Olfactory changes at threshold and suprathreshold levels following septoplasty with partial inferior turbinectomy

Partial inferior turbinectomy with septoplasty is routinely carried out for airway obstruction. However, its effects on the sense of smell have not been systematically evaluated. The aim of this prospective study was to evaluate the influence of septoplasty with partial inferior turbinectomy on threshold and suprathreshold olfactory acuity. The subjects were 30 patients undergoing septoplasty including partial inferior turbinectomy. Olfactory function was determined by the "Sniffin' Sticks," which allow the assessment of odor thresholds, odor discrimination, and odor identification. The patients rated both olfactory function and nasal airflow using visual analog scales. Nasal airflow was measured by anterior rhinomanometry. Multivariate analyses of variance for repeated measures were used to analyze the results before and after surgery (mean interval, 9.1 weeks). After operation, 87% of the patients had increased airflow, 80% had improved olfactory function in terms of odor identification, and in 70% odor discrimination was found to be improved - but only 54% had improved olfactory function in terms of odor thresholds. Surgery increased ratings of nasal airflow in 93%, and those of olfactory function in 77% (p < .001). Similarly, bilateral inspiratory nasal flow increased (p < .001) and olfactory function was improved (p < .001) after surgical treatment. However, this increase was most pronounced for suprathreshold tests, while it was moderate for odor thresholds (interaction "surgery" x "olfactory test," p = .001). The present investigation suggests that septoplasty in combination with inferior turbinectomy has a beneficial effect on olfaction, mainly on suprathreshold olfactory functions. This effect may be partly due to interactions between the increased perception of nasal airflow and cognitive factors involved in olfactory sensitivity. According to the present results and data from the literature, a moderate decrease of olfactory function appears to occur in as many as 20% of patients. However, anosmia seems to be an extremely rare complication of septoplasty and partial turbinectomy.