{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T05:20:56Z","timestamp":1787721656977,"version":"build-2784847793"},"reference-count":27,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T00:00:00Z","timestamp":1787702400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Med."],"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Glutamic acid decarboxylase 65 (GAD65) antibody-associated autoimmune encephalitis is an uncommon immune-mediated neurological disorder with heterogeneous neuropsychiatric manifestations. Diagnosis is particularly challenging in older adults when symptoms of recent traumatic brain injury (TBI) overlap with structural or metabolic conditions.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Case presentation<\/jats:title>\n                    <jats:p>We report a 79-year-old man who developed recurrent headache, progressive confusion, abnormal behavior, poor oral intake, intermittent myoclonic jerks, and low-grade fever after TBI complicated by chronic subdural hematoma. Initial laboratory testing revealed hyponatremia, and the working diagnosis was post-traumatic brain syndrome with syndrome of inappropriate antidiuretic hormone secretion (SIADH). Although serum sodium was corrected and nocturnal agitation partially improved, persistent daytime confusion, cognitive impairment, behavioral abnormalities, and low-grade fever prompted further investigation. Cerebrospinal fluid (CSF) analysis showed mild inflammatory changes with pleocytosis and elevated protein. CSF metagenomic next-generation sequencing (mNGS) and paraneoplastic antibody testing were negative, whereas the autoimmune encephalitis panel was positive for GAD65 antibody at a titer of 1:32. Whole-body positron emission tomography-computed tomography (PET-CT) did not reveal malignancy. The diagnosis was therefore revised to GAD65 antibody-associated autoimmune encephalitis. Because high-dose corticosteroids were considered unsuitable owing to his history of gastric ulcer and previous gastrointestinal bleeding, he was treated with intravenous immunoglobulin (IVIG) at a total dose of 2 g\/kg divided over 3 consecutive days followed by oral azathioprine 50 mg daily. His fever resolved within 1 week, and his mental status and responsiveness gradually improved. At 6-month follow-up, he had achieved near-baseline mental status, was able to walk with a cane, and was almost fully independent in daily activities, without relapse or serious treatment-related adverse events.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>This case highlights the diagnostic difficulty of recognizing autoimmune encephalitis after TBI. The clinical overlap between post- traumatic syndrome and immune-mediated brain injury often delays diagnosis, emphasizing the value of targeted CSF autoantibody testing in atypical cases.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Traumatic brain injury may obscure the onset of GAD65-associated autoimmune encephalitis. Early recognition and a corticosteroid-sparing immunotherapy strategy (IVIG and azathioprine) can yield favorable outcomes in elderly patients with medical comorbidities.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fmed.2026.1929756","type":"journal-article","created":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T04:50:59Z","timestamp":1787719859000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Diagnostic challenge of GAD65-associated autoimmune encephalitis mimicking post-traumatic complications in an older adult: a case report"],"prefix":"10.3389","volume":"13","author":[{"given":"Xiuqing","family":"Huang","sequence":"first","affiliation":[{"name":"Department of Rehabilitation, Quzhou People\u2019s Hospital; The Quzhou Affiliated Hospital, Wenzhou Medical University, Quzhou","place":["Zhejiang, 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