title: Hearing outcomes after surgical plugging of the superior semicircular canal by a middle cranial fossa approach.
abstract: OBJECTIVE
  To determine postoperative hearing outcomes after surgical plugging via middle cranial fossa approach for superior semicircular canal dehiscence syndrome (SCDS).
  
  
  METHODS
  Clinical review.
  
  
  METHODS
  Tertiary care medical center.
  
  
  METHODS
  Forty-three cases of SCDS based on history, physical examination, vestibular function testing, and computed tomography imaging confirming the presence of a dehiscence. All patients underwent surgical plugging of the superior semicircular canal via middle cranial fossa approach.
  
  
  METHODS
  Pure tone audiometry was performed preoperatively and at 7 days and at least 1 month postoperatively.
  
  
  METHODS
  Change in air-bone gap (ABG) and pure tone average (PTA).
  
  
  RESULTS
  Preoperative average ABG across 0.25, 0.5, 1, and 2 kHz was 16.0 dB (standard deviation [SD], 7.5 dB). At 7 days postoperatively, average ABG was 16.5 dB (SD, 11.1; p = 0.42), and at greater than 1 month was 8.1 dB (SD, 8.4; p < 0.001). 53% (95% confidence interval, 33-69) of affected ears had greater than 10 dB increase in their 4-frequency (0.5, 1, 2, and 4 kHz) PTA measured by bone-conduction (BC) threshold 7 days postoperatively and 25% (95% confidence interval, 8-39) at greater than 1 month postoperatively. Mean BC PTA of affected ears was 8.4 dB hearing loss (HL) (SD, 10.4) preoperatively. Compared with baseline, this declined to 19.2 dB HL (SD, 12.6; p < 0.001) at 7 days postoperatively and 16.4 dB HL (SD, 18.8; p = 0.01) at greater than 1 month. No significant differences in speech discrimination score were noted (F = 0.17).
  
  
  CONCLUSIONS
  Low-frequency air-bone gap decreases after surgical plugging and seems to be due to both increased BC thresholds and decreased AC thresholds. Surgical plugging via a middle cranial fossa approach in SCDS is associated with mild high-frequency sensorineural hearing loss that persists in 25% but no change in speech discrimination.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland 21287, USA. bward15@jhmi.edu
authors.forename: Bryan K
authors.initials: BK
authors.lastname: Ward
authors.forename: Yuri
authors.initials: Y
authors.lastname: Agrawal
authors.forename: Elena
authors.initials: E
authors.lastname: Nguyen
authors.forename: Charles C
authors.initials: CC
authors.lastname: Della Santina
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Limb
authors.forename: Howard W
authors.initials: HW
authors.lastname: Francis
authors.forename: Lloyd B
authors.initials: LB
authors.lastname: Minor
authors.forename: John P
authors.initials: JP
authors.lastname: Carey
mesh_terms: D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold / Q000502:physiology; D001844:Bone Conduction / Q000502:physiology; D035301:Cranial Fossa, Middle / Q000601:surgery*; D003627:Data Interpretation, Statistical; D004427:Ear Diseases / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006309:Hearing / Q000502:physiology*; D006319:Hearing Loss, Sensorineural / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D013506:Otologic Surgical Procedures / Q000379:methods*; D012665:Semicircular Canals / Q000601:surgery*; D013067:Speech Perception; D025321:Surgery, Computer-Assisted; D013525:Surgical Instruments; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014724:Vestibular Function Tests