I see where others have helped with the list of major centers for treating BE.
There are a couple more that I would also like to mention. From what I understand and could be worth checking out if one is close to these areas: Mt.Sinai in NYC that is now associated with National Jewish in Denver; NYU Langone and another is Dr. Elizabeth Anne O'Donnell at Georgetwon Univ. Washington, DC. All are at great distance, however, compared to Atlanta from Nashville and certainly Atlanta is closer for 'you all.''
I mention these in case you have family in these areas due to the possibility of having to stay in one of the areas for several days for medical testing etc. Hoping your husband experiences a positive difference in doing the plan.