Hearing outcomes after surgical plugging of the superior semicircular canal by a middle cranial fossa approach

Otol Neurotol. 2012 Oct;33(8):1386-91. doi: 10.1097/MAO.0b013e318268d20d.


Objective: To determine postoperative hearing outcomes after surgical plugging via middle cranial fossa approach for superior semicircular canal dehiscence syndrome (SCDS).

Study design: Clinical review.

Setting: Tertiary care medical center.

Patients: 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.

Intervention: Pure tone audiometry was performed preoperatively and at 7 days and at least 1 month postoperatively.

Main outcome measures: 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).

Conclusion: 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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Aged
  • Audiometry, Pure-Tone
  • Auditory Threshold / physiology
  • Bone Conduction / physiology
  • Cranial Fossa, Middle / surgery*
  • Data Interpretation, Statistical
  • Ear Diseases / surgery
  • Female
  • Follow-Up Studies
  • Hearing / physiology*
  • Hearing Loss, Sensorineural / surgery
  • Humans
  • Male
  • Middle Aged
  • Otologic Surgical Procedures / methods*
  • Semicircular Canals / surgery*
  • Speech Perception
  • Surgery, Computer-Assisted
  • Surgical Instruments
  • Tomography, X-Ray Computed
  • Treatment Outcome
  • Vestibular Function Tests