Objective: Endovascular treatment of wide-necked and fusiform aneurysms has been advanced by the introduction of the flexible intracranial Neuroform stent (Boston Scientific/Target, Fremont, CA). It is recognized that these deployed intracranial stents are thrombogenic until endothelialization of the stent presumably takes place. We report here the first postmortem histological analysis of a patient with an internal carotid artery aneurysm treated with the Neuroform stent.
Methods: A 51-year-old man had a right-sided supraclinoid internal carotid artery aneurysm. After discussions, he underwent elective stenting (Neuroform stent; 4.5 x 20 mm) across the neck of the aneurysm without complications. Repeat angiography at the 3-month follow-up examination revealed a decrease in size of the aneurysm. Attempted coiling at that time was unsuccessful. The patient died 1 month later of a left-sided intracranial hemorrhage (122 d after stent deployment), and, according to his wishes, his brain was donated for scientific study. On receipt, the right cavernous internal carotid artery was removed and sent for histological evaluation (Boston Scientific Laboratories, Fremont, CA).
Results: The parent artery demonstrated mild intimal thickening proximal to the stent. The stent itself was noted to be abutting the internal elastic lamina with moderate intimal hyperplasia, but this was not noted to cause significant stenosis. The aneurysm was filled with fibrocellular tissue in the periphery, which extended along the neck. However, the midportion of the neck was void of any fibrocellular tissue, with thrombus-like material noted inside the aneurysm.
Conclusion: Cadaveric histological evaluation of the implanted Neuroform stent 4 months after stenting showed complete endothelialization of the stent and well as significant de novo fibroelastic tissue formation along the neck of the aneurysm. Longer follow-up studies are needed to evaluate the dynamics and delayed effects of endothelialization of the Neuroform stent.