ENT • ORIGINAL ARTICLE Impact of rapid palatal expansion on the internal nasal valve and obstructive nasal symptoms in children Audrey Yoon 1,2 & Mohamed Abdelwahab 3,4 & Stanley Liu 3 & James Oh 1 & Heeyeon Suh 2 & Michael Trieu 5 & Kevin Kang 5 & Daniela Silva 1 Received: 23 March 2020 /Revised: 15 June 2020 /Accepted: 24 June 2020 # Springer Nature Switzerland AG 2020 Abstract Objective The aim of this study is to evaluate the impact of rapid palatal expansion (RPE) on the nasal airway subjectively by utilizing patient-reported outcome measures (PROM) and objectively by evaluating validated internal nasal valve (INV) measurements obtained from cone beam computed tomography (CBCT) in pediatrics. Materials and methods In this retrospective cohort study, subjects who underwent RPE from March to December 2018 with cone beam CT and Nasal Obstruction Symptom Evaluation (NOSE) scores were included. Exclusion criteria included cranio- facial deformity, allergies, asthma, recent nasal trauma, or surgery. INV measurements (angle and cross-sectional area), diastema, midpalatal suture opening, and NOSE scores were evaluated. Results Fifty-one subjects met the inclusion criteria with a mean age of 10.1 ± 2.6. Pre-expansion mean NOSE score was 32.55 (moderate) while post-expansion was 13.92 (mild). Mean NOSE score improved significantly by an average of 18.63 following post-expansion (P < 0.0001). The patients’ right and left INV angles increased significantly by a mean of 2.42° and 2.65° respectively (P < 0.0001). Right and left INV cross-sectional areas increased significantly by an average of 14.35 mm 2 (P < 0.0001) and 14.17 mm 2 (P < 0.0001) respectively. An average expansion of the diastema and the suture was 1.60 mm and 3.05 mm respectively (P < 0.0001), with an average of 6.29 mm of expansion. We found the amount of diastema expansion to correlate with change in NOSE score (R = - 0.32, P = 0.022). Age and diastema showed a negative correlation (R = - 0.44, P = 0.0019), while INV angle and diastema showed a statistically significant positive correlation (R = 0.28, P = 0.048). Conclusions RPE showed improvement in both NOSE scores and objective measures of the INV. This may show the possibility of considering RPE in managing resistant pediatric nasal airways. Future studies should include collaboration with pediatric otolaryngologists, with the inclusion of pediatric patients with persistent nasal obstruction. Keywords Rapid palatal expansion . Internal nasal valve . Midpalatal suture . Nasal obstruction in children . Rapid maxillary expander . Nasal breathing Introduction Nasal obstruction is a common symptom presenting to both primary care physicians and otolaryngologists with estimates of approximately one-third of the US population afflicted to varying degrees. Potential etiologies include anatomic, phys- iologic, and pathophysiologic factors [1, 2]. During inspira- tion, air enters through the vestibule of the nose and flows through the nasal valves, the nasal cavity, and nasopharynx [1, 2]. Obstruction or narrowing along any component of the upper airway can disrupt normal breathing and is a critical component in obstructive sleep apnea [3]. The internal nasal valve (INV) is the narrowest cross-sectional area within the upper airway. It represents 50% of the total airflow resistance * Daniela Silva drsilva@dentistry.ucla.edu 1 Sections of Pediatric Dentistry and Orthodontics, Division of Growth and Development, UCLA School of Dentistry, Los Angeles, CA 90095, USA 2 Department of Orthodontics, Arthur A. Dugoni School of Dentistry at the University of the Pacific, San Francisco, CA 94103, USA 3 Division of Sleep Surgery, Department of Otolaryngology-Head & Neck Surgery, School of Medicine, Stanford University, Stanford, CA 94305, USA 4 Department of Otolaryngology - Head & Neck Surgery, Faculty of Medicine, Mansoura University, Mansoura 35516, Egypt 5 UCLA School of Dentistry, Los Angeles, CA 90095, USA Sleep and Breathing https://doi.org/10.1007/s11325-020-02140-y