MS developing after NMDAR encephalitis: A Portuguese case report and literature review

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune disorder characterized by IgG autoantibodies targeting the GluN1 subunit of the NMDAR. We present a case of a 20-year-old male diagnosed with NMDAR encephalitis, who two years later developed symptoms and MRI lesions suggestive of multiple sclerosis (MS).

The patient initially exhibited depressive symptoms progressing to severe neuropsychiatric manifestations including catatonia, hallucinations, and dysphagia. Positive anti-NMDAR antibodies in the CSF and serum were found, and extensive investigations, including imaging and CSF analysis, ruled out alternative diagnoses. After treatment with methylprednisolone and intravenous immunoglobulins the patient recovered completely and remained asymptomatic until presenting two years later with optic neuritis and new demyelinating MRI lesions consistent with MS. The patient had negative tests for aquaporin-4 and myelin oligodendrocyte glycoprotein antibodies, and met 2017 McDonald criteria for MS.

This case adds to the sparse literature on overlap between NMDAR encephalitis and MS, suggesting a potential link between the autoimmune processes in these disorders. Further research is warranted to elucidate the underlying mechanisms and optimize management strategies for such cases.