Olfactory function after microscopic endonasal surgery in patients with nasal polyps.

A controlled prospective study on 31 patients with nasal polyps was performed to evaluate the time course of olfactory function after endonasal surgery. A modified Connecticut Chemosensory Clinical Research Center (CCCRC) olfactory function test was used to measure olfactory threshold, odor identification ability, and odor discrimination ability. The test was performed in all patients 1-3 days before surgery (V1), 7-10 days after surgery (V2), and after 1 (V3), 2 (V4), 3 (V5), and 6 (V6) months. Mean olfactory threshold in the CCCRC butanol test was 4.19 at V1 (= moderate hyposmia). At V2, it decreased to 3.46 (= severe hyposmia), before increasing to 5.16 at V3 and 5.22 at V4 (= mild hyposmia). After the second postoperative month, olfactory threshold decreased again until the end of the study: 5.13 at V5 and 4.87 at V6 (= moderate hyposmia). The time course for odor identification ability and odor discrimination ability showed comparable results. This study demonstrates that olfactory function is impaired in patients with nasal polyps. Endonasal sinus surgery might improve olfactory function with best results within 3 months after surgery.