1. Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts.
2. Department of Otolaryngology, Massachusetts Eye and Ear, Boston, Massachusetts.
3. Department of Radiology, Massachusetts Eye and Ear, Boston, Massachusetts.
4. Department of Otolaryngology-Head and Neck Surgery, University of Arizona College of Medicine, Tucson, Arizona.
5. Department of Physical Medicine and Rehabilitation, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.
6. Department of Neurosurgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.