Tegmen Dehiscence and Audiologic Outcomes in the Middle Fossa Repair of Superior Semicircular Canal Dehiscence.

OBJECTIVE

To investigate the audiologic presentation and post-surgical audiologic outcomes of superior semicircular canal dehiscence (SSCD) with concurrent tegmen tympani dehiscence with or without dural-ossicular contact.

METHODS

We reviewed 358 middle fossa repairs of SSCD at an institution from 2011 to 2022. Primary outcomes were preoperative and pre- to postoperative change in pure-tone average (PTA) and low-frequency air-bone gap (LF-ABG). Tegmen tympani dehiscence and dural-ossicular contact status were assessed on CT imaging and treated as independent variables in multivariable models.

RESULTS

Compared with the SSCD-alone cohort, the SSCD + tegmen tympani dehiscence group had significantly higher preoperative PTA (B = 5.40; p  = 0.007) and ABG at 500 Hz (B = 5.08; p  = 0.007) and 1,000 Hz (B = 4.58; p  = 0.003). Similar findings were seen in the SSCD + tegmen tympani dehiscence + combined dural-ossicular contact cohort for PTA (B = 5.32; p  = 0.017) and ABG at 500 Hz (B = 4.50; p  = 0.029) and 1,000 Hz (B = 4.66; p  = 0.006). The SSCD + tegmen tympani dehiscence + unilateral dural-ossicular contact cohort had significantly higher preoperative ABG at 500 Hz (B = 5.11; p  = 0.023) and 1,000 Hz (B = 5.18; p  = 0.005), whereas the bilateral dural-ossicular contact group showed no significant differences. No cohort exhibited significant changes in PTA or LF-ABG postoperatively.

CONCLUSION

Concurrent SSCD and tegmen tympani dehiscence with or without dural-ossicular contact present with greater preoperative PTA and LF-ABG but no significantly different surgical outcomes compared with SSCD alone. Therefore, although tegmen tympani defects may contribute to greater baseline auditory deficits, the MCF approach offers similar levels of improvement in hearing across both groups.