Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare genetic disorder caused by mutations in the NOTCH3 gene, resulting in subcortical infarctions and leukoencephalopathy. It predominantly affects the brain's small blood arteries, resulting in repeated ischemic episodes including transient ischemic attacks and strokes leading to cognitive impairment and mental symptoms. We provide a case study of a 25-year-old patient suspected of having meningoencephalitis. CADASIL was diagnosed based on clinical examination, imaging investigations, and genetic analysis. Optimal patient care for this complicated illness requires early detection and proper management.