I'm sorry to hear your girl had a seizure. I wouldn't rule out doing anesthesia completely before talking to your vet, doing blood tests. There are Yorkies here who have seizure disorders who can have anesthesia.
Do you know what kind of anesthesia your doctor uses? Here is a sticky post on anesthesia protocol:
http://www.yorkietalk.com/forums/yor...-protocol.html
Keep us updated on the results of your girl's biopsy. Sending best wishes.