Italian Professor Canavero, who is the director of the Turin Advanced Neuromodulation Group, announced the success in a press conference in Vienna.
The professor said: "The first human transplant on human cadavers has been done.
"A full head swap between brain dead organ donors is the next stage and that is the final step for the formal head transplant for a medical condition which is imminent."
Spiridonov had volunteered because he suffers from Werdnig-Hoffmann disease, which causes severe spinal muscular atrophy, and he was willing to try anything to prolong his life.
There had been an angry backlash to the potential surgery from religious groups, who said it was going against God.
Spiridonov was fully prepared for the body to reject his head but it was also possible that fusing his head with another body - including the spinal cord and jugular vein - might result in never-before experienced levels of insanity.
Doctor Canavero said before the operation that he was anticipating it to be a 36-hour procedure that would involve 150 doctors and nurses.
Arthur Caplan, director of medical ethics at New York University's Langone Medical Centre, had previously said that the bodies of head transplant patients "would end up being overwhelmed with different pathways and chemistry than they are used to and they'd go crazy".
The body rejected the new head and the monkey was left unable to breathe or move because the spinal cord of the head and body weren't properly connected.
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