Advice? Still having seizures and MRI is normal.

I need advice, My brother has been having seizures since we were a year old and our whole lives we have been told that it is just epilepsy he’s even been told that it is just anxiety. over the years he has had a bunch of different cocktails of medications, and neurologists he is currently seeing an epileptologist who has recommended that he goes to the mayo clinic because he has had seizures more frequent in the last few months and it has been impacting his quality of life and he is super frustrated and wants answers we went to the clinic and they did an MRI which came back completely normal and they want to do a PET scan in November has anyone found any other causes for seizures other than the brain or is there anything else we should be looking out for it would be appreciated