2026 Proffered Presentations
S217: POSTERIOR CEREBRAL ARTERY ANEURYSMS IN MOYAMOYA DISEASE: PATTERNS OF PRESENTATION, TREATMENT, AND OUTCOMES
Kashif Qureshi, MS; Egemen Gok; Kivanc Yangi, MD; John E Wanebo, MD; Mark C Preul, MD; Barrow Neurological Institute
Introduction: Moyamoya disease (MMD) is a progressive steno-occlusive arteriopathy of the internal carotid artery and its proximal branches. Hemodynamic changes induced by MMD may lead to flow-related aneurysm formation on major arteries and fragile peripheral collaterals. This is particularly evident in the posterior circulation, which serves as a primary collateral pathway, where increased hemodynamic stress may result in formation of posterior cerebral artery (PCA) aneurysms. Although rare, these aneurysms may create significant therapeutic challenges. We reviewed existing evidence, characterizing anatomical distribution, clinical presentation, treatment patterns, and outcomes of MMD-related PCA aneurysms.
Methods: Systematic searches of PubMed/Medline, Scopus, Embase, and Cochrane Library were conducted in accordance with PRISMA guidelines. Studies were eligible if they reported MMD patients with aneurysms confined to PCA segments. Data on demographics, aneurysm characteristics, presentation, interventions, outcomes, and Suzuki stage were extracted. Methodological quality was assessed using appropriate tools.
Results: 33 cases (57.6% female; mean age 46.1±13.8 years) were identified. Predominant clinical presentation was intracranial hemorrhage (79%, n=26), accompanied by various symptoms, including sudden severe headache, vomiting, impaired consciousness, focal neurological deficits, and/or seizures. Radiologically, subarachnoid hemorrhage (SAH) was the most frequent finding (n=15, 45%), followed by intracerebral hemorrhage (ICH, n=5, 15%). Non-hemorrhagic presentations (n=6, 18%) were less common and included ischemic events, such as infarction leading to hemianopia or dysphasia. Analysis revealed a predominance of proximal lesions, with P1 being the most frequent location (n=7, 21%), followed by P1–P2 junction (n=5, 15%), and isolated P2 aneurysms (n=4, 12%). Lesions on more distal PCA were less frequent (n=9, 27%) but were documented across a range of locations, including P2–P3 junction (n=3), P3 (n=1), P4 (n=1), and in one case, multiple PCA segments. Endovascular therapy was the most common treatment approach (n = 15, 45%), including coiling and parent artery occlusion. Microsurgical clipping was performed in 5 cases (15%). Revascularization procedures (STA-MCA or OA-PCA bypass with embolization) accounted for 8 cases (24%). Conservative management or aborted procedures were rare (n=2). Of 28 patients with outcome data, 22 (79%) achieved favorable recovery (modified Rankin Scale (mRS) score 0–2 or equivalent), whereas 6 patients (21%) had poor outcomes (mRS 3–6). Rebleeding occurred in 4 patients (12%), often after revascularization procedures or rupture of de novo aneurysms. Suzuki staging was reported in 13 patients. Most were in advanced stages (III–V), with 4 cases stage III, 2 stage IV, 3 stage V, 1 stage I.
Conclusions: MMD-related PCA aneurysms, although relatively uncommon, represent a distinct entity that more often arise from proximal PCA segments, may present with hemorrhage, and require neurosurgeons to recognize their features and adjust treatment strategies accordingly. Endovascular therapy is the predominant management strategy, though revascularization is often necessary to address the underlying hemodynamic instability. While most treated patients achieve favorable outcomes, risk of subsequent hemorrhage from the index aneurysm or other sites remains of concern. The fact that most patients presented in advanced Suzuki stages suggests that these aneurysms are flow-related lesions, arising from compensatory posterior circulation hemodynamic stress after severe anterior circulation stenosis.