Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a monogenic cerebral small-vessel disease, which is characterized by migraine, recurrent ischemic strokes, psychiatric disorder, progressive cognitive decline, and occasionally intracerebral hemorrhage (ICH). ICH events have been reported in a high proportion of East Asian CADASIL patients with R544C mutation in exon 11 of NOTCH3; however, whether any other specific NOTCH3 mutation determines the ICH phenotype has yet to be explored.

We report the case of a 60-year-old male CADASIL patient with a novel R558C mutation in exon 11 of the NOTCH3 gene, who presented with ICH in the basal ganglia and cerebellum. Brain imaging revealed multiple confluent white matter hyperintensities and abundant cerebral microbleeds (CMBs) in the bilateral basal ganglia, thalamus, and cerebellum. The patient had been having recurrent ischemic strokes prior to this ICH event, and had taken antiplatelet and antihypertensive agents for six months. We analyzed the possible reasons for ICH onset in the patient to recommend certain guidelines for the clinic.

Novel R558C mutation-related CADASIL vasculopathy and numerous CMBs, uncontrolled hypertension, and antiplatelet therapy could collectively contribute to ICH onset in the patient with CADASIL. These findings suggest that a diagnosis of CADASIL should also be considered when patients present with ICH, whenever MRI imaging reveals typical white matter abnormalities. Furthermore, this case report emphasizes the importance of CMB assessment, appropriate blood pressure control, and cautious assessment of the risk-benefits of antiplatelet medication in patients with CADASIL.