Sleep Polygraphic Study of Children and Adolescents With Narcolepsy/Cataplexy

Long sleep time and excessive need for sleep: State of the art and perspectives

The mechanisms underlying the individual need for sleep are unclear. Sleep duration is indeed influenced by multiple factors, such as genetic background, circadian and homeostatic processes, environmental factors, and sometimes transient disturbances such as infections. In some cases, the need for sleep dramatically and chronically increases, inducing a daily-life disability. This "excessive need for sleep" (ENS) was recently proposed and defined in a European Position Paper as a dimension of the hypersomnolence spectrum, "hypersomnia" being the objectified complaint of ENS. The most severe form of ENS has been described in Idiopathic Hypersomnia, a rare neurological disorder, but this disabling symptom can be also found in other hypersomnolence conditions. Because ENS has been defined recently, it remains a symptom poorly investigated and understood. However, protocols of long-term polysomnography recordings have been reported by expert centers in the last decades and open the way to a better understanding of ENS through a neurophysiological approach. In this narrative review, we will 1) present data related to the physiological and pathological variability of sleep duration and their mechanisms, 2) describe the published long-term polysomnography recording protocols, and 3) describe current neurophysiological tools to study sleep microstructure and discuss perspectives for a better understanding of ENS.

Sleep Stage Transitions and Sleep-Dependent Memory Consolidation in Children with Narcolepsy-Cataplexy

Electroencephalographic sleep stage transitions and altered first REM sleep period transitions have been identified as biomarkers of type 1 narcolepsy in adults, but not in children. Studies on memory complaints in narcolepsy have not yet investigated sleep-dependent memory consolidation. We aimed to explore stage transitions; more specifically altered REM sleep transition and its relationship with sleep-dependent memory consolidation in children with narcolepsy. Twenty-one children with narcolepsy-cataplexy and twenty-three healthy control children completed overnight polysomnography and sleep-dependent memory consolidation tests. Overnight transition rates (number of transitions per hour), global relative transition frequencies (number of transitions between a stage and all other stages/total number of transitions × 100), overnight transitions to REM sleep (transition from a given stage to REM/total REM transitions × 100), and altered first REM sleep period transitions (transitions from wake or N1 to the first REM period) were computed. Narcoleptic children had a significantly higher overnight transition rate with a higher global relative transition frequencies to wake. A lower sleep-dependent memory consolidation score found in children with narcolepsy was associated with a higher overnight transition frequency. As observed in narcoleptic adults, 90.48% of narcoleptic children exhibited an altered first REM sleep transition. As in adults, the altered sleep stage transition is also present in children with narcolepsy-cataplexy, and a higher transition rate could have an impact on sleep-dependent memory consolidation. These potential biomarkers could help diagnose type 1 narcolepsy in children more quickly; however, further studies with larger cohorts, including of those with type 2 narcolepsy and hypersomnia, are needed.

Restless Legs Syndrome and Restless Sleep Disorder in Children

Restless legs syndrome (RLS) affects 2% of children presenting with symptoms of insomnia, restless sleep, decreased quality of life, and effects on cognition and behavior. The International RLS Study Group and the American Academy of Sleep Medicine have published guidelines for the diagnosis and treatment of RLS in children. Restless sleep disorder has been recently identified in children and presents with frequent movements during sleep and daytime symptoms with polysomnography findings of at least 5 large muscle movements at night. Treatment options for both disorders include iron supplementation, either oral or intravenous with improvement in nighttime and daytime symptoms.

Restless Sleep Disorder (RSD): a New Sleep Disorder in Children. A Rapid Review

PURPOSE OF REVIEW

Restless sleep disorder (RSD) is a recently identified pediatric sleep disorder characterized by frequent movements during sleep associated with daytime symptoms. In this review we summarize the expanding evidence of the clinical presentation of RSD, potential pathophysiology, associated comorbidities, and current treatment options that will help the pediatrician identify children with RSD in a timely manner.

RECENT FINDINGS

RSD is diagnosed in 7.7% of children referred evaluated in a pediatric sleep center. Children with RSD present with frequent nightly movements during sleep for at least 3 months, and have daytime symptoms related to poor sleep quality including excessive sleepiness, hyperactivity, irritability among other symptoms. Current evidence shows an increased sympathetic predominance, increased NREM sleep instability, and iron deficiency, as well as increased prevalence in parasomnias and attention deficit hyperactivity disorder. Consensus diagnostic criteria were recently published to diagnose RSD and emergent evidence suggests that iron supplementation improves its nighttime and daytime symptoms.

Periodic limb movements during sleep: a narrative review

Objective

Using narrative review techniques, this paper evaluates the evidence for separable underlying patho-mechanisms of periodic limb movements (PLMs) to separable PLM motor patterns and phenotypes, in order to elucidate potential new treatment modalities.

Background

Periodic limb movement disorder (PLMD) is estimated to occur in 5–8% of the paediatric population and 4–11% of the general adult population. Due to significant sleep fragmentation, PLMD can lead to functional impairment, including hyperactivity and delayed language development in children, and poor concentration and work performance in adults. Longitudinal data demonstrate that those with PLMD are at greater risk of depression and anxiety, and a 4-fold greater risk of developing dementia. PLMD has been extensively studied over the past two decades, and several key insights into the genetic, pathophysiological, and neural correlates have been proposed. Amongst these proposals is the concept of separable PLM phenotypes, proposed on the basis of nocturnal features such as the ratio of limb movements and distribution throughout the night. PLM phenotype and presentation, however, varies significantly depending on the scoring utilized and the nocturnal features examined, across age, and co-morbid clinical conditions. Furthermore, associations between these phenotypes with major neurologic and psychiatric disorders remain controversial.

Methods

In order to elucidate potential divergent biological pathways that may help clarify important new treatment modalities, this paper utilizes narrative review and evaluates the evidence linking PLM motor patterns and phenotypes with hypothesised underlying patho-mechanisms. Distinctive, underlying patho-mechanisms include: a pure motor mechanism originating in the spinal cord, iron deficiency, dopamine system dysfunction, thalamic glutamatergic hyperactivity, and a more cortical-subcortical interplay. In support of the latter hypothesis, PLM rhythmicity appears tightly linked to the microarchitecture of sleep, not dissimilarly to the apnoeic/hypopneic events seen in obstructive sleep apnea (OSA).

Conclusions

This review closes with a proposal for greater investigation into the identification of potential, divergent biological pathways. To do so would require prospective, multimodal imaging clinical studies which may delineate differential responses to treatment in restless legs syndrome (RLS) without PLMS and PLMS without RLS. This could pave the way toward important new treatment modalities.

Leg movement activity during sleep in multiple sclerosis with and without restless legs syndrome

STUDY OBJECTIVES

To carry out an analysis of leg movement activity during sleep in a polysomnography dataset of patients with multiple sclerosis (MS) in comparison to idiopathic restless legs syndrome (iRLS) and healthy controls.

METHODS

In this cross-sectional, observational, instrumental study, 57 patients (males/females: 11/46; mean age 46.2 ± 10.2 years) with a diagnosis of MS underwent a telephone interview assessing the 5 standard diagnostic criteria for RLS and polysomnography. Sleep architecture and leg movement activity during sleep were subsequently compared: 1) 40 patients with MS without RLS (MS-RLS) vs 28 healthy controls; 2) 17 patients with MS with RLS (MS+RLS) vs 35 patients with iRLS; 3) MS+RLS vs MS-RLS.

RESULTS

MS-RLS and MS+RLS presented increased sleep latency, percentage of sleep stage N1, and reduced total sleep time compared to healthy controls and iRLS, respectively. The periodic limb movements during sleep (PLMS) index was higher in MS-RLS than in healthy controls (P = .035) and lower in MS+RLS compared to iRLS (P = .024). PLMS in MS+RLS were less periodic, less often bilateral, and with shorter single movements compared to the typical PLMS in iRLS.

CONCLUSIONS

MS is a risk factor for RLS, PLMS, and for a lower sleep quality in comparison to healthy patients. PLMS in MS+RLS are fewer and shorter if compared to iRLS. Our results suggest a dissociation between motor (PLMS) and sensory symptoms (RLS sensory component) in RLS secondary to MS, with possible treatment implications.

CITATION

Ferri R, Sparasci D, Castelnovo A, et al. Leg movement activity during sleep in multiple sclerosis with and without restless legs syndrome. J Clin Sleep Med. 2022;18(1):11-20.

Leg Movements during Sleep in Children Treated with Serotonergic Antidepressants

STUDY OBJECTIVES

To evaluate leg movements during sleep (LMS) in children taking serotonergic antidepressants, compared to those of children with restless legs syndrome (RLS) and controls, and to assess the time structure of intermovement intervals (IMI).

METHODS

Twenty-three children (12 girls, mean age 14.1 years) on antidepressants and with a total LMS index ≥15/hour, 21 drug-naïve RLS children (11 girls, mean age 13.6 years) also with total LMS index ≥15/hour, and 35 control children (17 girls, mean age 14.3 years) were recruited. LMS were scored and a series of parameters was calculated, along with the analysis of their time structure.

RESULTS

Children taking antidepressants showed higher total and periodic LMS (PLMS) indexes than both controls and RLS children, as well as higher short-interval and isolated LMS indexes than controls. LMS periodicity was highest in children on antidepressants. In children taking antidepressants, a well-defined PLMS IMI peak corresponding to ~10-60 s, with a maximum at ~20 s was present, which was much less evident in RLS patients and absent in controls. A progressive decrease of PLMS during the night and more frequent arousals were found in children on antidepressants and with RLS.

CONCLUSIONS

Children taking serotonergic antidepressants show higher periodicity LMS than children with RLS or controls and have a higher number of PLMS through the night. Antidepressant-associated PLMS in children seem to have features similar to PLMS of adults with RLS. Whether this is a marker of an increased risk to develop RLS later in life needs to be determined.

Cortical arousal frequency is increased in narcolepsy type 1

STUDY OBJECTIVES

Hypocretin deficient narcolepsy (type 1, NT1) presents with multiple sleep abnormalities including sleep-onset rapid eye movement (REM) periods (SOREMPs) and sleep fragmentation. We hypothesized that cortical arousals, as scored by an automatic detector, are elevated in NT1 and narcolepsy type 2 (NT2) patients as compared to control subjects.

METHODS

We analyzed nocturnal polysomnography (PSG) recordings from 25 NT1 patients, 20 NT2 patients, 18 clinical control subjects (CC, suspected central hypersomnia but with normal cerebrospinal (CSF) fluid hypocretin-1 (hcrt-1) levels and normal results on the multiple sleep latency test), and 37 healthy control (HC) subjects. Arousals were automatically scored using Multimodal Arousal Detector (MAD), a previously validated automatic wakefulness and arousal detector. Multiple linear regressions were used to compare arousal index (ArI) distributions across groups. Comparisons were corrected for age, sex, body-mass index, medication, apnea-hypopnea index, periodic leg movement index, and comorbid rapid eye movement sleep behavior disorder.

RESULTS

NT1 was associated with an average increase in ArI of 4.02 events/h (p = 0.0246) compared to HC and CC, while no difference was found between NT2 and control groups. Additionally, a low CSF hcrt-1 level was predictive of increased ArI in all the CC, NT2, and NT1 groups.

CONCLUSIONS

The results further support the hypothesis that a loss of hypocretin neurons causes fragmented sleep, which can be measured as an increased ArI as scored by the MAD.

Defining disrupted nighttime sleep and assessing its diagnostic utility for pediatric narcolepsy type 1

STUDY OBJECTIVES

Disrupted nighttime sleep (DNS) is a core narcolepsy symptom of unconsolidated sleep resulting from hypocretin neuron loss. In this study, we define a DNS objective measure and evaluate its diagnostic utility for pediatric narcolepsy type 1 (NT1).

METHODS

This was a retrospective, multisite, cross-sectional study of polysomnograms (PSGs) in 316 patients, ages 6-18 years (n = 150 NT1, n = 22 narcolepsy type 2, n = 27 idiopathic hypersomnia, and n = 117 subjectively sleepy subjects). We assessed sleep continuity PSG measures for (1) their associations with subjective and objective daytime sleepiness, daytime sleep onset REM periods (SOREMPs), self-reported disrupted nocturnal sleep and CSF hypocretin levels and (2) their predictive value for NT1 diagnosis. We then combined the best performing DNS measure with nocturnal SOREMP (nSOREMP) to assess the added value to the logistic regression model and the predictive accuracy for NT1 compared with nSOREMP alone.

RESULTS

The Wake/N1 Index (the number of transitions from any sleep stage to wake or NREM stage 1 normalized by total sleep time) was associated with objective daytime sleepiness, daytime SOREMPs, self-reported disrupted sleep, and CSF hypocretin levels (p's < 0.003) and held highest area under the receiver operator characteristic curves (AUC) for NT1 diagnosis. When combined with nSOREMP, the DNS index had greater accuracy for diagnosing NT1 (AUC = 0.91 [0.02]) than nSOREMP alone (AUC = 0.84 [0.02], likelihood ratio [LR] test p < 0.0001).

CONCLUSIONS

The Wake/N1 Index is an objective DNS measure that can quantify DNS severity in pediatric NT1. The Wake/N1 Index in combination with or without nSOREMP is a useful sleep biomarker that improves recognition of pediatric NT1 using only the nocturnal PSG.

Cardiovascular autonomic dysfunction, altered sleep architecture, and muscle overactivity during nocturnal sleep in pediatric patients with narcolepsy type 1

Study Objectives

Arterial blood pressure (ABP) decreases during sleep compared with wakefulness and this change is blunted in mouse models of and adult patients with narcolepsy type 1 (NT1). We tested whether: (1) pediatric patients with NT1 have similar cardiovascular autonomic abnormalities during nocturnal sleep; and (2) these abnormalities can be linked to hypocretin-1 cerebrospinal fluid concentration (CSF HCRT-1), sleep architecture, or muscle activity.

Methods

Laboratory polysomnographic studies were performed in 27 consecutive drug-naïve NT1 children or adolescents and in 19 matched controls. Nocturnal sleep architecture and submentalis (SM), tibialis anterior (TA), and hand extensor (HE) electromyographic (EMG) activity were analyzed. Cardiovascular autonomic function was assessed through the analysis of pulse transit time (PTT) and heart period (HP).

Results

PTT showed reduced lengthening during total sleep and REM sleep compared with nocturnal wakefulness in NT1 patients than in controls, whereas HP did not. NT1 patients had altered sleep architecture, higher SM EMG during REM sleep, and higher TA and HE EMG during N1–N3 and REM sleep when compared with controls. PTT alterations found in NT1 patients were more severe in subjects with lower CSF HRCT-1, but did not cluster or correlate with sleep architecture alterations or muscle overactivity during sleep.

Conclusion

Our results suggest that pediatric NT1 patients close to disease onset have impaired capability to modulate ABP as a function of nocturnal wake–sleep transitions, possibly as a direct consequence of hypocretin neuron loss. The relevance of this finding for cardiovascular risk later in life remains to be determined.

Clinical Characteristics and Burden of Illness in Pediatric Patients with Narcolepsy

BACKGROUND

Narcolepsy is a chronic and lifelong neurologic disorder with onset commonly occurring in childhood or adolescence, and affecting approximately 0.025% to 0.05% of the general population. The primary symptom is excessive daytime sleepiness, which is accompanied by cataplexy in 70% of patients. Other common symptoms include sleep paralysis, hallucinations upon falling asleep or waking, and disrupted nocturnal sleep. Narcolepsy is associated with a considerable burden of illness (BOI), which has been well characterized in adults, and is exacerbated by delays in symptom recognition, diagnosis, and intervention.

METHODS

This review describes the specific characteristics and BOI of pediatric narcolepsy, using a wide range of published research data.

RESULTS

Pediatric narcolepsy presents distinct challenges in diagnosis and management. Narcolepsy symptoms often initially manifest differently in children and adolescents versus adults, which may pose diagnostic dilemmas. Children often respond to sleepiness with irritability, hyperactivity, and poor attention, which may be misinterpreted as misbehavior or neurocognitive sequelae of other conditions. Pediatric cataplexy symptoms may include subtle and unusual facial expressions or choreic-like movements, which are not observed in adults. Insufficient sleep and circadian rhythm disorders presenting with excessive daytime sleepiness are common in adolescents, potentially confounding narcolepsy diagnosis. Pediatric narcolepsy is also associated with comorbidities including rapid weight gain, precocious puberty, and attention deficit hyperactivity disorder, and increased risk for deficits in social functioning, depression, and anxiety. School performance is also typically impaired, requiring special education services.

CONCLUSIONS

Thus, the discrete BOI of pediatric narcolepsy underscores the need for prompt and accurate diagnosis, and appropriate treatment of this disorder.

Impact of acute administration of sodium oxybate on heart rate variability in children with type 1 narcolepsy

BACKGROUND

Currently, cardiovascular measurements in children affected with type 1 narcolepsy (NT1) have never been investigated, and neither have their modulation by the administration of sodium oxybate (SO).

METHODS

Twelve drug-naïve NT1 children (four males, eight females) with a mean age of 11 ± 3.16 years underwent a nocturnal polysomnography, at baseline and during the first night of SO administration. Data were contrasted with those recorded in 23 age-matched healthy controls. Heart rate variability (HRV) analysis was performed by analyzing the electrocardiogram signal for automatic detection of R waves with a computer program calculating a series of standard time-domain measures and obtaining spectral parameters, by means of a Fast-Fourier Transform.

RESULTS

In sleep stages N2 and N3, NT1 children showed increased power in the low-frequency (LF) and very-LF (VLF) ranges, when compared to controls. In addition, HRV (as measured by time domain parameters) during all sleep stages tended to be slightly higher in patients when compared to controls. Treatment with SO did not change significantly any parameter, but an overall trend to mildly decreased HRV that reached a significant value only during R sleep.

CONCLUSIONS

HRV during all sleep stages tended to be slightly higher in young patients when compared to controls, confirming the presence of a slight sympathovagal system imbalance even in NT1 children. SO tends to decrease these values especially during REM sleep and in that regard, further studies supporting these preliminary findings and considering the long-term effects of SO on heart rate parameters are warranted.

The spectrum of REM sleep-related episodes in children with type 1 narcolepsy

Type 1 narcolepsy is a central hypersomnia due to the loss of hypocretin-producing neurons and characterized by cataplexy, excessive daytime sleepiness, sleep paralysis, hypnagogic hallucinations and disturbed nocturnal sleep. In children, close to the disease onset, type 1 narcolepsy has peculiar clinical features with severe cataplexy and a complex admixture of movement disorders occurring while awake. Motor dyscontrol during sleep has never been systematically investigated. Suspecting that abnormal motor control might affect also sleep, we systematically analysed motor events recorded by means of video polysomnography in 40 children with type 1 narcolepsy (20 females; mean age 11.8 ± 2.6 years) and compared these data with those recorded in 22 age- and sex-matched healthy controls. Motor events were classified as elementary movements, if brief and non-purposeful and complex behaviours, if simulating purposeful behaviours. Complex behaviours occurring during REM sleep were further classified as 'classically-defined' and 'pantomime-like' REM sleep behaviour disorder episodes, based on their duration and on their pattern (i.e. brief and vivid-energetic in the first case, longer and with subcontinuous gesturing mimicking daily life activity in the second case). Elementary movements emerging either from non-REM or REM sleep were present in both groups, even if those emerging from REM sleep were more numerous in the group of patients. Conversely, complex behaviours could be detected only in children with type 1 narcolepsy and were observed in 13 patients, with six having 'classically-defined' REM sleep behaviour disorder episodes and seven having 'pantomime-like' REM sleep behaviour disorder episodes. Complex behaviours during REM sleep tended to recur in a stereotyped fashion for several times during the night, up to be almost continuous. Patients displaying a more severe motor dyscontrol during REM sleep had also more severe motor disorder during daytime (i.e. status cataplecticus) and more complaints of disrupted nocturnal sleep and of excessive daytime sleepiness. The neurophysiological hallmark of this severe motor dyscontrol during REM sleep was a decreased atonia index. The present study reports for the first time the occurrence of a severe and peculiar motor disorder during REM sleep in paediatric type 1 narcolepsy and confirms the presence of a severe motor dyscontrol in these patients, emerging not only from wakefulness (i.e. status cataplecticus), but also from sleep (i.e. complex behaviours during REM sleep). This is probably related to the acute imbalance of the hypocretinergic system, which physiologically acts by promoting movements during wakefulness and suppressing them during sleep.

Sleep-Related Disorders in Children with Attention-Deficit Hyperactivity Disorder: Preliminary Results of a Full Sleep Assessment Study

BACKGROUND AND METHODS

We present the preliminary results of a prospective case-control sleep study in children with a diagnosis of attention-deficit hyperactivity disorder (ADHD). A deep sleep assessment including sleep questionnaires, sleep habits, a video-polysomnographic recording with full high-density electroencephalography (EEG) and cardiorespiratory polygraphy, multiple sleep latency test, and 1-week actigraphic recording were performed to verify whether children with ADHD may be classified into one of the following five phenotypes: (1) hypoarousal state, resembling narcolepsy, which may be considered a "primary" form of ADHD; (2) delayed sleep onset insomnia; (3) sleep-disordered breathing; (4) restless legs syndrome and/or periodic limb movements; and (5) sleep epilepsy and/or EEG interictal epileptiform discharges.

RESULTS

Fifteen consecutive outpatients with ADHD were recruited (two female, mean age 10.6 ± 2.2, age range 8-13.7 years) over 6 months. The narcolepsy-like sleep phenotype was observed in three children, the sleep onset insomnia phenotype was observed in one child, mild obstructive sleep apnea was observed in three children, sleep hyperkinesia and/or PLMs were observed in five children, while IEDs and or nocturnal epilepsy were observed in three children. Depending on the sleep phenotype, children received melatonin, iron supplementation, antiepileptic drugs, or stimulants.

CONCLUSIONS

Our study further highlights the need to design an efficient sleep diagnostic algorithm for children with ADHD, thereby more accurately identifying cases in which a full sleep assessment is indicated.

When insomnia is not just insomnia: the deeper correlates of disturbed sleep with reference to DSM-5

Recent scientific evidences have brought a paradigm shift in our approach towards the concepts of insomnia and its management. The differentiation between primary and secondary insomnia was proved more hypothetical than actual and based upon the current evidences insomnia subtypes described in earlier system have been lumped into one-insomnia disorder. Research in this field suggests that insomnia occurring during psychiatric or medical disorders has a bidirectional and interactive relationship with and coexisting medical and psychiatric illnesses. The new approach looks to coexist psychiatric or medical disorders as comorbid conditions and hence specifies two coexisting conditions. Therefore, the management and treatment plans should address both the conditions. A number of sleep disorders may present with insomnia like symptoms and these disorders should be treated efficiently in order to alleviate insomnia symptoms. In such cases, a thorough history from the patient and his/her bed-partner is warranted. Moreover, some patients may need polysomnography or other diagnostic tests like actigraphy to confirm the diagnosis of the underlying sleep disorder. DSM-5 classification system of sleep–wake disorders has several advantages, e.g., it has seen insomnia across different dimensions to make it clinically more useful; it focuses on the assessment of severity and guides the mental health professional when to refer a patient of insomnia to a sleep specialist; lastly, it may encourage the psychiatrists to opt for sleep medicine as a career.

Sleep cyclic alternating pattern and cognition in children: a review

Several studies have been recently focused on the relationship between sleep cyclic alternating pattern (CAP) and daytime cognitive performance, supporting the idea that the CAP slow components may play a role in sleep-related cognitive processes. Based on the results of these reports, it can be hypothesized that the analysis of CAP might be helpful in characterizing sleep microstructure patterns of different phenotypes of intellectual disability and a series of studies has been carried out that are reviewed in this paper. First the studies exploring the correlations between CAP and cognitive performance in normal adults and children are described; then, those analyzing the correlation between CAP and cognitive patterns of several developmental conditions with neurocognitive dysfunction (with or without mental retardation) are reported in detail in order to achieve a unitary view of the role of CAP in these conditions that allows to detect a particular "sleep microstructure phenotype" of children with neurologic/neuropsychiatric disorders.

Non-respiratory indications for polysomnography and related procedures in children: an evidence-based review

OBJECTIVE

This evidence-based review provides a systematic and comprehensive review of the literature regarding the utility of polysomnography for the evaluation of non-respiratory sleep disorders in children including hypersomnias, parasomnias, sleep-related movement disorders, and sleep in other special populations.

METHODS

A task force of pediatric sleep medicine experts performed a systematic review of the literature regarding the use of polysomnography for non-respiratory sleep disorders in children. They identified and graded 76 papers as evidence.

RESULTS

The main results include (1) polysomnography combined with the multiple sleep latency test is useful for evaluating disorders of excessive somnolence to objectively quantify sleepiness. The results have to be interpreted with consideration of the pubertal stage and regularity of the sleep patterns of the child; (2) polysomnography is indicated in children with parasomnias or sleep related movement disorders who have a high likelihood of having obstructive sleep apnea (OSA); (3) polysomnography is not routinely indicated in children with enuresis unless there is a high likelihood of OSA; (4) polysomnography can be helpful in evaluating children with restless legs syndrome (RLS) and when periodic limb movement disorder (PLMD) is suspected.

CONCLUSIONS

These findings suggest that, in children with non-respiratory sleep disorders, polysomnography should be a part of a comprehensive sleep evaluation in selected circumstances to determine the nature of the events in more detail or when the suspicion of OSA is relatively high.

Capturing PLMS and their variability in children with sickle cell disease: does ankle activity monitoring measure up to polysomnography?

OBJECTIVES

To test agreement and define differences in periodic limb movements in sleep (PLMS) measured by polysomnography and an ankle activity monitor, and to describe PLMS variability across nights, feasibility of home monitoring, and correlates of PLMS in children with sickle cell disease (SCD).

METHODS

Twenty children with SCD and restless legs syndrome (RLS) symptoms or polysomnography-documented PLMS underwent concurrent attended polysomnography and ankle activity monitoring over one to two nights and home activity monitoring for three nights. Serum iron and ferritin were measured pre- and post-polysomnography.

RESULTS

Adequate sensitivity (1.00), specificity (0.69), and mean bias (5.0±7.4 PLMS/h) for identifying elevated PLMS by activity monitor were obtained when scoring the period from sleep onset to offset rather than time in bed per manufacturer recommendation, and using a cut-point of 10 PLMS/h. Compared to activity monitor, only polysomnographic PLMS demonstrated periodicity, at inter-movement intervals (IMI) 20-35 s; the activity monitor overscored PLMS at the beginning and end of sleep and at shorter IMI (5-15s; p≤0.003), suggesting misclassification of nonperiodic leg movements as PLMS by activity monitor. PLMS varied across four nights by 16.1±13.4 PLMS/h. Post-polysomnography ferritin was associated (positively) with PLMS (p=0.034); RLS symptoms were not.

CONCLUSIONS

Ankle activity monitoring is a valid screening measure for PLMS in children with SCD and can readily be performed at home. Interpretation should incorporate a threshold for elevated PLMS of 10/h and scoring from sleep onset to offset, which could be identified with concurrent wrist actigraphy, to better account for true PLMS.

Iron deficiency anemia in infancy exerts long-term effects on the tibialis anterior motor activity during sleep in childhood

OBJECTIVES

To explore the eventual connection between iron deficiency anemia (IDA) in infancy and altered leg movements during sleep in a 10-year follow-up study in children who did or did not have IDA in infancy.

SUBJECTS AND METHODS

Polysomnographic studies were performed in 32 10-year-old children (13 females and 19 males) who had IDA in infancy and 26 peers (10 females and 16 males) who were nonanemic controls. The time structure of their polysomnographically recorded leg movements (LM) was analyzed by means of an approach particularly able to consider their quantity, periodicity, and distribution during the night.

RESULTS

All LM indexes and those related to periodic LM during sleep (PLMS) were slightly higher in the former IDA group than in the control group, but not always significant. The Periodicity index during NREM sleep was higher and was reflected by a small but significant increase in PLMS separated by 10-50s intervals. PLMS index tended to be higher in former IDA children than in controls throughout the whole night.

CONCLUSION

The association between IDA in infancy, despite iron therapy, and PLMS in childhood could lead to new research in this area. Indeed, transient infantile IDA, a common nutritional problem among human infants, may turn out to be important for understanding the mechanisms of PLMS or restless legs syndrome, which are common in adulthood.

The sleep phenotypes of attention deficit hyperactivity disorder: the role of arousal during sleep and implications for treatment

About 25-50% of children and adolescents with attention-deficit hyperactivity disorder (ADHD) experience sleep problems. An appropriate assessment and treatment of such problems might improve the quality of life in such patients and reduce both the severity of ADHD and the impairment it causes. According to data in the literature and to the overall complexity of the interaction between ADHD and sleep, five sleep phenotypes may be identified in ADHD: (i) a sleep phenotype characterized mainly by a hypo-arousal state, resembling narcolepsy, which may be considered a "primary" form of ADHD (i.e. without the interference of other sleep disorders); (ii) a phenotype associated with delayed sleep onset latency and with a higher risk of bipolar disorder; (iii) a phenotype associated with sleep disordered breathing (SDB); (iv) another phenotype related to restless legs syndrome (RLS) and/or periodic limb movements; (v) lastly, a phenotype related to epilepsy/or EEG interictal discharges. Each sleep phenotype is characterized by peculiar sleep alterations expressed by either an increased or decreased level of arousal during sleep that have important treatment implications. Treatment with stimulants is recommended above all in the primary form of ADHD, whereas treatment of the main sleep disorders or of co-morbidities (i.e. bipolar disorders and epilepsy) is preferred in the other sleep phenotypes. All the sleep phenotypes, except the primary form of ADHD and those related to focal benign epilepsy or focal EEG discharges, are associated with an increased level of arousal during sleep. Recent studies have demonstrated that both an increase and a decrease in arousal are ascribable to executive dysfunctions controlled by prefrontal cortical regions (the main cortical areas implicated in the pathogenesis of ADHD), and that the arousal system, which may be hyperactivated or hypoactivated depending on the form of ADHD/sleep phenotype.

Restless legs syndrome, periodic leg movements, and periodic limb movement disorder in children

The characteristic symptoms of restless legs syndrome (RLS) have been known for hundreds of years and were first reported in medicine in the 1600s. Clinicians must consider potential mimics, comorbid, and associated conditions when evaluating children with RLS symptoms. The traditional differentiation of RLS from periodic limb movement disorder (PLMD) is noted in children as well as adults. Because current pediatric RLS research is sparse, this article provides the most up-to-date evidence-based as well as consensus opinion-based information on the subject of childhood RLS and PLMD. Prevalence, pathophysiology, diagnosis, treatment, and clinical associations are discussed.

Cyclic alternating pattern (CAP): the marker of sleep instability

Cyclic alternating pattern CAP is the EEG marker of unstable sleep, a concept which is poorly appreciated among the metrics of sleep physiology. Besides, duration, depth and continuity, sleep restorative properties depend on the capacity of the brain to create periods of sustained stable sleep. This issue is not confined only to the EEG activities but reverberates upon the ongoing autonomic activity and behavioral functions, which are mutually entrained in a synchronized oscillation. CAP can be identified both in adult and children sleep and therefore represents a sensitive tool for the investigation of sleep disorders across the lifespan. The present review illustrates the story of CAP in the last 25 years, the standardized scoring criteria, the basic physiological properties and how the dimension of sleep instability has provided new insight into pathophysiolology and management of sleep disorders.

Narcolepsy: a review

Narcolepsy is a lifelong sleep disorder characterized by a classic tetrad of excessive daytime sleepiness with irresistible sleep attacks, cataplexy (sudden bilateral loss of muscle tone), hypnagogic hallucination, and sleep paralysis. There are two distinct groups of patients, ie, those having narcolepsy with cataplexy and those having narcolepsy without cataplexy. Narcolepsy affects 0.05% of the population. It has a negative effect on the quality of life of its sufferers and can restrict them from certain careers and activities. There have been advances in the understanding of the pathogenesis of narcolepsy. It is thought that narcolepsy with cataplexy is secondary to loss of hypothalamic hypocretin neurons in those genetically predisposed to the disorder by possession of human leukocyte antigen DQB1*0602. The diagnostic criteria for narcolepsy are based on symptoms, laboratory sleep tests, and serum levels of hypocretin. There is no cure for narcolepsy, and the present mainstay of treatment is pharmacological treatment along with lifestyle changes. Some novel treatments are also being developed and tried. This article critically appraises the evidence for diagnosis and treatment of narcolepsy.

Cyclic alternating pattern: A window into pediatric sleep

Cyclic alternating pattern (CAP) has now been studied in different age groups of normal infants and children, and it is clear that it shows dramatic changes with age. In this review we first focus on the important age-related changes of CAP from birth to peripubertal age and, subsequently, we describe the numerous studies on CAP in developmental clinical conditions such as pediatric sleep disordered breathing, disorders of arousal (sleep walking and sleep terror), pediatric narcolepsy, learning disabilities with mental retardation (fragile-X syndrome, Down syndrome, autistic spectrum disorder, Prader-Willi syndrome) or without (dyslexia, Asperger syndrome, attention-deficit/hyperactivity disorder). CAP rate is almost always decreased in these conditions with the exception of the disorders of arousal and some cases of sleep apnea. Another constant result is the reduction of A1 subtypes, probably in relationship with the degree of cognitive impairment. The analysis of CAP in pediatric sleep allows a better understanding of the underlying neurophysiological mechanisms of sleep disturbance. CAP can be considered as a window into pediatric sleep, allowing a new vision on how the sleeping brain is influenced by a specific pathology or how sleep protecting mechanisms try to counteract internal or external disturbing events.