Impact of Middle Turbinectomy on Airflow to the Olfactory Cleft: A Computational Fluid Dynamics Study

Abstract

Background The impact of middle turbinate resection (MTR) on olfaction remains a point of debate in the current literature. Few studies have objectively evaluated olfactory cleft airflow following MTR; thus, the mechanism by which MTR may impact olfaction is poorly understood. It is not known whether the postsurgical changes in airway volume, flow, and resistance increase odorant transport or disrupt the patterns of normal airflow. Computational fluid dynamics can be used to study the nasal airway and predict responses to surgical intervention. Objective To evaluate the functional impact of MTR on nasal airflow, resistance, and olfaction. Methods Five maxillofacial computed tomography scans of patients without signs of significant sinusitis or nasal polyposis were used. Control models for each patient were compared to their corresponding model after virtual total MTR. For each model, nasal airway volume, nasal resistance, and air flow rate were determined. Odorant transport of 3 different odorants in the nasal cavity was simulated based on the computed steady airflow field. Results Total airflow significantly increased following bilateral MTR in all patient models ( P < .05). Consistent with our airflow results, we found a decrease in nasal resistance following MTR. MTR significantly increased area averaged flux to the olfactory cleft when compared to controls for phenylethyl alcohol (high-sorptive odorant). Results for carvone (medium sorptive) were similarly elevated. MTR impact on limonene, a low flux odorant, was equivocal. Conclusion MTR increases nasal airflow while decreasing the nasal resistance. Overall, olfactory flux increased for high sorptive (phenylethyl alcohol) and medium sorpitve (l-carvone) odorants. However, the significant variation observed in one of our models suggests that the effects of MTR on the nasal airflow and the resultant olfaction can vary between individuals based on individual anatomic differences.

The cotton test redistributes nasal airflow in patients with empty nose syndrome

“…This suggests that the relationship between airflow distribution, regional airflow rate, and regional resistance may be exceedingly complex, and are important factors to consider when designing, implementing, or selecting implants for patients with ENS symptoms. This distribution of airflow in the presence of cotton placement is comparable with previous CFD results from healthy controls, and cotton parameters, such as volume and position, should be further explored to characterize its impact on optimizing the distribution of nasal airflow.…”

Editorial

“…Alam et al 9 applied computational fluid dynamics to evaluate the functional impact of middle turbinate resection in a virtual model on nasal airflow, resistance, and olfaction. Their results suggest that middle turbinate resection generally appears to increase nasal airflow while decreasing nasal resistance and may result in increased airflow to the olfactory region although this was variable within their data set.…”

Inhalation and deposition of spherical and pollen particles after middle turbinate resection in a human nasal cavity

“…There have been extensive computational studies investigating different nasal surgeries and their effect on nasal airflow (Xiong et al, 2008;Rhee et al, 2011;De Wang et al, 2012;Frank et al, 2013a;Hariri et al, 2015;Dayal et al, 2016;Maza et al, 2019;Inthavong et al, 2019;Siu et al, 2020a), which showed the ability of virtual surgery to guide surgical interventions to alleviate nasal airway obstruction. Previous CFD studies of middle turbinate resection (Zhao et al, 2014;Alam et al, 2019;Lee et al, 2016) have demonstrated shifts in airflow toward the area of middle turbinate resection and decreased airflow velocity, decreased wall shear stress, and increased local air pressure. Chen et al (2012) found that following functional endoscopic sinus surgery, a moderate inspiratory airflow rate and a particle diameter of approximately 10µm improved intranasal deposition into the maxillary sinuses.…”