Professor Dowell's Testament
In Professor Dowell’s Testament (1984), based on Alexander Beliaev’s 1925 Professor Dowell’s Head, the title character is kept alive as a detached head.
Professor Dowell and his assistant surgeon Dr. Kern are working on the resurrection of the dead. Dr. Kern kills Dowell in a set up car accident. Professor Dowell's head is now kept alive and used by Dr. Kern for extraction of scientific secrets. Next - the living head of a killed woman gets a body of a young woman. That body belongs to the girlfriend of Dowell's son. Dr. Kern is anxious to announce himself as the inventor. But Dowell's son helps his father's head to get in front of the cameras. The head of professor Dowell tells all and dies. - IMDb
Below you can find the trailer and the full movie in the original version — no subtitles, unfortunately: