Risk factors for severe hearing loss in Susac syndrome: A national cohort study.

BACKGROUND

Nonreversible hearing loss (HL) is the main sequelae of Susac syndrome (SuS). We aimed to identify risk factors for HL in SuS.

METHODS

The CARESS study is a prospective national cohort study that started in December 2011, including all consecutive patients with SuS referred to the French reference center. The CARESS study was designed with a follow-up including fundoscopy, audiometry, and brain magnetic resonance imaging at 1, 3, 6, and 12 months after diagnosis and then annually for 5 years. The primary outcome was the occurrence at last follow-up of severe HL defined as the loss of 70 dB in at least one ear on audiometry or the need for hearing aids.

RESULTS

Thirty-six patients (female 66.7%, median age 37.5 [range 24.5-42.5] years) included in the clinical study were analyzed for the primary outcome. Thirty-three patients (91.7%) had cochleovestibular involvement at SuS diagnosis including HL >20 dB in at least one ear in 25 cases. At diagnosis, 32 (88.9%), 11 (30.6%), and 7 (19.4%) patients had received steroids, intravenous immunoglobulin, and/or immunosuppressive (IS) drugs, respectively. After a median follow-up of 51.8 [range 29.2-77.6] months, 19 patients (52.8%) experienced severe HL that occurred a median of 13 [range 1.5-29.5] months after diagnosis. Multivariable analysis showed that the odds of severe HL were lower in patients who received IS drugs at diagnosis (OR 0.15, 95% CI 0.01-1.07, p = 0.058).

CONCLUSIONS

Severe HL in SuS is associated with the absence of IS drugs given at diagnosis. Our findings support the systematic use of IS drugs in SuS.