Audiometric Outcomes After the Middle Cranial Fossa Repair of Superior Semicircular Canal Dehiscence.

OBJECTIVE: To evaluate the audiometric outcomes after the middle cranial fossa approach (MCF) for superior canal dehiscence (SCD) repair.

STUDY DESIGN: Retrospective review.

SETTING: Tertiary referral center.

PATIENTS: SCD cases presented to a single institution between 2012 and 2022.

INTERVENTIONS: The MCF repair of SCD.

MAIN OUTCOME MEASURES: Air conduction (AC) threshold (250-8,000 Hz), bone conduction threshold (BC) (250-4,000 Hz), and air bone gap (ABG) (250-4,000 Hz) at each frequency, pure tone average (PTA) (500, 1,000, 2,000, 3,000 Hz).

RESULTS: Among 202 repairs, 57% were bilateral SCD disease and 9% had previous surgery on the affected ear. The approach significantly narrowed ABG at 250, 500, and 1,000 Hz. The narrowing of ABG was achieved by both decreased AC and increased BC at 250 Hz, but mediated primarily by increased BC at 500 Hz and 1,000 Hz. Among cases without previous ear surgery, mean PTA remained in the normal hearing range (mean: preop, 21 dB; postop, 24 dB) and clinically important hearing loss (PTA increased by ≥10 dB) after the approach was noted in 15% of cases. Among cases with previous ear surgery, mean PTA remained in the mild hearing loss range (mean: preop, 33 dB; postop, 35 dB) and clinically important hearing loss after the approach was noted in 5% of cases.

CONCLUSION: This is the largest study to date examining the audiometric outcomes after the middle cranial fossa approach for SCD repair. Findings of this investigation support that the approach is effective and safe with long-term hearing preservation for most.