Postoperative evaluation of olfactory dysfunction in eosinophilic chronic rhinosinusitis - comparison of histopathological and clinical findings

Background: Olfactory dysfunction in eosinophilic chronic rhinosinusitis (ECRS) is poorly understood. Objective: To compare olfactory mucosal injury due to eosinophil infiltration in ECRS with postoperative olfactory function. Methods: Seventeen ECRS patients (ECRS group) and 18 bilateral rhinosinusitis (non-ECRS group) patients were compared. At 3 and 12 months post-endoscopic sinus surgery (ESS), all patients were evaluated for subjective symptoms (nasal obstruction, nasal discharge and olfactory dysfunction), endoscopic nasal findings, CT score and T&T olfactometer recognition threshold test. The eosinophil count, OMP-positive cells and epithelial erosion in olfactory mucosa collected during ESS were compared with the postoperative olfactory function. Results: The non-ECRS group showed significant improvement in all clinical findings at 3 and 12 months, but the ECRS group showed worsening of the olfactory dysfunction symptoms and T&T olfactometer recognition threshold at 12 months because of recurrence of sinusitis. The groups differed significantly in the Delta T&T value (i.e. pre-ESS T&T recognition threshold - post-ESS T&T recognition threshold) at both 3 and 12 months, and the degree of olfactory improvement differed. Histologically, the ECRS group showed significantly more eosinophils, fewer OMP-positive cells and greater epithelial erosion than the non-ECRS group. Conclusions: Eosinophilic inflammation was thought to cause olfactory mucosal injury/dysfunction.