[1] Univ Colorado, Dept Neurosurg & Otolaryngol, Mail Stop C307,12631 East 17th Ave, Aurora, CO 80045 USA
[2] Univ Colorado, Dept Neurosurg, Aurora, CO USA
[3] Univ Colorado, Dept Otolaryngol, Aurora, CO USA
[4] St Josephs Hosp, Barrow Neurol Inst, Dept Neurosurg, Phoenix, AZ USA