I was on topamax for 2.5 years after my injury. I tried it at various doses, mostly at 100mg twice a day for most of the 2.5 years. The neurologist did try to up it to 400mg a day, but once I got even a little above 200mgs a day, I started to get kidney side effects and had to go back down to 200 mgs.

I'm not sure it was super helpful for me, the only real difference I noticed in my head pain was that instead of it waking me up at night crying in pain, I would just wake up in pain, but be able to go back to sleep after a while.

I didn't have any other real dramatic improvements with it, but my head pain seems to be atypical.

I've been off Topamax for about 6 months now and was hoping when I came off it, that I would feel less dopey and stupid, but it made no difference there either. Apparently the dopey, stupid feeling is just my normal now.

The only other thing I noticed while on Topamax was food tasted weird and it decreased my appetite. I was not a soda pop drinker before, but I tasted it a couple times while taking Topamax and man it was disgusting!

Generally it seems to be a drug that either works well for people, or there are too many intolerable side effects. For me, it was just meh, but it was one of the only drugs of MANY that I tried that I tolerated at all.

Probably worth a try and maybe you'll be one of the ones that gets on well with it.
Good luck!
Starr