Learning objectives
To review anatomical variants of posterior cerebral circulation such as artery of Percheron,
to underline the importance of MRI in detection of vascular thalamic lesions.
Background
The thalamus is a bilateral symmetric,
obliquely oriented ovoid mass of gray matter that lies posteromedial to the lentiform nuclei and forms the lateral wall of the third ventricle [1].
Each thalamus is subdivided into several groups of nuclei and has a complex blood supply,
with significant variation and overlap,
mostly made of multiple small vessels originating from posterior communicating arteries (PcomA) and from segments P1 and P2 of the posterior cerebral arteries (PCA) [2].
Classically thalamic vascularization can be categorized into four territories: anterior,...
Findings and procedure details
The artery of Percheron,
first described in 1973 [4],
has a variable prevalence ranging between 4% and 12% in the general population according to Arauz et al [5].
PA occlusion causes bilateral paramedian thalamic stroke generally due to proximal embolism,
with asymmetric involvement in two-thirds of cases.
A predisposition to embolism due to patent foramen ovale might be a possibility.
Hypertension,
hyperlipidaemia and smoking are other common risk factors for stroke [6].
The clinical presentation is complex due to the presence of multiple nuclei and...
Conclusion
The diagnosis of bithalamic infarction may be difficult at first,
because clinical features can be unusual and vary according to the extent of the affected territory.
Artery of Percheron occlusion can be proved by CT,
MRI and angiography but its diagnosis is often delayed.
Stroke due to AOP should be suspected in patients with acute onset of symptoms related to deficit in posterior circulation.
MRI imaging,
with DWI and the midbrain “V-sign” still remains a very important tool to improve diagnosis of AOP infarction and...
References
[1] Osborn AG,
Hedlund GL,
Salzman KL.
Osborn's Brain.
Elsevier; 2017: 907
[2] Lazzaro NA,
Wright B,
Castillo M,
et al.
Artery of percheron infarction: imaging patterns and clinical spectrum.
AJNR Am J Neuroradiol.
2010; 31(7):1283-9
[3] Liu WL,
Lin SH,
Chiang SY,
Lai CC.
Artery of Percheron infarction.
Intern Med.
2013;52(17):2007-8
[4] Percheron G.
The anatomy of the arterial supply of the human thalamus and its use for the interpretation of the thalamic vascular pathology.
Z Neurol 1973;205:1–13
[5] Arauz A,
Patiño-Rodríguez HM,
Vargas-González...