Abstract: Background Delirium is one of the most prevalent conditions seen in older patients. Some of the newer known causes of delirium involve the body’s immune system attacking healthy brain cells, leading to inflammation of the brain known as autoimmune encephalitis. Method We herein report the case of an 80-year-old man presenting with progressive confusion, hallucinations, behavioral changes, insomnia, and weight loss. Results Despite negative findings on preliminary workup, further investigation revealed Contactin-associated protein-like-2-IgG (CASPR2-IgG) autoantibodies. With accurate diagnosis, he was able to receive the appropriate treatment with steroids that improved his condition. Conclusion Accurate diagnosis is essential for patients with autoimmune encephalitis to receive the treatment that can address the underlying problem. Too often, individuals with autoimmune encephalitis are misdiagnosed with psychiatric conditions which can lead to unnecessary psychotropic medication trials, psychiatric hospitalizations, and irreversible damage due to delays or lack of appropriate treatment.

中文翻译：

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CASPR2 IgG 相关自身免疫性脑炎：谵妄的不寻常原因

摘要：背景谵妄是老年患者最常见的疾病之一。一些较新的谵妄原因涉及身体的免疫系统攻击健康的脑细胞，导致大脑发炎，称为自身免疫性脑炎。方法 我们在此报告一例 80 岁男性，表现为进行性意识模糊、幻觉、行为改变、失眠和体重减轻。结果 尽管初步检查结果为阴性，但进一步的调查显示存在 Contactin 相关蛋白样 2-IgG (CASPR2-IgG) 自身抗体。通过准确的诊断，他能够接受适当的类固醇治疗，从而改善了他的病情。结论 准确的诊断对于自身免疫性脑炎患者接受能够解决潜在问题的治疗至关重要。