Blister-like supraclinoid internal carotid artery pseudoaneurysm in a 15-year-old male: case report and review of the literature.

With an incidence of less than 1-3 per million, pediatric aneurysms are rare clinical entities. A traumatic etiology is implicated in a large proportion of these cases, leading to the formation of both 'false' and 'true' aneurysms. These occur most often in the distal circulation, but have also been described in the supraclinoid distal internal carotid artery (ICA). Blood blister aneurysms are also found in this location; however, they have not been described in the pediatric population. We report the case of a 15-year-old male who presented following cranial trauma with diffuse basal subarachnoid hemorrhage and limited additional intracranial pathology. Computed tomography angiography demonstrated a small, 2-mm blister-like aneurysm arising from the dorsal surface of the left supraclinoid ICA at a non-branching site. Despite early endovascular treatment with Guglielmi detachable coils, the lesion continued to grow over subsequent studies, necessitating open surgical clipping. At the time of surgery, gross pathology of the native ICA was observed, raising the possibility of a preexisting blood-blister aneurysm. We review the epidemiology, pathophysiology and diagnostic considerations of these lesions. The endovascular and surgical management of these complex non-branching supraclinoid ICA aneurysms is also discussed.