Risk of progressive hearing loss in untreated superior semicircular canal dehiscence

Objective: Patients with incidental or minimally symptomatic superior semicircular canal dehiscence (SSCD) are usually observed, without surgical repair. However, it remains unknown whether a labyrinthine fistula of the superior semicircular canal is associated with progressive conductive or sensorineural hearing loss over time.

Study design: Retrospective review at two tertiary care academic referral centers.

Methods: Adults analyzed were diagnosed with SSCD by high-resolution temporal bone computed tomography and vestibular evoked myogenic potential testing and observed with a minimum of two sequential audiograms. Patients with other potential causes of hearing impairment were excluded.

Results: A total of 40 ears in 30 adult patients (median age: 59 years; 63% female) were analyzed. Median audiometric follow-up was 23 months (range 1-136 months). None experienced a sudden hearing loss over the follow-up period. In patients with audiometric follow-up of at least 20 months (median 34 months), the median change in air-conduction pure tone average and air-bone gap was 0.9 decibels (dB) per year (interquartile range [IQR] 0-2.1) and 0.7 dB per year (IQR 0-2.0), respectively. Speech discrimination scores did not differ when comparing median initial (100%) and median final (98%) scores (P = 0.77). There was no statistically significant change in bone-conduction thresholds at 0.5, 1, 2, and 4 kHz over the period of observation.

Conclusion: The risk of progressive hearing loss with observed SSCD is low during short- and intermediate-term follow-up. Further studies are necessary to determine whether late hearing loss occurs. Such information may be critical toward patient counseling regarding the need for and timing of surgery.

Level of evidence: 4. Laryngoscope, 127:1181-1186, 2017.