I saw this when I was a kid, so late-80s/early-90s. I don't remember anything but one scene (which I think was the end?) - a woman attempting escape from an evil doctor, who captures her and transplants her brain into the body of his wife, whom he has preserved.
I recall the special effects being very lo-fi, and (I *think*) it was back and white, possibly tinted blue. (I am really fuzzy about that last detail.)
I know that's not a lot to go on, but I've been looking for it for over a decade!
It's starting to sound like maybe SOMEONE BEHIND THE DOOR (1971).
Also try:
DR. BUTCHER, M.D./ZOMBIE HOLOCAUST (1980)
BLOOD RELATIONS (1988)
INTENT TO KILL (1958)
SHORT NIGHT OF GLASS DOLLS (1971)
Holy mackerel, you found it! It was Blood Relations. THANK YOU!
O.P. "7Z" confirms that BLOOD RELATIONS is correct! MOVE THIS ONE TO SOLVED, plz!