A Young Adult with White Matter Changes and Recurrent Stroke Symptoms

White matter changes on MRI can be a diagnostic puzzle as a large group of inflammatory, autoimmune, infectious, and neoplastic conditions can present in this way. An otherwise healthy 36-year-old male presented with his second episode of unilateral weakness, the first episode occurring five years previously. He did not have sensory or cerebellar symptoms with the current or previous episode. He reported that his grandfather, father, two of his aunts, and an uncle had multiple sclerosis (MS), dying in their 40s-50s from their disease. The MRI during his first hospitalization revealed acute ischemia as well as diffuse white matter hyperintensities. The current MRI revealed new ischemic changes as well as progression of the white matter hyperintensities with notable temporal lobe involvement. While small vessel disease and multiple sclerosis can present similarly, the history of stroke, lesion distribution, and family history suggested an alternative diagnosis. Due to high clinical suspicion, genetic testing was performed for CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) and confirmed the diagnosis. This case report describes the approach to the adult with white matter changes and describes the typical presentation and findings of CADASIL, the most common heritable cause of stroke and vascular dementia in adults.