The clinical spectrum of narcolepsy with cataplexy: a reappraisal

Idiopathic hypersomnia with a video recording of a spontaneous sleep attack: A case report

RATIONALE

Although patients with central disorders of hypersomnolence (CDH) exhibit characteristic symptoms of hypersomnia frequently, it takes 5 to 15 years from the onset for its diagnosis due to the lack of symptom recognition. Here, we present a case of idiopathic hypersomnia (IH), a CDH, wherein early diagnosis was aided by a video footage of a spontaneous sleep attack.

PATIENT CONCERNS

A 21-year-old man lost consciousness while driving and experienced an accident. He had complained of excessive daytime sleepiness (EDS) over half a year. During his hospitalization for close monitoring of the loss of consciousness, an in-room surveillance camera captured a 14-minutes long spontaneous sleep attack, during which he experienced general muscle weakness and loss of consciousness without warnings or convulsions leading to a fall from the bed. There were no abnormalities in vital signs.

DIAGNOSES

There was no significant cataplexy and less than 2 sleep-onset rapid eye movements (SOREM) in 2 sleep latency tests, with a mean sleep latency of 2.1 and 4.6 minutes. Other sleep deprivation syndromes were excluded from differential diagnosis and finally, a diagnosis of IH was confirmed according to the criteria of the Third Edition of the International Classification of Sleep Disorders. During the course of the disease, attention-deficit/hyperactive disorder (ADHD) and a gaming disorder also diagnosed.

INTERVENTIONS

Pharmacological treatment with modafinil was administered for IH and methylphenidate for ADHD. Cognitive behavioral therapy was performed for the gaming disorder.

OUTCOMES

The EDS improved, and sleep attacks were no longer observed. The disruption of daily life caused by the gaming disorder was also reduced.

LESSONS

Video recordings of sleep attacks are beneficial for identifying the cause of loss of consciousness. Home video recordings may be helpful in the early diagnosis of IH.

Sleepy Kids: are the current diagnostic criteria for multiple sleep latency tests enough?

Excessive daytime sleepiness (EDS) is common in childhood and is currently quantified using adult criteria on a multiple sleep latency test (MSLT). This study aimed to describe paediatric MSLT results, particularly focussing on a previously proposed alternative mean sleep latency (MSL) threshold for children of 12 min, and assess the impact of a 5th nap. We performed a retrospective analysis of MSLTs at a single paediatric centre from 2004 to 2021. Narcolepsy was defined as a mean sleep latency (MSL) ≤8min with ≥2 sleep onset REM (SOREM) periods. Idiopathic Hypersomnia (IH) was defined as a MSL ≤8min with <2 SOREMs. An ambiguous MSLT result was defined as a MSL 8-12min and/or ≥2 SOREM periods. Of 214 MSLTs [50 % female, median age 14.0y (range 3.3-20.1y)], narcolepsy was diagnosed in 48 (22 %), IH in 22 (10 %) and the result was ambiguous in 44 (21 %). Those with ambiguous MSLT results were older (15.6 vs 13.4y, p = 0.006) with a higher proportion of females (61 % vs 35 %, p = 0.01) in comparison to the narcolepsy group. A 5th nap was performed in 60 (28 %) of MSLTs and only changed the outcome in one case. In conclusion, MSLT results are borderline in 21 % of paediatric cases, suggesting that current adult diagnostic criteria may miss narcolepsy and IH in children. A 5th nap usually makes no difference or increases the MSL, suggesting that a four nap MSLT protocol could be used apart from rare cases where the result is borderline after the 4th nap.

Clinical Evaluation and Management of Narcolepsy in Children and Adolescents

While sleepiness is common among children, and particularly adolescents, profound sleepiness in the setting of apparently adequate sleep should prompt consideration of a central disorder of hypersomnolence. These disorders, which include narcolepsy, idiopathic hypersomnia, Kleine-Levin syndrome, and others, are likely underrecognized in the pediatric population. Narcolepsy in particular should be of interest to child neurologists as the unique signs and symptoms of this disease often prompt evaluation in pediatric neurology clinics. While sleepiness may appear to be a straightforward complaint, its evaluation requires a nuanced approach. Cataplexy, a hallmark of narcolepsy, can be confused for other neurologic conditions, though understanding its various manifestations makes it readily identifiable. Clinicians should be aware of these symptoms, as delay in diagnosis and misdiagnosis are common in childhood narcolepsy. While treatment options have been limited in the past, many new therapeutic options have become available and can result in significant improvement in symptoms. Given the age at presentation, paroxysmal and chronic features, diagnostic modalities, and available treatment options, the field of child neurology is well equipped to see patients with narcolepsy. In this review, I will focus on the presentation, evaluation, and management of pediatric patients with narcolepsy.

Harriet Tubman's Hypersomnia: Insights from Historical and Medical Perspectives

Harriet Tubman, a hero of the abolitionist movement and early civil rights advocate, suffered a head injury in childhood and subsequently developed sleep attacks associated with visions that were extensively documented in historical accounts. Her contemporaries perceived these visions together with unpredictable and unavoidable urges to sleep as manifestations of her deep faith, rather than as symptoms of an illness. While religious perspectives remain crucial to understanding Tubman's sleep-related experiences, some may consider them insufficient in view of modern medical advances. We propose the parallel explanation that her sleep attacks, usually attributed to temporal lobe epilepsy, actually represent a hypersomnia that is most consistent with the modern diagnosis of post-traumatic narcolepsy. Using historical analysis as well as current understandings of sleep medicine, we aim to shed light on this under-recognized aspect of Tubman's life. In addition, this case study allows us to review the potential long-term effects of severe traumatic brain injuries; consider a differential for excessive daytime sleepiness and hypnagogic hallucinations; and familiarize readers with the pathophysiology, diagnosis, and treatment of narcolepsy. Whether her symptoms are viewed through the lens of the past or measured against current biomedical standards, Tubman demonstrated an inspiring ability to persevere despite intrusive sleep episodes and to realize her dreams for the betterment of others.

Reliability and validity of the Japanese version of the Ullanlinna Narcolepsy Scale and Swiss Narcolepsy Scale for screening Japanese individuals with narcolepsy type 1

OBJECTIVE

To validate the Japanese versions of the Ullanlinna Narcolepsy Scale (J-UNS) and Swiss Narcolepsy Scale (J-SNS) for screening narcolepsy in the Japanese population and to discuss strategies for their use in hypersomniac individuals.

METHODS

We selected 451 outpatients with excessive daytime sleepiness (EDS) already diagnosed according to the International Classification of Sleep Disorders third edition. They responded to both scales twice at 1-month intervals. After eliminating individuals who met the exclusion criteria, validity and reliability analyses were performed on 408 and 381 participants, respectively.

RESULTS

Patients with narcolepsy type 1 (NT1) displayed higher J-UNS and lower J-SNS scores than those with NT2 and other sleep disorders. The intraclass correlation coefficients and weighted κ coefficient for scale scores in the total participants and patients with NT1 were ≥0.70 and ≥ 0.40, respectively, indicating high reliability. Furthermore, both the sensitivity and specificity of these scales upon using the original cut-off scores (14 for UNS and 0 for SNS) for detecting NT1 were 0.70 or ≥0.70, suggesting high validity. Additionally, the receiver operating characteristic curve analysis revealed that the best cut-off score did not change for the J-SNS but that for the J-UNS, it increased to 18. In our study, the scale's sensitivity and specificity changed from 96% to 82% and 58%-78%, respectively.

CONCLUSIONS

Both scales revealed satisfactory screening abilities for NT1 in the Japanese population. However, it may be better to use J-UNS cut-off scores of 18 for a population with EDS.

LC-MS/MS-Based Proteomics Approach for the Identification of Candidate Serum Biomarkers in Patients with Narcolepsy Type 1

Narcolepsy type 1 (NT1) is the most common type of narcolepsy known to be caused by the loss of specific neurons responsible for producing peptide neurotransmitters (orexins/hypocretins), resulting in a sleep-wake cycle disorder. It is characterized by its association with cataplexy and abnormalities in rapid eye movement. To date, no cure has been established for this life-threatening condition. Misdiagnosis of NT1 is also quite common, although it is not exceedingly rare. Therefore, successfully identifying candidate serum biomarkers for NT1 would be a head start for accurate diagnosis and development of therapeutics for this disorder. This study aims to identify such potential serum biomarkers. A depletion protocol was employed for 27 human serum samples (16 NT1 and 11 healthy controls), followed by applying LC-MS/MS bottom-up proteomics analysis, then LC-PRM-MS for validation. The comparison of the proteome profiles of the low-abundant proteins in the samples was then investigated based on age, sex, sample groups, and the presence of the Human Leukocyte Antigen (HLA) DQB1*0602 allele. The results were tracked to gene expression studies as well as system biology to identify key proteins and understand their relationship in the pathogenesis of NT1. Our results revealed 36 proteins significantly and differentially expressed. Among the impaired pathways and bioprocesses, the complement activation pathway is impaired by six of the differentially expressed proteins (DEPs). They are coded by the genes C2, CFB, C5, C1R, C1S, and MASP1, while 11 DEPs are involved in Acute Phase Response Signaling (APRS), which are coded by the genes FN1, AMBP, APOH, CFB, CP, ITIH2, C5, C2, F2, C1, and ITIH4. The combined AUCs of the downregulated and upregulated DEPs are 0.95 and 0.76, respectively. Overall, this study reveals potential serum-protein biomarkers of NT1 and explains the possible correlation between the biomarkers and pathophysiological effects, as well as important biochemical pathways involved in NT1.

Hyperhidrosis in sleep disorders - A narrative review of mechanisms and clinical significance

Hyperhidrosis is characterized by excessive sweating beyond thermoregulatory needs that affects patients' quality of life. It results from an excessive stimulation of eccrine sweat glands in the skin by the sympathetic nervous system. Hyperhidrosis may be primary or secondary to an underlying cause. Nocturnal hyperhidrosis is associated with different sleep disorders, such as obstructive sleep apnea, insomnia, restless legs syndrome/periodic limb movement during sleep and narcolepsy. The major cause of the hyperhidrosis is sympathetic overactivity and, in the case of narcolepsy type 1, orexin deficiency may also contribute. In this narrative review, we will provide an outline of the possible mechanisms underlying sudomotor dysfunction and the resulting nocturnal hyperhidrosis in these different sleep disorders and explore its clinical relevance.

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.

"It Started After Trauma": The Effects of Traumatic Grief on Sleep Paralysis

Adverse life events are associated with the often-terrifying REM sleep parasomnia of sleep paralysis (SP), but the impact of bereavement on SP has not been specifically examined. This exploratory, mixed-methods study (N = 168) includes qualitative data from 55 participants who described factors they believed led to their SP. Of these, almost half with a traumatic loss listed death-related precipitants. In unadjusted (bivariate) negative binomial regression models, traumatic death, time since death, religiosity, and age estimated increased SP frequency in the prior month, prior year, or both. In multivariable models, traumatic death, time since death, and age estimated increased frequency in the prior month, prior year, or both. Unexpectedly, in all models, as compared to death ≥9 years earlier, prior month SP was greater with death 1-6 years earlier, but not <1 year earlier. Discussion includes the possible role of social constraints in traumatic grief trajectories and care provider recommendations.

Development and Validation of the Pediatric Hypersomnolence Survey

BACKGROUND AND OBJECTIVES

Narcolepsy and idiopathic hypersomnia usually begin in early adolescence, but diagnostic delays ranging from 5 to 10 years are common, affecting disease burden. To improve early identification of these treatable conditions, we developed and validated the Pediatric Hypersomnolence Survey (PHS).

METHODS

Content was developed through literature review, patient focus groups, interviews with experts in the field, and field testing. We then validated the 14-item self-reported survey across 3 hospitals and web recruitment from patient groups. In the validation phase, we recruited a total of 331 participants (patients with narcolepsy type 1 [n = 64], narcolepsy type 2 [n = 34], idiopathic hypersomnia [n = 36], and other sleep disorders [n = 97] and healthy controls [n = 100], ages 8-18 years) to complete the survey. We assessed a range of psychometric properties, including discriminant diagnostic validity for CNS disorders of hypersomnolence using receiver operating characteristic curve analysis and reliability across a 1-week period.

RESULTS

Confirmatory factor analysis indicated a 4-domain solution with good reliability expressed by satisfactory omega values. Across groups, the PHS total score showed appropriate positive correlations with other validated surveys of sleepiness (r = 0.65-0.78, p < 0.001) and negative correlations with multiple sleep latency test measures (mean sleep latency: r = -0.27, p = 0.006; number of sleep-onset REM periods: r = 0.26, p = 0.007). Compared to controls and patients with other sleep disorders, the area under the curve for participants with narcolepsy or idiopathic hypersomnia was 0.87 (standard error 0.02, 95% CI 0.83-0.91) with high sensitivity (81.3, 95% CI 73.7%-87.5%) and specificity (81.2%, 95 CI 75.1%-86.4%). Test-retest reliability was r = 0.87.

DISCUSSION

The PHS is a valid and reliable tool for clinicians to identify pediatric patients with narcolepsy and idiopathic hypersomnia. Implemented in clinical practice, the PHS will potentially decrease diagnostic delays and time to treatment, ultimately reducing disease burden for these debilitating conditions.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that the PHS accurately identifies patients with central disorders of hypersomnolence.

Narcolepsy: a model interaction between immune system, nervous system, and sleep-wake regulation

Narcolepsy is a rare chronic neurological disorder characterized by an irresistible excessive daytime sleepiness and cataplexy. The disease is considered to be the result of the selective disruption of neuronal cells in the lateral hypothalamus expressing the neuropeptide hypocretin, which controls the sleep-wake cycle. Diagnosis and management of narcolepsy represent still a substantial medical challenge due to the large heterogeneity in the clinical manifestation of the disease as well as to the lack of understanding of the underlying pathophysiological mechanisms. However, significant advances have been made in the last years, thus opening new perspective in the field. This review describes the current knowledge of clinical presentation and pathology of narcolepsy as well as the existing diagnostic criteria and therapeutic intervention for the disease management. Recent evidence on the potential immune-mediated mechanisms that may underpin the disease establishment and progression are also highlighted.

Prevalence, incidence, and health care utilization of patients with narcolepsy: a population-representative study

STUDY OBJECTIVES

Previous estimated prevalence of narcolepsy in Europe was 47 patients per 100,000 persons, with a yearly incidence of 0.64-1.37 per 100,000. However, analyses of representative datasets from large cohorts are limited. This study aimed to estimate the population-based diagnostic prevalence and incidence of narcolepsy in Germany, and to describe these patients and their health care resource utilization.

METHODS

This study used the InGef research database, an anonymized representative dataset of 4 million persons covered by statutory health insurance in Germany. Patients with confirmed narcolepsy diagnoses in 2018 were included. Mid-p exact tests were used to calculate 95%-confidence intervals. Patients with narcolepsy diagnoses and narcolepsy-targeting therapy in 2014-2018 were included to describe health care resource utilization in the year prior to diagnosis.

RESULTS

In 2018 diagnostic prevalence was estimated as 17.88 (95%-CI 16.45-19.40), and 12-month incidence as 0.79 (0.52-1.15) per 100,000 persons. 46% patients were in psycho-behavioral therapeutic treatment and 61% of employees had sick-leave days. One in three patients was hospitalized for any cause. 28% received antibiotics.

CONCLUSIONS

Diagnostic prevalence was lower, but incidence was consistent with previous reports, though previous estimates may diverge in terms of age/gender-distributions. Patients showed a substantial utilization of health care resources, including sick leave and hospitalization. Almost half the patients underwent psycho-behavioral treatment in the year prior to diagnosis, which might indicate high burden of psychiatric symptoms. The increased use of antibiotics could indicate more frequent infections than in the general population.

Dissociative Symptoms are Highly Prevalent in Adults with Narcolepsy Type 1

INTRODUCTION

The core symptoms of narcolepsy such as excessive daytime sleepiness and cataplexy are well known. However, there is mounting evidence for a much broader symptom spectrum, including psychiatric symptoms. Disordered sleep has previously been linked with dissociative symptoms, which may imply that patients with narcolepsy are more prone to develop such symptoms.

OBJECTIVES

To investigate the frequency of dissociative symptoms in adult patients with narcolepsy type 1 compared to population controls.

METHODS

In a retrospective case control study, sixty adult patients fulfilling the criteria for narcolepsy type 1 and 120 matched population control subjects received a structured interview using the Schedules for Clinical Assessment in Neuropsychiatry (SCAN) to assess dissociative symptoms and disorders.

RESULTS

A majority of narcolepsy patients reported dissociative symptoms, and even fulfilled the DSM-IV-TR criteria of a dissociative disorder (62% vs 1% in controls, p < .001). Most frequently reported symptoms were "dissociative amnesia" (37% vs 1%, p < .001) and "dissociative disorder of voluntary movement" (32% vs 1%, p < .001).

CONCLUSION

Dissociative symptoms are strikingly prevalent in adult patients with narcolepsy type 1. Although a formal diagnosis of dissociation disorder should not be made as the symptoms can be explained by narcolepsy as an underlying condition, the findings do illustrate the extent and severity of the dissociative symptoms. As for the pathophysiological mechanism, there may be symptom overlap between narcolepsy and dissociation disorder. However, there may also be a more direct link between disrupted sleep and dissociative symptoms. In either case, the high frequency of occurrence of dissociative symptoms should result in an active inquiry by doctors, to improve therapeutic management and guidance.

The incubus phenomenon: Prevalence, frequency and risk factors in psychiatric inpatients and university undergraduates

BACKGROUND

The incubus phenomenon is a paroxysmal sleep-related disorder characterized by the visuotactile sensation of a person or entity exerting pressure on one's thorax during episodes of sleep paralysis and (apparent) wakefulness. This terrifying phenomenon is relatively unknown even though a previous meta-analysis indicated a lifetime prevalence of 0.11 for individuals in the general population and of 0.41 for selected at-risk groups, including people diagnosed with schizophrenia and students. Since the studies reviewed did not always make a strict distinction between the incubus phenomenon and isolated sleep paralysis, we carried out a cross-sectional study in a contemporary patient and student sample to attain current, more detailed data on the incubus phenomenon.

MATERIALS AND METHODS

In a cross-sectional design, we used the Waterloo Unusual Sleep Experience Questionnaire (WUSEQ) to screen patients with severe psychiatric disorders and university undergraduates to establish and compare prevalence rates, frequencies of occurrence, and risk factors for the incubus phenomenon.

RESULTS

Having interviewed 749 people, comprising 606 students and 143 patients with a schizophrenia spectrum or related disorder who had been acutely admitted to a secluded nursing ward, we computed a reported lifetime prevalence of 0.12 and 0.09, respectively, which rates were not statistically different. In both groups, the phenomenon was more common in people with a non-Western European background. Risk factors noted for the students were the use of psychotropic medication and the lifetime presence of an anxiety disorder, eating disorder, or sleeping disorder. We found no associations with age or gender in either group.

CONCLUSION

The 0.09 and 0.12 lifetime prevalence rates we recorded for the incubus phenomenon in students and psychiatric inpatients is substantially lower than the 0.41 found in an earlier meta-analysis. We tentatively attribute this difference to an overgeneralization in previous studies but also discuss alternative explanations. The elevated prevalence among non-Western European participants may well be due to the fact that the topic continues to be part of the cultural and religious heritage of many non-Western countries.

Narcolepsy type 1 features across the life span: age impact on clinical and polysomnographic phenotype

STUDY OBJECTIVES

Narcolepsy type 1 (NT1) is a chronic neurological disorder typically arising during adolescence and young adulthood. Recent studies demonstrated that NT1 presents with age-specific features, especially in children. With this study we aimed to describe and to compare the clinical pictures of NT1 in different age groups.

METHODS

In this cross-sectional, multicenter study, 106 untreated patients with NT1 enrolled at the time of diagnosis underwent clinical evaluation, a semistructured interview (including the Epworth Sleepiness Scale), nocturnal video-polysomnography, and the Multiple Sleep Latency Test. Patients were enrolled in order to establish 5 age-balanced groups (childhood, adolescence, adulthood, middle age, and senior).

RESULTS

The Epworth Sleepiness Scale score showed a significant increase with age, while self-reported diurnal total sleep time was lower in older and young adults, with the latter also complaining of automatic behaviors in more than 90% of patients. Children reported the cataplexy attacks to be more frequent (> 1/d in 95% of patients). "Recalling an emotional event," "meeting someone unexpectedly," "stress," and "anger" were more frequently reported in adult and older adult patients as possible triggers of cataplexy. Neurophysiological data showed a higher number of sleep-onset rapid eye movement periods on the Multiple Sleep Latency Test in adolescent compared to senior patients and an age-progressive decline in sleep efficiency.

CONCLUSIONS

Daytime sleepiness, cataplexy features and triggers, and nocturnal sleep structure showed age-related difference in patients with NT1; this variability may contribute to diagnostic delay and misdiagnosis.

Efficacy of Pitolisant on the Treatment of Narcolepsy: A Systematic Review

Narcolepsy is characterized by excessive daytime sleepiness (EDS) and cataplexy. Histamine neurons play an important role in enhancing wakefulness. The objective of our study was to evaluate the efficacy of pitolisant, a histamine 3 (H3)-receptor antagonist/inverse agonist, in patients with a high burden of narcolepsy symptoms. We conducted an advanced PubMed search strategy with inclusion and exclusion criteria. The outcome included the Epworth Sleepiness Scale (ESS) and adverse effects frequency. Our primary outcome included the mean ESS score at the endpoint and showed that pitolisant was superior to the placebo, but not non-inferior to modafinil. Adverse effects were less common and shorter in duration in the pitolisant group compared to the modafinil-treated patients. Pitolisant was efficacious in reducing excessive daytime sleepiness and cataplexy compared with placebo, and it was well-tolerated in patients with severe narcolepsy symptoms as compared with modafinil.

The Swiss Primary Hypersomnolence and Narcolepsy Cohort study (SPHYNCS): Study protocol for a prospective, multicentre cohort observational study

Narcolepsy type 1 (NT1) is a disorder with well‐established markers and a suspected autoimmune aetiology. Conversely, the narcoleptic borderland (NBL) disorders, including narcolepsy type 2, idiopathic hypersomnia, insufficient sleep syndrome and hypersomnia associated with a psychiatric disorder, lack well‐defined markers and remain controversial in terms of aetiology, diagnosis and management. The Swiss Primary Hypersomnolence and Narcolepsy Cohort Study (SPHYNCS) is a comprehensive multicentre cohort study, which will investigate the clinical picture, pathophysiology and long‐term course of NT1 and the NBL. The primary aim is to validate new and reappraise well‐known markers for the characterization of the NBL, facilitating the diagnostic process. Seven Swiss sleep centres, belonging to the Swiss Narcolepsy Network (SNaNe), joined the study and will prospectively enrol over 500 patients with recent onset of excessive daytime sleepiness (EDS), hypersomnia or a suspected central disorder of hypersomnolence (CDH) during a 3‐year recruitment phase. Healthy controls and patients with EDS due to severe sleep‐disordered breathing, improving after therapy, will represent two control groups of over 50 patients each. Clinical and electrophysiological (polysomnography, multiple sleep latency test, maintenance of wakefulness test) information, and information on psychomotor vigilance and a sustained attention to response task, actigraphy and wearable devices (long‐term monitoring), and responses to questionnaires will be collected at baseline and after 6, 12, 24 and 36 months. Potential disease markers will be searched for in blood, cerebrospinal fluid and stool. Analyses will include quantitative hypocretin measurements, proteomics/peptidomics, and immunological, genetic and microbiota studies. SPHYNCS will increase our understanding of CDH and the relationship between NT1 and the NBL. The identification of new disease markers is expected to lead to better and earlier diagnosis, better prognosis and personalized management of CDH.

The evolution of the narcolepsy concept in Russia: A historical view

Following the first descriptions of narcolepsy with cataplexy by Westphal, Gelineau, and Fischer (1878-1880), Russian authors started to report on "narcolepsy cases" in 1894. It was, however, only in 1925 that Mankovsky reported a (postencephalitic) case, satisfying current diagnostic criteria for the disease. In the following 66 years (the last publication appeared in 1991), Russian authors including Davidenkov, Vein, and Yakhno made interesting contributions on the clinical features, neurophysiological correlates (e.g., sleep states and boundary dyscontrol), pathogenesis (e.g., hypothalamic origin), etiology (e.g., infectious, postvaccinal triggers, focal encephalitis), and treatment (e.g., use of sodium oxybate) of narcolepsy. Until recently, Pavlov's theory of narcolepsy as a "cortical excitatory-inhibitory phenomenon" strongly influenced the Russian view on the disease, contrasting with the current neurobiological insights acknowledged internationally. A Narcolepsy Network, including currently 10 member centers, was recently founded to promote knowledge, awareness, management, and research on this still poorly known disease in Russia.

Pharmacokinetics and Pharmacodynamics of the Dual Orexin Receptor Antagonist Daridorexant in Japanese and Caucasian Subjects

PURPOSE/BACKGROUND

Daridorexant is a dual orexin receptor antagonist in development for the treatment of sleep disorders. Thus far, it has not yet been studied in Japanese subjects. Study objectives were to evaluate the pharmacokinetics (PK), pharmacodynamics (PD), and safety of single- and multiple-dose administration of daridorexant in healthy Caucasian and Japanese subjects.

METHODS/PROCEDURES

This was a double-blind, placebo-controlled, randomized study. Subjects received once-daily doses of daridorexant (25 or 50 mg) or placebo for 5 days. Pharmacokinetics and safety were investigated using standard assessments. To assess PD effects, a battery of tests (saccadic peak velocity, body sway, adaptive tracking performance, and visual analog scales for alertness, mood, and calmness), known to be sensitive to sleep-promoting drugs was used.

FINDINGS/RESULTS

On day 1, PK variables were similar between Caucasian and Japanese subjects. On day 5, slight accumulation occurred in Japanese but not in Caucasian subjects, resulting in a higher maximum concentration (1403 vs 1006 ng/mL) and area under the curve (8256 vs 6306 ng·h/mL) at a dose of 50 mg, whereas values for time to maximum concentration and half-life were similar. Daridorexant dose-dependently reduced vigilance, attention, visuomotor coordination, and postural stability. Pharmacokinetic effects were detectable within 1 hour after drug administration and returned to baseline 4 to 8 hours postdose. Overall, Japanese showed slightly larger PD effects and reported more adverse events than Caucasians. The most frequently reported were somnolence, fatigue, and headache. Changes in other safety assessments were unremarkable.

IMPLICATIONS/CONCLUSIONS

The PK, PD, and safety profile of daridorexant were similar in Japanese and Caucasian subjects.

Investigation of the effect of the dual orexin receptor antagonist almorexant on ophthalmological, spermatogenic, and hormonal variables in healthy male subjects

BACKGROUND/AIMS

The aim of this single-center, double-blind study was to investigate the effect of a 4-week once daily administration of 200 mg almorexant on tear film break-up time, spermatogenesis, hormone levels, and pancreatic elastase in stool in healthy male subjects.

METHODS

Almorexant 200 mg or matching placebo was administered in the evening for 4 weeks once daily to 56 healthy male subjects. Changes in ophthalmological variables, sperm composition, hormone levels, and pancreatic elastase levels in stool were evaluated periodically up to 8 weeks after discontinuation of drug administration. Blood samples for pharmacokinetic measurements were taken after 4 weeks to confirm compliance to study drug intake.

RESULTS

The results of this study revealed no treatment effects of almorexant, neither on tear film break-up time nor on other ophthalmological variables investigated during this study. Furthermore, spermatogenesis, hormones of the hypothalamic-pituitary-adrenal and -gonadal axes, and endocrine pancreatic secretion were shown to be not affected by a 4-week once daily administration of almorexant.

CONCLUSION

Almorexant was well tolerated and had no effect on the spectrum of pharmacodynamic variables assessed. Ophthalmology and testicular findings detected in preclinical studies were not observed in this clinical study. Therefore, these preclinical findings appear not to be relevant for humans and do not prevent from conducting larger clinical trials with either healthy subjects or patients.

Evaluation of the Effectiveness of the Risk Minimization Measures of Sodium Oxybate in the European Union

BACKGROUND

Sodium oxybate (Xyrem^®), approved by the European Medicines Agency (EMA) for narcolepsy with cataplexy, is only available through risk mitigation programs due to potential adverse effects including respiratory and central nervous system depression, neuropsychiatric events, and misuse.

OBJECTIVE

We report findings from a survey evaluating effectiveness of the European Union Xyrem^® Risk Management Plan (RMP).

PATIENTS AND METHODS

A cross-sectional, online, multiple-choice survey was distributed to randomly selected healthcare professionals (HCPs) from six European countries (April 2016-May 2018). Eligibility criteria: current/potential Xyrem^® prescriber and/or sleep disorder specialist; contact information available; on the Xyrem^® RMP educational materials mailing list.

PRIMARY OUTCOME

proportion of respondents answering each question correctly (< 50% responses correct = unsatisfactory comprehension, 50% to < 70% = satisfactory, ≥ 70% = excellent), with precision assessed using 95% confidence intervals (CIs).

RESULTS

Of the 709 HCPs contacted, 601 did not agree to take part, 108 were screened with 35/108 eligible for inclusion; 31 HCPs completed the survey. Of the 31 respondents, 29 (93.5%; 95% CI 84.4-100.0) reported receiving Xyrem^® safety information, commonly from a sales representative, EMA Summary of Product Characteristics (SmPC), or educational meeting; only 9/31 (31.0%; 14.3-50.0) recalled receiving mailed educational materials. The number of HCPs answering dosing-related questions correctly ranged from 24/31 to 31/31. All Xyrem^® contraindications were correctly identified by 26/31 (83.9%; 70.0-96.7) respondents. All respondents 'always' or 'sometimes' completed SmPC recommended activities upon treatment initiation. The majority indicated signs of abuses/misuse/diversion (23/31; 74.2%; 58.6-88.0) and criminal use (23/31; 74.2%; 59.4-89.3) should be monitored at follow-up.

CONCLUSIONS

These data demonstrate the importance of providing a range of educational materials. However, the low sample size limits interpretation; increased HCP engagement would improve understanding of how best to develop educational materials.

EUROPEAN POST-AUTHORIZATION STUDY (PAS) REGISTER NUMBER

EUPAS15024.

Clinical pharmacology of the dual orexin receptor antagonist ACT-541468 in elderly subjects: Exploration of pharmacokinetics, pharmacodynamics and tolerability following single-dose morning and repeated-dose evening administration

BACKGROUND

The dual orexin receptor antagonist ACT-541468 showed sedative pharmacodynamic effects during initial clinical testing in adult subjects. The present study explored pharmacokinetics, pharmacodynamics and tolerability in healthy elderly subjects.

METHODS

Double-blind, placebo-controlled, randomised, single-ascending dose study in 24 male/female elderly (65-80 years, 5, 15 and 25 mg in the morning, 6/2 active/placebo per group). Additionally, 10 subjects (8/2 active/placebo) received 25 mg for 7 days in the evening. Pharmacokinetics, pharmacodynamics (saccadic peak velocity, adaptive tracking, body sway, visual analogue scales according to Bowdle and Bond and Lader, Karolinska Sleepiness Scale) and tolerability were assessed. In particular, pharmacodynamics results are to be interpreted exploratorily.

RESULTS

Absorption was quick with a median time to maximum concentration of ∼ 1.0 h. The mean elimination half-life was 8.5-9.8 h, the area under the curve and the maximum plasma concentration increased proportionally with dose. Following repeated evening administration of 25 mg, minimal accumulation was observed. There were no pharmacodynamic effects at 5 mg. At 15 mg, saccadic peak velocity (degree/s; SD) was reduced (69; 38), while other variables showed no effects. At 25 mg, effects on all objective pharmacodynamic parameters were observed. At 8-12 h post-dose, there were no differences to placebo and no next-day effects on pharmacodynamic variables after evening administration. Elderly subjects reported fewer adverse events compared to adults in previous studies.

CONCLUSION

ACT-541468 in elderly subjects was well tolerated and pharmacokinetics and pharmacodynamics are compatible with a drug for the treatment of insomnia. Clinicaltrials.gov: NCT02571855.

Neuroimaging of Narcolepsy and Primary Hypersomnias

Advances in neuroimaging open up the possibility for new powerful tools to be developed that potentially can be applied to clinical populations to improve the diagnosis of neurological disorders, including sleep disorders. At present, the diagnosis of narcolepsy and primary hypersomnias is largely limited to subjective assessments and objective measurements of behavior and sleep physiology. In this review, we focus on recent neuroimaging findings that provide insight into the neural basis of narcolepsy and the primary hypersomnias Kleine-Levin syndrome and idiopathic hypersomnia. We describe the role of neuroimaging in confirming previous genetic, neurochemical, and neurophysiological findings and highlight studies that permit a greater understanding of the symptoms of these sleep disorders. We conclude by considering some of the remaining challenges to overcome, the existing knowledge gaps, and the potential role for neuroimaging in understanding the pathogenesis and clinical features of narcolepsy and primary hypersomnias.

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.

Multiple-dose clinical pharmacology of ACT-541468, a novel dual orexin receptor antagonist, following repeated-dose morning and evening administration

ACT-541468 is a dual orexin receptor antagonist with sleep-promoting effects in humans. Following entry-into-humans, its pharmacokinetics (PK) including dose-proportionality and accumulation, pharmacodynamics (PD), safety, and tolerability following multiple-ascending oral dose (MAD) administration in the morning, and next-day residual effects after repeated evening administration were investigated in a double-blind, placebo-controlled, randomized study. 31 healthy male and female subjects in 3 dose-groups (10, 25, and 75 mg) received study drug in the morning for 5 days (MAD part), and 20 healthy subjects received 25 mg in the evening for 1 week (evening part). PK, PD (saccadic peak velocity (SPV), adaptive tracking, body sway, Bond and Lader visual analogue scales (VAS), Karolinska Sleepiness Scale (KSS), VAS Bowdle for assessment of psychedelic effects), Digit Symbol Substitution Test (DSST), and Simple Reaction Time Test (SRTT), safety, and tolerability were assessed. ACT-541468 was absorbed with a median t_max of 1.0-2.0 h across the 3 dose groups. The geometric mean elimination half-life (t_½) on Day 5 was between 5.6 and 8.5 h, and the exposure (area under the curve (AUC)) showed dose proportionality. No accumulation and no influence of sex on the multiple-dose PK parameters of ACT-541468 was observed. No effects were observed at 10 mg. Administration of 25 and 75 mg during the day showed clear dose-dependent effects on the PD parameters, while next-day effects were absent after evening administration of 25 mg. The drug was safe and well tolerated. In conclusion, multiple-dose PK/PD of ACT-541468 were compatible with a drug designated to treat insomnia.

Ullanlinna Narcolepsy Scale in diagnosis of narcolepsy

STUDY OBJECTIVES

To validate Ullanlinna Narcolepsy Scale (UNS) as a screening tool for narcolepsy in a clinical population and to compare it with Swiss Narcolepsy Scale (SNS) and Epworth Sleepiness Scale (ESS).

METHODS

UNS questionnaires of 267 participants visiting Helsinki Sleep Clinic were analyzed. The diagnoses of the participants were narcolepsy type 1 (NT1, n = 89), narcolepsy type 2 (NT2, n = 10), other hypersomnias (n = 24), sleep apnea (n = 37), restless legs syndrome or periodic limb movement disorder (n = 56), and other sleep-related disorders (n = 51). In addition, ESS and SNS scores in a subset of sample (total N = 167) were analyzed and compared to UNS.

RESULTS

Mean UNS score in NT1 was 22.0 (95% confidence interval [CI] = 20.4 to 23.6, range 9-43), which was significantly higher than in other disorders, including NT2 (mean 13.7, 95% CI = 10.3 to 17.1, range 7-21, p = .0013). Sensitivity and specificity of UNS in separating NT1 from other disorders were 83.5% and 84.1%, respectively. Positive and negative predictive values were 82.5% and 85.1%, respectively. Sensitivities of SNS and ESS in NT1 were 77.2% and 88.6%, and specificities 88.6% and 45.5%, respectively. There were no differences in receiver operating characteristic curves between UNS and SNS. UNS had moderate negative correlation with hypocretin-1 levels (rs = -.564, p < .001), and mean sleep latency in multiple sleep latency test (rs= -.608, p < .001).

CONCLUSIONS

UNS has high specificity and sensitivity for NT1 in a sleep clinic setting. UNS scores below 9 strongly suggest against the diagnosis of narcolepsy.

Physiological and pathological covariates of persistent concussion-related fatigue: results from two regression methodologies

BACKGROUND

Fatigue severity in persons with mild traumatic brain injury (mTBI) has received little research attention, despite its typically positively skewed nature. Investigation of covariates across a range of fatigue severity may provide insight into important contributors.

OBJECTIVE

To assess the relative significance of a priori-hypothesized covariates of physiological and pathological (mental and physical) fatigue in persons with mTBI/concussion, applying ordinary least squares (OLS) and quantile regression (QR) approaches.

METHODS

We conducted a cross-sectional investigation in 80 participants with mTBI/concussion (mean age 45.4 ± 10.1 years, 59% male). The fatigue severity scale (FSS) was used as an outcome measure. Predictors of this outcome, grouped into physiological and pathological models of fatigue were assessed using OLS and QR.

RESULTS

The mean total FSS score was 46.13 ± 14.59, and the median was 49 (interquartile range 37-57), demonstrating positive skewness. Fatigue severity was associated with variables within the mental, psychological and psychiatric domains at different levels of the fatigue score distribution.

CONCLUSION

Results highlighted that some covariates had a significant impact on the FSS total score at non-central parts of its distribution, while others exhibited significant impact across the entire distribution. Addressing covariates of fatigue across the severity continuum can enhance research and clinical management.

The multiple sleep latency test

The measurement of daytime sleepiness is important in the evaluation of patients with excessive sleepiness. The multiple sleep latency test (MSLT) is an objective test that measures the tendency to fall asleep under controlled conditions. It is based on the notion that sleep latency reflects underlying physiological sleepiness. The MSLT consists of four to five naps given 2h apart during the day, following a standardized procedure. The mean sleep latency from all naps is used as the measure of sleepiness. The test has been shown to be valid and reliable and is part of the diagnostic criteria for narcolepsy and idiopathic hypersomnia. However, the MSLT is affected by numerous variables including insufficient sleep, drugs, activity, and arousal level. Adherence to the established protocol is necessary to limit the effect of these extraneous factors on the MSLT. While the test is a valuable and widely used diagnostic tool for narcolepsy and idiopathic hypersomnia, the use of MSLT in other sleep disorders is not well established.

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.

Sleep-Wake Cycling and Energy Conservation: Role of Hypocretin and the Lateral Hypothalamus in Dynamic State-Dependent Resource Optimization

The hypocretin (Hcrt) system has been implicated in a wide range of physiological functions from sleep-wake regulation to cardiovascular, behavioral, metabolic, and thermoregulagtory control. These wide-ranging physiological effects have challenged the identification of a parsimonious function for Hcrt. A compelling hypothesis suggests that Hcrt plays a role in the integration of sleep-wake neurophysiology with energy metabolism. For example, Hcrt neurons promote waking and feeding, but are also sensors of energy balance. Loss of Hcrt function leads to an increase in REM sleep propensity, but a potential role for Hcrt linking energy balance with REM sleep expression has not been addressed. Here we examine a potential role for Hcrt and the lateral hypothalamus (LH) in state-dependent resource allocation as a means of optimizing resource utilization and, as a result, energy conservation. We review the energy allocation hypothesis of sleep and how state-dependent metabolic partitioning may contribute toward energy conservation, but with additional examination of how the loss of thermoregulatory function during REM sleep may impact resource optimization. Optimization of energy expenditures at the whole organism level necessitates a top-down network responsible for coordinating metabolic operations in a state-dependent manner across organ systems. In this context, we then specifically examine the potential role of the LH in regulating this output control, including the contribution from both Hcrt and melanin concentrating hormone (MCH) neurons among a diverse LH cell population. We propose that this hypothalamic integration system is responsible for global shifts in state-dependent resource allocations, ultimately promoting resource optimization and an energy conservation function of sleep-wake cycling.

Clinical update on central hypersomnias

The central hypersomnias encompass a range of conditions causing persisting or intermittent excessive daytime sleepiness (EDS). These conditions therefore present not infrequently in general clinical sleep practice, and remain in the differential for patients presenting with sleepiness. Our understanding of the pathophysiology, diagnosis and management of these conditions has progressed significantly over recent years, and in this article we review this group of disorders, focussing in particular on recent changes in classification and diagnosis, pathophysiological advances, and novel treatment options.

Unexpected Fat Distribution in Adolescents With Narcolepsy

Narcolepsy type 1 is a chronic sleep disorder with significantly higher BMI reported in more than 50% of adolescent patients, putting them at a higher risk for metabolic syndrome in adulthood. Although well-documented, the body fat distribution and mechanisms behind weight gain in narcolepsy are still not fully understood but may be related to the loss of orexin associated with the disease. Orexin has been linked to the regulation of brown adipose tissue (BAT), a metabolically active fat involved in energy homeostasis. Previous studies have used BMI and waist circumference to characterize adipose tissue increases in narcolepsy but none have investigated its specific distribution. Here, we examine adipose tissue distribution in 19 adolescent patients with narcolepsy type 1 and compare them to 17 of their healthy peers using full body magnetic resonance imaging (MRI). In line with previous findings we saw that the narcolepsy patients had more overall fat than the healthy controls, but contrary to our expectations there were no group differences in supraclavicular BAT, suggesting that orexin may have no effect at all on BAT, at least under thermoneutral conditions. Also, in line with previous reports, we observed that patients had more total abdominal adipose tissue (TAAT), however, we found that they had a lower ratio between visceral adipose tissue (VAT) and TAAT indicating a relative increase of subcutaneous abdominal adipose tissue (ASAT). This relationship between VAT and ASAT has been associated with a lower risk for metabolic disease. We conclude that while weight gain in adolescents with narcolepsy matches that of central obesity, the lower VAT ratio may suggest a lower risk of developing metabolic disease.

Attention deficit hyperactivity disorder symptom severity and sleep problems in adult participants of the Netherlands sleep registry

BACKGROUND

We examined whether current overall attention deficit hyperactivity disorder (ADHD), inattention, or hyperactivity symptom severities are associated with the current presence and persistent history of sleep problems.

METHODS

N = 942 participants of the Netherlands Sleep Registry filled out online several validated questionnaires. Regression analyses were performed to assess the association between (1) current overall ADHD symptom severity and the current presence of sleep problems, (2) current ADHD symptom-severity groups and the persistent history of sleep problems, and (3) current inattention or hyperactivity symptom severities and the current presence of sleep problems.

RESULTS

(1) Current overall ADHD symptom severity was associated with the odds of suffering from probable obstructive sleep apnea syndrome (OSAS), restless legs syndrome (RLS), periodic limb movement disorder (PLMD), insomnia disorder (ID) with predominant difficulties initiating sleep (DIS) and maintaining sleep (DMS), but not with the odds of suffering from narcolepsy or ID with predominant early-morning awakening (EMA). Current overall ADHD symptom severity was also associated with an extreme evening chronotype but not with short sleep. (2) The group with the most severe current ADHD symptoms was more likely to have a history of persistent OSAS, RLS, and ID. (3) The severity of symptoms of hyperactivity, but not of inattention, was specifically associated with probable RLS, PLMD, ID with DIS or DMS, and short sleep. Inattention symptom severity was only related to the probability of being an extreme evening chronotype.

CONCLUSION

ADHD severity, especially the severity of hyperactivity, is associated with the current presence and persistent history of sleep problems.

Evaluation of the Sleepy Patient: Differential Diagnosis

Excessive daytime sleepiness is defined as the inability to maintain wakefulness during waking hours, resulting in unintended lapses into sleep. It is important to distinguish sleepiness from fatigue. The evaluation of a sleep patient begins with a careful clinical assessment that includes a detailed sleep history, medical and psychiatric history, a review of medications, as well as a social and family history. Physical examination should include a general medical examination with careful attention to the upper airway and the neurologic examination. Appropriate objective testing with a polysomnogram and a multiple sleep latency test if needed will help confirm the diagnosis and direct the appropriate treatment plan.

Patient-Reported Measures of Narcolepsy: The Need for Better Assessment

STUDY OBJECTIVES

Narcolepsy, a chronic disorder of the central nervous system, is clinically characterized by a symptom pentad that includes excessive daytime sleepiness, cataplexy, sleep paralysis, hypnopompic/hypnagogic hallucinations, and disrupted nighttime sleep. Ideally, screening and diagnosis instruments that assist physicians in evaluating a patient for type 1 or type 2 narcolepsy would be brief, easy for patients to understand and physicians to score, and would identify or rule out the need for electrophysiological testing.

METHODS

A search of the literature was conducted to review patient-reported measures used for the assessment of narcolepsy, mainly in clinical trials, with the goal of summarizing existing scales and identifying areas that may require additional screening questions and clinical practice scales.

RESULTS

Of the seven scales reviewed, the Epworth Sleepiness Scale continues to be an important outcome measure to screen adults for excessive daytime sleepiness, which may be associated with narcolepsy. Several narcolepsy-specific scales have demonstrated utility, such as the Ullanlinna Narcolepsy Scale, Swiss Narcolepsy Scale, and Narcolepsy Symptom Assessment Questionnaire, but further validation is required.

CONCLUSIONS

Although the narcolepsy-specific scales currently in use may identify type 1 narcolepsy, there are no validated questionnaires to identify type 2 narcolepsy. Thus, there remains a need for short, easily understood, and well-validated instruments that can be readily used in clinical practice to distinguish narcolepsy subtypes, as well as other hypersomnias, and for assessing symptoms of these conditions during treatment.

Sleep stage distribution in persons with mild traumatic brain injury: a polysomnographic study according to American Academy of Sleep Medicine standards

OBJECTIVE AND BACKGROUND

Sleep stage disruption in persons with mild traumatic brain injury (mTBI) has received little research attention. We examined deviations in sleep stage distribution in persons with mTBI relative to population age- and sex-specific normative data and the relationships between such deviations and brain injury-related, medical/psychiatric, and extrinsic factors.

PATIENTS AND METHODS

We conducted a cross-sectional polysomnographic investigation in 40 participants diagnosed with mTBI (mean age 47.54 ± 11.30 years; 56% males).

MEASUREMENTS

At the time of investigation, participants underwent comprehensive clinical and neuroimaging examinations and one full-night polysomnographic study. We used the 2012 American Academy of Sleep Medicine recommendations for recording, scoring, and summarizing sleep stages. We compared participants' sleep stage data with normative data stratified by age and sex to yield z-scores for deviations from available population norms and then employed stepwise multiple regression analyses to determine the factors associated with the identified significant deviations.

RESULTS

In patients with mTBI, the mean duration of nocturnal wakefulness was higher and consolidated sleep stage N2 and REM were lower than normal (p < 0.0001, p = 0.018, and p = 0.010, respectively). In multivariate regression analysis, several covariates accounted for the variance in the relative changes in sleep stage duration. No sex differences were observed in the mean proportion of non-REM or REM sleep.

CONCLUSIONS

We observed longer relative nocturnal wakefulness and shorter relative N2 and REM sleep in patients with mTBI, and these outcomes were associated with potentially modifiable variables. Addressing disruptions in sleep architecture in patients with mTBI could improve their health status.

Measurement of narcolepsy symptoms: The Narcolepsy Severity Scale

OBJECTIVE

To validate the Narcolepsy Severity Scale (NSS), a brief clinical instrument to evaluate the severity and consequences of symptoms in patients with narcolepsy type 1 (NT1).

METHODS

A 15-item scale to assess the frequency and severity of excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, sleep paralysis, and disrupted nighttime sleep was developed and validated by sleep experts with patients' feedback. Seventy untreated and 146 treated adult patients with NT1 were evaluated and completed the NSS in a single reference sleep center. The NSS psychometric properties, score changes with treatment, and convergent validity with other clinical parameters were assessed.

RESULTS

The NSS showed good psychometric properties with significant item-total score correlations. The factor analysis indicated a 3-factor solution with good reliability, expressed by satisfactory Cronbach α values. The NSS total score temporal stability was good. Significant NSS score differences were observed between untreated and treated patients (dependent sample, 41 patients before and after sleep therapy; independent sample, 29 drug-free and 105 treated patients). Scores were lower in the treated populations (10-point difference between groups), without ceiling effect. Significant correlations were found among NSS total score and daytime sleepiness (Epworth Sleepiness Scale, Mean Sleep Latency Test), depressive symptoms, and health-related quality of life.

CONCLUSIONS

The NSS can be considered a reliable and valid clinical tool for the quantification of narcolepsy symptoms to monitor and optimize narcolepsy management.