Mitomicin C (0.4 mg/ml) will be provided in a sterile vial and prepared by pharmacist at the Faculty of Medicine Ramathibodi Hospital.The treatment solution will be drawn and soaked ono two one inch neurosurgical cotton pledgets. Each pledget will be placed on each side of the nose for 5 minutes. The nurse will set the alarm for removal of the cotton pledgets, then normal saline will be used to irrigate both sides of the nose, using 100 ml on each side.

Identical placebo solution

Mitomicin C (0.4 mg/ml) will be provided in a sterile vial and prepared by pharmacist at the Faculty of Medicine Ramathibodi Hospital.The treatment solution will be drawn and soaked ono two one inch neurosurgical cotton pledgets. Each pledget will be placed on each side of the nose for 5 minutes. The nurse will set the alarm for removal of the cotton pledgets, then normal saline will be used to irrigate both sides of the nose, using 100 ml on each side.

The primary outcome of interest is time to event, with the event as the occurrence of nasal synechia. The date of surgery will be used as the beginning date, and the last date will be the date that patient was defined as synechia, or the end of the study period if that patient does not have synechia on follow up.

Scoring of translated SNOT-22 disease-specific quality of life measurement

Clinical symptom score of patients, measured by visual analog score which will be given by research nurse for a patient to fill in at baseline, 1 week, 1, 3, and 6 months.