Abstract
RATIONALE: With the update of novel autoantibodies and the expansion of the clinical spectrum, our understanding of autoimmune encephalitis (AE) is rapidly evolving. Anti-CASPR2 meningoencephalitis is a relatively rare condition that may be induced by infections. PATIENT CONCERNS: A young man presented with 3 episodes of meningoencephalitis potentially triggered by possible viral, Salmonella, and severe acute respiratory syndrome coronavirus 2. Neuroimaging revealed a thickening of the cerebral dura mater. Laboratory tests found positive serum CASPR2 antibodies in the third episode. DIAGNOSES: Across all 3 episodes, similar clinical manifestations and imaging features were observed. Although autoantibodies in the previous 2 phases were negative, the possibility of infection-related anti-CASPR2 meningoencephalitis remains highly suspected. INTERVENTIONS: The treatment regimen comprised antimicrobial agents, corticosteroid therapy, intravenous immunoglobulin, and rituximab administration. OUTCOMES: Following treatment, the patient's condition improved with no recurrence to date. Repeat testing showed undetectable anti-CASPR2 immunoglobulin G in both serum and cerebrospinal fluid. Post-treatment contrast-enhanced magnetic resonance imaging demonstrated the resolution of dural thickening. LESSONS: We further reviewed the mechanism of various infection-related AE and characteristics of CASPR2-related disease. To our knowledge, this is the first report of CASPR2 meningoencephalitis with thickened dura mater, indicating the importance of paying attention to antibody-negative AE and monitor antibodies repeatedly when necessary. In addition to immunotherapy, we recommend comprehensive management throughout the disease process.