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CASE SERIES Table of Contents  
Ahead of print publication
A case series: Artery of percheron syndrome revisited

1 Department of Stroke Medicine, Worcestershire Acute Hospitals NHS Trust, Worcester, England, UK
2 Department of Stroke Medicine, Consultant Neurologist and Clinical Lead for Stroke Medicine, Worcestershire Acute Hospitals NHS Trust, Worcester, England, UK
3 Department of Medicine, Murshidabad Medical College, Berhampore, Murshidabad, West Bengal, India

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Date of Submission01-Jan-2022
Date of Decision03-Feb-2022
Date of Acceptance08-Feb-2022
Date of Web Publication04-Aug-2022


The artery of Percheron is an uncommon anatomical variant that was first described in 1973 by a French neurologist called Gerard Percheron. Stroke due to occlusion of this anatomical variant artery may present with diagnostic challenges. Here, we are sharing our experience in four cases with variable outcomes. This may add our knowledge to existing literature.

Keywords: Artery of Percheron syndrome, dyskinesia, stroke

How to cite this URL:
Hassan MS, Omojowolo O, Shrourou AM, Ribeiro NP, Ghosh K. A case series: Artery of percheron syndrome revisited. APIK J Int Med [Epub ahead of print] [cited 2022 Sep 25]. Available from: https://www.ajim.in/preprintarticle.asp?id=353254

  Introduction Top

The thalami and mesencephalon share a complex blood supply usually derived from perforators arising from posterior cerebral artery (PCA) and posterior communicating artery. However, there are multiple anatomical variations in the arterial supply of this important area. The artery of Percheron (AOP) is a rare anatomical variation where a single trunk arising from one PCA supplies bilateral paramedian thalamic areas and rostral midbrain. Occlusion of AOP causes ischemic infarct in the area supplied by this artery leading to AOP syndrome. This syndrome is characterized by three cardinal features: vertical gaze palsy, memory impairment, and coma. AOP infarcts account for only 0.1%–0.3% of all ischemic infarcts, of which up to one-third are associated with thalamic infarcts without midbrain involvement. We share our experience of managing four cases of AOP strokes from a teaching hospital in West Midlands, England.

  Clinical Cases Top

Case 1

A 74-year-old woman was admitted with confusion, fluctuating consciousness, and collapse. She was treated with intravenous (IV) antibiotics and high flow oxygen for pneumonia. Subsequently, computed tomography pulmonary angiogram showed bilateral pulmonary embolism which was treated with therapeutic dose enoxaparin. Her Glasgow Coma Scale (GCS) remained low associated with facial twitching. She was started on IV acyclovir and IV levetiracetam for suspected encephalitis. She had dysarthric speech, right facial palsy, right eye ptosis, and anisocoria as well as left hemiparesis 3/5. Electroencephalogram (EEG) did not show epileptiform discharges. Her 72-h electrocardiogram (ECG) showed paroxysmal atrial fibrillation. Magnetic resonance imaging (MRI) head showed diffusion restriction in both thalami representing AOP stroke [Figure 1]. Acyclovir was stopped, and she was prescribed usual stroke prevention medications. Unfortunately, she passed away after a few weeks.
Figure 1: Magnetic resonance imaging (MRI) head showed diffusion restriction in both thalami representing AOP stroke

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Case 2

A 69-year-old man suddenly collapsed in his bedroom and was found unconscious on the floor by his wife. On arrival at A and E, he was alert and oriented. He had slurred speech and left-sided significant weakness. His right pupil was dilated and fixed with restricted vertical and lateral gaze due to oculomotor nerve palsy. Subsequently, his GCS dropped to 6/15, but he was maintaining airway on room air. He was initially treated as encephalitis, due to neutropenia, with IV antibiotics, acyclovir, and levetiracetam.

Later, the MRI head showed bilateral acute paramedian thalamic infarcts likely due to the AOP infarct [Figure 2]. He was started on secondary prevention medications for stroke. His fluctuating conscious level was treated with modafinil. The patient had standard stroke inpatient rehabilitation. He gradually improved clinically and was discharged home.
Figure 2: MRI head showed bilateral acute paramedian thalamic infarcts

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Case 3

A 49-year-old woman presented to A and E with sudden collapse in the kitchen followed by loss of consciousness. Her past medical history includes diabetes mellitus type 2, hypertension, and hypercholesterolemia. On examination, she was hypertensive and tachycardic. Her GCS was 7/15 with fluctuating conscious level. She had a dysarthric and hypophonic speech. There were complete right-sided ptosis, mydriatic right pupil with absent reflex to light, vertical gaze palsy, and right facial palsy. She was also quadriparetic. Initial computed tomography (CT) head was normal. Hence, she was treated with IV thrombolysis therapy. Standard secondary prevention medications were started. Further workup including ECHO and 72-h ECG was unremarkable. Workup informs of thrombophilia and vasculitis screening were found to be negative. MRI head showed bilateral paramedian thalamic acute infarcts [Figure 3]. Computed tomography angiography (CTA) head and neck was normal. She made good recovery after inpatient intensive rehabilitation and secondary preventive therapy. She was discharged home with some residual neurological deficit.
Figure 3: MRI head showed bilateral paramedian thalamic acute infarcts

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Case 4

A 67-year-old female patient presented to A and E after the sudden collapse and loss of consciousness preceded by vomiting. She had a background of diabetes type 2, hypertension, and hypercholesterolemia. On examination, the patient was drowsy but arousable with loud verbal stimuli. She had dysarthric speech. Cranial nerve abnormalities included dysconjugate gaze, skew deviation of eyes, vertical gaze palsy, and right upper motor neuron type seventh nerve palsy. The patient had no recall of her presentation. Blood results, chest X-ray, ECG, and EEG were unremarkable. Plain CT head showed no acute findings. However, the MRI head revealed diffusion restriction in the anteromedial aspect of thalami bilaterally, consistent with acute infarct in the distribution of AOP [Figure 4]. She was provided with multidisciplinary rehabilitation and established on secondary preventive medical therapy for ischemic stroke. The patient had a good recovery and was discharged home in 3 weeks.
Figure 4: MRI head showed diffusion restriction in the anteromedial aspect of thalami bilaterally, consistent with acute infarct in the distribution of AOP

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  Discussion Top

Thalami have a variable blood supply that overlaps with midbrain. Characteristic clinical signs and symptoms complemented by comprehensive radiological workup including CT/MRI head and CTA/magnetic resonance angiography (MRA) head assist in the diagnosis of AOP infarct. AOP is not always easily seen in conventional angiographic imaging as it is a very minute blood vessel. Demonstration of AOP on CTA/MRA is not mandatory for diagnosing AOP infarct.

Bilateral thalamic infarcts have a wide range of clinical presentations[1] such as elucidated in the cases in this series. One common denominator, however, is the affectation of the level of consciousness. Mental status changes, including somnolence, stupor, and coma, are common; others include behavior and memory impairment with confusion, agitation, apathy, disinhibition, and pseudobulbar affect. Dysphagia and ophthalmoplegia with or without pupillary involvement, motor and sensory deficits, cerebellar signs, and symptoms such as ataxia and dysmetria are also common manifestations. A patient may also present with hypersomnia, tremors, seizures, and hyperthermia.

Physicians have to be aware that a stroke involving the reticular activating system (RAS) or its connections can cause an abrupt onset of coma.[2],[3],[4],[5] The RAS is a network of neurons that is responsible for wakefulness, originates in the pons, and extends through the midbrain, then up into the bilateral thalami, before projecting into the cortical hemispheres bilaterally.

Four distinct variants of AOP infarcts have been identified in medical literature.[2] First, infarction of bilateral paramedian thalami and rostral midbrain makes up about 43% of cases. Second, bilateral paramedian thalamic infarction without involvement of midbrain accounts for nearly 38% of cases. Third, bilateral paramedian and anterior thalamic infarction with midbrain involvement made up 14% of cases. Fourth, bilateral paramedian and anterior thalamic infarction without midbrain involvement is the least prevalent, encompassing only 5% of cases.

These clinical cases illustrate how the diagnosis of AOP infarct could often be delayed or missed, thus hampering early and correct treatment. It may be difficult to suspect bithalamic infarcts because of the complex anatomy which causes a large clinical variability, especially when the initial imaging study is unremarkable. However, it is important to note that AOP infarct usually manifests with the typical triad of ophthalmological signs (65%) (abnormal pupillary reflex and/or vertical gaze palsy), memory impairment (58%), and altered mental status (42%) (hypersomnolence, drowsiness, confusion, stupor, and coma).[2],[6] The patient in the second case actually woke up briefly while he was on the CT scanner, answered a few questions correctly, and quickly went back to sleep.

If bilateral thalami are acutely ischemic, two other forms of stroke also need to be considered. Both thalami drain venous blood into the deep cerebral venous sinus. Thrombosis of this venous sinus can lead to bilateral thalamic infarcts, but the clinical presentation is usually distinct from an acute arterial infarct, and other structures are likely to be involved as well. Large-vessel occlusion of the distal basilar artery, the so-called “top of the basilar syndrome,” can also result in infarcts of bilateral thalami.[7] However, the basilar artery is responsible for the blood supply of many anatomical structures, so the infarcts tend to often involve the pons, cerebellum, and occipital lobes.

Nonvascular diseases also affect both the thalami. These include toxins such as cyanide, methanol, and carbon monoxide, metabolic diseases such as Wernicke's encephalopathy, osmotic demyelination, hypoxic–ischemic encephalopathy, Wilson's disease, neurodegenerative diseases (e.g., Creutzfeldt–Jakob and Fahr's disease), infections (e.g., flavivirus encephalitis, toxoplasmosis, and human immunodeficiency virus), and cancers.

The imaging modality of choice for diagnosing AOP infarct early is MRI brain with FLAIR and diffusion-weighted sequences.[8] Although an initial normal MRI brain cannot completely rule out AOP ischemic infarcts. Therefore, a repeat MRI brain should be considered. CT perfusion imaging can help us in the identification of infarcted areas as compared with noncontrast CT brain.

In general, the standard of care for the treatment of an acute ischemic stroke depends on timing, location of the lesion, and contraindications to the use of thrombolytics. Since the diagnosis of AOP infarct is often delayed, implementation of this treatment recommendation is difficult.[2],[6],[9],[10] Furthermore, AOP represents a small diameter, distal artery of the posterior circulation of the brain. Thus, endovascular revascularization has seldom been used as an option in AOP infarcts, as it is too small to be visualized.

  Conclusion Top

Occlusion of AOP causes a rare form of ischemic stroke syndrome. However, recognition of the possible presence of an AOP involvement both clinically and by neuroimaging is essential for the administration of time-sensitive treatments. The symptom complex of AOP syndrome may be variable depending localization of the infarct. This, in combination with radiological challenges, makes this condition difficult to diagnose. Prompt diagnosis allows for earlier initiation of appropriate treatment, which positively affects the prognosis. Keeping AOP infarcts in the list of differential diagnoses in patients with a variety of symptoms may be beneficial to stroke patients.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Pitts-Tucker T, Small J. Artery of percheron: An unusual stroke presentation. BMJ Case Rep 2018;2018:r-222185.  Back to cited text no. 1
Kichloo A, Jamal SM, Zain EA, Wani F, Vipparala N. Artery of Percheron infarction: A short review. J Investig Med High Impact Case Rep 2019;7:5.  Back to cited text no. 2
Leventoğlu A, Morkavuk G. Acute bilateral paramedian thalamic and mesencephalic infarcts due to occlusion of the Percheron artery: A case report. Eur Res J 2019;5:916-9.  Back to cited text no. 3
Goico A, Mikesell T. Artery of Percheron infarction: A rare cause of somnolence in a patient with sepsis and atrial fibrillation. Oxf Med Case Reports 2018;2018:omy032.  Back to cited text no. 4
Sandvig A, Lundberg S, Neuwirth J. Artery of Percheron infarction: A case report. J Med Case Rep 2017;11:221.  Back to cited text no. 5
Wong ML, Edlow JA. Artery of Percheron stroke. J Emerg Med 2018;55:114-7.  Back to cited text no. 6
Teoh HL, Ahmad A, Yeo LL, Hsu E, Chan BP, Sharma VK. Bilateral thalamic infarctions due to occlusion of artery of Percheron. J Neurol Sci 2010;293:110-1.  Back to cited text no. 7
Lazzaro NA, Wright B, Castillo M, Fischbein NJ, Glastonbury CM, Hildenbrand PG, et al. Artery of percheron infarction: Imaging patterns and clinical spectrum. AJNR Am J Neuroradiol 2010;31:1283-9.  Back to cited text no. 8
Malik A, Ahmad M, Khan A. Artery of Percheron infarction in a patient with atrial fibrillation: A rare stroke syndrome. J Case Rep 2013;3:96-100.  Back to cited text no. 9
Amin OS, Shwani SS, Zangana HM, Hussein EM, Ameen NA. Bilateral infarction of paramedian thalami: A report of two cases of artery of Percheron occlusion and review of the literature. BMJ Case Rep 2011;2011:bcr0920103304.  Back to cited text no. 10

Correspondence Address:
Kaushik Ghosh,
Flat No 401, Crystal Apartment, 14/1 Natun Para Road, Murshidabad, West Bengal
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ajim.ajim_1_22


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]


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    -  Omojowolo O
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