Research is key when seeking new treatment and management strategies for children with sleep disorders

Recent research has now established fairly convincingly that sleep apnea and other primary sleep disorders are common in children, but seldom diagnosed—let alone addressed. And that is not all. Studies exploring other aspects of pediatric sleep are uncovering a variety of insights on matters ranging from the polysomnographic testing of kids to the behavioral problems exhibited by the child who fails to achieve deep, restful sleep.

“New and useful data have come out in the last 2 or 3 years in this field,” says Ronald D. Chervin, MD, MS, director of the Sleep Disorders Center, Department of Neurology, University of Michigan, Ann Arbor. “We’re seeing, for example, new data establishing a link between periodic limb movement disorder in children during sleep and cognitive and behavioral difficulties.

“Studies also are beginning to tell us about nasal pressure monitoring for children. On the adult side, the development of nasal pressure monitoring to replace thermistors and thermocouples has been an issue for the last few years, but some concern has been raised that the monitoring cannula would obstruct small nares. So we don’t know completely whether and to what extent nasal pressure is a better option in children, although there have been data in the last couple of years that seem to show that by using nasal pressure you do detect many more respiratory events.”

Researchers are learning, too, about how genetics impacts on childhood sleep problems. “There are interesting data coming out that sleep apnea definitely runs in families,” Chervin says. “Certain traits, medical backgrounds, and race can sometimes affect the odds of a child having sleep apnea. There is an indication in the last several years that African-American children have sleep apnea more often than non-African-American children. Similarly, the chances of a child having sleep apnea seem to be higher if one adult in the family has it.”

It also is coming to be understood that some sleep disorders previously thought to afflict only adults actually begin manifesting in childhood. Narcolepsy is one example. Investigators in China and the United States working as a team not long ago indicated that perhaps as many as half of the adult narcoleptics experienced symptoms in childhood. That insight prompted the researchers to examine an effort at one pediatric referral hospital in North China to create a recognition profile aimed at diagnosing narcolepsy in children. According to the investigators, the recognition profile—which entails use of testing for the presence of human leukocyte antigen in conjunction with the administration of multiple sleep latency testing—was able to identify a surprising number of children with narcolepsy syndromes.¹

No Place Like Home?
On the testing front, recent work has begun showing that even very young children might be able to undergo sleep monitoring at home, Chervin reports.

“Of course, we have at this juncture little data on the utility or cost-effectiveness of home studies in children; what we do have now is data suggesting that home polysomnography or modified versions of polysomnography for children can be done with reasonable accuracy and reliability,” he says. “Most polysomnographers have been very hesitant to do home monitoring involving children. But the studies are at least showing it’s feasible, that you don’t lose a lot of data since children are not going to necessarily be pulling off the electrodes. Most of the time you do get reasonable data back, so home testing is at least looking more promising in the future.”

Whether testing is conducted in the home or in a laboratory, it is plainer than ever that what is acceptable on an adult’s sleep study may be grounds for concern on a child’s, and vice versa, Chervin tells. “It is uncommon for a child who has sleep-disordered breathing and is suffering the consequences to show frank sleep apnea with 10-second periods of no breathing, which is the standard indication in an adult,” he says. “In children, the events often tend to be much shorter and they tend not to be full apnea. Children more often than adults will fail to show an arousal with an apneic event. But just because apnea doesn’t have an arousal doesn’t mean it’s not significant.”

According to Owens et al,² few of the sleep survey methods used in school-aged children examine both behaviorally based and medical sleep disorders, and most have not been formulated according to any of the standardized systems for categorization of clinical sleep disorders. Owens notes, for instance, that “...[T]he definition of a sleep ‘disturbance’ vs a sleep ‘behavior’ in these studies has been based on often arbitrary thresholds set by the authors and have not included parental definitions of sleep problems in the context of the individual family.”

Seeking to address this problem, Owens developed a survey for children between the ages of 4 and 10, called the Children’s Sleep Habits Questionnaire (CSHQ). “The design of the CSHQ is based in common clinical symptom presentations of the most prevalent pediatric International Classification of Sleep Disorders diagnoses,” Owens wrote. “The CSHQ is a retrospective, 45-item parent questionnaire. The CSHQ includes items relating to a number of key sleep domains that encompass the major presenting clinical sleep complaints in this age group: bedtime behavior and sleep onset; sleep duration; anxiety around sleep; behavior occurring during sleep and night walkings; sleep-disordered breathing; parasomnias; and morning waking/daytime sleepiness. Parents are asked to recall sleep behaviors occurring over a ‘typical’ recent week. Items are rated on a three-point scale: ‘usually’ if the sleep behavior occurred five to seven times/week; ‘sometimes’ for two to four times/week; and ‘rarely’ for zero to one time/week.”

Owens explains that the CSHQ is designed primarily to be a screening tool since the sleep domains reflected in seven of its eight subscales parallel symptom constellations associated with International Classification of Sleep Disorders categories that represent the most common sleep disorders in the age group; however, the CSHQ has limitations, Owens hastens to add.

“As in any parent report measure, the role of both parental and retrospective bias in completing the scale must be considered,” Owens writes. “Despite data suggesting that parental report is reasonably accurate for identifying many types of sleep disturbances when compared to objective data... parents of older children in particular may not always be aware of any difficulties in initiating and maintaining sleep.

“[Still], the CSHQ may have utility as a screening instrument for sleep disorders in the clinical practice setting....[A] brief parent-report survey such as the CSHQ could provide a relatively simple tool for identifying problematic sleep in a context of a well child encounter, for example. The eight CSHQ subscales roughly correspond to the most common presenting sleep complaints in pediatric practice. In particular, the CSHQ could be useful in identifying co-morbid sleep disturbances which might complicate the presentation of underlying medical or mental health concerns in children, including chronic illnesses and psychiatric diagnoses.”

Linking Sleep and Behavior
Attention deficit hyperactivity disorder (ADHD) has been a subject of significant interest to sleep researchers lately. “Studies making their way into the literature since 2000 have looked at daytime behavior and how it relates to nighttime sleep in children,” Chervin says. “Data have come out showing that children with sleep apnea, for example, tend to do worse in school. Indeed, whereas a primary effect of apnea in adults is overt daytime sleepiness, in children it may be just the opposite—daytime hyperactivity and disruptive behavior. Children with obstructive sleep-disordered breathing, in the form of obstructive sleep apnea or upper airway resistance syndrome, are reported to have inattentive, hyperactive, and aggressive behavior.”

One such study sought to assess a total of six sleep parameters in older children with ADHD and their normally developing peers through the use of multiple sleep measures. Each of these two groups consisted of 25 children—20 of whom were male—and ranged in age from 7 to 11. Parents completed a retrospective questionnaire that evaluated sleep problems over the prior 6 months. Each child wore an actigraph for 7 consecutive nights, during which time the parents compiled a sleep diary. The researchers observed that parents of children with ADHD reported significantly more sleep problems than parents of normally developing children. In particular, child-parent interactions during bedtime routines were more challenging in the ADHD group, which the researchers concluded might explain many of the sleep problems of children with ADHD.³

Chervin says the frequency with which ADHD and obstructive sleep-disordered breathing occur together in children is unknown, but believes that ADHD affects at least 5% of youngsters while undiagnosed obstructive sleep-disordered breathing is found in about 1% to 3% of all children.

Chervin, joined by University of Michigan colleague Kristen Hedger Archibold, RN, PhD, in 2000, studied hyperactivity in sleep-troubled children and came up with some rather interesting observations.⁴ “In that study we administered behavioral measures and looked at how laboratory polysomnography compares to those,” he says. “Somewhat to our surprise, we found there was no direct correlation between measures of apnea severity on the one hand and measures of hyperactivity severity on the other; however, we did find that children who had a high number of periodic leg movements during sleep did tend to be those with higher hyperactivity measures. This suggested to us that perhaps there is not a direct relationship between apnea and hyperactivity, but that maybe there is one between hyperactivity and periodic leg movements. Interestingly, this study still suggested that sleep apnea may play some role in the emergence of disruptive daytime behavior; the association between leg movements and hyperactivity occurred only in children with sleep apnea and not in those without sleep apnea.

“We have had some new data since then. For example, we studied a series of children who were scheduled for tonsillectomy, many of whom had sleep apnea. We looked to see the extent to which their polysomnographic variables predicted two different measures of hyperactivity. We found again that the most reliable predictor was periodic leg movement, even in this group that was selected only by being scheduled for a tonsillectomy.”

Team Approach
The good news is that, once obstructive sleep-disordered breathing is diagnosed and treated, clinical experience suggests behavior may improve and the stimulants prescribed to treat ADHD sometimes can be discontinued, Chervin says.

Meanwhile, because of the increased recognition of behavioral and other complexities in these children, sleep clinicians “should at least have it in the back of their mind that an undiagnosed sleep disorder could be a comorbid condition,” Chervin advises. “In the literature, there is at least some early support for the idea that diagnosing and treating sleep disorders in patients where there is comorbidity may lead to improvement not only of the sleep disorder but also of the behavioral situation.”

Looking ahead, Chervin says he expects to perhaps some day soon see new treatments and management strategies for these youngsters. “As just one illustration, there is interesting research into what extent we can treat restless legs and periodic limb movement disorder in children,” he says. “There is very little information on it, but a clinical trial of one promising drug is about to get under way and it will be interesting to see how this develops. “Sleep medicine is a relatively young field and pediatric sleep medicine is ‘younger’ still. It’s an exciting frontier that should produce substantial advances to help many children in years to come.”

Rich Smith is a contributing writer for Sleep Review.

References
1. Han F, Chen E, Wei H, et al. Childhood narcolepsy in North China. Sleep. 2001;24:321-324.
2. Owens JA, Spirito A, McGuinn M. The children’s sleep habits questionnaire (CSHQ): psychometric properties of a survey instrument for school-aged children. Sleep. 2000;23:1043-1051.
3. Corkum P, Tannock R, Moldofsky H, Hogg-Johnson S, Humphries T. Actigraphy and parental ratings of sleep in children with attention-deficit/hyperactivity disorder (ADHD). Sleep. 2001;24:303-312.
4. Chervin RD, Archbold KH. Hyperactivity and polysomnographic findings in children evaluated for sleep-disordered breathing. Sleep. 2001;24:313-320.