I had seizures during my crack and cocaine use. However, I think I had a predilection to them, and was always a heavy drinker, so I can't say cocaine or crack was the sole reason.
I can say they stopped after I stopped using cocaine in any form, gained some weight, and stopped drinking.
Your brother needs to stop smoking crack -- one thing that happened to me was to have a seizure in jail. That is pretty scary. He is obviously robbing you of your peace of mind, so whether or not he thinks his cocaine use is helping or hurting him, he is having a harmful effect on others!