Fatal Delayed Stent-edge Rupture Confirmed by Autopsy after Stent-assisted Coil Embolization for a Blood Blister-like Aneurysm.

Blood blister-like aneurysms of the internal carotid artery are uncommon lesions that often present with subarachnoid hemorrhage and are considered part of the spectrum of intracranial arterial dissections. Although endovascular treatment options have expanded in recent years, serious complications remain a clinical concern. We report the case of a 42-year-old woman with a ruptured blood blister-like aneurysm arising from the anterior wall of the internal carotid artery who was treated with stent-assisted coil embolization. The initial postoperative course was uneventful and follow-up imaging showed no evidence of aneurysmal recurrence. However, the patient died 3 months after treatment. Autopsy revealed rupture of the parent artery at the opposite wall of the distal stent edge, with extravascular exposure of the stent. Histopathological examination demonstrated disruption of the internal elastic lamina extending both distal and proximal to the aneurysm, indicating that arterial dissection was more extensive than detectable by angiography. This case suggests that multiple factors, including stent-induced vessel straightening, incomplete wall apposition, antithrombotic therapy, and pre-existing wall fragility, may contribute to delayed stent-edge rupture following stent-assisted coil embolization for blood blister-like aneurysms. Careful selection of stent type and length to adequately cover the dissected segment may be important to reduce the risk of delayed parent artery failure.