title: Vestibular hypofunction in the initial postoperative period after surgical treatment of superior semicircular canal dehiscence.
abstract: OBJECTIVE
  1) Determine the prevalence of vestibular hypofunction in the immediate postoperative period after surgical treatment of superior semicircular canal dehiscence syndrome. 2) Evaluate whether dehiscence length is associated with risk of postoperative vestibular hypofunction. 3) Compare the prevalences of immediate and late postoperative vestibular hypofunction.
  
  
  METHODS
  Clinical review.
  
  
  METHODS
  Tertiary referral center.
  
  
  METHODS
  Subjects with superior canal dehiscence syndrome (n = 42) based on history, physiologic testing, and computed tomography findings, who underwent middle fossa craniotomy and superior canal dehiscence plugging.
  
  
  METHODS
  Dehiscence length was measured intraoperatively. Bedside horizontal head thrust testing (hHTT) was administered between postoperative days 1 to 7 to diagnose immediate postoperative vestibular hypofunction. Both hHTT and quantitative vestibulo-ocular reflex testing were administered 6 to 29 weeks postoperatively to detect late vestibular hypofunction.
  
  
  METHODS
  Dehiscence length and hypofunction in response to hHTT.
  
  
  RESULTS
  Thirty-eight percent of the subjects (95% confidence interval, 25-54) had hypofunction in response to hHTT within 1 week after surgery. Mean dehiscence lengths were 4.9 (range, 2.0-10.5 mm) and 3.4 mm (range, 1.0-5.5 mm) in subjects with and without postoperative hypofunction, respectively (p = 0.0018). Each 1-mm increase in dehiscence length increased the odds of immediate postoperative hypofunction 2.6-fold (95% confidence interval, 1.3-5.1). The prevalence of vestibular hypofunction was significantly higher in the early compared with the late postoperative period.
  
  
  CONCLUSIONS
  Immediate postoperative vestibular hypofunction is common, particularly with larger dehiscences. This hypofunction may typically resolve, given that the prevalence of vestibular hypofunction 6 weeks postoperatively is low. Possible mechanisms include intraoperative loss of perilymph, which may be more likely with larger dehiscences.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Agrawal
authors.forename: Americo A
authors.initials: AA
authors.lastname: Migliaccio
authors.forename: Lloyd B
authors.initials: LB
authors.lastname: Minor
authors.forename: John P
authors.initials: JP
authors.lastname: Carey