[1] Univ Calif San Francisco, Dept Neurol Surg, San Francisco, CA USA
[2] Univ Calif San Francisco, Dept Radiat Oncol, San Francisco, CA USA
[3] Univ Calif San Francisco, Dept Otolaryngol Head & Neck Surg, San Francisco, CA USA
[4] New York Med Coll, Sch Med, Valhalla, NY USA
[5] Univ Calif San Francisco, San Francisco, CA 94143 USA