GAD65 antibody-associated autoimmune encephalitis with autoimmune polyendocrine gland syndrome type II: case report and literature review

Abstract Purpose: This report presents a case of autoimmune encephalitis associated with glutamic acid decarboxylase 65 (GAD65) antibodies, complicated by autoimmune polyendocrine syndrome type II (APS-II), aiming to elucidate the clinical spectrum and disease progression, thereby enhancing clinical comprehension of this condition. Methods: We analyzed the case data of a patient with autoimmune encephalitis associated with GAD65 antibodies, complicated by APS-II, and reviewed the pertinent literature. Results: The patient, a 29-year-old female, exhibited a subacute onset of the illness, manifesting as recurrent seizures. She tested positive for GAD65 antibodies in serum and cerebrospinal fluid, exhibited elevated fasting and 2-hour postprandial glucose levels, and had an elevated HbA1c. With a prior diagnosis of hyperthyroidism, she was diagnosed with GAD65-associated autoimmune encephalitis complicated by APS-II and responded well to hormonal anti-inflammatory and symptomatic treatment. Conclusions: Autoimmune encephalitis associated with GAD65 antibodies, complicated by APS-II, is a rare and complex clinical entity, prone to misdiagnosis. The prompt initiation of immunotherapy can markedly improve patient prognosis.