Phenotyping vestibulocochlear manifestations in Susac syndrome: a cohort study.

Purpose: To characterize vestibulocochlear involvement in patients with Susac syndrome (SuS), a rare immune-mediated endotheliopathy of cerebral, retinal and inner ear microvasculature causing a triad of encephalopathy, branch retinal artery occlusions and sensorineural hearing loss.

Methods: The electronic patient files of 21 patients with SuS are reviewed for data on demography, clinical presentation, disease course and audiovestibular testing.

Results: All 21 patients experienced some form of audiovestibular complaints during the disease course, with vertigo and instability being most frequently reported, followed by hearing loss, tinnitus and aural fullness. These audiovestibular symptoms did not always coincide. Fifteen patients had objectified predominant low- to midfrequency sensorineural hearing loss and 8 out of 18 patients showed abnormalities on vestibular testing, most frequently vestibular evoked myogenic potential-abnormalities, indicating otolith dysfunction. Treatment protocols consisted of uniformly extensive immunosuppressive therapy and hearing loss remained mostly mild.

Conclusion: Audiovestibular involvement is very common in patients with SuS. Characteristic findings include a "reverse-slope" configuration on audiological testing and otolith dysfunction on vestibular testing. Aggressive immunosuppression may prevent severe audiovestibular dysfunction. Symptoms as aural fullness and otolith dysfunction may indicate an underlying hydrops. Further investigations are necessary to elucidate the histopathological mechanisms underlying these preferentially involved cochleovestibular areas. Early recognition and treatment of SuS are important to stabilize or decrease disease activity and might also have beneficial effects on inner ear outcome. THE SUBMITTED MANUSCRIPT REPORTS DATA DERIVED FROM CLINICAL OBSERVATIONS IN HUMANS: Consent for the research was provided by the Ethics Committee of Ghent University hospital (application number 2019/1443, registration date 31/12/2021, principal investigator Guy Laureys).