Seizure related

I've heard of anethesia causing seizures, but I must say, it seems highly unusual to me for a dentist or anyone to proceed with any type of procedure when something like happens prior to.  Almost inconcievable that they would proceed!   I was diagnosed with grand-mal seizures when Iwas 15 yoa after having my first grand mal seizure.  After batteries of tests through the years (I am now 53 and seizure free for 18 years), I have never been given a reason for why.  After 36 years of being on Dilantin and those side effects, I was placed on Topamax in the last year and have tolerated it well so far.