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.