Inferior meatus augmentation procedure (IMAP) normalizes nasal airflow patterns in empty nose syndrome patients via computational fluid dynamics (CFD) modeling

BACKGROUND Empty nose syndrome (ENS) is a controversial upper airway disorder most commonly associated with tissue loss from the inferior turbinates. The inferior meatus augmentation procedure (IMAP) has been shown to effectively reduce ENS symptoms in a durable manner, but the precise mechanisms that may govern this symptomatic improvement remain unknown. METHODS Five patients with ENS who underwent bilateral IMAP via submucosal costal cartilage implant were assessed. Pre-implant and 6 months post-implant computed tomography (CT) imaging for each ENS patient was analyzed in a blinded fashion using computational fluid dynamics (CFD) modeling to investigate intrapatient changes in airflow parameters. RESULTS Following surgery, ENS patients have significantly improved symptoms as indexed by Empty Nose Syndrome 6-Item Questionnaire (ENS6Q) scoring (pre-implant: 14.00 ± 4.06 [mean ± standard deviation]; 95% confidence interval [CI], 10.44 to 17.56; post-implant: 4.8 ± 2.77; 95% CI, 2.37 to 7.23; Cohen's d = 2.64; p = 0.02). Using CFD, a significant shift in nasal airflow patterns was observed, where airflow deviates away from the middle meatus upon hitting the implant (pre-implant: 67.13% ± 11.14%; 95% CI, 60.22% to 74.04%; post-implant: 46.18% ± 12.81%; 95% CI, 38.23% to 54.12%; d = 1.74; p < 0.05) toward the inferior meatus (pre-implant: 30.55% ± 11.29%; 95% CI, 23.55% to 37.55%; post-implant: 42.59% ± 9.60%; 95% CI, 36.63 to 48.54%; d = 1.14; p < 0.05). No significant changes were found in nasal resistance (pre-implant: 0.102 ± 0.015; 95% CI, 0.092 to 0.112 Pa*s/mL; post-implant: 0.105 ± 0.041; 95% CI, 0.081 to 0.130 Pa*s/mL). In addition, the improvement of ENS6Q scoring significantly correlated with percent reduction in aberrant airflow through the middle meatus (R2 = 0.60, p = 0.04). CONCLUSION This study supports our prior working hypothesis that disordered vectors of nasal airflow congregate in the middle meatus contribute to ENS symptoms, not nasal resistance. Moreover, these data illuminate a paradoxical, but consistent, restoration of nasal airflow to the inferior meatus following the replacement of turbinate tissue volume in the inferior meatus via IMAP surgery, potentially due to the Coanda effect.