AB1855 SUSAC SYNDROME: CASE SERIES FROM ADULT & PEDIATRIC TERTIARY ACADEMIC MEDICAL CENTERS

Abstract

BackgroundSusac Syndrome (SS) is a rare autoimmune endotheliopathy that affects the brain, retina, and inner ear, characterized by a clinical triad of encephalopathy, branch retinal artery occlusion (BRAO), and sensorineural hearing loss (SNHL)[1]. Brain MRI, fluorescein angiogram (FA), and audiometry help to establish a diagnosis[2]. The clinical presentation of SS is often variable leading to a delay in the diagnosis.ObjectivesThis study aims to compare clinical features and therapeutic strategies in adult and pediatric populations with Susac Syndrome.MethodsThis was a retrospective chart review of cases with a diagnosis of SS from December 2010 to December 2020 at The Ohio State University Wexner Medical Center (OSUWMC) and Nationwide Children’s Hospital in Columbus, Ohio, USA (tertiary care centers). We analyzed the following: age, gender, ethnicity, symptoms at the time of presentation, diagnostic studies, autoimmune serologies, brain MRI, FA, audiometry, treatment approaches, and outcomes.ResultsAll the patients (seven adult- patients and two pediatric-onset patients) identified as females, and the majority (78%) were Caucasian. The age at presentation ranged from 10 to 45 years old with a mean age of 38 years. The time to diagnosis ranged from 3 to 17 months with a mean of 7.8 months. The most common symptoms at onset included dizziness, hearing loss, and visual change. ESR was elevated in 50% with a range of 23 to 52 mm/hr (normal<30 mm/hr). CRP was elevated in 22% of patients with a range of 11 to 22 mg/dl (normal <10 mg/dL). Low to medium titer ANA was positive in 30%. FA detected unilateral or bilateral BRAO in seven patients (78%). Sensorineural hearing loss was confirmed on audiogram testing in 7 of 9 patients, and 44% of patients had bilateral hearing loss. 88% of our patient population had evidence of corpus callosal involvement (“snowball lesions”) in the brain MRI. CSF study was done in 5 patients - 4/5 had elevated CSF protein at 77 mg/dL (range 15-45 mg/dL) and the mean cell count was <3 (normal), without any oligoclonal bands. One patient had a brain biopsy.The most common initial treatment was high-dose steroids followed by a taper. Oral immunosuppressive therapy with mycophenolate mofetil (MMF) was initiated in 78% and was maintained in 56% of patients, who remained stable. Intravenous immunoglobulin (IVIG) was initially used in 56% of patients. Two patients transitioned from MMF to azathioprine due to pregnancy. Due to the severity of the disease, one patient transitioned from MMF to tacrolimus and Rituximab. 20% had a disease flare after the initial therapy requiring additional immunosuppression.ConclusionOur series highlights the rarity of SS. A neurologic exam, brain MRI, fluorescein angiogram, and audiogram should be performed in every case. A brain biopsy is not necessary for the diagnosis, unless for exclusion. BRAO was detected in 75% of our patients, highlighting the importance of an ophthalmology evaluation with FA, even in the absence of visual symptoms. In our series, only 20% presented with the full clinical triad of visual, auditory, and central nervous system symptoms, indicating that presentation of SS is often incomplete and diagnosis relies on a high index of suspicion[3]. Treatment depends on the severity of the presentation and involves the use of high-dose corticosteroids along with immunosuppression including mycophenolate, IVIG, tacrolimus, rituximab, and cyclophosphamide[4].