Asymptomatic vs symptomatic septal perforations: a computational fluid dynamics examination

Abstract

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. 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. No statistical differences were found in perforation location, size (asymptomatic, 1.94 ± 1.88 cm2 ; symptomatic, 1.36 ± 1.44 cm2 ), 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/cm2 , 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. 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.