PurposeTo investigate the correlation of tissue eosinophil count and chemosensory functions in patients with chronic rhinosinusitis with nasal polyps (CRSwNP) after endoscopic sinus surgery (ESS).MethodsThis was a cross-sectional study including 40 patients with a history of ESS for CRSwNP recruited consecutively. Visual analog scale score and the Lund-Kennedy endoscopic score were recorded. Biopsies of the ethmoidal sinus mucosal were performed and evaluated. Chemosensory functions were measured by Sniffin' Sticks and chemosensory event-related potentials (CSERP). The associations between chemosensory functions and tissue eosinophil count were analyzed using Spearman correlation and partial correlation after adjusting the confounding factors. Kendall's tau-b correlation was performed between sneezing score and CSERP with ethyl alcohol (EAL) stimulation.ResultsOlfactory and trigeminal nerve function was successfully evaluated using CSERP. Postoperative tissue eosinophil count was correlated with threshold (T) score (partial correlation coefficient r=-0.460, p=0.012) and CSERP peak latency for olfactory (N1: partial r=0.471, p=0.010; P2: partial r=0.487, p=0.007) and mixed olfactory-trigeminal (N1: partial r=-0.516, p=0.008; P2: partial r=-0.590, p=0.002). There were also correlations between T score and N1 latency with phenyl ethyl alcohol (PEA) (partial r=-0.560, p<0.001), between sneezing score and N1 latency with EAL (Kendall's tau-b=-0.40, p=0.005).ConclusionsPostoperative tissue eosinophilia is significantly associated with postoperative olfactory disorders as assessed by Sniffin' Sticks and CSERP peak latency. Furthermore, olfaction as measured by T score correlates with olfactory ERP latency in inflammation-associated olfactory dysfunction. Trigeminal sensitivity also appears to relate to tissue eosinophilia, indicating mucosal inflammation can affect both sensory systems in the nose.