Thanks for responding. After my original question and the change in medication from valproate to lamotrigine, the tremors have stopped, the balance issues have resolved in the main and he has had 2 minor seizures.
His short term memory is still an issue but he had had various difficulties with that since he was young. (For example we had to delay our wedding reception for a couple of hours because his parents had to go back to their home to look for his car keys as he had misplaced them that morning.)

I don't have an answer for you but you are the first person I have found here who is dealing with post stroke epilepsy. My husband is on zonisamide and lamotrigine, but it is not controlling the seizures. Will keep you in my prayers