seizures
"I have a brain tumor. I've been on 1500mg/day since Feb 2011. I had a gran-mal seizure in the middle of the night. First seizure, first indication of the brain tumor. Haven't had a seizure since. Radiation took care of the tumor. Have not experienced any of the side-effects that most other people comment on other than occasional constipation. My dreams seem to be more vivid and realistic than before.  I'm 50 in two months."