title: Focal nerve enlargement is not the cause for increased distal motor latency in ALS: Sonographic evaluation.
abstract: OBJECTIVE
  To elucidate the mechanism of focal conduction slowing in the median nerve in ALS.
  
  
  METHODS
  The patients with ALS and CTS and normal control subjects were tested with sonography of the median and ulnar nerves. The cross-sectional areas (CSAs) and the wrist-forearm CSA ratios were compared with the parameters of nerve conduction study.
  
  
  RESULTS
  The median motor distal latency was frequently prolonged in ALS and CTS. CSA and the wrist-forearm ratio of the median nerve were smaller in ALS than in CTS. The ulnar nerve sonography was similar in all the groups.
  
  
  CONCLUSIONS
  Selective conduction slowing of the median nerve at the wrist in ALS is unlikely due to secondary compressive neuropathy, as seen in carpal tunnel syndrome.
  
  
  CONCLUSIONS
  Unique vulnerability of the median nerve in ALS may explain the selective conduction slowing.
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Mori
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan. Electronic address: hnodera@tokushima-u.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nodera
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan; Department of Neurology, Vihara Hananosato Hospital, Hiroshima, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Takamatsu
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Shimatani
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Maruyama
authors.affiliation: Department of Neurology, Vihara Hananosato Hospital, Hiroshima, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Oda
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan; Department of Neurology, Vihara Hananosato Hospital, Hiroshima, Japan. Electronic address: yizumi@clin.med.tokushima-u.ac.jp.
authors.forename: Yuishin
authors.initials: Y
authors.lastname: Izumi
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.
authors.forename: Ryuji
authors.initials: R
authors.lastname: Kaji
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002349:Carpal Tunnel Syndrome / Q000000981:diagnostic imaging / Q000503:physiopathology; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology*; D014463:Ultrasonography
keywords: ALS; Carpal tunnel syndrome; Distal latency; Median nerve; Sonography