Background Susac syndrome is characterised by the triad of encephalopathy with or without focal neurological signs, branch retinal artery occlusions and hearing loss. Establishment of the diagnosis is often delayed because the triad is complete only in a minority of patients at disease onset. This leads to a critical delay in the initiation of appropriate treatment. Our objective was to establish criteria for diagnosis of either definite or probable Susac syndrome.
Method The establishment of diagnostic criteria was based on the following three steps: (1) Definition of a reference group of 32 patients with an unambiguous diagnosis of Susac syndrome as assessed by all interdisciplinary experts of the European Susac Consortium (EuSaC) team (EuSaC cohort); (2) selection of diagnostic criteria, based on common clinical and paraclinical findings in the EuSaC cohort and on a review of the literature; and (3) validation of the proposed criteria in the previously published cohort of all Susac cases reported until 2012.
Results Integrating the clinical presentation and paraclinical findings, we propose formal criteria and recommend a diagnostic workup to facilitate the diagnosis of Susac syndrome. More than 90% of the cases in the literature fulfilled the proposed criteria for probable or definite Susac syndrome. We surmise that more patients could have been diagnosed with the recommended diagnostic workup.
Conclusions We propose diagnostic criteria for Susac syndrome that may help both experts and physicians not familiar with Susac syndrome to make a correct diagnosis and to prevent delayed treatment initiation.
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IK, JD and MR contributed equally.
Contributors The authors belong to the European Susac Consortium (EuSaC) and the EuSaC study group. Every author contributed to the collection of data, the conception of the project, the design of the study and the acquisition and analysis of data. IK, JD, MR, YB, BS, AA and TD drafted the manuscript and provided a significant portion of the figures.
Competing interests IK received travel support and speaker honoraria from CSL Behring and receives a research grant (IMF grant ‘The pathophysiological role and clinical impact of the immune system in Susac syndrome’ (KL111421)). JD received research support from Novartis and Bayer Healthcare, speaker honoraria from Novartis, Teva, Genzyme, Biogen, Allergan, Merck-Serono, and Bayer Healthcare, honoraria for advisory from Teva, Genzyme, Novartis, and Bayer Healthcare, travel support from Bayer Healthcare, Biogen, and Novartis. MR received speaker honoraria from Novartis and Bayer Vital GmbH and travel reimbursement from Bayer Schering, Genzyme and Biogen Idec. CCG's work has been funded by the German Research Foundation individual research grant ‘The role of natural killer cells in the immunoregulation of multiple sclerosis’ (DFG, GR3946/2-1) and the IMF grant ‘The pathophysiological role and clinical impact of the immune system in Susac syndrome’ (KL111421). CCG received speaker honoraria and travel expenses for attending meetings from Genzyme, Novartis Pharma GmbH, and Bayer Healthcare. RG has received research grants from Novartis, speaker honoraria from Novartis and Bayer healthcare and travel reimbursement from Bayer healthcare. FP was supported by German Research Foundation (DFG exc257), BMBF Competence Network Multiple Sclerosis, EU FP7 Framework Program (combims.eu), Guthy Jackson Charitable Foundation, Arthur Arnstein Foundation; research support and personal compensation for activities with Alexion, Biogen, Chugai, Teva, Genzyme, Merckserono, Novartis, Bayer and Medimmune. HWi is member of Scientific Advisory Boards/Steering Committees for Bayer Healthcare, Biogen Idec, Sanofi Genzyme, Merck Serono, Novartis, Roche and Teva. He received speaker honoraria and travel support from Bayer Vital GmbH, Bayer Schering AG, Biogen, CSL Behring, EMD Serono, Fresenius Medical Care, Genzyme, Merck Serono, Omniamed, Novartis and Sanofi Aventis and Teva. He received compensation as a consultant from Biogen Idec, Merck Serono, Novartis, Omniamed, Roche and Sanofi Genzyme. He has got research supports from Bayer Healthcare, Bayer Vital, Biogen Idec, Merck Serono, Novartis, Sanofi Genzyme, Sanofi US and Teva Pharma as well as German Ministry for Education and Research (BMBF), German Research Foundation (DFG), Else Kröner Fresenius Foundation, Fresenius Foundation, Hertie Foundation, Merck Serono, Novartis, NRW Ministry of Education and Research, Interdisciplinary Center for Clinical Studies (IZKF) Muenster, RE Children's Foundation. TD received honoraria and travel expenses from Genzyme, Shire, Bristol-Myers Squibb, Boehringer-Ingelheim Pharma, Sanofi Aventis, Eisai, Novartis, Bayer Vital, Merz Pharma, Actelion, Lundbeck for serving as a speaker and consultant and research support from Genzyme, Shire and Actelion. For conducting of studies on dementia, TD received grants from Novartis and Merz Pharma.
Ethics approval The local ethical board in Münster, Germany.
Provenance and peer review Not commissioned; externally peer reviewed.