Abstract
Objective: Among autoimmune limbic encephalitis syndromes, glutamic acid decarboxylase 65 (GAD65) antibody-associated syndromes represent a relatively rare and clinically heterogeneous subtype characterized by prominent temporal lobe involvement and diverse neurological manifestations. GAD65 is an intracellular antigen involved in gamma-aminobutyric acid (GABA) synthesis, and associated autoantibodies have been identified across several autoimmune and neurological conditions with limited diagnostic specificity and variable neurological and neuropsychological presentations. Method: This case report involves a young woman with confirmed anti-GAD65 autoimmune encephalitis (AE), who underwent serial neuropsychological evaluations over a period of two years. Results: The patient exhibited refractory temporal lobe epilepsy, neuropsychiatric and behavioral disturbance, and a pattern of neuropsychological deficits suggesting prominent temporal lobe dysfunction. Despite being untreated for approximately two years, the patient did not demonstrate a pattern of globally impaired neuropsychological dysfunction. Rather, her profile showed primary, severe impairment in memory and semantically-mediated language functions. What is particularly striking about this case was the severity of the patient's neurocognitive deficits. Specifically, she had a complete amnestic memory syndrome and substantial degradation of semantic knowledge, despite only experiencing seizures for two years, prior to which she was functioning normally. Conclusions: This case represents an illustrious example of how neuropsychological evaluation played a critical role in documenting the patient's persisting deficits to more accurately tailor treatment recommendations and planning. It also represents a sobering example of the kinds of lasting deficits that can occur without timely diagnosis and treatment.