[1] Aleris Hosp Trondheim, Ctr Endoscop Nasal & Sinus Surg, Trondheim, Norway
[2] St Olavs Univ Hosp, Dept Otolaryngol Head & Neck Surg, Trondheim, Norway
[3] Norwegian Univ Sci & Technol, Inst Neurosci, Trondheim, Norway
[4] NTNU, Med Fac, Dept Neurosci, N-7489 Trondheim, Norway