1. Medical College of Wisconsin, Milwaukee, Wisconsin, USA
2. University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
3. Medical University of South Carolina, Charleston, South Carolina, USA
4. Case Western Reserve University, Cleveland, Ohio, USA
5. University Hospital Mannheim, Mannheim, Germany
6. Saint Lucas Andreas Hospital, Amsterdam, Netherlands
7. University of Cincinnati Medical Center, Cincinnati, Ohio, USA
8. Wayne State University, Detroit, Michigan, USA
9. University of South Florida College of Medicine, Tampa, Florida, USA
10. Advanced ENT, Atlanta, Georgia, USA
11. Antwerp University Hospital, Edegem, Belgium