Background/Purpose: Susac syndrome (SuS) is a rare vasculitis affecting the brain, retina and inner ear in young women. Nonreversible hearing loss is the main long-term damage of SuS and requires hearing aids in more than 50% of patients. There are no known predictive factors for poor outcomes in SuS. We aimed to identify risk factors for severe hearing loss in Susac Syndrome.

Methods: SuS patients have been included in the prospective national cohort study (CarESS study) involving 20 different centres in France. CarESS study is an ongoing cohort study that started in December 2011 including all consecutive patients with SuS referred to the French reference center (Department of Internal Medicine, Bichat Claude Bernard Hospital, Paris). SuS was defined either by the triad of encephalopathy with corpus callosum ischemic lesions on brain MRI, cochleo-vestibular damage including sensorineural hearing loss and multiple occlusions of retinal central artery branches and/or retinal vasculitis on retinal fluorescein angiography. Collected data included age, gender, physical examination, fundoscopy, retinal angiography, visual acuity, visual field, audiogram, cerebrospinal fluid, brain MRI and treatment received. The CarESS study was designed with a follow-up at 1, 3 months, 6 months, 12 months after diagnosis and then annually for 5 years and/or in the event of a relapse. Fundoscopy, audiogram, and brain MRI were systematically scheduled at each time-point. The primary outcome was the occurrence of severe hearing loss (HL) at last follow-up. Severe HL was defined as the loss of 70dB in at least one ear on audiogram or the need for hearing aids.

Results: Overall, 36 SuS patients were analyzed for the primary outcome. Twenty-four patients (66.7%) were women and the median age at diagnosis was 37.5 [24.5-42.5] years. The triad was complete in 29 (80.6%) patients at disease onset. Thirty-three patients (91.7%) had cochlea-vestibular involvement at SuS diagnosis including tinnitus (n=16), dizziness (n=15), ataxia (n=7) and HL >20dB in at least one ear (n=25). At diagnosis, thirty-two (88.9%), 11 (30.6%) and 7 (19.4%) patients have received steroids, intravenous immunoglobulin and/or immunosuppressive drugs (IS), respectively. After a median follow up of 50.7 [24-73.4] months, 20 patients (58.3%) experienced severe HL that occurred a median time of 2.1 [0.3 – 13.6] months after diagnosis. Multivariable logistic regression model showed that odds of severe HL were lower in patients who received IS drugs at diagnosis (OR 0.13 95% CI [0.01-0.93], p=0.041).

Conclusion: Severe hearing loss is frequent in patients with Susac syndrome and associated with the absence of immunosuppressive drugs given at diagnosis. Our findings support the systematic use of immunosuppressive drugs in Susac syndrome to prevent poor outcome, which should be tested in a multicenter prospective randomized trial.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/risk-factors-for-severe-outcome-in-susac-syndrome-a-national-cohort-study/