Bilateral Superior Cerebellar Artery Embolic Occlusion with a Fetal-Type Posterior Cerebral Artery Providing Collateral Circulation

Abstract

Bilateral infarction of the superior cerebellar arteries with sparing of the rest of the posterior circulation, particularly the posterior cerebral arteries, is an uncommon finding in neurological practice. Most commonly, the deficits of the superior cerebellar arteries and posterior cerebral arteries occur together due to the close proximity of their origins at the top of the basilar artery. A patient was transferred to the neurological intensive care unit with a history of recent-onset falls from standing, profound hypertension, dizziness, and headaches. The neurological exam revealed cerebellar signs, including dysmetria of the right upper extremity and a decreased level of consciousness. Computed tomography of the head and neck revealed decreased attenuation throughout most of the cerebellar hemispheres suggestive of ischemic injury with sparing of the rest of the brain. Further investigation with a computed tomography angiogram revealed a fetal-type posterior cerebral artery on the right side that was providing collateral circulation to the posterior brain. Due to this embryological anomaly, the patient was spared significant morbidity and mortality that would have likely occurred had the circulation been more typical of an adult male.

The Fetal Type of Posterior Cerebral Artery

“…Neurosurgeons have to avoid occluding an FPCA while treating ICA-PComA aneurysms, to avoid ischemic events in the PCA territory [ 16 ]. An FPCA could provide collateral circulation to the posterior brain after an embolus had occluded the top of the BA [ 19 ]. Ischemic events, however, also depend on the collateral anastomoses of the leptomeningeal vessels, allowing, or not, a vertebrobasilar supply of the ICA territory and vice versa [ 10 ].…”