Pediatric periodic limb movement disorder: sleep symptom and polysomnographic correlates compared to obstructive sleep apnea.

STUDY OBJECTIVES: Although periodic limb movements in sleep (PLMS) have been described in multiple pediatric publications, periodic limb movement disorder (PLMD) has not. The aims of this study were to describe the prevalence, sleep-related correlates, and polysomnographic correlates of PLMD in a large pediatric case series, and compare these to pediatric obstructive sleep apnea (OSA). METHODS: All PLMD cases (defined by International Classification of Sleep Disorders, 2nd edition criteria + respiratory disturbance index [RDI] < 3) and OSA cases (defined by RDI ≥ 3 + PLMS < 5), from a single pediatric sleep practice, over a 2-year time span, were included. Chart, questionnaire, and polysomnographic data were compiled. Of 468 referred children, 66 PLMD cases were identified (14%). RESULTS: The PLMD cases, mean age 8.1 years (range 1-17), were clinically characterized by frequent sleep onset and maintenance problems, difficulty awakening, restless sleep, leg pain/discomfort at night, and parasomnias. Compared to 90 OSA children, those with PLMD had a history of significantly more sleep onset and maintenance problems, leg pain/discomfort at night, parasomnias, getting out of bed at night, and family history of restless legs syndrome. Polysomnographically, PLMD cases had more awakenings, stage 1 sleep, stage shifts, and spontaneous arousals. CONCLUSIONS: These data indicate that pediatric PLMD has important clinical and polysomnographic correlates. In addition, PLMD has many characteristics that are different from pediatric OSA, suggesting that PLMD is a distinct pediatric sleep disorder, of which clinicians should be aware.

Parents of children with periodic limb movement disorder versus sleep-disordered breathing report greater daytime mood and behavior difficulties in their child: the importance of using ICSD-2nd Edition criteria to define a PLMD study group.

Data from 249 children referred to a pediatric sleep clinic were analyzed. The first question of interest examined whether an International Classification of Sleep Disorders-Second Edition (ICSD-2)-based diagnosis of periodic limb movement disorder (PLMD) or sleep-disordered breathing (SDB) would more strongly associate with parental perceptions of daytime attention and behavior problems in their child. The second question was whether the outcome would differ based on PLMD diagnostic criteria-that is, previously used criteria to define PLMD (Periodic Limb Movement Index [PLMI] < 5 per hour vs. PLMI >or= 5 per hour only) versus the ICSD-2 criteria. Parents of children with ICSD-2-defined PLMD perceived more problems with daytime behavior and attention, more symptoms of internalizing and externalizing, longer sleep latency, and more difficulty falling back to sleep than did parents of children with SDB. Most effects were lost when groups were defined by PLMI alone. The PLMI had acceptable sensitivity but low specificity in diagnosing PLMD.

Maternal cigarette-smoking during pregnancy disrupts rhythms in fetal heart rate.

OBJECTIVE: To examine the effects of maternal cigarette smoking during pregnancy on the developing infant's autonomic regulation before the possible effects of parturition and neonatal withdrawal could alter outcome measures. METHODS: Heart rate variability (HRV) was assessed for 10 min during late gestation for 21 cigarette-exposed (CE) and 22 nonexposed (NE) fetuses. RESULTS: HRV was significantly lower in fetuses whose mothers smoked cigarettes during pregnancy. Spectrum analysis of that variability showed temporally organized rhythms at a frequency similar to rhythms previously found in fetal cyclic motility (approximately .3 cycles per min). Lower powered rhythms--associated with poorer development--at the first, second, and dominant rhythms, as well as lower overall power of the power spectrum, were found for CE fetuses. Pearson correlations showed significant negative correlations between the amount of maternal cigarette smoking during the first trimester of pregnancy and measures of fetal HRV and power of spectral peaks. CONCLUSIONS: Results show that CE fetuses have lower HRV and disrupted temporal organization of autonomic regulation before effects of parturition, postnatal adaptation, and possible nicotine withdrawal contributes to differences in infant neurobehavioral function.

Fetal rate of behavioral inhibition and preference for novelty during infancy.

BACKGROUND: Correlations between infant measures of information processing and later IQ have been established, and a few studies have extended this continuum by examining links between various fetal measures and cognitive measures during infancy. AIMS: This study compared fetal rate of behavioral habituation among infants identified as at high or low cognitive risk. STUDY DESIGN: This study was a retrospective examination of differences in fetal rate of behavioral habituation as a function of cognitive risk status at 6.5 and 9 months postpartum, using an independent two-group design. SUBJECTS: Participants were 32 infants who were born between 36 and 42 weeks gestational age at normal birth weight and had normal APGAR scores. OUTCOME MEASURES: The Fagan Test of Infant Intelligence (FTII) was used to obtain a measure of preference for novelty, which served as the basis for identification of infants at high or low risk for cognitive difficulty. These infants had undergone up to three habituation trials using a vibroacoustic stimulus during fetal development. RESULTS: Infants who were classified as being at high cognitive risk at 6 months had required more trials to habituation as fetuses. CONCLUSIONS: Fetal rate of behavioral habituation is associated with information processing during the first 6 months of infancy. We suggest that fetal habituation may be influenced by early cognitive mechanisms and therefore represents an immature but real form of information processing.

Parent-reported periodic limb movement, sleep disordered breathing, bedtime resistance behaviors, and ADHD.

The purpose of this study was to compare the relative strength of association between symptoms of attention deficit/hyperactivity disorder (ADHD) with sleep disordered breathing (SDB), periodic limb movement disorder (PLMD), and bedtime resistance behaviors (BRBs). The Pediatric Sleep Questionnaire was completed by parents of 283 children. Scales were derived to indicate risk for specific sleep disorders, then correlated with symptoms of ADHD. Strong independent interrelationships between symptoms of PLMD and symptoms of ADHD emerged, with potential additional contributions by bedtime resistance. These interrelationships remained after controlling for age, SDB, sleepiness, or BRBs. These data suggest ADHD symptoms may be especially related to PLMD but that insufficient sleep duration secondary to bedtime resistance and noncompliance may make an independent contribution.

Prenatal cocaine exposure and infants' preference for novelty and distractibility.

The authors used the Fagan Test of Infant Intelligence (J. F. Fagan, L. T. Singer, J. E. Montie, & P. A. Shepherd, 1986) to examine preferences for novelty and to evaluate several indicators of attention (off- and on-task indexes and durations) in 6- and 9-month-old infants who had been prenatally exposed to cigarette smoke only or to cocaine plus other substances. The infants were matched for socioeconomic status. The authors found no group differences in preference for novelty, but the off-task distractibility index and duration were affected by exposure history and showed effects of dosage at the 9-month test time. Infants exposed to cocaine had a higher off-task index and a shorter average off-task look duration than did infants in the other groups. The authors interpreted this pattern of behavior as an indicator of distractibility or stimulation seeking. There were no group differences in measures involving on-task looks or duration at either test time. Correlations between the off-task look index and duration and teratogen use produced moderate correlations at 9 months of age. The authors calculated partial correlations between teratogen exposure and the off-task index at each trimester. Cocaine use during the 1st and 2nd trimesters was significantly correlated with the off-task index at 9 months of age, even when the authors controlled for neonatal measures (e.g., gestational age, birth weight) and during the 1st trimester when they controlled for alcohol and cigarette exposure.

Physician beliefs and practices regarding SIDS and SIDS risk reduction.

The AAP has alerted pediatricians to the importance of safe sleep environment for infants. The elements of a safe sleep environment include supine sleep position, safe crib, and avoidance of smoke exposure, soft bedding, and overheating. With the Back to Sleep campaign, prone sleeping among all U.S. infants has decreased to less than 20%, and the incidence of SIDS has decreased 40%. However, the decline in SIDS and prone sleeping has leveled off in recent years. Further declines may be possible with decreasing other modifiable risk factors, such as prenatal and postnatal exposure to cigarette smoking. Prior studies have demonstrated that health care professional advice is influential in determining infant care practices. It is important that physicians caring for infants be aware of the importance of a safe sleep environment and understand other modifiable risk factors for SIDS. We surveyed a random sample of 3,717 physicians in North Carolina and the metropolitan Washington, DC, area to determine knowledge, beliefs, and practices regarding SIDS and SIDS risk reduction among physicians caring for pregnant women and infants. Twenty-three percent (835) responded. Most physicians are aware of prone sleeping and cigarette smoke exposure as risk factors for SIDS. Almost all physicians agree that there are measures that can be taken to reduce the risk of SIDS, and they consider it important to discuss SIDS and SIDS risk reduction strategies with parents of young infants. In spite of this belief, only 56% of family/general practitioners, 18% of obstetrician-gynecologists, and 79% of pediatricians discuss SIDS routinely. Only 35% of pediatricians, 15% of family/general practitioners, and 16% of obstetrician-gynecologists provide written information. In addition, only 38% of physicians recommend supine, while 50% recommend side or back, 6% side, and 7% prone. Only two thirds of pediatricians and one third of family/general practitioners are aware that the AAP recommends supine as the preferred sleep position for infants. Pediatricians are more likely to be aware of the AAP recommendation (p<0.0001) and to discuss SIDS risk reduction strategies with parents (p=0.03). We conclude that many physicians who care for infants are unaware of the AAP's most current recommendation for sleep position and are incorrectly recommending the side position. Physicians may also be unaware of other sleep environment hazards. Further educational efforts must continue for physicians who provide care to pregnant women and children to ensure a continued decline in the incidence of SIDS.

State Control in the Substance-Exposed: Fetus I. The Fetal Neurobehavioral Profile: An Assessment of Fetal State, Arousal, and Regulation Competency.

Behavioral states are stable structures of behaviors that become more definable and coordinated with increasing age. With ultrasound we can see the fetus move, breathe, and react to changes in its environment. Ultrasound used in conjunction with Doppler fetal heart rate recording provides behavioral and neurophysiologic data useful in state determination. The Fetal neurobehavioral Profile (FNP) was developed by our group as an assessment of fetal behaviors reflecting CNS integrity in the drug-exposed fetus. The FNP was designed to parallel methods of examining the newborn infant, especially in state-related behaviors. The FNP measures: fetal responsiveness and arousal after environmental perturbation with vibroacoustic stimulation (VAS);habituation to VAS; state recovery; and self-regulation post-VAS. From the behavioral and physiologic recordings, the constructs of state differentiation, organization, and regulation as well as fetal arousal and regulation competency can be measured. Previous work using the FNP showed that those fetuses with abnormal or suspect fetal state regulation demonstrated impaired performance on the NBAS (Am. J. Obstet. Gynecol. 161: 685,1989). To expand these observations, three populations are currently being studied: prenatal nicotine-exposed, prenatal cocaine-exposed, and controls. Data are from 97 women/fetus dyads and a total of 236 FNP at ages 28-30 weeks gestational age, 31-34 weeks gestational age, and > 36 weeks gestational age. Although there are no group differences in the ability to achieve state by 36 weeks, interesting trends emerge: fetuses prenatally cocaine-exposed spend less time in 1F, more time in 4F, and have fewer transitions. At FNP1, fewer cocaine-exposed fetuses had an initial reaction to VAS, whereas fewer nicotine-exposed fetuses habituated. Although the ability to habituate to VAS did not discriminate the cocaine group from the control or nicotine groups, the number of stimuli required for habituation differed between groups: 7 for the cocaine-exposed, 3 for the nicotine, and 5 for the control groups. Thus latency, a measure of arousal, differs among these groups Preliminary data also susggest a correlation of prenatal data with postnatal outcome.