Spontaneous thrombosis and resolution of an unruptured giant posterior cerebral artery aneurysm

A 51-year-old woman presented to our institution in November 2021 with a 4-month history of intermittent headaches.She had a 10-year history of hypertension, well controlled with regular medication.Physical examination revealed no significant abnormalities.Cranial computed tomography (CT) and magnetic resonance imaging demonstrated a lesion in the interpeduncular cistern (Fig 1a andb).Subsequent CT angiography revealed a giant aneurysm in the P1 segment of the left posterior cerebral artery, along with occlusion of the left internal carotid artery (Fig 1c).