Neurologists do an EMG test to test the viability of the phrenic nerve. .https://www.mayoclinic.org/tests-procedures/emg/about/pac-20393913 People generally have to go to a larger medical facility to have this done; but if you're in the Mayo System, you shouldn't have any problem finding a doctor to do it. Which Mayo facility to you go to? I've read about excellent thoracic surgeons who deal with diaphragm issues in Rochester, Florida and Arizona and could pass their names on if you tell me where you are. There is an excellent facebook group for people with paralyzed diaphragms if you're ever interested in connecting with around 1400 people who know exactly what you're going through.