Cerebral hyperperfusion phenomenon in secondary medium vessel occlusion after M1 distal occlusion

Abstract We report a case of spontaneous secondary medium vessel occlusion (MeVO) concomitant with cerebral hyperperfusion phenomenon (CHP) detected by preoperative computed tomography perfusion (CTP). MeVO is the occlusion of the M2, M3, A2, A3, P2 or P3 segment. MeVOs are increasingly recognized as a target for endovascular treatment in acute ischemic stroke patients. However, there is little data on cerebral perfusion in MeVO compared with large vessel occlusion (LVO). In MeVOs, secondary MeVOs (sMeVOs) occur due to thrombus migration or fragmentation spontaneously or iatrogenically after large vessel occlusion (LVO). It has been reported that infarcts can be seen outside the territory of the occluded vessel in some sMeVOs patients, which is known as MeVO with discrepant infarcts. However, there are no reports regarding CHP outside the territory of the occluded vessel in patients with sMeVO. CHP can occur outside the territory of spontaneously recanalized artery in patients with sMeVO, and it can support the diagnosis of sMeVO.