Dissecting Posterior Cerebral Artery Aneurysm Presenting with Orthostatic Headaches and Transient Homonymous Hemianopsia, Treated by Coiling and Low-Profile Flow Diverter Stent: Aneurysm Exclusion, Arterial Reconstruction, and Symptom Resolution

Posterior cerebral artery (PCA) aneurysms are rare vascular lesions. They are usually non-saccular or dissecting and often have a complex shape. Holosegmental involvement of the PCA is a common feature. Most PCA aneurysms occur in the P1 and P2 segments. The most frequent clinical manifestation of PCA aneurysms is subarachnoid hemorrhage; however, up to one-fourth of these patients present with visual alterations such as oculomotor palsy and/or hemianopsia due to compression or ischemia. A 38-year-old man with a history of addiction to opioids and repeated surgeries for a failed back syndrome consulted a neurologist after repeated episodes of headaches and visual alterations that he had attributed to stress. The patient’s symptoms occurred when standing and resolved when supine (orthostatic transient ischemic attacks [TIAs]). Cranial CT and CT angiography (CTA) showed a midsized, irregularly shaped, proximal left PCA aneurysm with no ischemic lesions in the PCA territory. CTA suggested focal stenosis of P2. MRI with intracranial vessel wall imaging was obtained 6 weeks later and showed variable thick and thin enhancement patterns of the aneurysm wall. The patient was scheduled for diagnostic cerebral angiography and endovascular treatment of the aneurysm 9 weeks after his initial CT examination. Rotational angiography of the left vertebral artery (VA) with tridimensional image reconstruction showed the midsized, irregularly shaped, left P1–P2 aneurysm. The aneurysm distorted the P1–P2 junction, and the PCA segments were structurally separated by the aneurysm with misalignment in a zigzag fashion. Based on this anatomy, we anticipated difficulty in the antegrade microcatheterization of P2. The focal stenosis of P2 depicted on CTA was not seen on angiography and raised the suspicion of dissection, remodeling, or a healing process. Based on the patient’s clinical presentation with headaches and transient self-limited episodes of homonymous hemianopsia, we attributed his symptoms to both compression and ischemia. We decided to treat the aneurysm to control the risk of hemorrhage, reconstruct the PCA’s disrupted integrity, and narrow its caliber to reestablish a stable and sufficient blood flow. Treatment of this aneurysm consisted of coiling the fundus and body and implanting a low-profile flow diverter stent that was expanded using a double-lumen balloon. This strategy proved technically challenging but allowed angiographic exclusion of the aneurysm and positive reconstruction of the PCA with complete clinical resolution of presenting symptoms. This case describes the unusual clinical scenario of orthostatic TIAs with a dissecting aneurysm in a patient who presented with transient episodes of hemianopsia due to suspected compromise in occipital lobe perfusion. Resolution of the clinical symptoms following treatment supports previous observations concerning the feasibility, safety, and effectiveness of reconstructive techniques for the management of non-saccular PCA aneurysms.