Auditory outcomes after labyrinthine surgery for superior semicircular canal dehiscence repair and posterior canal occlusion

Background: Superior semicircular canal dehiscence (SSCD) and benign paroxysmal positional vertigo (BPPV) are pathologies originating from within the semicircular canals that can be extremely debilitating and impair quality of life. Surgical procedures including SSCD repair and posterior canal occlusion (PCO) provide relief from severe and intractable symptoms; however, they carry the risk of sensorineural hearing loss (SNHL). In the current literature, there is conflicting evidence on the hearing outcomes after labyrinthine surgery during SSCD repair and PCO. The aim of this study is to examine the sensorineural hearing outcomes after SSCD repair and PCO to facilitate improved pre-operative consultation of hearing risks to patients undergoing these procedures. Methods: A retrospective case review was conducted of all adult subjects who underwent SSCD repair or PCO at a tertiary referral centre in Western Australia, Australia between 2009 and 2024. Patient data including pre- and post-operative audiograms and operation reports were collected from the electronic records. Patients were included if they were adults and had pre- and post-operative audiograms. Results: There were 32 procedures on 30 patients, including 22 middle cranial fossa (MCF) repairs, 5 transmastoid (TM) repairs, and 5 PCOs. In a pooled analysis, there was a statistically significant worsening bone conduction pure tone average (BC PTA) from a median of 15.0 dB pre-operatively to 17.0 dB post-operatively, with a point estimate for the median of the difference of 3.5 dB [95% confidence interval (CI): 0.5, 6.5, W=365.5, P=0.022, rank biserial correlation (rrb) =−0.47]. Procedures performed to treat SSCD had a worsening in BC PTA from a median of 15.0 dB pre-operatively to 16.0 dB post-operatively, with a point estimate of 4.0 dB (95% CI: 1.0, 7.5, W=278, P=0.009, rrb=−0.58). The MCF approach was associated with a worsening BC PTA from a median of 16.0 dB pre-operatively to a median of 16.5 dB post-operatively, with a point estimate of 4.0 dB (95% CI: 1.0, 9.5, W=180.5, P=0.025, rrb=−0.56). There was no statistically significant change in BC PTA after the TM approach (4.5 dB, 95% CI: −3, 8, W=13, P=0.188, rrb=−0.73) or PCO (−1.0 dB, 95% CI: −12, 10, W=7, P=1.000, rrb=0.07); however, sample sizes were small. Conclusions: In this study, SSCD repair and SSCD repair via an MCF approach were associated with a statistically significant SNHL of <5 dB, which should be discussed with patients during pre-operative counselling. Sensorineural hearing outcomes for SSCD repair via the TM approach and PCO for BPPV were not statistically significant.