Hi Mic.
FND is very real for those that deal with it. I know someone who was diagnosed with FND quite some years ago. Her parents as well as myself did not believe that she had FND. Her parents spent hundreds of thousands of dollars in testing, repeat testing and a wide range of different specialties.
The final outcome was, yes it is truly FND.
From the Movement Disorder Forum:
Functional neurological disorder
Take care...