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Stanford, CA
Drs. Guilleminault and Lee are affiliated with the Stanford University Sleep Disorders Clinic.
Correspondence to: Christian Guilleminault, MD, BiolD, Stanford University Sleep Disorders Clinic, 401 Quarry Rd, No. 3301, Stanford, CA 94305l; e-mail: cguil{at}stanford.edu
The American Academy of Pediatrics1 has recommended that all children who snore be evaluated. The best test to investigate whether snoring is a health risk is the nocturnal polysomnogram. But there are many variations in what are considered to be normal or abnormal polysomnograms in children. The article by Li and colleagues in this issue of CHEST (see page 1467) is an example of the problems associated with the use of standard guidelines derived from criteria that were initially developed for adult sleep-disordered breathing (SDB). In their study, on 2 nights of polysomnography in children, these authors indicated that "We classified an individual with normal obstructive apnea index but with nocturnal snoring for > 4 nights per week as suffering from primary snoring." They argue that the absence of consensus did not allow the selection of any other definition of SDB. Many questions are raised by this study, which relate to the following: (1) the definition of the children’s group (ie, is age sufficient to define grouping?); (2) the use, for research purposes, of an obstructive apnea index when we know that SDB in children is rarely associated with sleep apnea; (3) can we expect good research outcome from usage of limited equipment for home recording?; and finally, (4) does "primary snoring" really exist?
Regarding age, age grouping is important in children, but to ignore the occurrence of puberty that leads to enlargement of tongue and mucosa, particularly the nasal mucosa, is a problem. We systematically use Tanner staging,2 particularly for patients between 9 and 15 years of age. Even if Tanner staging involves a subjective component, this allows us to place teenagers who are in Tanner stage 5 in the "young adult scoring criteria" group. In considering the effect on sleep and on the size of the upper airway, we integrate Tanner staging in the formation of our subgroup of patients who are 10 to 14 years old. A 10 or 11-year-old patient who is in Tanner stage 1 is not the same as one who is in Tanner stage 2 or 3. Age is also important in that, by 2 years of age, > 98% of children in our normative database have a respiratory rate during any stage of sleep of < 20 breaths/min. This allows us to calculate easily the number of 30-s epochs with elevated respiratory rates. As breathing frequency x tidal volume = minute ventilation, tachypnea during sleep that is associated with snoring is a polysomnographic indication of abnormal breathing, which was distinctly shown in an outcome study looking also at clinical complaints.34 But age subdivision is also critical during the prepuberty years, as 60% of the adult craniofacial features will be developed by 4years of age, and 90% by around 12 years of age.5 The investigation of craniofacial growth patterns is important, and the impairment of skeletal maxillomandibular growth is critical when considering a diagnosis of SDB. The impairment of nasal breathing leads to noisy breathing, increases in respiratory effort, mouth breathing, and further abnormal skeletal development that can impact on upper airway size. This skeletal change occurs much before the puberty-related soft-tissue enlargement.
With regard to the choice of the apnea index as the sole selection criterion, abnormal breathing during sleep has been linked, for example, to sleepwalking, sleep terror, bedwetting, anxiety, phobia, aggressive behavior, inattention, hyperactivity, school difficulties, morning headache, nausea, vomiting, and reflux, and all these symptoms have been seen in patients with an obstructive apnea index of < 1, but with a variable degree of flow limitation, indicating the failure of the scoring system.3
Also quite frequently, little effort is made to integrate our great amount of knowledge on the impact of regular snoring, mouth breathing, and abnormal skeletal development4 with our knowledge of another health problem: snoring and SDB. The common view is that "crooked" teeth, malocclusion, cross-bite, tongue thrust, and overbite, for example, are in the domain of dentists, not pediatricians. But are they not also costly health problems? Orthodontic problems are present due to the abnormal skeletal development of the maxilla and mandible during these prepubertal years, and are most often seen in children who experience regular snoring and mouth breathing during sleep. A constricted maxilla will lead to nasal disuse and an elongated soft palate, a narrow mandible will lead to narrowing behind base of tongue, and both will further impact the skeletal growth and decrease the size of the upper airway (see bibliography in Gaultier and Guilleminault6). The indication of the problem could be a clinical complaint, but it could also be the presence of a high and narrow hard palate, the development of enlarged tonsils related also to mouth breathing,7 overlapping teeth, a large overbite or overjet, the recommendation of braces and orthodontic treatment, with regular snoring. The evaluation of clinical symptoms of abnormal breathing in children must involve the evaluation of orthodontic problems. This health problem must be taken as seriously as school problems, chronic sleepwalking, or daytime tiredness, perhaps even more, as maxillary and mandibular growth problems signal abnormal development of the skeletal support of the upper airway. And this abnormal skeletal development happens before the enlargement of soft tissues that will further reduce the size of the airway, setting the field for the development of adult sleep apnea.
With regard to the sleep studies, the recognition that limited change in airflow during sleep has important long-term consequences is not new by far,8 but specialists have hidden behind the difficulties of easily performing polysomnography at home due to the equipment involved. The Tucson Children’s Assessment of Sleep Apnea Study9 put this fear to rest. This study was performed at home on a large group of children who were recruited from the city school system. Commercially available equipment was used to record EEG and nasal cannula pressure transducer signals.10 This study has brought very valuable information to light concerning the frequency of sleep disorders in children. Such types of recordings can be replicated if valid data are the goal, and it should be possible to integrate such findings into a health-care system. There may be controversy about the criteria used to score SDB, but there is no controversy about the association of clinical problems in association with mild flow limitation during sleep.4 Children will try adapting to many respiratory challenges and may choose to breathe faster during sleep at a time when they cannot increase their effort, as in rapid eye movement sleep. These patterns are easy to recognize. To use criteria that are known to be too limited may limit greatly the finding of a research protocol.
And finally with regard to primary snoring, one has to investigate all health impairment, including the maxillomandibular changes that lead to orthodontic problems, before concluding that primary snoring is present. One must not have a myopic or specialty related view of what a pediatric health problem is. Chronic regular snoring always has had a health impact when we have investigated a child appropriately, and we have never seen a child with only primary snoring.
References
This article has been cited by other articles:
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  A. C. Halbower, S. L. Ishman, and B. M. McGinley Childhood Obstructive Sleep-Disordered Breathing: A Clinical Update and Discussion of Technological Innovations and Challenges Chest, December 1, 2007; 132(6): 2030 - 2041. [Abstract] [Full Text] [PDF]
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L. C.K. Leung, D. K. Ng, M. W. Lau, C.-h. Chan, K.-l. Kwok, P.-y. Chow, and J. M.Y. Cheung Twenty-Four-Hour Ambulatory BP in Snoring Children With Obstructive Sleep Apnea Syndrome. Chest, October 1, 2006; 130(4): 1009 - 1017. [Abstract] [Full Text] [PDF]
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D. K. Ng, C.-h. Chan, K.-L. Kwok, P.-y. Chow, J. M. Cheung, A. Li, and Y. K. Wing Necessity of 2-Night Polysomnographic Study in Children With Sleep-Related Disordered Breathing Chest, July 1, 2005; 128(1): 463 - 464. [Full Text] [PDF]
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