Zombie '90: Extreme Pestilence (1991)

A military machine carrying untested lethal chemicals crashes into a forest, a dead patient comes back to life in the operation room and mutilated bodies are being found all over the country. A new epidemic has broken out, the "Extreme Pestilence". Two doctors discover the epidemic and take on the hopeless fight against the living dead. The only way to kill the zombies is to destroy the brain or separate the brain from the rest of the body.