Does olfactory function improve after endoscopic sinus surgery?

OBJECTIVE: To examine the impact of endoscopic sinus surgery (ESS) on olfactory impairment in patients with chronic rhinosinusitis (CRS) over intermediate and long-term follow-up. We hypothesized that patients with mild olfactory dysfunction (hyposmia) would benefit from ESS, whereas patients with severe olfactory dysfunction (anosmia) would not. STUDY DESIGN: Prospective, multi-institutional cohort study. SUBJECTS AND METHODS: A total of 111 patients presenting for ESS for treatment of CRS were examined preoperatively, and at 6 and 12 months postoperatively. Demographic, comorbidity, and Smell Identification Test (SIT) data were collected at each time point. Univariate and multivariate analyses were performed. RESULTS: The prevalence of gender-adjusted olfactory dysfunction prior to surgery was 67.5 percent. Surprisingly, hyposmic patients did not significantly improve after surgery. In contrast, patients with anosmia significantly improved after ESS (baseline, 6-month SIT scores: 9.7 +/- 2.0, 21.3 +/- 11.2; P = 0.001). Improvement was sustained at 12-month follow-up (21.7 +/- 10.7; P = 0.001). Multivariate linear regression analysis showed that baseline olfactory category and nasal polyposis were significantly associated with improvement in postoperative olfactory function (P = 0.035, P = 0.002). CONCLUSION: Contrary to our hypotheses, patients with severe olfactory dysfunction significantly improved after ESS and sustained improvement over time, whereas patients with mild olfactory dysfunction did not.