[Effect of endoscopic sinus surgery on olfactory function in patients with chronic rhinosinusitis with nasal polyps]

Objective:To evaluate the effect of surgery on olfactory function in patients with chronic rhinosinusitis with nasal polyps（CRSwNP） by subjective and objective olfactory tests. Method:This was a retrospective study. Forty patients with CRSwNP who underwent endoscopic sinus surgery（ESS） from 2015 to 2017 in Beijing Anzhen Hospital were enrolled. Postoperative time was 6-46 months. The patients were followed up in October 2018 and examined using Sniffin' sticks olfactory test and olfactory event-related potentials （oERP）. The polyps collected during surgery were performed to eosinophil count and percentage calculation. They were divided into eosinophilic CRSwNP（ECRS） and non-eosinophilic CRSwNP（NECRS）. The subjective and objective olfactory functions between the two groups were compared before and after surgery respectively and the paired T test was performed between the postoperative and the preoperative Sniffin' sticks olfactory test. Covariance analysis was used to adjust the effect of different postoperative time on postoperative olfactory recovery. Result:There were 21（52.5%） ECRS and 19（47.5%） NECRS patients of the 40 patients with nasal polyps. There was statistical difference in the posterior ethmoid score and the posterior olfactory cleft score of CT. According to the criterion of total TDI increased more than 5.5, olfactory function in 21（52.5%） patients had improved. In addition, there was a significant improvement in olfactory function in ECRS group either in unilateral T/TDI or bilateral T/D/TDI, but only unilateral T/TDI increased in NECRS group. There was no significant difference in Sniffin' sticks olfactory test between the two groups, but there was a statistically significant difference in the latency of oERP after surgery. Conclusion:ESS could improve olfactory function in patients with CRSwNP by more than 50%. Bilateral olfactory improvement in ECRS was better than that in NECRS, but olfactory function in postoperative ECRS was still lower than that in NECRS. oERP can more objectively and accurately reflect the severity of olfactory disorders associated with eosinophilic inflammation.