Hi,
Yes, in non convulsive seizures the brain imaging studies do not always pick up abnormality.
EEG is the diagnostic tool of choice for these type of seizures.
I think I have a seizure disorder too, but my MRI and CAT scan was normal. Allthough, it was three years ago , and they could not use contrast because I was pregnant. I am not better at all today. I have been taking an anti-convulsant medicine, and that doesn't even help. I know there is a twenty four hour EEG( brain wave test) they can perform that would be more accurate in your case and mine because it won't show up in a regular eeg most of the time unless you are having a seizure during the test. I hope this helps. You could check you spinal cord to see if there is any excess fluid accumilation in your brain, which can cause intracranial pressure and seizures.A person can have a partial sezure depending on what part of the brain is effected.I know I stiffin up in my whold upper body and clench my teeth. I also think I may be having an abscence seizure because people see me staring and can't get my attention for anything. I hope this helps you.