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Commentary by David McIntosh; MBBS, FRACS, PhD; Paediatric ENT Specialist; Associate Professor, James Cook University in Australia

January 2019


Research and Clinical Otolaryngological Experience

I’m concerned about what currently seems to be misconceptions given to dentists and others about mouth breathing causing enlargement of the tonsils and adenoids. I’ve posted a bit about it recently, but now I have more to discuss. My intent is to provide evidence, so you may make your own mind up based on existing research. The following are some ideas we have heard expressed on this topic.

Idea: “Mouth breathing causes enlarged tonsils and adenoids due to low nitric oxide level exposure.” This paper demonstrates nitric oxide levels are normal, and if anything higher in those with large tonsils and adenoids:

Idea: “Mouth breathing means the filtration effect of the nose is lost.” If filtration by the nose was effective, the adenoids which are enlarged would have less bacteria and viruses in them and those children would have less colds and flus. However, large adenoids have more viral particles within them:

These ideas fail to address things such as research on the impact of having had glandular fever in terms of subsequent large adenoids:

Idea: “Mouth breathing impacts the temperature of the tonsils and adenoids.” Firstly, most body organs are the same temperature. If mouth breathing and temperature change were significant, we would theoretically see different sized tonsils and adenoids in kids living in a cold climate such as Alaska versus a hot climate such as the United Arab Emirates. But, we don’t see this in practice. Or, if we have people with a metabolic derangement such as an under active or over active thyroid (which would change core body temperatures), we would see the size of their tonsils changing which we don’t see clinically.

Idea: “Diaphragmatic movement is what primarily moves the lymph fluid from the tonsils and adenoids.” Now, first up, there is an element of truth in that the movement of the diaphragm helps lymph flow from the peritoneum. This is against gravity. All lymph flowing against gravity is pumped. This is not just by the diaphragm, which is a muscle, but by all of the muscles. Be it the fingers or toes, the muscles locally pump the lymph away.

So singling out the diaphragm does not account for all of the other muscles contributing to this process. If there was a genuine lymph flow problem, this would manifest itself as lymphoedema well before the tonsils and adenoids would somehow be affected. And likewise, all the other lymph glands around the neck would be affected which does not usually happen.

Lastly, in reference to lymphatic tissue, singling out tonsils and adenoids does not account for Waldeyer’s ring and the lingual tonsils. With the ideas expressed above, the lingual tonsils should be greatly enlarged in mouth breathers too. The reality is they are not enlarged very often as seen in clinical practice.

I draw your attention to these ideas as it is quite concerning when apparent misconceptions are circulated. This can be a disservice to patients and may compromise professional integrity if others happen to pass it on and are then later asked to justify the information. As I have said before, enlarged tonsils and adenoids may co-occur with mouth breathing, but there does not seem to be a cause and effect relationship.

Why Children Mouth Breathe

When a child presents with mouth breathing, there is usually a physical obstruction significant enough that nasal breathing is no longer adequate for ventilation: It does not have to be a complete blockage to be causing a problem: This article states, “... it is possible that the nasal obstruction does not completely block the upper airways, but can increase negative intrathoracic pressure, leading to sleep fragmentation.”

When forced, or encouraged, to breathe against resistance, the pressure drop within the lung cavity is magnified. This is the increase in the negative intrathoracic pressure to which the above quote refers. Children may be able to take in air through their noses, but increased effort can have a deleterious effect on the heart: The important thing to note is the right side of the heart fills with more blood when breathing against resistance. This means the heart needs to pump harder to empty the blood. As it does, this blood is pumped through the lungs. So, here is the next problem, 20-25% of children with upper airway obstruction have a condition called pulmonary hypertension.

Here are a few papers, including how surgery helps to alleviate airway upper airway obstruction:

When there is pulmonary hypertension, increased breathing effort to overcome resistance to airflow results in a worsening of the situation. This occurs because more blood goes to the right side of the heart, and the heart has to squeeze harder than normal against the resistance of the pulmonary circulation. The pressure level is too high.

So in a nutshell, when a child is a mouth breather, the first and most important person to be involved is an otolaryngologist (also known as an ear, nose, and throat doctor, ENT), so the doctor can determine if there is an obstruction and then treat appropriately. I teach and write about this topic.


It’s becoming apparent to me there is a misconception regarding the value of adeno-tonsillectomy for children with sleep disordered breathing within dental and other circles. The argument goes something like this: Surgery does not fix everyone in the short term. Of those it does fix, there are a percentage who then relapse later on. Given surgery does not help everyone, we need to find alternative treatments to surgery.

So here’s the problem. The role of surgery is not to effect a complete and long lasting cure but to deliver a prompt and immediate improvement in the airway from its starting baseline. In doing so, surgery will be adequate in the short term in 80% and in the long term for about 65% of children. We can actually achieve better results, but I’m quoting published averages.

There are a multitude of reasons for inadequate improvement in the short term and likewise a multitude of reasons for long term failure. Those failures do not change the role of surgery nor its timing.

I totally understand and appreciate the value of dental interventions and myofunctional therapy. But surgery comes first when appropriate. This means seeing an ENT when the child snores, mouth breathes, or has apnoeas. We need a quick fix, at the very least, to lessen the severity of the problem.

Research suggests surgery needs to occur within 6 months of the onset of the airway issue. I hope I’m explaining this properly. I’m trying to help people contemplate treatment protocols for kids. I’ve got plenty of references to back up this approach, and getting the sequence right is very important. Aside from that, the research shows improvements in maxillary arch form spontaneously after surgery and likewise a resolution of myofunctional issues in a high percentage of cases.  So, surgery is also helping those other treatments as well.

One longitudinal study of kids having adeno-tonsillectomy demonstrated lasting benefits: I was taught that adeno-tonsillectomy for children with sleep disordered breathing fixes 80% of children. However, it turns out that about 20% of those 80% will have relapses down the track. So that brings us to a magic number of 64% long term success with adeno-tonsillectomy alone. That last part is very important. I rarely find kids that need just tonsils and adenoids sorted. There is a whole range of other variables in play.

Here is the paper on 4,000 children assessed about 5 years after surgery with about 68% maintaining improvement: Reasons for relapse were not discussed, but associations with initial interventions and relapse were. The big one for me is age. The younger sleep disordered breathing begins, the more problems children are likely to have later on. The reasons for this are multifactorial, and we will become better at treating these kids for life. We are constantly learning more about what we did not know.

It’s a complicated story as discussed above. So, let me clarify this process. In any child who has sleep disordered breathing due to a problem with tonsils or adenoids, or both, benefits from surgery regardless of the short or long term research outcomes. It is the standard of care. Appropriate dental care and orofacial myofunctional therapy can be an important adjunct to this treatment when needed: This is a team approach.

People sometimes ask me what I believe about a certain aspects of otolaryngology. My answer is I do not believe any of it. All I can do is formulate an opinion based on the best available evidence, integrate that with my pre-existing knowledge and experience, and when the facts seem to be changing move progressively in the direction new knowledge suggests. A specific belief system is too rigid and given some of what I was taught has been proven to be wrong, then it is best not to hold too many beliefs.


Abreu, R. R., Rocha, R. L., Lamounier, J. A., & Guerra, Â. F. M. (2008). Etiology, clinical manifestations and concurrent findings in mouth-breathing children. Jornal de pediatria, 84(6), 529-535.

Arslan, H., Çandar, T., & Vural, Ö. (2018). Increased anti-EBV VCA IgG antibody levels are associated with need for surgery in patients developing upper respiratory tract complications. International Journal of Pediatric Otorhinolaryngology, 111, 84-88. doi: 10.1016/j.ijporl.2018.05.032

Camacho, M., Certal, V., Abdullatif, J., Zaghi, S., Ruoff, C. M., Capasso, R., & Kushida, C. A. (2015). Myofunctional therapy to treat obstructive sleep apnea: a systematic review and meta-analysis. Sleep, 38(5), 669-675.

Choi, J. H., Oh, J. I., Kim, T. M., Yoon, H. C., Park, I. H., Kim, T. H., ... & Lee, S. H. (2015). Long-term subjective and objective outcomes of adenotonsillectomy in Korean children with obstructive sleep apnea syndrome. Clinical and experimental otorhinolaryngology, 8(3), 256.

Cohen-Levy, J., Quintal, M. C., Abela, A., Rompré, P., Almeida, F. R., & Huynh, N. (2018). Persistent sleep disordered breathing after adenoidectomy and/or tonsillectomy: a long-term survey in a tertiary pediatric hospital. Sleep and Breathing, 22(4), 1197-1205.

Mahajan, M., Thakur, J. S., Azad, R. K., Mohindroo, N. K., & Negi, P. C. (2016). Cardiopulmonary functions and adenotonsillectomy: surgical indications need revision. The Journal of Laryngology & Otology, 130(12), 1120-1124.

Martha, V. F., da Silva Moreira, J., Martha, A. S., Velho, F. J., Eick, R. G., & Goncalves, S. C. (2013). Reversal of pulmonary hypertension in children after adenoidectomy or adenotonsillectomy. International journal of pediatric otorhinolaryngology, 77(2), 237-240.

Migueis, D. P., Thuler, L. C. S., de Andrade Lemes, L. N., Moreira, C. S. S., Joffily, L., & de Araujo-Melo, M. H. (2016). Systematic review: the influence of nasal obstruction on sleep apnea. Brazilian journal of otorhinolaryngology, 82(2), 223-231.

Orji, F. T., Ujunwa, F. A., Umedum, N. G., & Ukaegbe, O. (2017). The impact of adenotonsillectomy on pulmonary arterial pressure in West African children with adenotonsillar hypertrophy. International journal of pediatric otorhinolaryngology, 92, 151-155.

Pressman, G. S., Cepeda-Valery, B., Codolosa, N., Orban, M., Samuel, S. P., & Somers, V. K. (2016). Dynamic cycling in atrial size and flow during obstructive apnoea. Open heart, 3(1), e000348.

Torretta, S., Marchisio, P., Esposito, S., Garavello, W., Cappadona, M., Clemente, I. A., & Pignataro, L. (2011). Exhaled nitric oxide levels in children with chronic adenotonsillar disease. International journal of immunopathology and pharmacology, 24(2), 471-480.

About the Author

Associate Professor Dr. David McIntosh of ENT Specialists Australia was kind enough to write this month’s blog. He also contributes to Facebook groups collaborating with other specialists who manage breathing problems in children. They talk about mouth-breathing, and how it can lead to serious health concerns, in the hope that parents will take a proactive role in finding breathing problems in their own children and insist doctors take their concerns seriously.

David is a Paediatric ENT Specialist with a particular interest in airway obstruction, facial, and dental development and its relationship to ENT airway problems and middle ear disease. He also specialises in sinus disease and provides opinions on the benefit of revision of previous sinus operations. He is passionate about Indigenous Health. And, he has undertaken advanced surgical training in ENT and Head and Neck Surgery and Paediatric training at Starship Children’s Hospital in Auckland, New Zealand. He is the author of Snored to Death: Are You Dying in Your Sleep?

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