In 1980 Alberca et al. described a patient with a syndrome of increased muscle irritability, who presented ondulating muscle rolling movements and electrically silent cramps, myoedema and muscle reactions to mechanical stimulation similar to myotonic response, suggesting a disfunction at myofibrillar level.
For c-3po, it was a costume, Anthony Daniels played c-3po: For R2-D2, It was a costume and a remote controlled robot. CGI was also used in the prequel trilogy. So, they had Kenny Baker to play him : And from Portrayal section of wookieepedia article on R2-D2 :
Issac Ryan Brown is one of the supporting actors of Devious Maids, portraying the role of Deion. Not much is known about Brown's life. In 2012, he appeared on season 7 of NBC's America's Got Talent. He was given a pass to Las Vegas by the show's three judges, but he was eliminated during the second round of competition.