Hmmm i reckon i've solved my own problem....
The most confusing issue in my case is that i have been esxperiencing minimal symptoms from my right occluded MCA, however extremely frequent symptoms that appear to be originating from the basilar region.
You'd think that I'd be having symptoms similar to what I experienced from the occluded artery on my left side - speech & coordination problems, loss of feeling etc.. - however, i'm not.
Possible explanation:
Now.... in most people their posterior cerebral arteries originate from their vertebrobasilar artery .... but in some (30%) the PCA originates from their internal carotid artery (this is called
fetal PCA).
I haven't had a stroke in the basilar region [yet]... and the stenoses there don't appear to be enough to give me such major symptoms, but i guess i'm getting a few warnings!
PCA strokes occur like any other - a local interruption of bloodflow to the brain. However in a patient with fetal PCA, a stroke in the PCA region can be the result of an occlusion in the Internal Carotid Artery - which I have.
So it would make the most sense to perform a by-pass on the occluded ICA (MCA) to restore bloodflow to the PCA region in order to prevent a stroke.
Some of "my" team have queried whether or not the
basilar region should be operated on next.. but apart from that being a much more complex operation (and recovery from any surgical complications is MUCH more difficult - particularly for visual field defects) it also doesn't make sense that I could be experiencing such severe symptoms from a small stenoses such as what I have in that region.
As yet though the report from a recent MRI/MRA on thursday hasn't been confirmed so we might find more juicy details on that!

Hmmmm i'm kinda leaning towards applying for a research position at the hospital.. hehe... this is all very interesting..... pity my mechanical engineering background is probably not entirely appropriate.