Thrombosis and recanalization of a blister-like aneurysm: letter to the editor

Abstract

Dear Editor, We would like to report the first case of a complete thrombosis and recanalization of a blister-like aneurysm. The partial or complete spontaneous aneurysmal thrombosis is reported by multiple authors and ranges between 13 and 20 % of giant aneurysms [4]. This phenomenon has been exceptionally reported in nongiant aneurysms and has never been documented with a blister-like aneurysm. A 54-year-old man was diagnosed with a subarachnoid hemorrhage (SAH) of Fisher grade III (GCS: 14). Arteriography showed an aneurysm of the left MCA bifurcation. Four days after its complete clipping, the patient deteriorated due to a new SAH. An aneurysm on the left A1 segment was disclosed. The patient died 72 h after this second SAH. The autopsy demonstrated a ruptured blister-like aneurysm of A1, which was probably also responsible for the first SAH (Fig. 1). Blister-like aneurysms account for only 1 % of all intracranial aneurysms [1]. They are characterized by their small size and a broad base. Their very thin wall is associated with growth in short intervals and rapid evolution towards the rupture [2]. The diagnosis of blister-like aneurysms, uneasy to distinguish from normal variants, remains complicated [5]. In our case, the blister-like ICA was not visualized at the first CT angiography. The occurrence of false-negative cerebral angiography in acute non-traumatic SAH is 5 %. The main cause of SAH with negative angiogram is a nonvisualized aneurysm. The incidence of ruptured ICA disclosed at a delayed angiography is about 16 %. Five possible reasons have been reported: inadequate angiography, obliteration of aneurysm by the hemorrhage, aneurysm thrombosis, an aneurysm too small to be visualized, and lack of aneurysm filling due to vasospasm [6]. The hypothesis the most probable is thrombosis of the aneurysm shortly after its rupture preventing its visualization at the first angiography. The spontaneous aneurysmal thrombosis is well known in giant aneurysms [4]. Intrinsic factors influencing its occurrence are the aneurysm morphology (narrow neck), the presence of endothelial lesion and hemodynamic patterns in the parent artery. An extrinsic factor can be the compressive effect exerted by the hematoma around the aneurysm. In many cases, aneurysmal thrombosis has an unfavorable natural evolution with the occurrence of thromboembolic events, recanalization, and bleeding [3]. In non-giant aneurysms, such in blister-like ones, this process is poorly documented and not understood. Such an occurrence seems to be exceptional. We report, for the first time, a complete thrombosis and recanalization of a blister-like aneurysm, disclosed after a D. Tassigny :G. Vaz : C. Raftopoulos (*) Department of Neurosurgery, University Hospital St-Luc, Universite Catholique de Louvain (UCL), Avenue Hippocrate, 10, 1200 Brussels, Belgium e-mail: christian.raftopoulos@uclouvain.be