The authors present an extremely rare case of a 54-year-old female patient with subarachnoid hemorrhage due to a rupture of a dissecting internal carotid artery (ICA) aneurysm, who developed de novo vertebral artery dissection in the spasm period after endovascular trapping of the ICA. Interestingly, postoperative cardiopulmonary monitoring showed high global end-diastolic volume index and mean arterial pressure, which could contribute to this de novo dissection via hemodynamic stress in the cerebral circulation. Spontaneous intracranial artery dissection of more than two arteries is rare, and we believe this is the first case of de novo dissection occurring on a circulating vessel different from that of the initial dissection. The clinical implications are discussed in relation to postoperative hemodynamic stress with a review of the literature.