Conversation so far:
When did lewis first fall ill?
March 20, 1965.
What caused the illness?
illnesses and addictions related both to aging and a back injury sustained.
How did he hurt his back?
comedic pratfall from a piano while performing at the Sands Hotel and Casino on the Las Vegas Strip.
Are there any other interesting aspects about this article?
Lewis had a Medtronic "Synergy" neurostimulator implanted in his back, which helped reduce the discomfort.

Question: How did this illness affect him?
Self-contained rewrite: How did Jerry Lewis' illness affect him?