AVMs have been reported to rupture at a formidable annual rate of 2% to 3% at natural progression, often resulting in longterm neurological deficits and poor functional outcomes.The reported risk of hemorrhagic presentation in patients with AVMs is 41% to 65%. While many studies suggest a correlation between higher hemorrhage risk and the concurrent presence of AVM and aneurysms, few authors have focused specifically on flow-related aneurysms alone. In many instances, the source of rupture is also unclear. Meta-analysis from 2016 suggested that 49.2% of hemorrhages were secondary to aneurysm rupture, 45% from AVM rupture, and 5.7% were undetermined.In a study of 302 patients, of which 52.6% had a hemorrhagic presentation, demonstrated a significant increase in rate of hemorrhage in those with flow-related aneurysms. Thus, it is necessary to figure out risk factors related to ruptured flow-related aneurysms in pAVM.

Inclusion Criteria:

1. pAVM with flow-related aneurysms were identified by DSA, and subarachnoid hemorrhage was confirmed by CT
2. No history of stroke, Marfan syndrome, polycystic kidney disease

Exclusion Criteria:

1. pAVM without flow-related aneurysms
2. Absence of clinical data

Patients with posterior circulation malformations combined with ruptured or unruptured flow-related aneurysms will be included. Morphological data such as aneurysm size, location, parent artery, feeding arteries, draining vein count, malformation size, malformation location, and the ratio of malformation/aneurysm volume will be analyzed. These factors will be examined alongside medical histories of hypertension, diabetes, and coronary artery disease to investigate the risk factors for ruptured flow-related aneurysms.