Paraophthalmic Internal Carotid Artery Aneurysm: Incidental Paraophthalmic Aneurysm of the Right Internal Carotid Artery, Treated with Intra- and Extrasaccular Flow Diversion; Hyperresponse on Antiplatelet Medication with Sulcal Subarachnoid Hemorrhage; Reduction of the Antiplatelet Medication Dosage; Thromboembolic Occlusion of the p64 Flow Diverter Only 24 h After the Last Intake of Ticagrelor; Thrombectomy with Recanalization of the p64 and Good Clinical Outcome

Abstract

A 66-year-old female patient presented to the referring hospital with a right hemispheric transient ischemic attack (TIA). During the workup of the TIA, an incidental paraophthalmic aneurysm of the right internal carotid artery was found. This aneurysm was treated with intra- and extrasaccular flow diversion. Dual platelet inhibition was achieved using 1× 100 mg ASA and 2× 90 mg ticagrelor PO daily. Three days after the treatment, the patient complained of severe headaches. MRI showed a minor subarachnoid hemorrhage (SAH) in the cortical sulci over both hemispheres. Multiplate and VerifyNow analyses showed excessive inhibition of platelet function. In order to reverse this hyperresponse, the evening dosage of 90 mg ticagrelor was withdrawn on the day following the diagnosis of the SAH. The next morning, the patient had a left hemiparesis, a severe dysarthria and fixed conjugate gaze deviation. MRI revealed a thrombotic occlusion of the right ICA at the site of the implanted flow diverter. The subsequent DSA showed reduced collateral flow from the left ICA to the right via the anterior communicating artery (AcomA) with a significant delay in right venous phase opacification. Multiplate and VerifyNow analyses confirmed inadequate P2Y12 receptor blockade only 24 h after the last dose of 90 mg ticagrelor. Due to the short duration of action of ticagrelor, the single omitted dose was sufficient to cause the recently implanted flow diverter to thrombose. The occluded right ICA was recanalized using aspiration thrombectomy and the deployment of a second p64 flow diverter. The patient recovered completely and follow-up DSA examinations confirmed the continued exclusion of the paraophthalmic aneurysm from the circulation. The pharmacokinetic properties of ticagrelor including its short duration of action are the main topic of this chapter.