Tuesday, March 31, 2015

Study group discussion: Artery of Percheron

*a picture of artery of Percheron was posted in the group on which this discussion took place *

That's vertebral arteries combining to form basilar. And again dividing to posterior cerebral arteries.

This is an anatomical variant.. Any odd thing in the picture?

The supply from the right branch of posterior cerebral artery. That seems odd! If it was normal.. It should have a bilateral supply.

Exactly.
It's called artery of Percheron.

What is special about it?

A rare anatomical variant where the thalamic perforator branch supplies both sides of the midline.

Any occlusion and you'll have bilateral paramedian thalamic infarction.

Ohh.. What would be the symptoms?

Yup.. How would unilateral infarction differ from bilateral?

I can't figure out which structure the artery is supplying!
They're thalamic peduncles. Unilateral you'll have sparing on one side. In Bilateral, the structures below the thalamus will be totally cut off from the structures above.

And symptomatically we are talking depending on which relay centre is affected? Or is there a very specific pure motor, pure sensory stroke we get?

Bilateral paramedian thalamic strokes are typically characterized by a triad of altered mental status, vertical gaze palsy, and memory impairment.

Altered mental status can present anywhere on the spectrum from drowsiness or confusion to hypersomnolence or coma...most probably due to damage to the reticular formation.

Vertical gaze palsy suggests mesencephalic involvement.

Memory deficits mostly are due to damage to the papez circuit. ..Anterior nucleus of thalamus is a part of the Papez circuit.
And also the thalamus acts as a 'search engine' for memories.

I looked up a few parts on the net...

That's awesome!

This is what I found in Harrison - Occlusion of the artery of Percheron produces paresis of upward gaze and drowsiness, and often abulia.

I liked the search engine bit. Nice info!

By the way, a similar sounding condition, 'Purtscher's retinopathy' is associated with acute pancreatitis.

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