What Caused an Acute Pontine Stroke in a Young Male Patient With a Patent Foramen Ovale?

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an important cause of stroke and cognitive decline in young adults due to a mutation in the NOTCH3 gene on chromosome 19 and is often underdiagnosed. We present to you a case of a middle-aged man who presents with acute stroke symptoms. He had a family history of recurrent transient ischemic attacks (TIAs) in his father and sister. Computed tomography (CT) of the head was negative, and magnetic resonance imaging (MRI) of the brain revealed an acute infarct involving the right pons and chronic small vessel ischemic changes. An echocardiogram showed a patent foramen ovale (PFO). It was then revealed that his sister had a questionable diagnosis of CADASIL disease. The patient's genetic testing revealed a positive monoallelic mutation of the NOTCH3 gene, confirming the diagnosis of CADASIL disease. CADASIL is a genetic disease that leads to acute stroke and dementia at a very young age and can often go undiagnosed in clinical practice. Recent advancements in molecular genetics and early recognition of this condition with genetic testing might help in risk stratification and preventing adverse cerebrovascular outcomes.