Asymptomatic vs symptomatic septal perforations: a computational fluid dynamics examination

Abstract

Background: A nasal septal perforation (NSP) can lead to frustrating symptoms for some patients while remaining completely asymptomatic for others, without a clear mechanism differentiating them. Methods:We applied individual computed tomography (CT)-based computational fluid dynamics (CFD) to examine the nasal aerodynamics differences between 5 asymptomatic and 15 symptomatic NSP patients. Patients' symptoms were confirmed through interviews, 22-item Sino-Nasal Outcome Test score (asymptomatic, 25 ± 18.8; symptomatic, 53.7 ± 18.2), nasal obstruction symptom evaluation score (asymptomatic, 28.0 ± 32.1; symptomatic, 62.2 ± 32.2), and review of medical history. Results:No statistical differences were found in perforation location, size (asymptomatic, 1.94 ± 1.88 cm 2 ; symptomatic, 1.36 ± 1.44 cm 2 ), nasal resistance (asymptomatic, 0.059 ± 0.012 Pa·s/mL; symptomatic, 0.063 ± 0.022 Pa·s/mL), and computed flow rate shunting across the perforation (asymptomatic, 52.9 ± 30.9 mL/s; symptomatic, 27.4 ± 23.6 mL/s; p > 0.05). However, symptomatic patients had significantly higher wall shear stress (WSS) and heat flux, especially along the posterior perforation margin (WSS, 0.54 ± 0.12 vs 1.15 ± 0.49 Pa, p < 0.001; heat flux, 0.21 ± 0.05 vs 0.37 ± 0.14 W/cm 2 , p < 0.01). A WSS cutoff at 0.72 Pa can separate asymptomatic vs symptomatic NSP with 87% sensitivity and 100% specificity. Flow visualization showed flow peaks toward the posterior margin that may be responsible for the high WSS and heat flux among symptomatic NSPs. Conclusion:This study is the first CFD examination of asymptomatic and symptomatic NSP with regional aerodynamics and stress abnormalities, beyond size or location, being implicated as the mechanism behind the symptomology of NSP. This finding could serve as an objective basis for future personalized treatment decisions and optimization. C 2019 ARS-AAOA, LLC. Key Words: nasal septal perforation; computational fluid dynamics; CT-based modeling; nasal airflow; nasal wall shear stress How to Cite this Article: Li C, Maza G, Farag AA, et al. Asymptomatic vs symptomatic septal perforations: a computational fluid dynamics examination. Int Forum Allergy Rhinol. 2019;9: 883-890.

The Relationship Between Nasal Obstruction Symptom Evaluation (NOSE) Scores and the Size and Location of Nasal Septal Perforations

“…While dryness, scabbing, epistaxis, and whistling are predominant symptoms in some patients, nasal obstruction is more common in others (1-3). Some patients can remain unaware of a perforation for many years and do not experience nasal obstruction (4). Upon evaluating the data for patients from the current study with the lowest and highest scores on the NOSE scale, the perforations were found to be close in size but were noted to have led to obstructions of varying degrees.…”

“…Some studies have also highlighted the importance of considering localization and size together. In a study where the symptoms of patients with NSP were evaluated with the Sino-Nasal Outcome Test-22 (SNOT-22), perforation sizes were found to be larger in asymptomatic patients than in symptomatic patients at a level that was not statistically significant (4). In another study where the sizes of NSPs were measured radiologically, the SNOT-22 values did not correlate with the sizes and positions of the NSPs (17).…”

“…Nasal septum perforation (NSP) is a condition in which both nasal passages are connected due to a full layer defect formed in the mucosa, cartilage, or bone section of the septum (1,2). It has a broad spectrum of symptoms, such as scabbing inside the nose, dryness, epistaxis, the formation of a whistling sound, impaired sense of smell, and breathing difficulty (3,4).…”

Repair of Septal Perforations

“…Li et al showed that the wall sheer stress (WSS) at this specific region of the perforation was closely correlated with patient symptoms, independent from location or size of the perforation. 34 The perfoplasty technique specifically modifies this posterior edge of the perforation which in turn leads to improved laminar flow through and past the perforation. Paradoxically, enlarging a small perforation in this fashion can actually lead to improved nasal breathing for the patient.…”

Numerical modelling of micron particle inhalation in a realistic nasal airway with pediatric adenoid hypertrophy: A virtual comparison between pre- and postoperative models

“…Numerous studies have explored approaches of measuring nasal airflow parameters by in-vitro experiments (11)(12)(13)(14). Gradually, compared with in-vitro replica experiment, researches trend to using computational fluid dynamics(CFD) method since its provides more accurate and detailed prospect of presenting complex and variable airflow patterns (15)(16)(17)(18). Compared with invitro studies, numerical simulation by computational fluid dynamics(CFD) method present significant advantages of providing rich flow patterns and inhalable particles transport.…”