title: Prognosis of severe carpal tunnel syndrome with absent compound muscle action potential.
abstract: Opponensplasty is a surgical option for patients with severe carpal tunnel syndrome (CTS). We investigated prognostic factors of patients who lack a preoperative compound muscle action potential (CMAP) of the abductor pollicis brevis (APB) muscle to determine the necessity for single-stage opponensplasty.
  
  
  
  We retrospectively enrolled 22 hands of 22 CTS patients. Prognostic factors considered were age, diabetes mellitus, the median sensory nerve action potential, distal motor latency of the second lumbrical (2L) CMAP (2L-DML), and its amplitude (2L-Amp). Postoperative APB-CMAP amplitude (post APB-Amp) at 12 months was used as the outcome measure.
  
  
  
  Only 2L-DML showed a significant correlation with post APB-Amp (r = -0.56). The contribution of 2L-Amp was not significant, although 3 hands with absent 2L-CMAP had a poor electrophysiological recovery.
  
  
  
  Prolonged 2L-DML and absent 2L-CMAP seem to be poor prognostic factors. Concurrent opponensplasty may not be necessary in patients with 2L-DML of 8 ms or less. Muscle Nerve 54: 427-431, 2016.
authors.affiliation: Department of Neurology, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Hisao
authors.initials: H
authors.lastname: Kamiya
authors.affiliation: Department of Orthopaedic Surgery, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Kimura
authors.affiliation: Central Laboratory, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hoshino
authors.affiliation: Faculty of Economics, Yokohama National University, Yokohama, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Kobayashi
authors.affiliation: Department of Neurology, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Sonoo
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000368:Aged; D000369:Aged, 80 and over; D002349:Carpal Tunnel Syndrome / Q000175:diagnosis* / Q000503:physiopathology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009431:Neural Conduction / Q000502:physiology*; D011379:Prognosis; D011930:Reaction Time / Q000502:physiology; D012189:Retrospective Studies; D013223:Statistics as Topic
keywords: carpal tunnel release; carpal tunnel syndrome; nerve conduction study; opponensplasty; prognosis; second lumbrical