Anti-Gamma-Aminobutyric Acid B (GABA-B) Receptor Encephalitis: A Case Series Analyzing Treatment Modalities and Cancer Screening Recommendations

This case series presents an alternative treatment approach for refractory epilepsy in the setting of anti-gamma-aminobutyric acid B receptor (GABA-B-R) encephalitis and examines current guidelines for long-term cancer screening. We present two cases of anti-GABA-B receptor encephalitis from Kansas City, Missouri. The first case describes a 53-year-old woman presenting with new-onset headache, seizures, and progressive encephalopathy, who was treated with corticosteroids and anti-seizure medications, followed by intravenous immunoglobulin (IVIG) and plasma exchange (PLEX). Cancer screening with chest CT was negative. Fluorodeoxyglucose (FDG)-PET revealed increased uptake in two cervical lymph nodes; however, her biopsy was negative for malignancy. The second case describes a 49-year-old woman presenting with confusion, dizziness, and seizures. Her seizures were refractory to anti-seizure medications and immunotherapy, but an excellent response and recovery were seen after the concurrent use of methylprednisolone, IVIG, and anti-seizure medications. Subsequent malignancy screenings remained negative in both cases. A combination of corticosteroids with IVIG or PLEX may be a promising option for refractory cases of anti-GABA-B-R autoimmune encephalitis (AE). Additionally, it is not clear whether malignancies other than small cell lung carcinoma (SCLC) are strongly associated with this condition. Further studies are needed to evaluate the option of combined immunotherapy and the association of other malignancies with anti-GABA-B AE.