Delayed post-traumatic saccular aneurysm of PICA in an adolescent.

Delayed traumatic intracranial aneurysms of the posterior circulation caused by nonpenetrating head injury are rare, especially in pediatric patients. The true incidence and natural history of these aneurysms are poorly understood. We report a case of a 15-year-old boy who initially presented with subarachnoid hemorrhage of the posterior fossa without any evidence of associated aneurysm. On a routine computed tomography of the head, however, he was found to have a saccular aneurysm of the proximal posterior inferior cerebellar artery. The patient was treated successfully by microsurgical clipping and PICA/PICA bypass.