Anti-gad autoimmune encephalitis: a case report

Autoimmune encephalitis (AE) refers to a group of immune-mediated inflammatory disorders of the central nervous system. Though AE related to GAD antibodies is rare, its diagnosis is increasing due to heightened clinical awareness and improved serological testing. We report a case of anti-GAD autoimmune encephalitis in a previously healthy 38-year-old male who presented with febrile illness followed by cognitive impairment, hallucinations, autonomic symptoms, and atypical seizures (manifesting as abdominal pain and persistent hiccups). Brain MRI was normal, but cerebrospinal fluid analysis showed lymphocytic pleocytosis, elevated protein, and a markedly increased opening pressure of 29 cm H₂O, consistent with intracranial hypertension. EEG demonstrated generalized background slowing without epileptiform discharges. Detection of anti-glutamic acid decarboxylase (GAD) antibodies confirmed the diagnosis. Immunotherapy with high-dose corticosteroids and rituximab led to full clinical resolution. At follow-up, the patient remained seizure-free and neurologically intact under maintenance rituximab therapy. This case underscores the importance of considering autoimmune encephalitis in patients with unexplained neuropsychiatric symptoms, even with normal imaging, and highlights the need for early immunomodulatory treatment to prevent long-term neurological sequelae and potential relapse.