Artery of Percheron infarction a rare anatomical variant and a diagnostic challenge: Case report

Abstract

The Artery of Percheron (AOP) is an uncommon anatomic variant that provides arterial supply to the paramedian region of the thalami and bilaterally to the rostral part of the midbrain; it is a solitary arterial trunk that branches from a proximal segment of the posterior cerebral artery (PCA). Although AOP infarction results in a characteristic pattern of ischemia, namely bilateral paramedian thalamic infarct with or without midbrain involvement, it may cause diagnostic difficulties due to the variety of its clinical presentations and wide differentials, as well as its small diameter and the difficulty of obtaining visualization through diagnostic imaging. Early neuroimaging of AOP infarction and correct diagnosis are mandatory for early initiation of the appropriate treatment and better patient outcomes. This study discusses the imaging patterns and imaging differentials of AOP infarction and its clinical presentation. A 55-year-old man presented to the emergency department unconscious with Glasgow Coma Scale score of 4. Pupillary light reflex on both eyes was poorly reactive with dilatated right pupil. The patient flexed his arm and extended his leg on painful stimulus. Laboratory tests and electrocardiogram were unremarkable. Emergency cerebral CT scan and transcranial Doppler ultrasound were normal. He gradually regained consciousness with residual somnolence, ptosis, and vertical gaze palsy. Second CT scan showed bilateral paramedian thalamic areas of hypodensity, CT angiography (CTA) was unremarkable. MRI showed bilateral high-signal intensity on paramedian thalami fast spin echo T2, FLAIR, and diffusion-weighted sequences, low signal on apparent diffusion coefficient sequence. MR angiography (MRA) revealed an abnormal tiny vessel arising from the P1 segment of the left posterior cerebral artery. Imaging findings were consistent with AOP infarction. Aspirin was started, 4 hours after admission the patient regained consciousness, and gradually improved on the following days till he was discharged on the 15th day, with mild neurologic deficit. AOP must be considered whenever paramedian thalamic infarction is noted in neuroimaging. The difficulty in visualizing the AOP using diagnostic imaging is due to its small diameter, leading to the limited abilities of MRA and CTA to diagnose AOP infarction. An absence of evidence of AOP infarction in MRA or even CTA does not exclude its diagnosis. Good knowledge of the imaging characteristics of AOP infarction will help in early diagnosis and the achievement of good patient outcomes.

Artery of Percheron infarction: A case report and literature review

“…2 , Fig. 3 ] further contributing to delays in the diagnosis of AOP infarction [15] . Delays in performing an MRI result in a late diagnosis, significantly impacting the management and prognosis of these patients, as was the case of our patient.…”

Artery of Percheron Infarction: A Case Report of Bilateral Thalamic Stroke Presenting with Acute Encephalopathy

“…There have been reported cases of bilateral thalamic strokes, who presented mainly with sudden onset of hypersomnia and fluctuating arousal as the thalamus plays an important role in sleep regulation and in maintaining arousal. Hypersomnolence can be due to the interruption of noradrenergic and dopaminergic pathways from the ascending reticular activating system to the thalamus [ 14 – 16 ].…”

Acute percheron infarction: a precision learning

“…Acute AOP ischemia has great variability with respect to symmetry, size, and territory, which is mainly due to the thalamic arteries vary between individuals. These differences are related to the parent vessel from which each branch arises, the number and position of the arteries and their tributaries [ 9 , 12 , 18 ]. Paramedian bithalami of the 23 patients showed high signal intensity on FLAIR with restricted diffusion and hypointense in the ADC map (positive in 100%).…”

“…The diameter of AOP is so small that magnetic resonance angiography (MRA) cannot show it, and even digital subtraction angiography (DSA) cannot show its existence, stenosis or occlusion in most cases. Only a few authors found AOP obstruction through DSA [ 9 , 10 ]. MRI, especially diffusion weighted imaging (DWI), plays an important role in the diagnosis of acute AOP infarction.…”