Artery of Percheron

The artery of Percheron is a rare variant of the posterior cerebral circulation characterized by a solitary arterial trunk that supplies blood to the paramedian thalami and the rostral midbrain bilaterally. From the original classification of arterial patterns at the origin of the paramedian arteries for the thalamus ¹, this variant is described as type II. Type I refers to the standard bilateral independent vascularization from the proximal segment of both posterior cerebral arteries while type III regards the existence of a communicating artery between these two independent origins, with either thalamus receiving bilateral arterial supply.

Epidemiology

The artery of Percheron is estimated to occur in up to 33% of the population ². Ischemic strokes affecting this artery are thought to be at the origin of 4-18% of all thalamic strokes ³.

The distribution of Percheron infarcts patterns involves³

• 43% - bilateral paramedian thalamic with midbrain
• 38% - bilateral paramedian thalamic without midbrain
• 14% - bilateral paramedian thalamic with anterior thalamus and midbrain
• 5% - bilateral paramedian thalamic with anterior thalamus without midbrain

Clinical presentation

The presentation of disease is dependent on the distribution of infarction, however the classic triad involves³

1. altered mental status
2. memory impairment
3. vertical gaze palsy

Gross anatomy

The term is used to refer to a solitary arterial trunk that branches from one of the proximal segments of either posterior cerebral artery (PCA). It supplies blood to the paramedian thalami and, most often, the rostral midbrain bilaterally ⁴.  Occasionally it supplies the anterior thalamus, particularly when the thalamotuberal (or polar) arteries are absent (30-60% of cases) ^1,3.

History and etymology

It is named after the French neurologist Gérard Percheron, who described it in 1973 ⁵.

Related pathology

• Percheron infarct: bilateral thalamic and mesencephalic infarctions; clinically patients are often obtunded, comatose, or agitated, with associated hemiplegia or hemisensory loss

Radiographic features

V-sign

• hyperintense signal along the midbrain surface adjacent to the interperduncular fossa
• seen on axial FLAIR and DWI images
• 67% sensitivity for Percheron infarction with midbrain involvement

Differential diagnosis 

Bilateral pathology of the thalamus include⁶

•  primary neoplasm
  • bilateral thalamic glioma (low-grade astrocytoma)
• metabolic and toxic disorders
  • wernicke encephalopathy
  • osmotic myelinolysis  
  • fabry disease
  • fahr syndrome
  • wilsons disease
  • leigh disease
• infection
  • encephalitis (West Nile, Japanese, Murray Valley, Eastern equine) 
  • rabies
  • creutzfeldt-Jakob disease
• vascular
  • top of the basilar syndrome
  • deep venous thrombosis
  • cerebral hypotension
  • posterior reversible encephalopathy syndrome