Trauma may affect vasa vasorum to promote thrombosis and enlargement of intracranial aneurysms: A case report.

Background: Thrombosed intracranial aneurysm (IA) is likely to occur in large or giant IAs. Almost all thrombosed IAs are found already in a thrombosed state, and few reports have depicted the process of thrombosis in unthrombosed aneurysm. Moreover, no reports appear to have described IA in which thrombosis accelerated after trauma.

Case Description: We report herein a case in which an unthrombosed large cerebral aneurysm rapidly thrombosed and grew within 3 months after trauma. The highlight in this unusual case was that during surgery, the aneurysm and anterior skull base were adherent and some blood vessels bridged between the aneurysm and dura mater. Histologically, intramural hemorrhage was seen in the tunica media of the aneurysm.

Conclusion: Trauma may act as a "second hit" causing adhesion between IAs and surrounding tissues, accelerating inflammation of the vasa vasorum and aneurysmal walls, and thrombosis in IAs.