Basilar Artery Trunk Aneurysm: Incidental Aneurysm of the Basilar Artery Trunk, Incorporating Cerebellar Arteries; Documented Growth, Implantation of Two Telescoping p64 Flow Diverter Stents Under Combined Dual Antiaggregation and Anticoagulation; Complete Aneurysm Occlusion; and Collateral Supply of the Cerebellar Arteries

Abstract

A 49-year-old female patient presented to hospital with recurrent severe headaches. Diagnostic work-up including DSA and MRI/MRA demonstrated a large aneurysm originating from the proximal trunk of the basilar artery just beyond the confluence of the vertebral arteries (maximum diameter 13 mm). Two efferent arteries, anatomically equivalent to anterior inferior cerebellar arteries (AICAs), originated from the aneurysm sac. The aneurysm was considered untreatable, and conservative management, including surveillance MRI/MRA examinations, was recommended. However, the patient only underwent a 1-year follow-up examination. Four years after the first MRI examination, another MRI/MRA examination was performed prior to paranasal sinus surgery. This demonstrated a significant size increase of the basilar trunk aneurysm (maximum diameter: 19 mm). At this stage, the patient underwent treatment with two p64 flow diverters implanted into her basilar artery covering the aneurysm neck. In addition to the standard dual antiplatelet treatment, with ASA and ticagrelor, oral anticoagulation with dabigatran was commenced in order to prevent rapid thrombus formation inside the aneurysm sac. A first follow-up DSA 2 months after treatment demonstrated partial thrombosis of the aneurysm sac with preserved patency of the efferent vessels. At this time the patient complained of diplopia, and a right abducens nerve palsy was found, which resolved during the following 6 weeks. A second follow-up DSA, performed 9 months after the procedure, demonstrated the complete exclusion of the aneurysm sac from the circulation. The efferent cerebellar arteries were occluded at their origins and collateralized via the pontine branches. MRI confirmed shrinkage of the aneurysm sac and no evidence of cerebellopontine ischemia. The patient was and remained, apart from the transient diplopia, neurologically asymptomatic. The treatment of basilar trunk aneurysms, with efferent arteries arising from the aneurysm sac, is the main topic of this chapter.