BACKGROUND: Thrombosed large intracranial aneurysms (TLIAs) are not continuously contemplated as stable lesions. Spontaneous recanalization of completely occluded large intracranial aneurysms has been described previously.; CASE DESCRIPTION: We report a middle-aged patient presenting with agitation, acute headache, visual field defects, and left hemiparesis. A large thrombosed posterior communicating (PCom) artery aneurysm was identified with an infarct at the same arterial territory on neuroimaging studies. Digital subtraction angiography (DSA) performed 1 week later demonstrated complete recanalization of the TLIA. It was treated endovascularly with coils. The patient returned several days later with augmenting headaches due to quadrigeminal system subarachnoid hemorrhage. Repeat DSA showed filling of the coiled aneurysm from the internal carotid artery injection. The PCom artery was catheterized and deconstructed. The patient was discharged to home with no additional neurologic deficits.; CONCLUSIONS: TLIAs are insidious vascular lesions. They can cause nerve or vessel damage by a mass effect or through ischemic stroke by emitting emboli into distal vasculature. We advise close periodic radiologic follow-up for TLIAs.
