A 39-year-old woman with no significant medical history was admitted in the emergency room with loss of consciousness. Computed tomography revealed right-sided putamen hemorrhage (Fig. 1, Panel A). The patient had no risk factors for intracranial hemorrhage, including hypertension, older age, alcohol intake, and dyslipidemia. Cerebral angiography showed steno-occlusive changes at the terminal internal carotid artery (ICA) portion bilaterally, with the development of collateral circulation and no aneurysm (Fig.