I refused surgery twice but like you was on Dilantin for over 40 years until it became to unstable and
would no longer maintain a normal therapeutic level. I don’t advise long term use since it has been known to cause Peripheral Neuropathy. Not to say it will happen to you but the longer you take these meds there are often consequences. I’ve had Uncontrollable Epilepsy for 51 years with seizures 46 of those years. I learned to late.
I wish you well in your future treatment whatever it may be. Think about surgery VERY carefully and get at least a second opinion.