When a Transient Ischemic Attack Is Not a Transient Ischemic Attack: Super-refractory Status Epilepticus in GAD65...

A 68-year-old woman with no prior medical history was diagnosed with probable glutamic acid decarboxylase 65 (GAD65) antibody-associated autoimmune encephalitis, which initially mimicked a transient ischemic attack (TIA) before progressing to super-refractory status epilepticus. She initially experienced a transient episode of right-sided weakness and dysarthria, leading to a presumed vascular diagnosis. Eight days later, she returned with right central facial palsy and conduction aphasia, which rapidly progressed to global aphasia and was followed by fever and seizures, prompting neurological reevaluation. Electroencephalography (EEG) demonstrated encephalopathic activity with epileptiform discharges, while cerebrospinal fluid (CSF) analysis revealed isolated protein elevation without pleocytosis. Extensive investigations for infectious, neoplastic, neurodegenerative, and systemic autoimmune causes were unrevealing. Brain fluorodeoxyglucose-PET/CT (FDG PET/CT) demonstrated diffuse cortical hypermetabolism, a finding compatible with autoimmune encephalitis but one that may also have been influenced by ongoing or recent ictal activity. Given the high suspicion for autoimmune status epilepticus, empiric treatment with methylprednisolone and intravenous immunoglobulin (IVIG) was initiated before the results of CSF autoimmune antibody testing became available. The patient subsequently demonstrated progressive clinical and electrographic improvement. After a prolonged ICU stay, she recovered with minimal disability. Follow-up serum testing revealed low-titer anti-GAD65 antibodies, which supported the diagnosis despite negative CSF autoimmune antibody testing. This report highlights the diagnostic challenges of GAD65 antibody-associated encephalitis presenting with cerebrovascular-like episodes, the potential discordance between serum and CSF antibody testing, and the importance of early empiric immunotherapy in suspected autoimmune encephalitis, even when initial diagnostic studies remain inconclusive.