The original was very faithful to the short story by George Langelaan, where it's told in the form of a confession from the wife after she's been committed to the lunatic asylum.
The original script by Charles Pogue for the 1986 version was closer to the short story than the version that was finally filmed, in that it was based around a mad scientist husband and his wife. David Cronenberg, who took over the project, changed it to the boy-meets-girl scenario. What's interesting is that all the gore & weird body mutilation that's traditionally associated with Cronenberg was in the original script, and Cronenberg's main contribution to the script was the love story.
That's one of my favourite ever scenes from a movie. Goldblum should have had at least an Oscar nomination for that performance, if not a win!