Artery of Percheron territory infarct is rare, on account of the relative rarity of the artery of Percheron, and presents with a variety of signs and symptoms collectively termed the paramedian thalamic syndrome. It is a type of posterior circulation infarction.
On imaging, it is classically characterized by bilateral infarcts in areas involving the rostral midbrain and/or ventromedial thalamus.
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Epidemiology
Artery of Percheron territory infarcts are thought to account for 4-18% of all thalamic ischemic strokes 2.
Clinical presentation
The symptoms may vary following infarct extension through thalamic or mesencephalic structures 2:
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bilateral paramedian thalamic involvement is usually characterized by a triad of
altered mental status
supranuclear vertical gaze palsy
memory impairment
when also accompanied by rostral midbrain lesions, a mesencephalothalamic or thalamopeduncular syndrome occurs, which includes other oculomotor disturbances, hemiplegia, cerebellar ataxia, and movement disorders, along with the aforementioned triad
Radiographic features
There are four major patterns of artery of Percheron infarction, all of which bilaterally involve the paramedian thalamus 2,9:
bilateral paramedian thalamic and midbrain infarction (most common - 35-43%)
isolated bilateral paramedian thalamic infarction (35-38%)
bilateral paramedian thalamic, anterior thalamic and midbrain infarction (14-26%)
bilateral paramedian thalamic and anterior thalamic without midbrain infarction (least common - 5-6%)
MRI
Artery of Percheron infarction is best visualized on DWI or FLAIR MRI sequences and it is often missed on initial CT. The midbrain V sign is a feature demonstrated in 30-67% of patients with artery of Percheron infarction involving the midbrain 2,9.
Differential diagnosis
Possible differential considerations include:
bilateral internal cerebral vein thrombosis (dural venous sinus thrombosis)
other causes of bithalamic lesions 8
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