title: Delayed improvement after endoscopic carpal tunnel release.
abstract: OBJECTIVE
  In most patients with carpal tunnel syndrome (CTS), pain and/or paresthesia disappeared or decreased in a month after endoscopic carpal tunnel release (ECTR). However, subpopulation of patients showed delayed improvement following ECTR. We analyzed the delayed improvement hands to investigate the characteristics of those patients and to determine the predictable factors of delayed improvement.
  
  
  METHODS
  Single-portal ECTRs were performed in 1194 hands of 793 CTS patients from 2002 to 2011. Five-hundred seventy hands with minimal 1-year postoperative follow-up were included. We divided the 545 satisfied hands into early (group A) and delayed (group B) groups according to improvement period of 1 month. Demographic data, clinical severity and electrodiagnostic abnormality were compared between groups.
  
  
  RESULTS
  Group A included 510 hands and group B included 35 hands. In group B, 11 hands improved in 2 months, 15 hands in 3 months and 9 hands in 6 months, respectively. In group A/B, according to clinical severity, 60/1 hands were graded to I, 345/24 hands to II, 105/10 hands to III. In group A/B, based on electrodiagnostic abnormality, 57/3 hands were classified to mild, 221/11 hands to moderate and 222/21 hands to severe group. Statistical analysis between groups did not reach significance but electrodiagnostic or clinical severity had a tendency to affect the delayed response.
  
  
  CONCLUSIONS
  It is difficult to predict the factors contributing to postoperatively-delayed response in subpopulation of CTS patients. However, we recommend that postoperative observation for at least 6 months is necessary in patients without symptomatic improvement.
authors.affiliation: Department of Neurosurgry, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
authors.forename: Dong-Ho
authors.initials: DH
authors.lastname: Kim
authors.affiliation: Department of Neurosurgry, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
authors.forename: Byung-Moon
authors.initials: BM
authors.lastname: Cho
authors.affiliation: Department of Neurosurgry, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
authors.forename: Sae-Moon
authors.initials: SM
authors.lastname: Oh
authors.affiliation: Department of Rehabilitation Medicine, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
authors.forename: Dong-Sik
authors.initials: DS
authors.lastname: Park
authors.affiliation: Department of Neurosurgry, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
authors.forename: Se-Hyuck
authors.initials: SH
authors.lastname: Park
keywords: Carpal tunnel syndrome; Delayed improvement; Endoscopy; Surgical decompression