De Novo Giant Partially Thrombosed Aneurysm Complicating STA-MCA Bypass Site in 3 Years: Case Report with Review of the Literature

Background and Importance: Aneurysm formation after superficial temporal artery (STA)-middle cerebral artery (MCA) bypass is a rare condition with only a handful of cases reported in the literature with various presentations and management strategies. Various theories have been postulated to explain such rare complication and to determine whether it is a de novo pathology or related to operative techniques. Clinical Presentation: We report on a 33-year-old man who had undergone STA-MCA bypass and parent vessel occlusion for a giant cavernous internal carotid artery aneurysm 3 years ago. He presented to us with headache and on follow-up radiologic investigations a giant aneurysm was found at the bypass site. We present this rare case and discuss its troublesome management. Conclusions: This is the first case reported with unruptured giant partially thrombosed aneurysm developing on the site of STA-MCA bypass. We discuss its management and possible etiologies for its formation with review of similar cases in the literature for future prevention and/or management of similar cases.