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

Idiopathic Hypersomnia: Neurobiology, Diagnosis, and Management

Idiopathic hypersomnia is a chronic neurologic sleep disorder that manifests as excessive daytime sleepiness despite normal or prolonged sleep times for age. Frequently, idiopathic hypersomnia is clinically characterized by marked sleep inertia, long and unrefreshing naps, and a high sleep efficiency. Since the initial description, there has been an ongoing evolution of its nomenclature, approach to diagnosis, characterization of symptoms, and determination of the burden of disease. In addition, an increased attention to and study of its epidemiology, neurobiology, and potential therapeutic strategies has begun to contribute to a better approach to identifying and treating it. At present, idiopathic hypersomnia is considered an orphan disease with unknown frequency and the cause is unknown; however, there is evidence to suggest circadian and sleep structure differences, structural brain changes, and neurochemical changes may contribute to the development and expression of this disease. The approach to treatment can be challenging owing to a limited number of approved treatments (calcium, magnesium, potassium, and sodium oxybates) in idiopathic hypersomnia. However, consideration of therapies shown to improve excessive daytime sleepiness in other disorders is frequently employed. Future directions require a clear consensus on the defining characteristics of idiopathic hypersomnia to enhance the opportunity for improved recognition, diagnosis, and treatment strategies to be established. This article provides a historical review of the evolving diagnostic classification of idiopathic hypersomnia, potential insights to the underlying pathophysiology, and a summary of proposed approaches for diagnosis and therapeutic intervention.

Novel Objective Measures of Hypersomnolence

Purpose of review

To provide a brief overview of current objective measures of hypersomnolence, discuss proposed measure modifications, and review emerging measures.

Recent findings

There is potential to optimize current tools using novel metrics. High-density and quantitative EEG-based measures may provide discriminative informative. Cognitive testing may quantify cognitive dysfunction common to hypersomnia disorders, particularly in attention, and objectively measure pathologic sleep inertia. Structural and functional neuroimaging studies in narcolepsy type 1 have shown considerable variability but so far implicate both hypothalamic and extra-hypothalamic regions; fewer studies of other CDH have been performed. There is recent renewed interest in pupillometry as a measure of alertness in the evaluation of hypersomnolence.

Summary

No single test captures the full spectrum of disorders and use of multiple measures will likely improve diagnostic precision. Research is needed to identify novel measures and disease-specific biomarkers, and to define combinations of measures optimal for CDH diagnosis.

Clinical considerations for the diagnosis of idiopathic hypersomnia

Idiopathic hypersomnia is a sleep disorder of neurologic origin characterized by excessive daytime sleepiness, with sleep inertia, long, unrefreshing naps, and prolonged nighttime sleep being key symptoms in many patients. Idiopathic hypersomnia is described in the International Classification of Sleep Disorders, 3rd Edition as a central disorder of hypersomnolence with distinct clinical features and diagnostic criteria; however, confirming the diagnosis of idiopathic hypersomnia is often challenging. Diagnosis of idiopathic hypersomnia is based on objective sleep testing and the presence of associated clinical features but may be difficult for clinicians to recognize and correctly diagnose because of its low prevalence, clinical heterogeneity, and symptoms, which are similar to those of other sleep disorders. The testing required for diagnosis of idiopathic hypersomnia also presents logistical barriers, and reliability of objective sleep measures is suboptimal. The pathophysiology of idiopathic hypersomnia remains unknown. In this review, clinical considerations related to the pathogenesis, diagnosis, and management of idiopathic hypersomnia will be discussed, including perspectives from the European Union and United States.

The Psychomotor Vigilance Test as a measure of alertness and sleep inertia in people with central disorders of hypersomnolence

STUDY OBJECTIVES

The central disorders of hypersomnolence (CDH) manifest with daytime sleepiness, often accompanied by cognitive symptoms. Objective tests characterizing cognitive dysfunction may have diagnostic utility. Further, because some people with CDH report worsening cognition upon awakening, cognitive testing before and after napping may provide additional diagnostic information.

METHODS

CDH patients with idiopathic hypersomnia (n = 76), narcolepsy type 1 (n = 19), narcolepsy type 2 (n = 22), and self-reported excessive daytime sleepiness not meeting current diagnostic criteria (n = 76), and non-sleepy controls (n = 33) underwent testing with the psychomotor vigilance test (PVT), a 10-minute reaction time test. A subset of participants underwent repeat testing during a Multiple Sleep Latency Test (MSLT), before and immediately after naps 2 and 4.

RESULTS

Most PVT metrics were significantly better in controls than in patients with CDH. Minimal group differences in PVT performance were observed by CDH diagnosis. PVT performance was weakly correlated to Epworth and MSLT mean sleep latency in the CDH group. Before and after naps, PVT metrics were minimally different for controls, while PVT performance generally worsened following naps in the CDH group, with significant worsening compared to controls for nap 2 mean, median, lapses, and fastest 10% of responses, and nap 4 lapses and slowest 10% of responses. Change in performance did not differ based on CDH diagnostic group for any metric on either nap.

CONCLUSIONS

The PVT, at baseline and following a short nap, may provide adjunctive diagnostic utility in separating individuals with CDH from controls.

Idiopathic Hypersomnia: Historical Account, Critical Review of Current Tests and Criteria, Diagnostic Evaluation in the Absence of Biological Markers and Robust Electrophysiological Diagnostic Criteria

Idiopathic hypersomnia was first described in 1976 under two forms: polysymptomatic, characterized by excessive daytime sleepiness, long and unrefreshing naps, nocturnal sleep of abnormally long duration and signs of sleep drunkenness upon awakening; monosymptomatic, manifested by excessive daytime sleepiness only. Yet, after 45 years, this sleep disorder is still poorly delineated and diagnostic criteria produced by successive International Classifications of Sleep Disorders are far from satisfactory. The first part of this review is a historical account of the successive names and descriptions of idiopathic hypersomnia: monosymptomatic and polysymptomatic idiopathic hypersomnia in 1976; central nervous system idiopathic hypersomnia in 1979; idiopathic hypersomnia in 1990; idiopathic hypersomnia with and without long sleep time in 2005; idiopathic hypersomnia again in 2014; and, within the last few years, the proposal of separating idiopathic hypersomnia into a well-defined subtype, idiopathic hypersomnia with long sleep duration, and a more heterogeneous subtype combining idiopathic hypersomnia without long sleep duration and narcolepsy type 2. The second part is a critical review of both current ICSD-3 diagnostic criteria and clinical features, scales and questionnaires, electrophysiological and circadian control tests, research techniques, currently used to diagnose idiopathic hypersomnia. The third part proposes a diagnostic evaluation of idiopathic hypersomnia, in the absence of biologic markers and of robust electrophysiological diagnostic criteria.

Safety and efficacy of lower-sodium oxybate in adults with idiopathic hypersomnia: a phase 3, placebo-controlled, double-blind, randomised withdrawal study

BACKGROUND

Idiopathic hypersomnia is a central hypersomnolence disorder mainly characterised by excessive daytime sleepiness, with prolonged night-time sleep and pronounced sleep inertia. Until August, 2021, no medication had regulatory approval for the treatment of idiopathic hypersomnia. This study aimed to evaluate the safety and efficacy of lower-sodium oxybate in idiopathic hypersomnia.

METHODS

This was a phase 3, multicentre (50 specialist sleep centres; six EU countries and the USA), placebo-controlled, double-blind, randomised withdrawal study. Participants (aged 18-75 years) with idiopathic hypersomnia (meeting criteria from the International Classification of Sleep Disorders, 2nd or 3rd editions) began lower-sodium oxybate treatment (oral solution once or twice nightly) in an open-label titration and optimisation period (10-14 weeks), followed by a 2-week, open-label, stable-dose period. After these open-label periods, participants were randomised (1:1) by means of an interactive web recognition system, stratified by participants' baseline medication use, to either placebo or lower-sodium oxybate (individually optimised dose; range 2·5-9·0 g/night) during a 2-week, double-blind, randomised withdrawal period. To maintain masking of treatment assignment, placebo and lower-sodium oxybate oral solutions were matched in volume, appearance, and taste. During the double-blind, randomised withdrawal period, participants and investigators were unaware of treatment assignments. The primary efficacy endpoint was change in Epworth Sleepiness Scale (ESS) score from the end of the stable-dose period to the end of the double-blind, randomised withdrawal period, which was assessed in the modified intention-to-treat population (defined as all participants who were randomly assigned, took at least one dose of study medication during the double blind, randomised withdrawal period, and had at least one set of post-randomisation assessments for the primary or key secondary endpoints). Adverse events were assessed in the safety population (defined as all participants who took at least one dose of study medication). This study is registered at ClinicalTrials.gov, NCT03533114, and at EU Clinical Trials, 2018-001311-79, and is complete.

FINDINGS

Between Nov 27, 2018, and March 6, 2020, 154 participants were enrolled and comprised the safety population. ESS scores decreased from a mean of 15·7 (SD 3·8) at baseline to 6·1 (4·0) by the end of the stable-dose period. After the open-label periods, 115 participants were randomly assigned either placebo (n=59) or lower-sodium oxybate (n=56) and comprised the modified intention-to-treat population. During the double-blind, randomised withdrawal period, ESS scores increased (worsened) in participants randomly assigned to placebo but remained stable in those assigned to lower-sodium oxybate (least squares mean difference -6·5; 95% CI -8·0 to -5·0; p<0·0001). Treatment-emergent adverse events included nausea (34 [22%] of 154), headache (27 [18%] of 154), dizziness (19 [12%] of 154), anxiety (17 [11%] 154), and vomiting (17 [11%] 154). No deaths were reported during the study.

INTERPRETATION

Lower-sodium oxybate treatment resulted in a clinically meaningful improvement in idiopathic hypersomnia symptoms, with an overall safety profile consistent with that reported for narcolepsy. Lower-sodium oxybate was approved in August, 2021, by the US Food and Drug Administration for the treatment of idiopathic hypersomnia in adults.

FUNDING

Jazz Pharmaceuticals.

Recognizing the Symptom Spectrum of Narcolepsy to Improve Timely Diagnosis: A Narrative Review

Narcolepsy is a chronic sleep disorder with a strong negative impact on quality of life, especially when untreated. Diagnostic delay is a persistent problem, with obvious detrimental effects on patients. A diagnosis of narcolepsy may be delayed because of its broad symptom presentation which is much more encompassing than the classical "tetrad" of sleepiness, cataplexy, hallucinations, and sleep paralysis. Furthermore, symptoms can vary over time. Presentation of symptoms can also be markedly different between children and adults. Finally, common sleep-related comorbidities increase the risk of narcolepsy being masked by overlapping symptoms or treatment. In this review, we provide a detailed description of the broad and dynamic symptom spectrum of narcolepsy, with specific attention to the different manifestations in both adults and children. The overarching goal is to help not only sleep specialists, but general practitioners, pediatricians, and other caregivers with early recognition and prompt diagnosis of this severe but treatable disorder.