Artery of Percheron stroke from carotid lesion

Abstract

To the Editor of Neurological Sciences, Here, we present a peculiar clinical case in which we highlight the importance of anatomical cerebral artery variations, which can give unusual presentations, and their essential knowledge with the development of stroke treatments. A 70-year-old man was found comatose and admitted to the emergency department. The time of symptom onset was unknown. His medical history was remarkable for hypertension, smoking, and type 2 diabetes. Medications included acetylsalicylic acid 100 mg as primary prevention for cardiovascular diseases. Brain computed tomography (CT) scan was normal; CT angiography showed an ulcerated atherosclerotic plaque in the right internal carotid artery (ICA, Fig. 1A), full fetal origin of the right-sided posterior cerebral artery (PCA, Fig. 1B), and no plaques at the aortic arch. Schematic representation of the intracranial circulation is depicted in Fig. 1C. Brain magnetic resonance imaging (MRI) demonstrated a bilateral thalamic ischemic stroke (right > left) with restricted signal in diffusion-weighted imaging (DWI), reduced apparent diffusion coefficient values (ADC), and hyperintensity in fluid-attenuated inversion recovery sequences (FLAIR) (Fig. 1D–F). The patient was not eligible for intravenous thrombolysis because of the lack of a DWI-FLAIR mismatch. He was therefore admitted to our Stroke Unit to continue clinical and instrumental monitoring. Antithrombotic therapy was switched from acetylsalicylic acid 100 mg to clopidogrel 75 mg, and high-dose statin was started for secondary prevention. During the following weeks, he gradually regained consciousness with residual somnolence. Echocardiography and prolonged cardiac rhythm monitoring, ongoing for at least 1 month, were unremarkable. The patient was diagnosed with artery of Percheron (AOP) territory stroke likely due to artery-to-artery embolism originating from the right ICA. Anatomical cerebral artery variations are relatively common and reflect embryological development. Knowledge of these variations has become of paramount importance with the development of stroke treatments and especially after the advent and spread of endovascular procedures [1]. PCA is defined as “fetal” when arising directly from the ipsilateral ICA, thus resulting in irrigation of the PCA territory by anterior circulation. By definition, full-fetal PCA has no connection with the posterior circulation, while partial fetal PCA receives only a small contribution from the basilar artery. It represents one of the most common persistent embryonic communications between the carotid and vertebro-basilar systems (estimated prevalence 10–37%) [1]. Clinical implications involve paradoxical infarction patterns and increased severity of anterior circulation strokes by the addition of PCA territory. In such cases, posterior circulation infarctions can be due to an anterior circulation source (in our case, symptomatic extracranial carotid stenosis) rather than to cardio-embolism, which is the most common cause of posterior ischemic strokes. Artery of Percheron (AOP) [2] is a rare anatomical variant consisting of a single thalamic perforating artery arising from one of the two PCAs and suppling both paramedian territories of the thalami. AOP occlusion is known as a rare cause of posterior circulation stroke. In most cases, thalamic involvement is asymmetrical, and ischemia is greater on the side of the origin of the AOP (in our case, the right side). Generally, AOP can be seen neither by CT nor conventional angiography, because of its small diameter. Thus, the diagnosis of AOP occlusion is inferred from the bi-thalamic ischemic pattern that can be identified even during the acute phase by MRI. Signs and symptoms include decreased consciousness, memory deficit, and impaired eye movements. Alternative diagnoses underlying a bi-thalamic infarction include top of the basilar occlusion and straight sinus thrombosis which are easily ruled out with a negative CT angiography. * Manuel Cappellari [email protected]