[1] Univ Minnesota Hosp & Clin, Dept Neurosurg, Minneapolis, MN 55455 USA
[2] Univ Minnesota Hosp & Clin, Dept Therapeut Radiol, Minneapolis, MN 55455 USA
[3] Univ Minnesota Hosp & Clin, Dept Internal Med, Div Infect Dis, Minneapolis, MN 55455 USA
[4] Univ Minnesota Hosp & Clin, Dept Otolaryngol Head & Neck Surg, Minneapolis, MN 55455 USA