Malformations of the lateral semicircular canal correlated with data from the audiogram.

Objective: Lateral semicircular canal (LSCC) malformations  are one of the most common inner ear malformations. The purpose of this study is to analyze the prevalence and type of hearing losses associated with LSCC malformations, compared to a control group.

Methods: We retrospectively included 109 patients (166 ears) presenting with a CT-confirmed LSCC malformation, compared to a control group (24 patients). The bony island surface and the width of the inner portion of the LSCC were measured to confirm the malformation. There results were correlated to audiogram data: sensorineural (SHNL), mixed (MHL) or conductive hearing loss (CHL) by an otologist.

Results: In the LSCC group, 60.9% of patients presented with an audiogram-confirmed hearing loss, especially SNHL (39.2%, n = 65) and MHL (12.7%, n = 21). Hearing was normal in 39.2% (n = 65) of the cases. Bilateral LSCC malformations (n = 57) were frequently associated with hearing loss (80.7%), SNHL in most of the cases (33.3%). Unilateral LSCC malformations were associated with hearing alterations (51.9%, n = 27), but we also observed a high rate (81%, n = 42) of contralateral abnormalities of the audiogram.

Conclusions: LSCC malformations are commonly associated with hearing loss (61%), especially SHNL (39%). The high rate (81%) of contralateral hearing disturbances in unilateral LSCC malformations should be taken into account in the patient's daily life to avoid triggering or exacerbating any hearing loss. Otologists and radiologists must cooperate to ensure that all malformations are correctly described on CT, especially to improve the patient's education regarding hearing preservation.