Case Report: Anti-GABA-B receptor encephalitis with refractory status epilepticus and favorable short-term recovery

Anti-gamma-aminobutyric acid type B receptor (anti-GABA-B receptor) encephalitis is a rare autoimmune limbic encephalitis that frequently presents with seizures and may be associated with malignancy, most commonly small-cell lung cancer. We report a 66-year-old man with anti-GABA-B receptor encephalitis who presented with a witnessed generalized tonic-clonic seizure after a 2-day prodrome of nocturnal repetitive stereotyped behaviors retrospectively suspicious for subtle focal seizures with automatisms. Brain magnetic resonance imaging showed right-predominant hippocampal and multifocal cortical hyperintensities, and cerebrospinal fluid analysis showed mild pleocytosis and elevated protein with negative infectious testing. He deteriorated on hospital day 5 with refractory status epilepticus and hypoxemic respiratory failure requiring intubation and intensive care. Anti-GABA-B receptor antibodies were subsequently confirmed in both serum and cerebrospinal fluid. Initial malignancy evaluation included contrast-enhanced computed tomography of the chest, abdomen, and pelvis; serum tumor markers; and an onconeural antibody panel. No malignancy was detected. Treatment included intravenous methylprednisolone, 10 sessions of therapeutic plasma exchange, and multi-agent antiseizure therapy. He was extubated after approximately 2 weeks and discharged on hospital day 39 with a modified Rankin Scale score of 3. At 3 months, he was seizure-free, with a modified Rankin Scale score of 1, a Barthel Index of 95/100, and a Mini-Mental State Examination score of 30/30. This single uncontrolled case is hypothesis-generating and does not establish treatment efficacy, optimal plasma exchange duration, long-term prognosis, or definitive non-paraneoplastic status. It illustrates that new-onset refractory status epilepticus should prompt expedited autoimmune encephalitis evaluation and that structured oncologic surveillance remains necessary despite negative initial tumor screening.