Kinetics of olfactory function following endonasal sinus surgery for nasal polyposis

Sinus surgery is known to improve olfactory function in patients with nasal polyposis. However, little is known about the kinetics of this process.

Fifty-two adult patients with nasal polyposis underwent endonasal sinus surgery. Olfactory testing was performed with the Sniffin' Sticks assessing threshold (T), discrimination (D) and identification (I) giving the TDI score. Testing was performed 2 days prior to surgery (T1), as well as 1 week (T2), 1 month (T3), 3 months (T4), and 6 months (T5) following surgery.

The median TDI score was 15.4 (range 8.0-35.5) at T1, indicating that half the patients were anosmic before surgery, while 13.5% were normosmic. At T2, the median TDI score dropped to 8.0 (range 8.0-32.1). Thereafter, it improved to 21.7 (range 8.0-36.9) at T3 (p = 0.04), 22.8 (range 8.0-38.0) at T4 (p < 0.0005), and 27.0 (range 8.0-37.9) at T5 (p < 0.0005), respectively. 43.1% of patients were normosmic at T5, however, 21.6% remained anosmic. Each subtest followed the same pattern. No significant effect on the kinetics of olfactory function could be found for variables such as systemic steroids, partial resection of the middle turbinate, inferior turbinotomy, and allergic rhinitis.

Endonasal sinus surgery significantly improved the severely impaired olfactory function in patients with nasal polyposis. Olfactory function dropped shortly after surgery, and subsequently increased steadily up to the endpoint of the study 6 months postoperatively.