The neurological complications of SARS-CoV-2 infection extend across the entire nervous system including cerebrovascular disorders, post-infectious encephalopathies/encephalitis, and peripheral nervous system manifestations, typically GBS and its variants. In addition, SARS-CoV-2 vaccine also has been reported to be associated with autoimmune disease such as Guillain-Barré syndrome (GBS) [4, 5]. In this report, we describe a previously healthy patient who developed autoimmune encephalitis the day after the second dose of the ChAdOx1-S vaccine, followed by recurrent seizures and progressive cognitive decline during a 4-week period. Although we evaluated the validity of this report using the Naranjo Adverse Drug Reaction Probability Scale, which corresponded to the total score of four with “possible” causality , it cannot be decisively confirmed owing to the lack of any identified direct causative biomarker or antibody. However, considering the low prevalence of autoimmune encephalitis in the general population, an estimated prevalence of 13.7/100,000 , as well as the immediate temporal relationship between the vaccination and the development of autoimmune encephalitis in a previously healthy individual, the diagnosis of vaccine-induced AE appears plausible.
Acute disseminated encephalomyelitis (ADEM) was reported after SARS-CoV-2 vaccination using inactivated SARS-CoV-2 (Vero Cells, Beijing Institute of Biological Products Co., Ltd., Beijing, China) . However, our case differs from typical ADEM in several aspects. The initial MRI lesion in our patient was restricted to the medial temporal and insular cortical ribbons excluding white matter or basal ganglia, which are the typical MRI features of limbic encephalitis, while most of ADEM shows several bilateral confluent white matter lesions in both cerebral hemispheres early in the course. Furthermore, the follow-up MRI demonstrated the encephalomalacic changes in the left temporal lobe suggesting axonal destruction rather than demyelinating disease such as ADEM. A positive oligoclonal IgG band and a negative MOG antibody test in our patient also favored the diagnosis of AE rather than ADEM [9, 10].
Recently, one case-series study which investigated patients with SARS-CoV-2 infection and neuropsychiatric symptoms raised the possibility of the central nervous system autoimmunity of the SARS-CoV-2 antibody based on the discovery of anti-SARS-CoV-2 IgG in the CSF .
In conclusion, our findings suggest the potential possibility of AE following vaccination with ChAdOx1-S. Further case reports are needed to confirm this association.