Vestibular mapping assessment in idiopathic sudden sensorineural hearing loss

The aim of this study was to investigate patterns of semicircular canal (SCC) and otolith organ dysfunction by vestibular mapping, and to determine the clinical implications of treatment outcomes in idiopathic sudden sensorineural hearing loss (ISSNHL).

We retrospectively reviewed 135 consecutive patients diagnosed with ISSNHL from January 2016 to December 2020. Patients underwent video-head impulse tests (vHIT) for each SCC, cervical vestibular-evoked myogenic potential test for the saccules, ocular vestibular-evoked myogenic potential test for the utricles, and hearing tests. Hearing outcomes were evaluated according to the American Academy of Otolaryngology-Head and Neck Surgery criteria and factors associated with prognosis were assessed. We also conducted vestibular mapping assessments and hierarchical cluster analysis.

Overall, utricular impairment (76, 56.3%) was the most frequent diagnosis in the 135 ISSNHL patients, followed by saccular impairment (59, 43.7%) and posterior SCC impairment (30, 22.2%). The mean number of affected end organs was 1.37 ± 1.24, with higher numbers in the complete recovery group than in the partial/no recovery groups. In a multivariate analysis, higher initial hearing level and abnormal vHIT results in the posterior SCC were associated with poor prognosis in ISSNHL. In hierarchical cluster analysis, horizontal SCC and anterior SCC showed the highest similarity but were in different clusters than posterior SCC, and the saccule and utricle were in separate clusters from the three SCCs.

The vestibular end organ showed various patterns of dysfunction in patients with ISSNHL. Of the five vestibular end organs, only abnormal posterior SCC was associated with poor prognosis for hearing recovery.