Posterior fossa arteriovenous malformations. Angioarchitecture in relation to their hemorrhagic episodes.

Classically, posterior fossa arteriovenous malformations (PF-AVMs) have been considered as lesions with high tendency to bleed. However, careful analysis of clinical and autopsy data from the literature demonstrate that in fact the incidence of hemorrhage is similar in infratentorial and supratentorial locations. The clinical perception that most of the diagnosed PF-AVMs had bled does not mean that they have a high risk of hemorrhage. It suggests that bleeding is the dominant way of expression, since other symptoms are uncommon. Furthermore, angioarchitectural analysis is similar in supra- an infratentorial locations. The causes of hemorrhage are probably related to venous anatomic and hemodynamic changes or associated aneurysms as in other intracranial AVMs.