Septal deviation and nasal resistance: An investigation using virtual surgery and computational fluid dynamics.

Abstract

Septal deviation is an extremely common anatomic variation in healthy adults. However, there are no standard criteria to determine when a deviated septum is clinically relevant. Presently, selection of patients for septoplasty is based on mostly clinical examination, which is prone to observer bias and may lead to unsuccessful treatment. The objective of this article is twofold. First, we investigate whether the location of a septal deviation within the nasal passages affects nasal resistance. Second, we test whether computer simulations are consistent with rhinomanometry studies in predicting that anterior septal deviations increase nasal resistance more than posterior deviations. A three-dimensional computational model of a healthy nose was created from computed tomography scans. Geometry-deforming software was used to produce models with septal deviations. Computational fluid dynamics techniques were used to simulate nasal airflow and compute nasal resistance. Our results revealed that the posterior nasal cavity can accommodate significant septal deviations without a substantial increase in airway resistance. In contrast, a deviation in the nasal valve region more than doubled nasal resistance. These findings are in good agreement with the rhinomanometry literature and with the observation that patients with anterior septal deviations benefit the most from septoplasty. In the model, anterior septal deviations increased nasal resistance more than posterior deviations. This suggests, in agreement with the literature, that other causes of nasal obstruction (dysfunction of the nasal valve, allergy, etc.) should be carefully considered in patients with posterior septal deviations because such deviations may not affect nasal resistance. This study illustrates how computational modeling and virtual manipulation of the nasal geometry are useful to investigate nasal physiology.