Circuitous embolic hemorrhagic stroke: carotid pseudoaneurysm to fetal posterior cerebral artery conduit: a case report

We present a patient with a left PCA territory, presumably embolic, stroke with early hemorrhagic transformation. The identified nidus of the embolus was a carotid artery pseudoaneurysm. Manifestations included right homonymous hemianopsia with right hemiparesis and hemisensory loss.Our case is unique, and of clinical interest, because it illustrates both the potential anterior-posterior circulation conduit provided by a fetal origin PCA as well as the apparent early hemorrhagic transformation of embolic infarcts that can lead to further confusion from a mechanistic standpoint.Unexplained hemorrhagic stroke is not infrequently encountered. There are a number of possible mechanisms for such a presentation and it is important to determine the pathogenesis as accurately as possible in an effort to prevent recurrence. Vascular dissection represents tearing of the vessel between the adventia and the intima or the intima and the media. Clinical presentation is usually related to hematoma formation which can compromise the vessel lumen and lead to cerebral infarction as the most common clinical presentation [1]. An alternative mechanism of stroke is aneurysmal outpouching of the affected vessel, resulting in what is termed a pseudoaneurysm, and this can be associated with thrombus formation with the potential for thrombo-embolism into the more distal circulation [2]. Fibromuscular dysplasia (FMD) can contribute to predisposition to vascular dissection [3,4].Internal carotid artery (ICA) thrombo-embolic disease can be impacted by the presence of a fetal origin ipsilateral posterior cerebral artery [5]. There have been infrequently reported cases of posterior circulation stroke attributed to such a potential conduit [6-9]. We report a patient with a left parieto-occipital hemorrhage in the setting of a left ICA pseudoaneurysm and ipsilateral fetal origin posterior cerebral artery (PCA).A 51 year old right-handed male presented with acute right sided weakness and right homony