Correlation between nasal anatomy and subjective patency: a prospective MRI study

Background: Variations in the thickness of the nasal septum are well documented¹ Objective: To determine if septal mucosal thickness and other parameters derived from MRI imaging correlate significantly with subjective sensation of nasal resistance. Methods: Forty patients undergoing MRI head scans for non-nasal disease were asked to complete a questionnaire immediately prior to the scan being taken. Subjective patency was scored for each nasal airway, patients were also asked about hayfever, URTIs, medication and history of nasal surgery or trauma. Scans were assessed using image analysis software. The following parameters were assessed at the level of the nasal valve: cross-sectional area of airway, horizontal thickness of inferior turbinate and maximum septal mucosal thickness. In addition, the presence of septal deviation (lateral to the vertical plane of the middle turbinate), and sinus mucosal thickening of 4 mm or more was assessed. Repeatability and inter-observer error was calculated. Data was analysed using non-parametric tests and multiple stepwise regression. Results: Overall correlation between anatomical parameters and subjective patency was low. Patients with sinus mucosal thickness greater than 4 mm on MRI scanning had subjectively poorer nasal airways (left P = 0.003, right P = 0.029). Multiple regression confirmed sinus mucosal thickening as the most significant predictor of patency but also negative correlation between ipsilateral mucosal thickness and patency (P < 0.002) and positive correlation between contralateral turbinate thickness (P < 0.01) and patency. Conclusions: Anatomical factors in both ipsilateral and contralateral nasal airways are of importance in subjective nasal patency. Sinus mucosal thickening correlates strongly with subjective nasal obstruction although the mechanism of this relationship is unclear. Non-anatomical and psychological factors are likely to be of considerable importance.