I too have experienced “brain zaps”!
In my case GBS set in one week after I had a brain tumor removed, which they found when I had a TIA. So between the tumor, mini stroke and GBS I am not sure what causes them or what helps them. I am having CT scans regularly so they know there is not enough of the tumor left to be causing them. Right now the doctors are just taking a watch and see approach.
I am 52 yrs old and was never sick a day before all this happened in May of this year.