It is a search that many of us have had to go thru.
I've found that large teaching hospitals, affiliated with medical schools
with a large neuro dept. - and does research in neurology - is a good place to look.
Johns Hopkins, The Jack Miller Center, Cornell-Weill, Mayo Clinic,(and others) are good places for effective PN treatment and testing.
Where, would be dependent on where you live, and your ability to get to one of these centers, at least once - for initial evaluation & testing.
After that, a neuro who would be recommended by them - in your area, or your PCP, could do the follow up and regular visits. (Whoever would be willing to work with the PN specialists and coordinate treatment.)
I only go back to Hopkins when necessary, every few years, for follow-up testing. My PCP does the rest, on a regular check-up basis.