memorial Hospital and University Medical College, Linkou Medical Center, No. 5, Fushing Street, Gueishan Township, Taoyuan County, Taoyuan 33305, Taiwan.
authors.forename: Rong-Kuo
authors.initials: RK
authors.lastname: Lyu
authors.forename: Ying-Chih
authors.initials: YC
authors.lastname: Huang
authors.forename: Yih-Ru
authors.initials: YR
authors.lastname: Wu
authors.forename: Hung-Chou
authors.initials: HC
authors.lastname: Kuo
authors.forename: Long-Sun
authors.initials: LS
authors.lastname: Ro
authors.forename: Chiung-Mei
authors.initials: CM
authors.lastname: Chen
authors.forename: Hong-Shiu
authors.initials: HS
authors.lastname: Chang
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology; D002648:Child; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006225:Hand / Q000294:innervation / Q000503:physiopathology; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology; D009431:Neural Conduction / Q000502:physiology*; D012189:Retrospective Studies; D014897:Spinal Muscular Atrophies of Childhood / Q000503:physiopathology*; D014459:Ulnar Nerve / Q000503:physiopathology*