Aneurysm of the posterior inferior cerebellar artery caused by a traumatic perforating artery tear-out mechanism in a child.

Traumatic posterior circulation aneurysms in the absence of fractures and penetrating wounds are extremely uncommon, especially in children. To our knowledge this is the first traumatic posterior inferior cerebellar artery(PICA) aneurysm reported that cannot be related to a skull fracture or a trauma caused by the edge of a rigid meningeal structure. In the present case, the initial subarachnoid hemorrhage (SAH) was caused by a perforating artery, originating from the PICA, which was torn out as the result of a deceleration trauma. Such a mechanism explains both the initial SAH and the development of the false aneurysm responsible for the second SAH.