I've posted this before (so please bear with me):
Puzo was one of those authors who can't resist passing on any bit of erudition they've picked up, whether or not it's relevant to the plot of the novel they're writing. I'm guessing that a female close to Puzo had had the condition and operation he ascribed to Lucy. He interested himself in the case. And (this is what pisses me off), he created that l-o-o-o-ng, boring Vegas sequence with Lucy and Jules just so he could describe the operation he learned about. I could have done without any and all of the Lucy/Jules stuff, all of the Nino crap, and all of the Johnny Fontaine nonsense after Connie's wedding.
Objectionable as it is, this stuff is nowhere near as bad as that Hollywood-insider strunz that nearly wrecked "The Last Don."