1. Department of Otolaryngology; University of Pittsburgh School of Medicine; Pittsburgh Pennsylvania U.S.A.
2. Department of Neurological Surgery; University of Pittsburgh School of Medicine; Pittsburgh Pennsylvania U.S.A.
3. Department of Otolaryngology-Head and Neck Surgery; Albany Medical College; Albany New York U.S.A.
4. Department of Neurological Surgery; University Hospitals Birmingham NHS Foundation; Birmingham United Kingdom
5. Department of Radiology; University of Pittsburgh School of Medicine; Pittsburgh Pennsylvania U.S.A.