Delayed aneurysm rupture due to residual blood flow at the inflow zone of the intracranial paraclinoid internal carotid aneurysm treated with the Pipeline embolization device: Histopathological investigation

Abstract

<jats:p> Cerebral aneurysm rupture is a serious complication that can occur after flow diverter (FD) placement, but the underlying mechanisms remain unclear. We encountered a case in which direct stress on the aneurysm wall caused by residual blood flow at the inflow zone near the neck during the process of thrombosis after FD placement appeared associated with aneurysm rupture. The patient was a 67-year-old woman with progressive optic nerve compression symptoms caused by a large intracranial paraclinoid internal carotid aneurysm. The patient had undergone treatment with a Pipeline embolization device (PED) with satisfactory adherence between the PED and vessel wall. Surgery was completed without complications, and optic nerve compression symptoms improved immediately after treatment. Postoperative clinical course was satisfactory, but the patient suddenly died 34 days postoperatively. Autopsy confirmed the presence of subarachnoid hemorrhage caused by rupture of the internal carotid aneurysm that had been treated with PED. Although the majority of the aneurysm lumen including the outflow zone was thrombosed, a non-thrombosed area was observed at the inflow zone. Perforation was evident in the aneurysm wall at the inflow zone near the neck, and this particular area of aneurysm wall was not covered in thrombus. Macrophage infiltration was not seen on immunohistochemical studies of the aneurysm wall near the perforation. A hemodynamically unstable period during the process of complete thrombosis of the aneurysm lumen after FD placement may be suggested, and blood pressure management and appropriate management with antiplatelet therapy may be important. </jats:p>

Quantitative Computed Tomographic Volumetry after Treatment of a Giant Intracranial Aneurysm with a Pipeline Embolization Device

“…The incidence of rupture is higher in giant than in small or large aneurysms, and most ruptures occur within 1 month of PED treat-ment 8. Causes of delayed aneurysm rupture include wall shear stress at the aneurysm dome, unfavorable hemodynamic status, and autolysis of the aneurysm wall by thrombosis-induced proteases 91011. Although yet to be established, we believe that progressive recanalization with redirected inflow may be a risk factor for rupture and a signal for further intervention.…”

Hemodynamic Analysis of Postoperative Rupture of Unruptured Intracranial Aneurysms after Placement of Flow-Diverting Stents: A Matched Case-Control Study

“…The mechanisms of postoperative rupture of IAs following flowdiversion treatment have been explored on the basis of clinical, morphologic, clinicopathologic, and hemodynamic characteristics. 5,8,22,23 However, most studies were case reports or included many confounding factors, such as differing locations and sizes of aneurysms. In the present study, we adjusted for and matched these confounding factors with an aim of investigating the hemodynamic risk factors for postoperative rupture.…”

Bailout Strategies and Complications Associated with the Use of Flow-Diverting Stents for Treating Intracranial Aneurysms

“…To date, there is no consensus on the management of such delayed rupture, and treatment options may be limited due to restricted intrasaccular access through the wall of the FDS. In a report on a fatal SAH 34 days after successful FDS treatment of a large paraclinoid ICA aneurysm, Ikeda et al [121] suggest that a hemodynamically unstable period may exist during the process of complete aneurysm thrombosis after flow diversion. During this time, blood pressure management and appropriate antiplatelet therapy may be important.…”