Long-term olfaction outcomes in transnasal endoscopic skull-base surgery: a prospective cohort study comparing electrocautery and cold knife upper septal limb incision techniques

Background: Olfactory nerve fibers are at risk of injury during transnasal endoscopic skull-base approaches. Olfactory outcomes for various techniques have not been thoroughly investigated. This study aims to report long-term olfactory outcomes when a cold knife upper septal limb incision technique is used compared to monopolar cautery. Methods: A prospective cohort study was performed at a tertiary referral center. Adult patients undergoing endoscopic approaches with septal incisions were randomized to cold knife or monopolar cautery groups. Patient demographics, clinical history, surgical data, and outcomes were collected. Preoperative, 3-month, and 12-month postoperative scores on the University of Pennsylvania Smell Inventory Test (UPSIT) and 22-item Sino-Nasal Outcome Test (SNOT-22) were measured. Fisher's exact tests were performed for categorical variables and t tests were performed for continuous variables. Results: Twenty-two (22) patients (10 cold knife, 12 cautery) were enrolled between March 2016 and August 2017. The average age ± standard deviation was 50.2 ± 14.0 years (p = 0.59), 54% (p = 0.69) were female, and the primary pathology was pituitary adenoma (73%, p = 1.00). Preoperative, 3-month, and 12-month postoperative UPSIT scores were similar between the cold knife and cautery groups (32.8 vs 32.4, p = 0.80; 33.1 vs 33.0, p = 0.96; 33.6 vs 33.3, p = 0.84). On the “sense of smell/taste” question of the SNOT-22, there was also no difference at all time points (p > 0.22). Conclusion: There was no significant change in patient UPSIT scores 1 year after transnasal skull-base approaches, and no short-term or long-term differences between cold knife and cautery upper septal limb incision techniques. Our study supports an individualized approach based on surgeon preference.