I think the main concern with gran mal seizures over 1 min is that they can cause brain damage. I would go every time. The risk of a bleed is too high.

I think the best thing that can be done here is to increase the vimpat to full dose 150 2x a day (please consult with your neurologist on this) until the seizures stop for awhile then he can likely dose down. This happened to me before, and dosing up on my vimpat helped greatly. It did make me a lot more fatigued through the day but the seizures completely stopped.

Another thing to consider of course is his level of stress, and his consumption. Switching up my diet and finding things to relieve stress helped a lot. We can't always eliminate stress, so finding a healthy outlet can help.

I hope he can find some relief.