Anterior Cerebral Artery (A1 Segment) Aneurysm: Ruptured Blood Blister-Like Aneurysm of the Proximal Anterior Cerebral Artery Causing Massive Subarachnoid Hemorrhage: Ventriculostomy, Dual Antiplatelet Medication plus Eptifibatide, and Flow Diversion Implant “Compressed” with a Compliant Double Lumen Balloon

Abstract

Originally thought to occur exclusively on the internal carotid artery (ICA), blister aneurysms can be found anywhere in the circle of Willis. These aneurysms tend to be small, with sessile or blister morphologies. They are more prone to rupture, and they often originate near perforating arteries. Blister aneurysms of the proximal anterior cerebral artery aneurysms (A1) are rare with unique characteristics.

This 71-year-old female presented with sudden onset severe headaches, repeated vomiting, and syncope followed by drowsiness that rapidly led to coma. She was intubated and ventilated in the emergency room. The neurological evaluation found her in a comatose state, with pupils equal and reactive, neck stiffness, and bilateral localizing motor response (Glasgow Coma Scale (GCS) 7). Admission cranial CT showed a non-localizing massive diffuse basal subarachnoid hemorrhage (SAH) (Hunt and Hess IV, Fisher grade 3). CT angiography failed to show any brain aneurysm or vascular malformation. She was admitted to the ICU, and external ventricular drainage was placed at bedside, revealing moderately elevated intracranial pressure. Immediately afterward, she was transferred to the neuroendovascular unit for diagnostic angiography. Selective six-vessel angiography ruled out brain aneurysm, but rotational angiogram of the right ICA followed by 3D reconstruction revealed an unrecognized small blister aneurysm at the proximal right anterior cerebral artery (ACA) measuring 1.7–2.4 mm in diameter and 12 mm in length. Left ICA angiograms confirmed hypoplasia of the left A1 segment. Retrospective revision of the CT angiography and diagnostic bidimensional angiogram failed to identify the right A1 microaneurysm, which arose from the artery’s posterior wall. The patient was loaded with aspirin and ticagrelor. Five minutes after administering antiplatelet drugs per nasogastric tube, we were notified that a patient with acute stroke requiring thrombectomy had arrived. We evaluated the platelet inhibition in a sample taken 12 min after antiplatelet drugs were administered and confirmed no ticagrelor effect (VerifyNow: PRU 330). We usually evaluate antiplatelet medication efficacy only 60 min after administering the drugs and proceed to stent only after confirming adequate platelet inhibition. However, due to the new waiting emergency, we administered a reduced intravenous eptifibatide dose and proceeded with the endovascular intervention. The smallest and shortest flow diverter stent we had on hand (2.25/15 mm) was implanted across the full extent of the right A1 segment and the aneurysm ostium. The stent did not extend into A2 or the anterior communicating artery (AcomA), but, as we anticipated, its proximal end protruded into the ICA bifurcation. We then proceeded to compress the protruding stent segment with the aid of a double-lumen balloon. The patient evolved satisfactorily, and follow-up angiography obtained only 6 weeks later confirmed aneurysm exclusion.

This case illustrates an uncommon, poorly characterized, and probably underdiagnosed type of aneurysm and supports its endovascular treatment.