Nancy,
I thought the same thing...is my sugar level contributing or causing my dizziness? (especially because I am diabetic?) Therefore, when I had a dizzy spell, I quickly took my blood sugar test with my One Touch Ultra (needle prick) and my sugar level was normal.
I also closely monitor my blood pressure at home, and it is absolutely normal (usually 120/80 - 135/87), so I don't believe it's my pressure.
Funny thing is..just like Mandy, my recent test seemed normal. My CT/CTA Perfusion Study confirmed "diminished perfusion" on my right side, but I think they already knew that since my surgery was on my right side. Other than that, there was no changes.

I totally feel your frustration about not knowing what is causing the dizzy spells!

I have an MRI/MRA Perfusion Study on the 13th of this month, so even though I'm praying that everything is normal, I'm wondering what the heck is going on!
You know, I did have a hematoma after my surgery...but I believe the CT/CTA PS showed that it is slowly decreasing. I do still feel some tightness around my right eye when I squint my right eye, so I guess it could be my nerves. That would make some sort of sense.
(I also had an indirect along with my double bypass..)
Hmmmm.....

Oh well... Thanks to all of you for sharing your experiences! It truly helps to know I'm not alone. These dizzy spells are sometimes very frightning!
Take care,
Shan