New diplopia should prompt aneurysm screening regardless of age or diabetes status. Non-contrast CT detects approximately 98% of subarachnoid hemorrhages within the first 24 hours but sensitivity declines rapidly thereafter. Smaller AVMs bleed more frequently than larger ones. Pregnancy increases AVM hemorrhage risk. MRI is mandatory for cerebral cavernous malformation diagnosis.

New diplopia should prompt aneurysm screening regardless of age or diabetes status.Screening indications: two or more affected first-degree relatives, or polycystic kidney disease.One affected first-degree relative: individualized risk-benefit discussion for screening.Non-contrast CT sensitivity for SAH: approximately 98% within 24 hours; declines rapidly thereafter.Fusiform aneurysm: diffuse arterial dilation at least 1.5 times normal size without a distinct neck; risk factors include male sex, older age, smoking, hypertension.Fusiform aneurysm complications: rupture, thromboembolism, mass effect (especially in posterior circulation).Dissecting aneurysm: false aneurysm from arterial wall tear; risk factors include trauma, atherosclerosis, fibromuscular dysplasia, infection, arteritis.AVMs most likely to bleed between ages 20 and 40.Smaller AVMs bleed more frequently; larger AVMs cause symptoms through mass effect.Pregnancy increases AVM hemorrhage risk.MRI is the diagnostic standard for cerebral cavernous malformations.