Brain zaps are usually a result of weaning off of a med. If you are not doing this currently, then it could just be caused by tension.
A lot of tension happens in the shoulders, neck/upper body and can result in head/scalp sensation and symptoms.
This seems to be a fairly common complaint...if you want to read more about
it, check out this link...
http://www.anxietycentre.com/anxiety-symptoms.shtml
S.C.