title: F Wave Study in Amyotrophic Lateral Sclerosis: Assessment of Segmental Motoneuronal Dysfunction.
abstract: BACKGROUND
  Dysfunctional spinal circuit may play a role in the pathophysiology of amyotrophic lateral sclerosis (ALS). The purpose of this study was to use F waves for assessment of segmental motoneuronal excitability following upper motor neuron (UMN) dysfunctions in ALS.
  
  
  METHODS
  We studied the F waves of 152 ulnar nerves recorded from abductor digiti minimi in 82 patients with ALS. Two groups of hands were defined based on the presence or absence of pyramidal signs in the same upper limb. The group with pyramidal signs in the upper limbs was designated as the P group, and the group without pyramidal signs in the upper limbs was designated as the NP group.
  
  
  RESULTS
  The mean (P < 0.001), median (P < 0.001) and maximum (P = 0.035) F wave amplitudes, mean (P < 0.001), median (P < 0.001) and maximum (P = 0.003) F/M amplitude ratio, index repeating neuron (P < 0.001) and index repeater F waves (P < 0.001) of the P group were significantly increased compared with the NP group. No significant differences were identified for F wave chronodispersion (P = 0.628), mean F wave latency (P = 0.151), minimum F wave latency (P = 0.211), maximum F wave latency (P = 0.199), F wave persistence (P = 0.738), F wave duration (P = 0.152), F wave conduction velocity (P = 0.813) and number of giant F waves (P = 0.072) between the two groups.
  
  
  CONCLUSIONS
  In this study, increased F wave amplitude, F/M amplitude ratio and number of repeater F waves reflected enhanced segmental motoneuronal excitability following UMN dysfunctions in ALS.
authors.forename: Jia
authors.initials: J
authors.lastname: Fang
authors.affiliation: Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
authors.forename: Li-Ying
authors.initials: LY
authors.lastname: Cui
authors.forename: Ming-Sheng
authors.initials: MS
authors.lastname: Liu
authors.forename: Yu-Zhou
authors.initials: YZ
authors.lastname: Guan
authors.forename: Xiao-Guang
authors.initials: XG
authors.lastname: Li
authors.forename: Bo
authors.initials: B
authors.lastname: Cui
authors.forename: Qing-Yun
authors.initials: QY
authors.lastname: Ding
mesh_terms: D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016472:Motor Neuron Disease / Q000503:physiopathology; D009046:Motor Neurons / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology; D014459:Ulnar Nerve / Q000502:physiology