We have seen these aneurysms with Cone Beam CT — probably in at least 1 in 4 perimesencephalic hemorrhages. We suspect that these are responsible for more — with the small perforator vessels closing after hemorrhage. Here is an example

Could the AVM have done it? Or the perinidal aneurysm? There is no blood around the 4th or tonsillar region. But, seriously, there is blood and AVM. Enough is enough?

Even a high quality “DYNA” like the one above seems negative for anything around the basilar

Because these aneurysms are tiny

This is the usual location. Just behind the bifurcation. Why? That’s the next question. We already answered the question of why paramesencephalic. So, on to the next “Why”

Its very real. And very much where the blood is.

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