[1] Univ Alberta, 1E4 Univ Alberta Hosp, Dept Surg, Div Otolaryngol Head & Neck Surg, Edmonton, AB T6G 2B7, Canada
[2] McMaster Univ, Dept Surg, Div Otolaryngol Head & Neck Surg, Room G811,50 Charlton Ave, Hamilton, ON L8N 4A6, Canada
[3] Univ Alberta, Div Pulm Med, Dept Med, 3-105 Cent Serv Bldg, Edmonton, AB, Canada