PMMA is the short term for non-resorbable polymethylmethacrylate microspheres. These are basically used as fillers for the body, mostly in the plastic surgery. What's interesting, is that it has been used for these medical purposes since 1930's, so for some reason I doubt this could be the reason of whatever condition that led him to death. However, I am personally not an advocate of using it for bodybuilding purposes, since it is not much better than synthol. It is safer, but yet it kills the whole purpose of muscle development.