Justification for New Diagnostic Criteria for Susac Syndrome: Evolving Beyond the Triad (S20.001)

Objective: To review published cases of SuS in order to lay a framework for proposed diagnostic criteria. Background: No published diagnostic criteria exist for Susac syndrome (SuS), a rare autoimmune microvascular endotheliopathy that causes ischemic injury to the brain, retina, and inner ear. At the time of initial evaluation, only 13% of patients exhibit the clinical triad (encephalopathy, BRAO, and sensorineural hearing loss). Although not part of the clinical triad, corpus callosal (CC) lesions may be pathognomonic for SuS. Establishment of diagnostic criteria for SuS are needed, both to enhance clinical care and to facilitate research. Design/Methods: Review of the 100 most recently published cases of SuS, with attention to clinical manifestations present at first evaluation and any reported disease evolution. Results: Evidence of the complete clinical triad (including an abnormal fluorescein angiogram, and an abnormal audiogram) was present in only 10 patients when first evaluated for their symptoms, and in 35/100 at last follow-up. Although branch retinal artery occlusion (BRAO) was the most common manifestation of retinal involvement, two cases presented with central retinal artery occlusion, and 1 case had only segmental hyperfluoresence without BRAO. Encephalopathy was absent in four patients who had neuropsychiatric syndromes. CC lesions were present in 75 cases at first evaluation and in 87 at final report. A sufficient evaluation for all three components of the clinical triad was not reported in 53 cases. Conclusions: The classical clinical triad of SuS has poor sensitivity for SuS, particularly at time of first evaluation. Presence of typical CC lesions may permit an earlier and more confident diagnosis. A standardized definition for the presence for each component would be beneficial. Diagnostic criteria should encompass the established heterogeneity of disease and guide evaluation so that patients may benefit from an earlier and more accurate diagnosis. Disclosure: Dr. Carruthers has received personal compensation for activities with Roche, Novartis, Biogen, Genzyme and Teva as a consultant/speaker. Dr. Carruthers has received research support from Teva. Dr. Paton has nothing to disclose. Dr. Sheldon has nothing to disclose. Dr. Traboulsee has received personal compensation for activities with Genzyme and Roche as a consultant. Dr. Traboulsee has received research support from Genzyme, Roche, and Chugai. Dr. Carruthers has nothing to disclose. Dr. Rennebohm has nothing to disclose.