An angiographic lesion mimicking pseudo-aneurysm in cerebral arteriovenous malformation

In cerebral arteriovenous malformations (AVMs), a pseudo-aneurysm represents rupture site, and its presence is known as a factor for rebleeding. We report a case of cerebral AVM presenting with intracerebral haemorrhage in which cerebral angiography showed a lesion mimicking pseudo-aneurysm. Although the patient needed urgent surgical decompression, it was delayed because early haematoma evacuation would induce rebleeding from the rupture site. The authors attempted to occlude the pseudoaneurysm interventionally before surgery. After surgical excision, the lesion that was believed to be a pseudo-aneurysm was revealed as a partially thrombosed venous sac having a thick fibrous wall. In this report, the authors discuss the pitfalls in the interpretation of pseudo-aneurysms in angiographic AVM architecture.