Corpus Callosum Lesions are not Inextricably Linked to CNS Symptoms in Reported Cases of Susac Syndrome

Abstract Objective To evaluate whether corpus callosum (CC) lesions are inextricably linked to CNS symptoms of Susac Syndrome (SuS) by reviewing published cases to find instances where: 1) CC lesions occur without CNS symptoms, and 2) whether patients with CNS symptoms lack CC lesions. Methods 100 reported cases of SuS were identified in PubMed. Clinical symptoms, para-clinical testing and MRI data were collected both at presentation and for any available follow-up and analyzed. Cases were reviewed to evaluate how they met European diagnostic criteria for SuS (EuSaC) both at first presentation and at most recent evaluation after followup, if available. Results Limited disease is a common finding in the 100 recently published cases and 56/100 cases did not meet EuSaC probable or definite criteria at first evaluation. CC lesions were not inextricably linked with encephalopathy, as 8 cases presented with CC lesions without CNS symptoms and 6 cases had encephalopathy without CC lesions. In five patients with both eye and ear involvement, isolated CC lesions or CNS symptoms could enhance diagnostic certainty. This may reduce specificity, but would increase sensitivity, ultimately benefitting patient care. Conclusion Patients with early SuS rarely meet diagnostic criteria at presentation. Future diagnostic criteria could make use of unlinked CC lesions or CNS symptoms.