Obstructive sleep apnea in narcolepsy

Exploring sleep characteristics in Chinese patients with narcolepsy: insights from the nocturnal sleep onset rapid eye movement period (nSOREMP)

STUDY OBJECTIVES

This study aimed to investigate the unique characteristics and clinical significance of the nocturnal sleep onset rapid eye movement period (nSOREMP) in the Chinese population with narcolepsy, enhancing our understanding and management of the disorder globally.

METHODS

This retrospective analysis investigated narcolepsy in Chinese patients from six hospitals, using the International Classification of Sleep Disorders. A parallel retrospective analysis of the Chinese Clinical Sleep Database focused on polysomnography records was conducted to evaluate nSOREMP prevalence in other sleep disorders.

RESULTS

The study found a 2.51% nSOREMP prevalence in other sleep disorders in the Chinese Clinical Sleep Database. Significant differences in age, N2 and rapid eye movement percentages, rapid eye movement latency, and various indexes were noted among patients with narcolepsy with or without nSOREMP and other sleep disorders with nSOREMP in the Chinese Clinical Sleep Database. nSOREMP prevalence in narcolepsy type 1 was 33.33% and in narcolepsy type 2 was 28.30%. Noteworthy disparities in narcolepsy type 1 included N2 percentages, rapid eye movement latency, and SOREMPs on Multiple Sleep Latency Test. In narcolepsy type 2, differences were significant for age, sleep latency, N2 and rapid eye movement latencies, arousal index, mean sleep latency on the Multiple Sleep Latency Test, and Multiple Sleep Latency Test SOREMPs.

CONCLUSIONS

This study highlights the distinct characteristics of nSOREMP in the Chinese population. Patients exhibiting symptoms suggestive of the onset of narcolepsy are advised to undergo a Multiple Sleep Latency Test, irrespective of the occurrence of SOREMP during nocturnal polysomnography.

CITATION

Zeng S, Feng F, Li W, et al. Exploring sleep characteristics in Chinese patients with narcolepsy: insights from the nocturnal sleep onset rapid eye movement period (nSOREMP). J Clin Sleep Med. 2024;20(8):1349-1355.

Ageing-related modification of sleep and breathing in orexin-knockout narcoleptic mice

Narcolepsy type-1 (NT1) is a lifelong sleep disease, characterised by impairment of the orexinergic system, with a typical onset during adolescence and young adulthood. Since the wake-sleep cycle physiologically changes with ageing, this study aims to compare sleep patterns between orexin-knockout (KO) and wild type (WT) control mice at different ages. Four groups of age-matched female KO and WT mice (16 weeks of age: 8 KO-YO and 9 WT-YO mice; 87 weeks of age: 13 KO-OLD and 12 WT-OLD mice) were implanted with electrodes for discriminating wakefulness, rapid-eye-movement sleep (REMS), and non-REMS (NREMS). Mice were recorded for 48 h in their home cages and for 7 more hours into a plethysmographic chamber to characterise their sleep-breathing pattern. Regardless of orexin deficiency, OLD mice spent less time awake and had fragmentation of this behavioural state showing more bouts of shorter length than YO mice. OLD mice also had more NREMS bouts and less frequent NREMS apneas than YO mice. Regardless of age, KO mice showed cataplexy-like episodes and shorter REMS latency than WT controls and had a faster breathing rate and an increased minute ventilation during REMS. KO mice also had more wakefulness, NREMS and REMS bouts, and a shorter mean length of wakefulness bouts than WT controls. Our experiment indicated that the lack of orexins as well as ageing importantly modulate the sleep and breathing phenotype in mice. The narcoleptic phenotype caused by orexin deficiency in female mice was substantially preserved with ageing.

Estimating the prevalence and clinical causality of obstructive sleep apnea in paediatric narcolepsy patients

BACKGROUND

Numerous risk factors in paediatric narcolepsy may predispose them to obstructive sleep apnea (OSA). The concurrent presence of OSA in these patients might lead to underdiagnosing narcolepsy. This research investigates the prevalence and potential causality between OSA and paediatric narcolepsy.

METHODS

A case-control study coupled with a two-sample Mendelian randomization (MR) analysis was employed to explore the prevalence and causal link between paediatric narcolepsy and OSA risk.

RESULTS

The case-control study revealed that paediatric narcolepsy patients are at an increased risk of OSA, with an Odds ratio (OR) of 4.87 (95% CI: 2.20-10.71; P < 0.001). The inverse-variance weighted (IVW) model further suggests a potential causal link between narcolepsy and OSA (IVW OR: 4.671, 95% CI: 1.925-11.290; P < 0.001). Additionally, sensitivity analysis confirmed these findings' reliability.

CONCLUSION

The findings highlight an elevated prevalence and genetic susceptibility to OSA among paediatric narcolepsy patients, underscoring the necessity for clinical screening of OSA. Continued research is essential to clarify the pathogenic mechanisms and develop potential treatments.

Narcolepsy and rapid eye movement sleep

Since the first description of narcolepsy at the end of the 19th Century, great progress has been made. The disease is nowadays distinguished as narcolepsy type 1 and type 2. In the 1960s, the discovery of rapid eye movement sleep at sleep onset led to improved understanding of core sleep-related disease symptoms of the disease (excessive daytime sleepiness with early occurrence of rapid eye movement sleep, sleep-related hallucinations, sleep paralysis, rapid eye movement parasomnia), as possible dysregulation of rapid eye movement sleep, and cataplexy resembling an intrusion of rapid eye movement atonia during wake. The relevance of non-sleep-related symptoms, such as obesity, precocious puberty, psychiatric and cardiovascular morbidities, has subsequently been recognized. The diagnostic tools have been improved, but sleep-onset rapid eye movement periods on polysomnography and Multiple Sleep Latency Test remain key criteria. The pathogenic mechanisms of narcolepsy type 1 have been partly elucidated after the discovery of strong HLA class II association and orexin/hypocretin deficiency, a neurotransmitter that is involved in altered rapid eye movement sleep regulation. Conversely, the causes of narcolepsy type 2, where cataplexy and orexin deficiency are absent, remain unknown. Symptomatic medications to treat patients with narcolepsy have been developed, and management has been codified with guidelines, until the recent promising orexin-receptor agonists. The present review retraces the steps of the research on narcolepsy that linked the features of the disease with rapid eye movement sleep abnormality, and those that do not appear associated with rapid eye movement sleep.

Machine learning-Based model for prediction of Narcolepsy Type 1 in Patients with Obstructive Sleep Apnea with Excessive Daytime Sleepiness

Background

Excessive daytime sleepiness (EDS) forms a prevalent symptom of obstructive sleep apnea (OSA) and narcolepsy type 1 (NT1), while the latter might always be overlooked. Machine learning (ML) models can enable the early detection of these conditions, which has never been applied for diagnosis of NT1.

Objective

The study aimed to develop ML prediction models to help non-sleep specialist clinicians identify high probability of comorbid NT1 in patients with OSA early.

Methods

Totally, clinical features of 246 patients with OSA in three sleep centers were collected and analyzed for the development of nine ML models. LASSO regression was used for feature selection. Various metrics such as the area under the receiver operating curve (AUC), calibration curve, and decision curve analysis (DCA) were employed to evaluate and compare the performance of these ML models. Model interpretability was demonstrated by Shapley Additive explanations (SHAP).

Results

Based on the analysis of AUC, DCA, and calibration curves, the Gradient Boosting Machine (GBM) model demonstrated superior performance compared to other machine learning (ML) models. The top five features used in the GBM model, ranked by feature importance, were age of onset, total limb movements index, sleep latency, non-REM (Rapid Eye Movement) sleep stage 2 and severity of OSA.

Conclusion

The study yielded a simple and feasible screening ML-based model for the early identification of NT1 in patients with OSA, which warrants further verification in more extensive clinical practices.

Narcolepsy Severity Scale-2 and Idiopathic Hypersomnia Severity Scale to better quantify symptoms severity and consequences in Narcolepsy type 2

STUDY OBJECTIVES

Narcolepsy type 2 (NT2) is an understudied central disorder of hypersomnolence sharing some similarities with narcolepsy type 1 and idiopathic hypersomnia (IH). We aimed: (1) to assess systematically the symptoms in patients with NT2, with self-reported questionnaires: Epworth Sleepiness Scale (ESS), Narcolepsy Severity Scale (NSS), IH Severity Scale (IHSS), and (2) to evaluate the responsiveness of these scales to treatment.

METHODS

One hundred and nine patients with NT2 (31.4 ± 12.2 years old, 47 untreated) diagnosed according to ICSD-3 were selected in a Reference Center for Narcolepsy. They all completed the ESS, subgroups completed the modified NSS (NSS-2, without cataplexy items) (n = 95) and IHSS (n = 76). Some patients completed the scales twice (before/during treatment): 42 ESS, 26 NSS-2, and 30 IHSS.

RESULTS

Based on NSS-2, all untreated patients had sleepiness, 58% disrupted nocturnal sleep, 40% hallucinations, and 28% sleep paralysis. On IHSS, 76% reported a prolonged nocturnal sleep, and 83% sleep inertia. In the independent sample, ESS and NSS-2 scores were lower in treated patients, with same trend for IHSS scores. After treatment, ESS, NSS-2, and IHSS total scores were lower, with a mean difference of 3.7 ± 4.1, 5.3 ± 6.7, and 4.1 ± 6.2, respectively. The minimum clinically important difference between untreated and treated patients were 2.1 for ESS, 3.3 for NSS-2, and 3.1 for IHSS. After treatment, 61.9% of patients decreased their ESS > 2 points, 61.5% their NSS-2 > 3 points, and 53.3% their IHSS > 3 points.

CONCLUSIONS

NSS-2 and IHSS correctly quantified symptoms' severity and consequences in NT2, with good performances to objectify response to medications. These tools are useful for monitoring and optimizing NT2 management, and for use in clinical trials.

Control of breathing by orexinergic signaling in the nucleus tractus solitarii

Orexin signaling plays a facilitatory role in respiration. Abnormalities in orexin levels correlate with disordered breathing patterns and impaired central respiratory chemoreception. Nucleus tractus solitarii (NTS) neurons expressing the transcription factor Phox2b contribute to the chemoreceptive regulation of respiration. However, the extent to which orexinergic signaling modulates respiratory activity in these Phox2b-expressing NTS neurons remains unclear. In the present study, the injection of orexin A into the NTS significantly increased the firing rate of the phrenic nerve. Further analysis using fluorescence in situ hybridization and immunohistochemistry revealed that orexin 1 receptors (OX1Rs) were primarily located in the ventrolateral subdivision of the NTS and expressed in 25% of Phox2b-expressing neurons. Additionally, electrophysiological recordings showed that exposure to orexin A increased the spontaneous firing rate of Phox2b-expressing neurons. Immunostaining experiments with cFos revealed that the OX1R-residing Phox2b-expressing neurons were activated by an 8% CO2 stimulus. Crucially, OX1R knockdown in these NTS neurons notably blunted the ventilatory response to 8% CO2, alongside an increase in sigh-related apneas. In conclusion, orexinergic signaling in the NTS facilitates breathing through the activation of OX1Rs, which induces the depolarization of Phox2b-expressing neurons. OX1Rs are essential for the involvement of Phox2b-expressing NTS neurons in the hypercapnic ventilatory response.

Long-term intermittent hypoxia induces anxiety-like behavior and affects expression of orexin and its receptors differently in the mouse brain

Studies have revealed a possible connection between orexin, narcolepsy, and obstructive sleep apnea (OSA). Orexin has an important role in the maintenance of arousal and wakefulness/sleeping states. To better understand the pathophysiological mechanism of OSA, we used a chronic intermittent hypoxia (CIH) model in mice to mimic OSA. In this way, we explored the effect of CIH on the locomotor activity and orexin system in the hypothalamus, cerebral cortex, and brainstem of mice. Male C57BL/6 J mice (8 weeks) in the CIH group were exposed in a hypoxia chamber for 8 h/day for 28 weeks. The re-oxygenation groups comprised the W2 group and W4 group, which were exposed to 28 weeks of CIH followed by 2 weeks and 4 weeks of re-oxygenation, respectively. The open field test was undertaken to observe locomotor activity. mRNA expression of orexin, orexin receptor type 1 (OX1R), and OX2R mRNA was evaluated by real-time reverse transcription-quantitative polymerase chain reaction. Mice subjected to long-term CIH exhibited significant anxiety-like behavior during the light period, and this behavior lasted until 4 weeks of re-oxygenation. mRNA expression of orexin was upregulated in the hypothalamus. mRNA expression of OX1R mRNA in the cerebral cortex and brainstem was downregulated by CIH. Two weeks and 4 weeks of re-oxygenation could not reverse these alternations. Long-term CIH may induce anxiety-like behavior and re-oxygenation cannot reverse these behavior. Moreover, OX1R has a significant role in the anxiety-related symptoms observed in long-term CIH.

Narcolepsies, update in 2023

Narcolepsy type 1 (NT1) and type 2 (NT2), also known as narcolepsy with and without cataplexy, are sleep disorders that benefited from major scientific advances over the last two decades. NT1 is caused by the loss of hypothalamic neurons producing orexin/hypocretin, a neurotransmitter regulating sleep and wake, which can be measured in the cerebrospinal fluid (CSF). A low CSF level of hypocretin-1/orexin-A is a highly specific and sensitive biomarker, sufficient to diagnose NT1. Orexin-deficiency is responsible for the main NT1 symptoms: sleepiness, cataplexy, disrupted nocturnal sleep, sleep-related hallucinations, and sleep paralysis. In the absence of a lumbar puncture, the diagnosis is based on neurophysiological tests (nocturnal and diurnal) and the presence of the pathognomonic symptom cataplexy. In the revised version of the International Classification of sleep Disorders, 3rd edition (ICSD-3-TR), a sleep onset rapid eye movement sleep (REM) period (SOREMP) (i.e. rapid occurrence of REM sleep) during the previous polysomnography may replace the diurnal multiple sleep latency test, when clear-cut cataplexy is present. A nocturnal SOREMP is very specific but not sensitive enough, and the diagnosis of cataplexy is usually based on clinical interview. It is thus of crucial importance to define typical versus atypical cataplectic attacks, and a list of clinical features and related degrees of certainty is proposed in this paper (expert opinion). The time frame of at least three months of evolution of sleepiness to diagnose NT1 was removed in the ICSD-3-TR, when clear-cut cataplexy or orexin-deficiency are established. However, it was kept for NT2 diagnosis, a less well-characterized disorder with unknown clinical course and absence of biolo biomarkers; sleep deprivation, shift working and substances intake being major differential diagnoses. Treatment of narcolepsy is nowadays only symptomatic, but the upcoming arrival of non-peptide orexin receptor-2 agonists should be a revolution in the management of these rare sleep diseases.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Targeting Orexin Receptors for the Treatment of Insomnia: From Physiological Mechanisms to Current Clinical Evidence and Recommendations

After a detailed description of orexins and their roles in sleep and other medical disorders, we discuss here the current clinical evidence on the effects of dual (DORAs) or selective (SORAs) orexin receptor antagonists on insomnia with the aim to provide recommendations for their further assessment in a context of personalized and precision medicine. In the last decade, many trials have been conducted with orexin receptor antagonists, which represent an innovative and valid therapeutic option based on the multiple mechanisms of action of orexins on different biological circuits, both centrally and peripherally, and their role in a wide range of medical conditions which are often associated with insomnia. A very interesting aspect of this new category of drugs is that they have limited abuse liability and their discontinuation does not seem associated with significant rebound effects. Further studies on the efficacy of DORAs are required, especially on children and adolescents and in particular conditions, such as menopause. Which DORA is most suitable for each patient, based on comorbidities and/or concomitant treatments, should be the focus of further careful research. On the contrary, studies on SORAs, some of which seem to be appropriate also in insomnia in patients with psychiatric diseases, are still at an early stage and, therefore, do not allow to draw definite conclusions.

Progress of autonomic disturbances in narcolepsy type 1

Narcolepsy type 1 is a kind of sleep disorder characterized by a specific loss of hypocretin neurons in the lateral hypothalamus and reduced levels of hypocretin-1 in the cerebrospinal fluid. Hypocretin deficiency is associated with autonomic disorders. This article summarizes the autonomic disorders and possible mechanisms associated with narcolepsy type 1. Patients with narcolepsy type 1 often have various systemic autonomic symptoms, including non-dipping blood pressure, reduced heart rate variability, dynamic cerebral autoregulation impairment, reduced gastric motility and emptying, sleep-related erectile dysfunction, skin temperature abnormalities, and blunted pupillary light reflex. Similar findings should strengthen the recognition and intervention of these disturbances in clinical practice. In addition to hypocretin deficiency, current evidence also indicates that pharmacological therapy (including psychostimulants and anti-cataplectic drugs) and comorbidities may contribute to the alterations of autonomic system observed in narcolepsy type 1.

Functional roles of orexin in obstructive sleep apnea: From clinical observation to mechanistic insights

Obstructive sleep apnea is the most common sleep-related breathing disorder. Repetitive episodes of the obstructive respiratory events lead to arousal, sleep fragmentation, and excessive daytime sleepiness. Orexin, also known as hypocretin, is one of the most important neurotransmitters responsible for sleep and arousal regulation. Deficiency of orexin has been shown to be involved in the pathogenesis of narcolepsy, which shares cardinal symptoms of sleep apnea and excessive daytime sleep with obstructive sleep apnea. However, the relationship between orexin and obstructive sleep apnea is not well defined. In this review, we summarize the current evidence, from in vitro, in vivo, and clinical data, regarding the association between orexin and obstructive sleep apnea. The effects of orexin on sleep apnea, as well as how the consequences of obstructive sleep apnea affect the orexin system function are also discussed. Additionally, the contrary findings are also included and discussed.

Status Cataplecticus with Rapid Eye Movement Sleep Excess in Late-onset Narcolepsy Type 1

A 57-year-old man presented with difficulty speaking and walking along with increased daytime somnolence. His symptoms fluctuated throughout the day but never completely disappeared. A neurological examination revealed mild dysarthria, limb weakness, and staggering gait. Polysomnography showed rapid eye movement (REM) sleep excess (55.0%). Multiple sleep latency tests revealed a mean sleep latency of zero minutes with sleep-onset REM periods in all naps. The Orexin-A concentration in the cerebrospinal fluid was low (50.8 pg/mL). Human leukocyte antigen testing demonstrated DQB1*0602 positivity. His neurological symptoms were relieved by clomipramine. Thus, he was diagnosed with late-onset narcolepsy type 1 with status cataplecticus.

Pediatric Narcolepsy—A Practical Review

Pediatric narcolepsy is a chronic sleep-wakefulness disorder. Its symptoms frequently begin in childhood. This review article examined the literature for research reporting on the effects of treatment of pediatric narcolepsy, as well as proposed etiology and diagnostic tools. Symptoms of pediatric narcolepsy include excessive sleepiness and cataplexy. In addition, rapid-eye-movement-related phenomena such as sleep paralysis, sleep terror, and hypnagogic or hypnapompic hallucinations can also occur. These symptoms impaired children’s function and negatively influenced their social interaction, studying, quality of life, and may further lead to emotional and behavioral problems. Therefore, early diagnosis and intervention are essential for children’s development. Moreover, there are differences in clinical experiences between Asian and Western population. The treatment of pediatric narcolepsy should be comprehensive. In this article, we review pediatric narcolepsy and its treatment approach: medication, behavioral modification, and education/mental support. Pharmacological treatment including some promising newly-developed medication can decrease cataplexy and daytime sleepiness in children with narcolepsy. Other forms of management such as psychosocial interventions involve close cooperation between children, school, family, medical personnel, and can further assist their adjustment.

Linking clinical complaints and objective measures of disrupted nighttime sleep in narcolepsy type 1

STUDY OBJECTIVES

Despite its high frequency in narcolepsy type 1(NT1), disrupted nocturnal sleep (DNS) remains understudied, and its determinants have been poorly assessed. We aimed to determine the clinical, polysomnographic (PSG), and biological variables associated with DNS in a large sample of patients with NT1, and to evaluate the effect of medication on DNS and its severity.

METHODS

Two hundred and forty-eight consecutive adult patients with NT1 (145 untreated, 103 treated) were included at the National Reference Center for Narcolepsy-France; 51 drug-free patients were reevaluated during treatment. DNS, assessed with the Narcolepsy Severity Scale (NSS), was categorized in four levels (absent, mild, moderate, severe). Clinical characteristics, validated questionnaires, PSG parameters (sleep fragmentation markers: sleep (SB) and wake bouts (WB), transitions), objective sleepiness, and orexin-A levels were assessed.

RESULTS

In drug-free patients, DNS severity was associated with higher scores on NSS, higher sleepiness, anxiety/depressive symptoms, autonomic dysfunction, worse quality of life (QoL). Patients with moderate/severe DNS (59%) had increased sleep onset REM periods, lower sleep efficiency, longer wake after sleep onset, more N1, SB, WB, sleep instability, transitions. In treated patients, DNS was associated with the same clinical data, and antidepressant use; but only with longer REM sleep latency on PSG. During treatment, sleepiness, NSS scores, depressive symptoms decreased, as well as total sleep time, WB, SB, transitions. DNS improved in 55% of patients, without predictors except more baseline anxiety.

CONCLUSION

DNS complaint is frequent in NT1, associated with disease severity based on NSS, several PSG parameters, and objective sleepiness in untreated and treated conditions. DNS improves with treatment. We advocate the systematic assessment of this symptom and its inclusion in NT1 management strategy.

50th anniversary of the ESRS in 2022-JSR special issue

This article addresses the clinical presentation, diagnosis, pathophysiology and management of narcolepsy type 1 and 2, with a focus on recent findings. A low level of hypocretin-1/orexin-A in the cerebrospinal fluid is sufficient to diagnose narcolepsy type 1, being a highly specific and sensitive biomarker, and the irreversible loss of hypocretin neurons is responsible for the main symptoms of the disease: sleepiness, cataplexy, sleep-related hallucinations and paralysis, and disrupted nocturnal sleep. The process responsible for the destruction of hypocretin neurons is highly suspected to be autoimmune, or dysimmune. Over the last two decades, remarkable progress has been made for the understanding of these mechanisms that were made possible with the development of new techniques. Conversely, narcolepsy type 2 is a less well-defined disorder, with a variable phenotype and evolution, and few reliable biomarkers discovered so far. There is a dearth of knowledge about this disorder, and its aetiology remains unclear and needs to be further explored. Treatment of narcolepsy is still nowadays only symptomatic, targeting sleepiness, cataplexy and disrupted nocturnal sleep. However, new psychostimulants have been recently developed, and the upcoming arrival of non-peptide hypocretin receptor-2 agonists should be a revolution in the management of this rare sleep disease, and maybe also for disorders beyond narcolepsy.

Sleep Disorders in Patients With Craniopharyngioma: A Physiopathological and Practical Update

Sleep disorders (SDs) represent an important issue in patients with craniopharyngioma (CP). Nearly 70% of these patients complain of sleep-wake cycle alterations and/or excessive diurnal somnolence due to sleep-related breathing disorders, such as obstructive sleep apnea (OSA) and/or central hypersomnia, including secondary narcolepsy. SDs may severely reduce quality of life, increase disease-related cardiorespiratory and cardiovascular morbidity, and finally play a major role in increased long-term mortality reported on patients with CP. A major risk factor for SDs is represented by the hypothalamic syndrome, which may develop because of direct hypothalamic damage by the tumor itself and/or complications of the treatments, neurosurgery and/or radiotherapy, and typically includes permanent neuroendocrine dysfunctions, morbid obesity, and secondary metabolic disorders. Despite increasing attention to SDs in the general population, and in particular to OSA as a risk factor for cardio-metabolic diseases and excessive daytime somnolence, sleep evaluation is still not routinely proposed to patients with CP. Hence, SDs are often underdiagnosed and undertreated. The aim of this paper is to update current knowledge of the pathogenesis and prevalence of SDs in patients with CP and propose practical algorithms for their evaluation and management in clinical practice. Particular attention is paid to screening and diagnostic tools for appropriate characterization of SDs, identification of risk factors, and potential role of hypothalamic sparing surgery in the prevention of morbid obesity and SDs. Available tools in sleep medicine, including lifestyle interventions, drugs, and respiratory devices, are discussed, as well as the importance of optimal hormone replacement and metabolic interventions. Current limits in the diagnosis and treatment of SDs in patients with CP and possible future avenues for research agenda are also considered.

Pharmacotherapy of residual excessive sleepiness among continuous positive airway pressure (CPAP) treated patients with sleep apnea

INTRODUCTION

Patients with persistent sleepiness after adequate treatment of obstructive sleep apnea (OSA) with nasal continuous positive airway pressure (nCPAP) experience impaired cognition, reduced productivity, and worse quality of life. Although the mechanisms responsible for this phenomenon are not completely understood, neuroimaging studies have identified reduced gray matter in the frontal cortex and alterations in white matter integrity suggestive of axonal and myelin damage. The intermittent hypoxia with resulting oxidative injury is considered a prime culprit behind the loss of wake-promoting catecholaminergic neurons.

AREAS COVERED

This narrative review gives an overview of the pathophysiology and approaches to managing patients with residual sleepiness. The authors explore different targeted strategies aimed at improving selection of appropriate pharmacotherapy.

EXPERT OPINION

Wake-stimulant medications (modafinil and armodafinil) have demonstrated efficacy in reducing sleepiness in adequately treated OSA. The recent FDA approval of pitolisant and solriamfetol complements the use of modafinil by substituting for direct sympathomimetic agents. The distinctive pharmacologic profile and mode of action of each of these agents offer the opportunity of a personalized approach to the management of this disorder. Further studies should be conducted on the long-term effect of these agents alone or in combination on brain structural and functional changes.

Disrupted nighttime sleep and sleep instability in narcolepsy

STUDY OBJECTIVES

This review aimed to summarize current knowledge about disrupted nighttime sleep (DNS) and sleep instability in narcolepsy, including self-reported and objective assessments, potential causes of sleep instability, health consequences and functional burden, and management.

METHODS

One hundred two peer-reviewed publications from a PubMed search were included.

RESULTS

DNS is a key symptom of narcolepsy but has received less attention than excessive daytime sleepiness and cataplexy. There has been a lack of clarity regarding the definition of DNS, as many sleep-related symptoms and conditions disrupt sleep quality in narcolepsy (eg, hallucinations, sleep paralysis, rapid eye movement sleep behavior disorder, nightmares, restless legs syndrome/periodic leg movements, nocturnal eating, sleep apnea, depression, anxiety). In addition, the intrinsic sleep instability of narcolepsy results in frequent spontaneous wakings and sleep stage transitions, contributing to DNS. Sleep instability likely emerges in the setting of orexin insufficiency/deficiency, but its exact pathophysiology remains unknown. DNS impairs quality of life among people with narcolepsy, and more research is needed to determine its contributions to cardiovascular risk. Multimodal treatment is appropriate for DNS management, including behavioral therapies, counseling on sleep hygiene, and/or medication. There is strong evidence showing improvement in self-reported sleep quality and objective sleep stability measures with sodium oxybate, but rigorous clinical trials with other pharmacotherapies are needed. Treatment may be complicated by comorbidities, concomitant medications, and mood disorders.

CONCLUSIONS

DNS is a common symptom of narcolepsy deserving consideration in clinical care and future research.

CITATION

Maski K, Mignot E, Plazzi G, Dauvilliers Y. Disrupted nighttime sleep and sleep instability in narcolepsy. J Clin Sleep Med. 2022;18(1):289-304.

Narcolepsia na Infância: A Atuação Multidisciplinar com a Psicologia do Sono do Diagnóstico ao Tratamento em um Relato de Caso

Resumo A narcolepsia, distúrbio neurológico crônico caracterizado pela sonolência diurna excessiva, pode ser associada à cataplexia, fragmentação do sono, alucinações relacionadas ao sono e paralisia do sono. Frequentemente, é confundida com outros transtornos, como Transtorno do Déficit de Atenção com Hiperatividade (TDAH), epilepsia e até esquizofrenia, assim, por vezes, é diagnosticada inadequadamente. Objetiva-se relatar o diagnóstico diferencial bem-sucedido da narcolepsia na infância e suas dificuldades, realizado por uma equipe multidisciplinar, enfocando a atuação da psicologia do sono em avaliação e intervenção. Um menino de 10 anos foi recebido no Ambulatório de Narcolepsia e Apneia do Sono Infantil (AMBNAP), alocado no Hospital Universitário Onofre Lopes da Universidade Federal do Rio Grande do Norte (UFRN) com queixas de sonolência diurna excessiva, sono fragmentado e episódios de perda de tônus muscular. Foi submetido a entrevistas psiquiátrica e psicológica pormenorizadas, a exames, aplicação de escalas específicas para rastreio e diagnóstico de transtornos de sono e diário de sono, solicitação de recursos de mídia e de relatório escolar e avaliação neurológica. A partir da investigação multidisciplinar, o diagnóstico foi de Narcolepsia e Síndrome da Apneia Obstrutiva do Sono (SAOS). O paciente foi submetido a técnicas da Terapia Cognitivo-Comportamental (TCC) e segue em acompanhamento, apresentando resultados satisfatórios. Este estudo evidencia que uma equipe multidisciplinar especializada na área de sono atuando em conjunto com a Psicologia do Sono oportuniza o diagnóstico e intervenções precoces eficazes para o tratamento do distúrbio do sono na infância.

Not Only Excessive Daytime Sleepiness but Also Depression Symptoms, Chronological Age and Onset-Age Were Associated with Impulsivity in Narcolepsy Type 1 Patients

OBJECTIVE

To detect the factors associated with total and subscales impulsivity scores in narcolepsy and further explore the non-linear relationship between these factors and impulsivity score.

METHODS

One hundred and fifty-eight narcolepsy type 1 (NT1) patients were involved in this cross-sectional study. Patients completed questionnaires evaluating impulsivity symptoms (Barratt impulse scale-11, BIS-11), depression symptoms (Center for Epidemiologic Studies Depression Scale for Children, CES-DC or Self-Rating Depression Scale, SDS) and sleepiness (Epworth Sleepiness Scale, ESS). Parameters from polysomnography and multiple sleep latency test were also collected. Linear regression analysis was performed to detect the factors associated with total and subscales impulsivity scores. Then, generalized additive models and smooth curve fitting were performed to explore the non-linear relationship between chronological age and impulsivity scores.

RESULTS

Factors associated with higher total impulsivity score were higher ESS, older onset and adolescents. Factors associated with higher attentional impulsivity score were higher ESS, older onset and adolescents. Factors associated with higher motor impulsivity score were higher ESS, younger onset and depression symptoms. Factors associated with higher non-planning impulsivity score were adolescents, older onset and depression symptoms. A non-linear relationship between age and impulsivity scores (total impulsivity score, attentional impulsivity score and non-planning impulsivity score) was detected in NT1 patients.

CONCLUSION

Not only excessive daytime sleepiness but also onset-age, depression symptoms and chronological age were associated with impulsivity in NT1 patients. The non-linear relationship between age and impulsivity scores suggested brain and mental development alterations in NT1 patients.

Comorbid Insomnia and Obstructive Sleep Apnea (COMISA): Current Concepts of Patient Management

Obstructive sleep apnea (OSA) and insomnia are the two most common sleep disorders among the general population, and they may often coexist in patients with sleep-disordered breathing (SDB). The higher prevalence of insomnia symptoms in patients with OSA (40–60%) compared to that observed in the general population has thus led researchers to identify a new disorder named comorbid insomnia and OSA (COMISA), whose true burden has been so far largely underestimated. The combined treatment of COMISA patients with positive-airway pressure ventilation (PAP) with cognitive behavioral therapy for insomnia (CBTi) has shown a better patient outcome compared to that obtained with a single treatment. Furthermore, recent evidence has shown that an innovative patient-centered approach taking into consideration patient characteristics, treatment preferences and accessibility to treatment is recommended to optimize clinical management of COMISA patients. However, in this complex mosaic, many other sleep disorders may overlap with COMISA, so there is an urgent need for further research to fully understand the impact of these therapies on outcomes for OSA patients with comorbidity. In light of this need, this review focuses on the major sleep disorders comorbid with OSA and the recent advances in the management of these insomniac patients.

Regional brain metabolism differentiates narcolepsy type 1 and idiopathic hypersomnia

STUDY OBJECTIVES

Daytime sleepiness is a manifestation of multiple sleep and neurologic disorders. Few studies have assessed patterns of regional brain metabolism across different disorders of excessive daytime sleepiness. One such disorder, idiopathic hypersomnia (IH), is particularly understudied.

METHODS

People with IH, narcolepsy (NT1), and non-sleepy controls underwent [ 18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) with electroencephalography (EEG). Participants were instructed to resist sleep and were awoken if sleep occurred. Voxel-wise parametric analysis identified clusters that significantly differed between each pair of groups, with a minimum cluster size of 100 voxels at a cluster detection threshold of p < 0.005. Correlations between glucose metabolism and sleep characteristics were evaluated.

RESULTS

Participants (77% women) had IH (n = 16), NT1 (n = 14), or were non-sleepy controls (n = 9), whose average age was 33.8 (+/-10.7) years. Compared to controls, NT1 participants demonstrated hypermetabolism in fusiform gyrus, middle occipital gyrus, superior and middle temporal gyri, insula, cuneus, precuneus, pre- and post-central gyri, and culmen. Compared to controls, IH participants also demonstrated hypermetabolism in precuneus, inferior parietal lobule, superior and middle temporal gyri, and culmen. Additionally, IH participants demonstrated altered metabolism of the posterior cingulate. Most participants fell asleep. Minutes of N1 during uptake was significantly negatively correlated with metabolism of the middle temporal gyrus.

CONCLUSION

NT1 and IH demonstrate somewhat overlapping, but distinct, patterns of regional metabolism.

Cardiovascular disorders in narcolepsy: Review of associations and determinants

Narcolepsy type 1 (NT1) is a lifelong disorder of sleep-wake dysregulation defined by clinical symptoms, neurophysiological findings, and low hypocretin levels. Besides a role in sleep, hypocretins are also involved in regulation of heart rate and blood pressure. This literature review examines data on the autonomic effects of hypocretin deficiency and evidence about how narcolepsy is associated with multiple cardiovascular risk factors and comorbidities, including cardiovascular disease. An important impact in NT1 is lack of nocturnal blood pressure dipping, which has been associated with mortality in the general population. Hypertension is also prevalent in NT1. Furthermore, disrupted nighttime sleep and excessive daytime sleepiness, which are characteristic of narcolepsy, may increase cardiovascular risk. Patients with narcolepsy also often present with other comorbidities (eg, obesity, diabetes, depression, other sleep disorders) that may contribute to increased cardiovascular risk. Management of multimorbidity in patients with narcolepsy should include regular assessment of cardiovascular health (including ambulatory blood pressure monitoring), mitigation of cardiovascular risk factors (eg, cessation of smoking and other lifestyle changes, sleep hygiene, and pharmacotherapy), and prescription of a regimen of narcolepsy medications that balances symptomatic benefits with cardiovascular safety.

Narcolepsy Type 1: A Remitting Disease? An Unusual Case Report

We describe the case of a male patient who was diagnosed with narcolepsy type 1 on the basis of sleep and wake symptoms, and the results of investigations including video-polysomnography, multiple sleep latency test, human leukocyte antigen status and orexin level in cerebrospinal fluid. During the first years after disease onset, the patient did not show any significant improvement despite treatment with a variety of stimulant and anti-cataplectic drugs. However, spontaneous remission of disease occurred after 15 years.

Dysregulation of the orexin/hypocretin system is not limited to narcolepsy but has far-reaching implications for neurological disorders

Neuropeptides orexin A and B (OX-A/B, also called hypocretin 1 and 2) are released selectively by a population of neurons which projects widely into the entire central nervous system but is localized in a restricted area of the tuberal region of the hypothalamus, caudal to the paraventricular nucleus. The OX system prominently targets brain structures involved in the regulation of wake-sleep state switching, and also orchestrates multiple physiological functions. The degeneration and dysregulation of the OX system promotes narcoleptic phenotypes both in humans and animals. Hence, this review begins with the already proven involvement of OX in narcolepsy, but it mainly discusses the new pre-clinical and clinical insights of the role of OX in three major neurological disorders characterized by sleep impairment which have been recently associated with OX dysfunction, such as Alzheimer's disease, stroke and Prader Willi syndrome, and have been emerged over the past 10 years to be strongly associated with the OX dysfunction and should be more considered in the future. In the light of the impairment of the OX system in these neurological disorders, it is conceivable to speculate that the integrity of the OX system is necessary for a healthy functioning body.

Effect of ambient temperature on sleep breathing phenotype in mice: the role of orexins

The loss of orexinergic neurons, which release orexins, results in narcolepsy. Orexins participate in the regulation of many physiological functions, and their role as wake-promoting molecules has been widely described. Less is known about the involvement of orexins in body temperature and respiratory regulation. The aim of this study was to investigate if orexin peptides modulate respiratory regulation as a function of ambient temperature (Ta) during different sleep stages. Respiratory phenotype of male orexin knockout (KO-ORX, N=9) and wild-type (WT, N=8) mice was studied at thermoneutrality (Ta=30°C) or during mild cold exposure (Ta=20°C) inside a whole-body plethysmography chamber. The states of wakefulness (W), non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS) were scored non-invasively, using a previously validated technique. In both WT and KO-ORX mice, Ta strongly and significantly affected ventilatory period and minute ventilation values during NREMS and REMS; moreover, the occurrence rate of sleep apneas in NREMS was significantly reduced at Ta=20°C compared with Ta=30°C. Overall, there were no differences in respiratory regulation during sleep between WT and KO-ORX mice, except for sigh occurrence rate, which was significantly increased at Ta=20°C compared with Ta=30°C in WT mice, but not in KO-ORX mice. These results do not support a main role for orexin peptides in the temperature-dependent modulation of respiratory regulation during sleep. However, we showed that the occurrence rate of sleep apneas critically depends on Ta, without any significant effect of orexin peptides.

Narcolepsy, Anesthesia, and Sedation: A Survey of the Perioperative Experience of Patients With Narcolepsy

BACKGROUND

Patients with narcolepsy may be at increased perioperative risk due to the interactions among anesthesia, narcolepsy, and narcolepsy medications. This study sought to determine the perioperative experience of narcoleptic patients undergoing anesthesia or sedation, the frequency of perioperative counseling, and self-reported surgical complications.

METHODS

A 22-question survey was developed by expert consensus and distributed by the Narcolepsy Network. Recruitment was via the Narcolepsy Network's list-serve and a Facebook link to the survey. One thousand and twenty respondents reported a diagnosis of narcolepsy and 1 or more procedures under anesthesia or sedation. Descriptive, comparative statistics and logistic regression were utilized.

RESULTS

Respondents were mostly women (79.5%) and Caucasian (84.9%), with a mean age of 45 ± 16 years. Most respondents did not receive counseling regarding the possibility of increased sleepiness (70%), cataplexy (90%), or drowsy driving (59%) postanesthesia. More than half of respondents reported adverse events (medication withdrawal symptoms, inadequate pain relief, increased cataplexy). Subjects with cataplexy more frequently reported surgical complications (70% vs 31%; P = .03) and medication withdrawal symptoms (stimulant medications: odds ratio, 3.0 [95% CI, 1.9, 3.06]; P > .001 and antidepressant medications: odds ratio, 6.5 [95% CI, 2.1-19.5]; P = .001). Of the total sample, 18% indicated surgical complications. Undergoing 5 or more separate surgeries or procedures was associated with a 2-fold increase in self-reported complications (odds ratio, 2.2 [95% CI, 1.3-3.4]; P = .001), difficulty waking (odds ratio, 2.1 [95% CI, 1.45-3.06]; P = .001), and inadequate pain relief (odds ratio, 1.77 [95% CI, 1.01-3.13]; P < .05).

CONCLUSIONS

Most narcoleptic patients report not receiving counseling regarding potential worsening of narcolepsy symptoms postanesthesia or an increased risk of drowsy driving. Enhanced education of perioperative providers about potential narcolepsy-related issues is essential. Respondents frequently self-report adverse events in the perioperative period. Future studies should clarify the perioperative risk associated with narcolepsy to optimize the care and safety of narcoleptic patients.

Knowledge Gaps in the Perioperative Management of Adults With Narcolepsy: A Call for Further Research

There is increasing awareness that sleep disorders may be associated with increased perioperative risk. The Society of Anesthesia and Sleep Medicine created the Narcolepsy Perioperative Task Force: (1) to investigate the current state of knowledge of the perioperative risk for patients with narcolepsy, (2) to determine the viability of developing perioperative guidelines for the management of patients with narcolepsy, and (3) to delineate future research goals and clinically relevant outcomes. The Narcolepsy Perioperative Task Force established that there is evidence for increased perioperative risk in patients with narcolepsy; however, this evidence is sparse and based on case reviews, case series, and retrospective reviews. Mechanistically, there are a number of potential mechanisms by which patients with narcolepsy could be at increased risk for perioperative complications. These include aggravation of the disease itself, dysautonomia, narcolepsy-related medications, anesthesia interactions, and withdrawal of narcolepsy-related medications. At this time, there is inadequate research to develop an expert consensus or guidelines for the perioperative management of patients with narcolepsy. The paucity of available literature highlights the critical need to determine if patients with narcolepsy are at an increased perioperative risk and to establish appropriate research protocols and clearly delineated patient-centered outcomes. There is a real need for collaborative research among sleep medicine specialists, surgeons, anesthesiologists, and perioperative providers. This future research will become the foundation for the development of guidelines, or at a minimum, a better understanding how to optimize the perioperative care of patients with narcolepsy.

Prevalence of Rapid Eye Movement-related Obstructive Sleep Apnea in Adult Narcolepsy

Objective The association between narcolepsy and rapid eye movement (REM)-related obstructive sleep apnea (OSA) has not been reported. This study aimed to examine the prevalence of REM-related OSA in narcolepsy patients. Methods From January 2013 to April 2018, 141 adult patients were diagnosed with narcolepsy using nocturnal polysomnography and the multiple sleep latency test. The prevalence of REM-related OSA in narcolepsy patients was retrospectively reviewed. Three criteria were used to determine REM-related OSA: Definition #1, an overall apnea-hypopnea index (AHI) ≥5 and AHI during REM (AHIREM)/AHI during non-rapid eye movement (NREM) (AHINREM) ≥2; Definition #2, an overall AHI ≥5 and AHI_REM/AHI_NREM≥2 and AHI_NREM <15; and Definition #3, an overall AHI ≥5 and AHI_REM/AHI_NREM≥2 and AHI_NREM <8 plus an REM sleep duration >10.5 minutes. Results Of the 141 narcolepsy patients, 26 were diagnosed with narcolepsy with cataplexy (NA-CA) and 115 with narcolepsy without cataplexy (NA w/o CA). Seventeen patients with NA-CA and 39 with NA w/o CA had OSA. According to Definition #1, the prevalence of REM-related OSA was 47.1% and 41.0%, respectively, in OSA patients with NA-CA and NA w/o CA; according to Definition #2, the respective prevalence was 47.1% and 38.5%, while that according to Definition #3 was 41.2% and 25.6%. No significant differences were found in the prevalence of REM-related OSA for each definition. Conclusion A high prevalence of REM-related OSA was confirmed in adult narcolepsy patients with OSA. Compared to previous reports, we noted a high frequency of REM-related OSA satisfying the relatively strict Definition #3. These results might reflect the pathophysiological characteristics of narcolepsy.

Clinical neurophysiology of CNS hypersomnias

Central nervous system hypersomnias (narcolepsy type 1 and type 2, idiopathic hypersomnia, and Kleine-Levin syndrome) are orphan sleep disorders in which the predominant symptom is excessive daytime sleepiness. The evaluation of sleepiness requires rigorous clinical and neurophysiologic approaches that may include the Epworth Sleepiness Scale, multiple sleep latency tests, and the maintenance of wakefulness test. However, to date, no gold standard measurement of excessive sleepiness exists, and there are no quantifiable biologic markers. The main pathophysiologic feature of central hypersomnias is thought to reflect a deficiency of arousal systems, rather than an overactivity of sleep systems or an imbalance between those systems. Impaired neurotransmission of hypocretin/orexin (neuropeptides of the lateral hypothalamus) is involved in the neurobiology of narcolepsy with cataplexy (NT1). NT1 is a well-characterized disorder, due to the destruction of hypocretin/orexin neurons by a probable autoimmune process. The biologic hallmarks of the other central hypersomnias remain unknown, and neurophysiologic biomarkers are still of major importance for the diagnosis and characterization of those disorders.

Comparison of the macro and microstructure of sleep in a sample of sleep clinic hypersomnia cases

The purpose of this study was to elucidate the differentiating or grouping EEG characteristics in various hypersomnias (type 1 and type 2 narcolepsy (N-1 and N-2) and idiopathic hypersomnia (IH) compared to an age-matched snoring reference group (SR). Polysomnogram sleep EEG was decomposed into a 4-frequency state model. The IH group had higher sleep efficiency (SE; 92.3% vs. 85.8%; sp < 0.05), lower WASO (IH = 35.4 vs. N-1 = 65.5 min; p < 0.01), but similar (i.e. high) arousal indices as N-1 (~33/h). N-1 and N-2 had earlier REM latency than IH and SR (N-1 = 64.8, N-2 = 76.3 vs. IH/SR = 118 min, p < 0.05). N-1 and N-2 showed an increase in MF1 segments (characteristic of stage 1 and REM) across the night as well as distinct oscillations every 2 h, but MF1 segment timing was advanced by 30 min compared to the SR group (p < 0.05). This suggests the presence of circadian organization to sleep that is timed earlier or of increased pressure and/or lability. MF1 demonstrated a mixed phenotype in IH, with an early 1^st oscillation (like N-1 and N-2), 2^nd oscillation that overlapped with the SR group, and a surge prior to wake (higher than all groups). This phenotype may reflect a heterogeneous group of individuals, with some having more narcolepsy-like characteristics (i.e. REM) than others. LF domain (delta surrogate) was enhanced in IH and N-1 and more rapidly dissipated compared to N-2 and SR (p < 0.05). This suggests an intact homeostatic sleep pattern that is of higher need/reduced efficiency whereas rapid dissipation may be an underlying mechanism for sleep disruption.

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Low frequency sleep (delta surrogate) was enhanced in Idiopathic Hypersomnia and Type 1 Narcolepsy and rapidly dissipated across the sleep period.

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Type 1 and 2 Narcoleptics demonstrated a mixed frequency 1 phenotype (REM surrogate) consistent with intact circadian control and advanced timing.

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Idiopathic hypersomnia was characterized by a variable mixed frequency 1 phenotype (REM surrogate), suggesting some with more “narcolepsy-like” REM characteristics than others.

The role of home sleep testing for evaluation of patients with excessive daytime sleepiness: focus on obstructive sleep apnea and narcolepsy

Excessive daytime sleepiness (EDS) is a common complaint in the general population, which may be associated with a wide range of sleep disorders and other medical conditions. Narcolepsy is a sleep disorder characterized primarily by EDS, which involves a substantial burden of illness but is often overlooked or misdiagnosed. In addition to identifying low cerebrospinal fluid (CSF) hypocretin (orexin) levels, evaluation for narcolepsy requires in-laboratory polysomnography (PSG). Polysomnography is the gold standard for diagnosis of obstructive sleep apnea (OSA) as well as other sleep disorders. However, the use of home sleep apnea testing (HSAT) to screen for OSA in adults with EDS has increased greatly based on its lower cost, lower technical complexity, and greater convenience, versus PSG. The most commonly used, types 3 and 4, portable monitors for HSAT lack capability for electroencephalogram recording, which is necessary for the diagnosis of narcolepsy and other sleep disorders and is provided by PSG. These limitations, combined with the increased use of HSAT for evaluation of EDS, may further exacerbate the under-recognition of narcolepsy and other hypersomnias, either as primary or comorbid disorders with OSA. Adherence to expert consensus guidelines for use of HSAT is essential. Differential clinical characteristics of patients with narcolepsy and OSA may help guide correct diagnosis. Continued EDS in patients diagnosed and treated for OSA may indicate comorbid narcolepsy or another sleep disorder. Although HSAT may diagnose OSA in appropriately selected patients, it cannot rule out or diagnose narcolepsy. Therefore, at present, PSG and MSLT remain the cornerstone for narcolepsy diagnosis.

Management Of Excessive Sleepiness In Patients With Narcolepsy And OSA: Current Challenges And Future Prospects

Excessive daytime sleepiness (EDS) can be caused by insufficient sleep but is also a manifestation of medical or sleep disorders and a side effect of medications. It impacts quality of life and creates safety concerns in the home, at work, and on the roads. Screening questionnaires can be used to estimate EDS, but further evaluation is necessary. EDS is a common symptom of both narcolepsy and obstructive sleep apnea (OSA). Polysomnography and multiple sleep latency testing are used to diagnose these disorders. However, isolating the primary etiology of EDS can be challenging and may be multifactorial. Untreated OSA can show polysomnographic findings that are similar to narcolepsy. The effects of sleep deprivation and certain medications can also affect the polysomnographic results. These challenges can lead to misdiagnosis. In addition, narcolepsy and OSA can occur as comorbid disorders. If EDS persists despite adequate treatment for either disorder, a comorbid diagnosis should be sought. Thus, despite advances in clinical practice, appropriate management of these patients can be challenging. This review is focused on EDS due to OSA and narcolepsy and addresses some of the challenges with managing this patient population.

A false alarm of narcolepsy: obstructive sleep apnea masquerading as narcolepsy and depression

PURPOSE

We report a case with symptoms and signs of obstructive sleep apnea (OSA), depression, and narcolepsy. Polysomnographic (PSG) and multiple sleep latency test (MSLT) findings, clinical characteristics, and diagnostic challenges in this case are discussed.

METHODS

A 23-year-old single male presented with excessive daytime sleepiness, low mood, lack of energy, and snoring for 3 years. In addition, he reported excessive weight gain, lack of interest in work, partial loss of muscle tone during excitations, and sleep attacks during work and driving. He had experienced three episodes of sleep paralysis. The patient underwent a sleep study including PSG and MSLT.

RESULTS

On baseline PSG, he had an apnea/hypopnea index (AHI) of 72.8/h. The MSLT showed a mean sleep latency of 3.8 min and two sleep-onset rapid eye movement periods (SOREMPs). On admission, he had an Epworth Sleepiness Scale (ESS) score of 21, and positive findings for depression in the clinical interview and psychometric scales. He was treated with continuous positive airway pressure without any medication. Follow-up PSG and MSLT were performed after 1 week, which showed an AHI of 0/h without SOREMPs. After 1 month, there was no sign of depression.

CONCLUSIONS

This study reflects that OSA can present with cataplexy-like features and false positive MSLT results for narcolepsy, as well as depressive symptoms. The case highlights the complexity in which OSA can present to physicians, and emphasizes that clinicians should be aware that OSA can mimic narcolepsy and present with depressive symptoms.

Residual excessive sleepiness in patients with obstructive sleep apnea on treatment with continuous positive airway pressure

PURPOSE OF REVIEW

One of the most common causes of excessive daytime sleepiness in clinical practice is obstructive sleep apnea syndrome (OSAS). So far, continuous positive airway pressure (CPAP) is the most effective treatment for OSA. Some of the patients do not improve on CPAP and remain sleepy despite using CPAP.This review provides updated information about the possible causes of residual sleepiness whilst using the CPAP in patients with OSAS.

RECENT FINDINGS

Prevalence of OSAS has increased recently to 23.4% in women and 49.7% in men. Periodic limb movement, behaviorally induced insufficient sleep syndrome and depression are the most common causes of persistent sleepiness on CPAP. Residual sleepiness after exclusion of all possible causes is 6%.

SUMMARY

There is still lack of sufficient evidence about the accurate characteristics and possible causes of this residual sleepiness and how to address this in large prospective studies.

Nocturnal REM Sleep Without Atonia Is a Diagnostic Biomarker of Pediatric Narcolepsy

STUDY OBJECTIVES

Compare nocturnal REM sleep without atonia (nRWA) and REM sleep behavior disorder (RBD) between pediatric patients with and without narcolepsy and determine if the nRWA index is a valid diagnostic biomarker for narcolepsy.

METHODS

Retrospective cohort study of children ages 6 to 18 years who completed a nocturnal polysomnogram (PSG) and Multiple Sleep Latency Test (MSLT). Our study sample included 11 patients with narcolepsy type 1 (NT1), 6 with narcolepsy type 2 (NT2), 12 with idiopathic hypersomnia (IH), and 11 with subjective hypersomnia (sHS). We compared group nRWA indices (epochs of RWA/total stage R sleep epochs) from the nocturnal PSGs and analyzed nRWA index receiver operating curve (ROC) statistics for narcolepsy diagnosis.

RESULTS

The median nRWA index of patients with NT1 was 15 to 30 times higher compared to sHS and IH (Ps < .005) but similar to that of the NT2 group (P = .46). RBD was present in 25% of patients with narcolepsy (NT1 and NT2). In comparing those with and without narcolepsy, the nRWA index area under the curve was 0.87 (0.6), 95% confidence interval (CI) = 0.75 to 0.99, P < .001. The threshold of having ≥ 1% of stage R sleep epochs with nRWA yielded a sensitivity of 88.2%, 95% CI = 63.6-98.5 and specificity of 60.9%, 95% CI = 38.5 to 80.3 for diagnosis of narcolepsy. In contrast, a threshold of ≥ 8% yielded a specificity of 95.7%, 95% CI = 78.1 to 99.9 and sensitivity of 52.9%, 95% CI = 27.8 to 77.

CONCLUSIONS

The nRWA index is a very good diagnostic biomarker of pediatric narcolepsy. Depending on the clinical cutoffs utilized, this biomarker can identify more children/adolescents with narcolepsy using just the PSG or reduce false-positive diagnostic results.

Perioperative risks of narcolepsy in patients undergoing general anesthesia: A case-control study

STUDY OBJECTIVE

To compare the perioperative outcomes between patients with narcolepsy and matched controls undergoing anesthetic management.

DESIGN

Retrospective 2:1 matched study design.

SETTING

Large tertiary medical center.

PATIENTS

Narcoleptic patients who underwent general anesthesia from January 1, 2011, through September 30, 2015, were matched with controls by age, sex, and type and year of surgery.

MEASUREMENTS

Medical records were reviewed for episodes of respiratory depression during phase I recovery and for other meaningful perioperative outcomes.

MAIN RESULTS

The perioperative courses of 76 narcoleptic patients and their controls were examined. Compared to controls, narcoleptic patients were more often prescribed central nervous system stimulants (73.7% vs 4.0%, P<0.001) and antidepressants (46.1% vs 27.6%, P=0.007) and more often had obstructive sleep apnea (40.8% vs 19.1%, P<0.001). The intraoperative course was similar. The number of episodes of respiratory depression was not different between patients and controls (5 [6.6%] vs 12 [7.9%], respectively; P=0.80). Narcoleptic patients had a higher frequency of emergency response team activations (5 of 76 [6.6%]; 95% CI, 2.2%-14.7%) compared to controls (2 of 152 [1.3%]; 95% CI, 0.2%-4.7%) (P=0.04). Hemodynamic instability was the indication for all emergency response team activations except 1, which was for a narcoleptic patient who had excessive postoperative sedation and respiratory depression.

CONCLUSIONS

Narcoleptic patients had similar intraoperative courses as the matched controls, including phase I anesthetic recovery. However, they had a higher rate of emergency response team activations than the controls, which suggests that patients with narcolepsy may be at increased perioperative risk.

Oral appliance therapy versus nasal continuous positive airway pressure in obstructive sleep apnoea syndrome: a randomised, placebo-controlled trial on self-reported symptoms of common sleep disorders and sleep-related problems

Obstructive sleep apnoea syndrome (OSAS) is associated with several sleep disorders and sleep-related problems. Therefore, the aim of this study was to compare the effects of a mandibular advancement device (MAD) with those of nasal continuous positive airway pressure (nCPAP) on self-reported symptoms of common sleep disorders and sleep-related problems in mild and moderate OSAS patients. In this randomised placebo-controlled trial, sixty-four OSAS patients (52·0 ± 9·6 years) were randomly assigned to an MAD, nCPAP or an intra-oral placebo appliance in a parallel design. All participants filled out the validated Dutch Sleep Disorders Questionnaire (SDQ) twice: one before treatment and one after six months of treatment. With 88 questions, thirteen scales were constructed, representing common sleep disorders and sleep-related problems. Linear mixed model analyses were performed to study differences between the groups for the different SDQ scales over time. The MAD group showed significant improvements over time in symptoms corresponding with 'insomnia', 'excessive daytime sleepiness', 'psychiatric sleep disorder', 'periodic limb movements', 'sleep apnoea', 'sleep paralysis', 'daytime dysfunction', 'hypnagogic hallucinations/dreaming', 'restless sleep', 'negative conditioning' and 'automatic behaviour' (range of P values: 0·000-0·014). These improvements in symptoms were, however, not significantly different from the improvements in symptoms observed in the nCPAP and placebo groups (range of P values: 0·090-0·897). It can be concluded that there is no significant difference between MAD and nCPAP in their positive effects on self-reported symptoms of common sleep disorders and sleep-related problems in mild and moderate OSAS patients. These beneficial effects may be a result of placebo effects.