Failure to close the gap: Concomitant superior canal dehiscence in otosclerosis patients.

Objective: Superior semicircular canal dehiscence (SSCD) causing conductive hearing loss with present reflexes is a known reason for stapes surgery failure. However, concomitant SSCD and otosclerosis occur rarely. We present a case series of SSCD diagnosed in positively identified otosclerosis patients.

Methods: Retrospective review of clinical case series in two tertiary-referral neurotologic practices was performed. Clinical histories, operative findings, audiograms, and computed tomography (CT) images were reviewed for patients diagnosed with both SSCD and otosclerosis. Patients with present stapedial reflexes were excluded. Comprehensive literature review was performed.

Results: Four cases were identified. Three reported improved hearing with partial or complete closure of the air-bone gap (ABG), including one patient with far-advanced otosclerosis. One patient had no improvement in pure tone average or ABG. One patient reported worsening of preoperative autophony and pulsatile tinnitus, but none developed new postoperative third-window symptoms. CTs demonstrated both SSCD and otosclerosis.

Conclusion: Failure to close the ABG in patients with positively identified otosclerosis intraoperatively may be due to SSCD as an occult concomitant diagnosis. SSCD should be considered as a possible cause of persistent conductive hearing loss after stapes surgery.

Level Of Evidence: 4 Laryngoscope, 130:1023-1027, 2020.