Basilar Artery Trunk Aneurysm: Symptomatic Basilar Artery Trunk Dissecting Aneurysm with Critical Vasospasm Treated by Blind Deconstructive Coiling, Angioplasty, Embolectomy, and Flow Diversion

Abstract

Dissecting intracranial aneurysms in the posterior circulation are a rare cause of subarachnoid hemorrhage (SAH) or brain ischemia. They are associated with a high risk of mortality and early rebleeding, making early treatment imperative. Aneurysms located on the basilar trunk are particularly infrequent. A 54-year-old man with a history of hypertension and thymoma surgery that had resulted in left subclavian artery and left vertebral artery (VA) occlusion experienced an episode of sudden onset severe headaches followed by loss of consciousness. The patient was brought to the emergency room with a Glasgow Coma Score (GCS) of 6. He was urgently intubated. A CT of the head confirmed subarachnoid and intraventricular hemorrhage, causing hydrocephalus. CTA showed a medium-sized proximal basilar artery aneurysm associated with critical vasospasm of both distal vertebral arteries and the basilar trunk. Urgent ventriculostomy was performed in the operating room, and the patient was immediately transferred to the neuroendovascular suite. An angiogram of the right vertebral artery confirmed the presence of a medium-sized dissecting aneurysm of the proximal third of the basilar trunk associated with severe bilateral vasospasm of the distal VAs and basilar trunk. There was retrograde supply of the distal left VA from the right VA. The left subclavian artery and proximal left VA were occluded. Angiography of the left common carotid artery (CCA) showed the left internal carotid artery (ICA) supplying the upper basilar trunk via a midsized posterior communicating artery (PcomA), with the right ICA feeding a smaller PcomA. Under general anesthesia, we proceeded to place a guiding catheter in the right vertebral artery and confirmed the lack of intracranial angiographic opacification. The ventricular fluid was drained, and vasoactive agents were selectively infused with no angiographic improvement. Then, under road map and blind intracranial navigation, the aneurysm and lower basilar trunk were coiled, and angioplasty of the right VA was performed. After regaining intracranial angiographic flow, we proceeded to perform a right-hand posterior inferior cerebellar artery (PICA)-VA embolectomy and to implant a vertebro-vertebral flow diverter. Underexpansion of the flow diverter required a balloon-expandable stent to be implanted with excellent results. The final angiogram confirmed that the aneurysm had been excluded, there was symmetric bilateral PICA territory supply, and the basilar trunk was being supplied via the left ICA-PcomA pathway. The management of a symptomatic dissecting basilar aneurysm, performing deconstructive therapy on it under adverse angiographic conditions, and ultimately implanting a flow diverter to preserve the vertebro-vertebral junction and secure aneurysm occlusion are the main topics of this chapter.