Hi there,
I'm pretty sure it's because of the drugs,especially carbamazepine(tegrital)..but u haven't talked about the class of seizures he's been havin..considerin the fact that he's on a dual therapy regimen,my guess is ,it'll be difficult changin over to a new line of treatment alltogether..but u might ask your physician about valproic acid,which is a first line drug for GTCS as well as partial seizures with secondary generalisation.Besides,it's free of bone marrow suppressive effects of tegital and phenytoin as well..