The Missouri version of the ad -- for Democrat Claire McCaskill's Senate campaign -- has had more than a million views on YouTube since it appeared Saturday.
Mr Limbaugh -- a Missouri native -- has suggested on his radio show that Mr Fox is exaggerating his movements because Mr Fox is, afterall, an actor:
Rush Limbaugh on Michael J Fox
Not so fast. If Rush's fact-checkers had done a little research they might have gotten some information that the folks at ThinkProgress.com got from the National Parkinson Foundation:
An official of the National Parkinson Foundation said movements like those exhibited by Fox are the result of taking medication to treat the disease, which would otherwise result in rigidity.Let's help Rush out with an even more nutjob conspiracy theory:
"When you see someone with those movements, it's not because they have not taken medication but because they probably have taken medication for some time," the official said. "If you don't take the medication, then you freeze."