Computational investigation of empty nose syndrome

Empty nose syndrome (ENS) is a rare but debilitating condition commonly resulting from resection of part or all of the inferior turbinate (Figure 1). The characteristic yet most perplexing symptom of ENS is the complaint of nasal obstruction despite objectively patent airways, termed paradoxical nasal obstruction. As benign as it sounds, the feeling of obstruction to nasal breathing can have a significant influence on patients’ well-being and cannot be remedied simply by instruction to breathe through the mouth. Patients feel constant discomfort during breathing and often get a feeling of mild suffocation which can result in symptoms such as irritability, exhaustion, or anxiety. Furthermore, ENS often occurs in patients suffering from atrophic rhinitis (AR). There has been debate as to whether ENS is a form of AR or a separate entity in itself, but many patients with ENS also present symptoms such as nasal crusting or malodor inside the nose. Computational fluid dynamics (CFD) offers a unique opportunity to study nasal airflow, allowing the visualization and quantification of airflow characteristics inside the nose. Nasal geometry can be generated from computed tomography (CT) scan data allowing simulation of patient-specific geometries. Little is known about the pathophysiology of ENS, many have speculated; however, few have simulated flow through nasal geometries of patients presenting symptoms of ENS. It has been widely proposed that the paradoxical nasal obstruction is linked to the [lack of] activation of thermoreceptors in the mucous membrane of the nose during convective cooling. It is unknown if symptoms arise out of damage to these receptors or from unfavorable airflow characteristics, but it has been shown that symptoms can be improved through nasal reconstructive surgery. The aims of this work are twofold, to further understand ENS through simulation of patients suffering from the condition, and to develop predictive capability to help determine patients who may be susceptible to ENS after turbinate resection. This information may be used as a surgical planning tool to inform turbinate resection or reconstruction surgery through the use of shape optimization of the interior geometry of the nose. The project remains in its early stages, and an outline of the progress made so far is presented here.