Help your medical expert frame what he knows to be the medical realities in terms of your burden of proof. As long as he realizes that you are not trying to tell him what to say, or attempting to alter his testimony, you will enjoy the support of a valuable ally. An inescapable fact is that law and medicine don't mix very well. Lawyers aren't familiar with doctors and the way they work. Doctors aren't familiar with lawyers and the way they work.
Most doctors are uncomfortable with the legal process, with lawyers, and with the courtroom.
In order to enlist the experts' cooperation and active participation, you must understand their feelings, respect their professional opinions, and initiate them gently into the ways of the law. You must help them to believe that your client's interests and the interest of justice are at the heart of the matter. Copyright permission requested.