Contralateral hyperacute intracerebral hemorrhage after carotid artery stenting with contralateral internal carotid artery occlusion

An 87-year-old man sustained an intracerebral hemorrhage in the watershed area of the contralateral frontal lobe immediately after carotid artery stenting (CAS) for severe cervical internal carotid artery (ICA) stenosis. The contralateral cervical ICA was occluded. CAS resulted in increased cross-flow through the anterior communicating artery and increased flow in the contralateral middle cerebral artery. This case demonstrates that CAS in patients with contralateral ICA occlusion and insufficient collateral flow can cause dramatically increased collateral flow through the circle of Willis and result in contralateral hyperperfusion. In patients with severely compromised cerebral perfusion, measures should be taken to prevent hyperperfusion-related complications.