Autoimmune Encephalitis with Bipolar Disorder, Seizures, and Peripartum Symptom Fluctuation Associated with Serum-Positive, Cerebrospinal Fluid-Negative Contactin-Associated Protein-Like 2 Antibodies

Abstract

A case of a 47-year-old woman with a history of autoimmune encephalitis, bipolar disorder, and seizures, whose symptoms improved during pregnancy and worsened in the postpartum period. She was found to have serum-positive, cerebrospinal fluid (CSF)-negative contactin-associated protein-like 2 (CASPR2) antibodies. This case is unique due to the presence of serum-positive immune markers and negative CSF findings, despite clinical symptoms that were exclusively referable to central nervous system (CNS) involvement, with less evidence of peripheral nervous system pathology. The patient’s neuropsychiatric symptoms and seizures responded to intravenous immunoglobulin (IVIG) and corticosteroid therapy. This report highlights the importance of considering autoimmune encephalitis in patients with neuropsychiatric comorbidities and CNS symptoms, even when immune markers are detected only in serum. Additionally, it underscores the modulatory and neuroprotective roles of sex hormones in autoimmune encephalitis, as evidenced by symptom improvement during pregnancy and exacerbation postpartum. [N A J Med Sci. 2026;19(1):001-003.   DOI:  10.7156/najms.2026.1901001]