Punctate Hyperdensity on Noncontrast-enhanced Computed Tomography before Rupture of a Mycotic Cerebral Aneurysm in a Patient with Infective Endocarditis: A Case Report

Mycotic cerebral aneurysms secondary to infective endocarditis carry a high risk of fatal rupture. Early identification and appropriate intervention are critical. We present a case in which a punctate hyperdense lesion on noncontrast-enhanced computed tomography appeared several days before aneurysm formation and rupture. A 43-year-old man with infective endocarditis presented with a ruptured mycotic aneurysm in the peripheral left middle cerebral artery. The patient underwent emergency craniotomy. During the postoperative follow-up, 2 new punctate hyperdense lesions were detected on noncontrast-enhanced computed tomography. A total of 3 days later, one of these lesions progressed to aneurysm formation and hemorrhage, requiring repeat surgery. The outcome was favorable, with a modified Rankin scale score of 2. This case highlights that punctate hyperdense lesions on noncontrast-enhanced computed tomography may serve as an early radiological marker of impending mycotic aneurysm formation and suggests the importance of close imaging surveillance to prevent catastrophic rupture.