New onset of Susac syndrome after mRNA COVID-19 vaccine: a case report

Susac syndrome (SuS) is a rare immune-mediated disorder, affecting microvessels in the brain, retina and inner ear, leading to central nervous system dysfunction, visual disturbances and sensorineural hearing loss. These events may occur simultaneously or in succession. Since its first description in 1979 by John Susac, about 400 cases have been described; however, SuS is probably underdiagnosed. SuS usually affects young adults between 20 and 40 years (female-to-male ratio of 3.5/1) [1, 2]. Occlusive microvascular endotheliopathy/basement membranopathy represents a disease hallmark, but the pathogenesis is still debated. Infections, diet or medications have been described as possible triggers of autoimmunity [1]. In 2006, a case of SuS after smallpox vaccination was reported. The COVID-19 pandemic has affected over 260 million people and different neurological disorders have been related to both Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection and vaccination [3]. Six cases of SuS related to SARS-CoV-2 infection or vaccination have been described: two following SARS-CoV2 infection, one related to ChAdOx1 vaccine, and three after Coronavac vaccine [4]. Here we report the first case of SuS after BNT162b2 mRNA COVID-19 vaccine (Comirnaty®).