If you take a Parkinson's disease product liability case to court, he prepared to have your integrity and motives impugned, and the extent of your illness belittled. The defendant's lawyers will do whatever they can to win the case, and they don't mind if it gets rough-and-tumble in the courtroom.
Depending on the state in which you live, there may be a cap on the amount of money you can expect to get for a Parkinson's disease-related lawsuit. Often the cap is there to limit what the courts see as excessive punitive damages, but the actual damages may be limited as well.