title: Relation between distal motor latency delay and sensory action potential absence of the median nerve in carpal tunnel syndrome.
abstract: OBJECTIVE
  To elucidate the cutoff value for distal motor latency (DML) at which sensory nerve action potentials (SNAPs) are absent in carpal tunnel syndrome (CTS) patients.
  
  
  METHODS
  We examined 157 hands in 129 patients with CTS retrospectively. We classified the patients according to whether SNAPs were successfully obtained. Group A consisted of hands with SNAPs, while Group B consisted of hands without SNAPs. The cutoff value for DML was determined by receiver-operating characteristic curve analysis. We enrolled 130 hands with CTS for the analysis, because measurements were successful in 130 hands for compound muscle action potentials and in 82 hands for SNAPs from a total of 157 hands investigated.
  
  
  RESULTS
  A significant correlation was observed between DML and SCV (P<0.0001, R*2=0.40). The most discriminative cutoff value for DML was 7.7ms, resulting in a sensitivity of 79.6% and specificity of 79.3%.
  
  
  CONCLUSIONS
  Cases in which SNAPs are evoked despite a DML longer than 7.7ms should raise suspicion.
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan; Department of Orthopedic Surgery, Yamaguchi Rosai Hospital, Yamaguchi, Japan. Electronic address: funa51.mf@gmail.com.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Funaba
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Kanchiku
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Imajo
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi Rosai Hospital, Yamaguchi, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Yamamoto
authors.affiliation: Department of Orthopedic Surgery, Ube Kosan Central Hospital, Yamaguchi, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Hiura
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Fujimoto
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Taguchi
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi Rosai Hospital, Yamaguchi, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kido
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002349:Carpal Tunnel Syndrome / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology*; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology*
keywords: Carpal tunnel syndrome; Distal motor latency; Sensory nerve conduction velocity; Thenar muscle branch