Scoring sleep in neurological patients: the need for specific considerations

Monitoring sleep stages with a soft electrode array: Comparison against vPSG and home-based detection of REM sleep without atonia

Sleep disorders are symptomatic hallmarks of a variety of medical conditions. Accurately identifying the specific stage in which these disorders occur is particularly important for the correct diagnosis of non-rapid eye movement and rapid eye movement parasomnias. In-lab polysomnography suffers from limited availability and does not reflect habitual sleep conditions, which is especially important in older adults and those with neurodegenerative diseases. We aimed to explore the feasibility and validity of a new wearable system for accurately measuring sleep at home. The system core technology is soft, printed dry electrode arrays and a miniature data acquisition unit with a cloud-based data storage for offline analysis. The positions of the electrodes allow manual scoring following the American Association of Sleep Medicine guidelines. Fifty participants (21 healthy subjects, mean age 56.6 ± 8.4 years; and 29 patients with Parkinson's disease, 65.4 ± 7.6 years) underwent a polysomnography evaluation with parallel recording with the wearable system. Total agreement between the two systems reached Cohen's kappa (k) of 0.688 with agreement in each stage of: wake k = 0.701; N1 = 0.224; N2 = 0.584; N3 = 0.410; and rapid eye movement = 0.723. Moreover, the system reliably detected rapid eye movement sleep without atonia with a sensitivity of 85.7%. Additionally, a comparison between sleep as measured in the sleep lab with data collected from a night at home showed significantly lower wake after sleep onset at home. The results demonstrate that the system is valid, accurate and allows for the exploration of sleep at home. This new system offers an opportunity to help detect sleep disorders on a larger scale than possible today, fostering better care.

Scoring sleep in neurodegenerative diseases: A pilot study in the synucleinopathies

BACKGROUND

Neurodegenerative diseases often alter sleep architecture, complicating the application of the standard sleep scoring rules. There are no recommendations to overcome this problem. Our aim was to develop a scoring method that incorporates the stages previously applied in dementia with Lewy Bodies (DLB), anti-IgLON5 disease, and fatal insomnia, and to test it in patients with alpha-synucleinopathies.

METHODS

Video-polysomnographies (VPSG) of nine patients (DLB:3, Parkinson's disease (PD):3, and multiple system atrophy (MSA):3) selected for their difficulty in applying standard rules were scored independently by two authors, using additional Sleep/Wake stages. These included Abnormal Wake, Subwake, Undifferentiated NREM sleep (UNREM), Poorly structured N2 (P-S N2) and abnormal REM sleep including REM without atonia (RWA), REM without low-amplitude, mixed-frequency EEG activity (RWL) and REM without rapid eye movements (RWR).

RESULTS

Patients (4 females) had a median age of 74 (range 63-85). Six patients (all with PD or DLB) had abnormal EEG awake and Subwake stage. UNREM sleep was present in all patients, typically at sleep onset, and was the most common sleep stage in five. P-S N2 was recorded only in the three patients with MSA. Periods of normal and abnormal NREM coexisted in three patients. RWA was the predominant REM subtype, RWR occurred mainly in patients with MSA and RWL in those with DLB. Six patients had brief REM episodes into NREM sleep which we termed "Encapsulated RBD".

CONCLUSION

Our scoring system allows an accurate description of the complex sleep-wake changes in patients with alpha-synucleinopathies.

Automatic sleep staging of EEG signals: recent development, challenges, and future directions

Modern deep learning holds a great potential to transform clinical practice on human sleep. Teaching a machine to carry out routine tasks would be a tremendous reduction in workload for clinicians. Sleep staging, a fundamental step in sleep practice, is a suitable task for this and will be the focus in this article. Recently, automatic sleep staging systems have been trained to mimic manual scoring, leading to similar performance to human sleep experts, at least on scoring of healthy subjects. Despite tremendous progress, we have not seen automatic sleep scoring adopted widely in clinical environments. This review aims to give a shared view of the authors on the most recent state-of-the-art development in automatic sleep staging, the challenges that still need to be addressed, and the future directions for automatic sleep scoring to achieve clinical value.

Video-polysomnography procedures for diagnosis of rapid eye movement sleep behavior disorder (RBD) and the identification of its prodromal stages: guidelines from the International RBD Study Group

Video-polysomnography (v-PSG) is essential for diagnosing rapid eye movement (REM) sleep behavior disorder (RBD). Although there are current American Academy of Sleep Medicine standards to diagnose RBD, several aspects need to be addressed to achieve harmonization across sleep centers. Prodromal RBD is a stage in which symptoms and signs of evolving RBD are present, but do not yet meet established diagnostic criteria for RBD. However, the boundary between prodromal and definite RBD is still unclear. As a common effort of the Neurophysiology Working Group of the International RBD Study Group, this manuscript addresses the need for comprehensive and unambiguous v-PSG recommendations to diagnose RBD and identify prodromal RBD. These include: (1) standardized v-PSG technical settings; (2) specific considerations for REM sleep scoring; (3) harmonized methods for scoring REM sleep without atonia; (4) consistent methods to analyze video and audio recorded during v-PSGs and to classify movements and vocalizations; (5) clear v-PSG guidelines to diagnose RBD and identify prodromal RBD. Each section follows a common template: The current recommendations and methods are presented, their limitations are outlined, and new recommendations are described. Finally, future directions are presented. These v-PSG recommendations are intended for both practicing clinicians and researchers. Classification and quantification of motor events, RBD episodes, and vocalizations are however intended for research purposes only. These v-PSG guidelines will allow collection of homogeneous data, providing objective v-PSG measures and making future harmonized multicentric studies and clinical trials possible.

Measuring Sleep, Wakefulness, and Circadian Functions in Neurologic Disorders

Neurologic disorders impact the ability of the brain to regulate sleep, wake, and circadian functions, including state generation, components of state (such as rapid eye movement sleep muscle atonia, state transitions) and electroencephalographic microarchitecture. At its most extreme, extensive brain damage may even prevent differentiation of sleep stages from wakefulness (eg, status dissociatus). Given that comorbid sleep-wake-circadian disorders are common and can adversely impact the occurrence, evolution, and management of underlying neurologic conditions, new technologies for long-term monitoring of neurologic patients may potentially usher in new diagnostic strategies and optimization of clinical management.

Interrater sleep stage scoring reliability between manual scoring from two European sleep centers and automatic scoring performed by the artificial intelligence-based Stanford-STAGES algorithm

STUDY OBJECTIVES

The objective of this study was to evaluate interrater reliability between manual sleep stage scoring performed in 2 European sleep centers and automatic sleep stage scoring performed by the previously validated artificial intelligence-based Stanford-STAGES algorithm.

METHODS

Full night polysomnographies of 1,066 participants were included. Sleep stages were manually scored in Berlin and Innsbruck sleep centers and automatically scored with the Stanford-STAGES algorithm. For each participant, we compared (1) Innsbruck to Berlin scorings (INN vs BER); (2) Innsbruck to automatic scorings (INN vs AUTO); (3) Berlin to automatic scorings (BER vs AUTO); (4) epochs where scorers from Innsbruck and Berlin had consensus to automatic scoring (CONS vs AUTO); and (5) both Innsbruck and Berlin manual scorings (MAN) to the automatic ones (MAN vs AUTO). Interrater reliability was evaluated with several measures, including overall and sleep stage-specific Cohen's κ.

RESULTS

Overall agreement across participants was substantial for INN vs BER (κ = 0.66 ± 0.13), INN vs AUTO (κ = 0.68 ± 0.14), CONS vs AUTO (κ = 0.73 ± 0.14), and MAN vs AUTO (κ = 0.61 ± 0.14), and moderate for BER vs AUTO (κ = 0.55 ± 0.15). Human scorers had the highest disagreement for N1 sleep (κ_N1 = 0.40 ± 0.16 for INN vs BER). Automatic scoring had lowest agreement with manual scorings for N1 and N3 sleep (κ_N1 = 0.25 ± 0.14 and κ_N3 = 0.42 ± 0.32 for MAN vs AUTO).

CONCLUSIONS

Interrater reliability for sleep stage scoring between human scorers was in line with previous findings, and the algorithm achieved an overall substantial agreement with manual scoring. In this cohort, the Stanford-STAGES algorithm showed similar performances to the ones achieved in the original study, suggesting that it is generalizable to new cohorts. Before its integration in clinical practice, future independent studies should further evaluate it in other cohorts.

Characterization of the sleep disorder of anti-IgLON5 disease

STUDY OBJECTIVE

To characterize the sleep disorder of anti-IgLON5 disease.

METHODS

We reviewed 27 video-polysomnographies (V-PSG), 6 multiple sleep latency tests (MSLT), 2 videsomnoscopies with dexmedetomidine, and 10 actigraphies recorded during the disease course of five patients. Due to severe sleep architecture abnormalities, we used a novel modified sleep scoring system combining conventional stages with a descriptive approach in which two additional stages were identified: undifferentiated-NREM (UN-NREM) and poorly structured N2 (P-SN2) sleep that were characterized by abnormal motor activation and absence or sparse elements of conventional NREM sleep.

RESULTS

Sleep-related vocalizations, movements, behaviors, and respiratory abnormalities were reported by bed-partners. In all patients, NREM sleep onset and sleep reentering after an awakening occurred as UN-NREM (median: 29.8% of total sleep time [TST]) and P-SN2 sleep (14.5% TST) associated with vocalizations and simple and quasi-purposeful movements. Sleep initiation was normalized in one patient with a high dose of steroids, but NREM sleep abnormalities reappeared in subsequent V-PSG. In all patients, if sleep continued uninterrupted, there was a progressive normalization with normal N2 (11.7% TST) and N3 (22.3% TST) sleep but stridor and obstructive apnea emerged. REM sleep behavior disorder (RBD) occurred in four patients. Sleep initiation was also altered in MSLT and dexmedetomidine-induced sleep. Actigraphy showed a 10-fold increase of nocturnal activity compared with controls. Sleep abnormalities remained stable during the disease.

CONCLUSIONS

The sleep disorder of anti-IgLON5 disease presents as a complex sleep pattern characterized by abnormal sleep initiation with undifferentiated NREM sleep, RBD, periods of normal NREM sleep, stridor, and obstructive apnea.

A data-driven system to identify REM sleep behavior disorder and to predict its progression from the prodromal stage in Parkinson's disease

OBJECTIVES

To investigate electroencephalographic (EEG), electrooculographic (EOG) and micro-sleep abnormalities associated with rapid eye movement (REM) sleep behavior disorder (RBD) and REM behavioral events (RBEs) in Parkinson's disease (PD).

METHODS

We developed an automated system using only EEG and EOG signals. First, automatic macro- (30-s epochs) and micro-sleep (5-s mini-epochs) staging was performed. Features describing micro-sleep structure, EEG spectral content, EEG coherence, EEG complexity, and EOG energy were derived. All features were input to an ensemble of random forests, giving as outputs the probabilities of having RBD or not (P (RBD) and P (nonRBD), respectively). A patient was classified as having RBD if P (RBD)≥P (nonRBD). The system was applied to 107 de novo PD patients: 54 had normal REM sleep (PDnonRBD), 26 had RBD (PD + RBD), and 27 had at least two RBEs without meeting electromyographic RBD cut-off (PD + RBE). Sleep diagnoses were made with video-polysomnography (v-PSG).

RESULTS

Considering PDnonRBD and PD + RBD patients only, the system identified RBD with accuracy, sensitivity, and specificity over 80%. Among the features, micro-sleep instability had the highest importance for RBD identification. Considering PD + RBE patients, the ones who developed definite RBD after two years had significantly higher values of P (RBD) at baseline compared to the ones who did not. The former were distinguished from the latter with sensitivity and specificity over 75%.

CONCLUSIONS

Our method identifies RBD in PD patients using only EEG and EOG signals. Micro-sleep instability could be a biomarker for RBD and for proximity of conversion from RBEs, as prodromal RBD, to definite RBD in PD patients.

Clinical and video-polysomnographic analysis of rapid eye movement sleep behavior disorder and other sleep disturbances in dementia with Lewy bodies

Objective

The main objective of this study was to study rapid eye movement (REM) sleep behavior disorder (RBD) and other sleep disorders in dementia with Lewy bodies (DLB).

Methods

Consecutive patients with DLB and mild dementia severity were recruited irrespective of sleep complaints. Patients underwent clinical interview, assessment of sleep scales, and video-polysomnography (V-PSG). RBD was diagnosed with V-PSG based on electromyographic and audiovisual analysis.

Results

Thirty-five patients (65.7% men; mean age 77.7 ± 6.1 years) were evaluated. Poor sleep quality (54.3%), hypersomnia (37.1%), snoring (60%), and abnormal nocturnal behaviors (77.1%) were reported. Sleep–wake architecture abnormalities occurred in 75% patients and consisted of occipital slowing on awake electroencephalography (EEG; 34.4%), the absence of sleep spindles and K complexes (12.9%), slow frequency sleep spindles (12.9%), delta activity in REM sleep (19.2%), and REM sleep without atonia (44%). Three patients showed hallucinatory-like behaviors and 10 patients showed abnormal behaviors during arousals mimicking RBD. RBD was diagnosed in 50% of those patients in whom sufficient REM sleep was attained. Of these, 72.7% were not aware of displaying dream-enacting behaviors and in 63.7% RBD preceded the onset of cognitive impairment. For RBD diagnosis, the sensitivity of Mayo Sleep Questionnaire was 50%, specificity was 66.7%, positive predictive value was 83.3%, and negative predictive value was 28%. False-positive RBD cases according to clinical history had hallucinatory-like behaviors, severe obstructive sleep apnea, and prominent periodic limb movements in sleep. Occipital EEG frequency while awake and rate of electromyographic activity in REM sleep were negatively correlated, suggesting a common subcortical origin.

Conclusion

In DLB, RBD and sleep–wake disorders are common, heterogeneous, and complex, challenging their identification without performing V-PSG.

A two-step automatic sleep stage classification method with dubious range detection

BACKGROUND

The limitations of the current systems of automatic sleep stage classification (ASSC) are essentially related to the similarities between epochs from different sleep stages and the subjects' variability. Several studies have already identified the situations with the highest likelihood of misclassification in sleep scoring. Here, we took advantage of such information to develop an ASSC system based on knowledge of subjects' variability of some indicators that characterize sleep stages and on the American Academy of Sleep Medicine (AASM) rules.

METHODS

An ASSC system consisting of a two-step classifier is proposed. In the first step, epochs are classified using support vector machines (SVMs) spread into different nodes of a decision tree. In the post-processing step, the epochs suspected of misclassification (dubious classification) are tagged, and a new classification is suggested. Identification and correction are based on the AASM rules, and on misclassifications most commonly found/reported in automatic sleep staging. Six electroencephalographic and two electrooculographic channels were used to classify wake, non-rapid eye movement (NREM) sleep--N1, N2 and N3, and rapid eye movement (REM) sleep.

RESULTS

The proposed system was tested in a dataset of 14 clinical polysomnographic records of subjects suspected of apnea disorders. Wake and REM epochs not falling in the dubious range, are classified with accuracy levels compatible with the requirements for clinical applications. The suggested correction assigned to the epochs that are tagged as dubious enhances the global results of all sleep stages.

CONCLUSIONS

This approach provides reliable sleep staging results for non-dubious epochs.

A novel non-rapid-eye movement and rapid-eye-movement parasomnia with sleep breathing disorder associated with antibodies to IgLON5: a case series, characterisation of the antigen, and post-mortem study

BACKGROUND

Autoimmunity might be associated with or implicated in sleep and neurodegenerative disorders. We aimed to describe the features of a novel neurological syndrome associated with prominent sleep dysfunction and antibodies to a neuronal antigen.

METHODS

In this observational study, we used clinical and video polysomnography to identify a novel sleep disorder in three patients referred to the Sleep Unit of Hospital Clinic, University of Barcelona, Spain, for abnormal sleep behaviours and obstructive sleep apnoea. These patients had antibodies against a neuronal surface antigen, which were also present in five additional patients referred to our laboratory for antibody studies. These five patients had been assessed with polysomnography, which was done in our sleep unit in one patient and the recording reviewed in a second patient. Two patients underwent post-mortem brain examination. Immunoprecipitation and mass spectrometry were used to characterise the antigen and develop an assay for antibody testing. Serum or CSF from 298 patients with neurodegenerative, sleep, or autoimmune disorders served as control samples.

FINDINGS

All eight patients (five women; median age at disease onset 59 years [range 52-76]) had abnormal sleep movements and behaviours and obstructive sleep apnoea, as confirmed by polysomnography. Six patients had chronic progression with a median duration from symptom onset to death or last visit of 5 years (range 2-12); in four the sleep disorder was the initial and most prominent feature, and in two it was preceded by gait instability followed by dysarthria, dysphagia, ataxia, or chorea. Two patients had a rapid progression with disequilibrium, dysarthria, dysphagia, and central hypoventilation, and died 2 months and 6 months, respectively, after symptom onset. In five of five patients, video polysomnography showed features of obstructive sleep apnoea, stridor, and abnormal sleep architecture (undifferentiated non-rapid-eye-movement [non-REM] sleep or poorly structured stage N2, simple movements and finalistic behaviours, normalisation of non-REM sleep by the end of the night, and, in the four patients with REM sleep recorded, REM sleep behaviour disorder). Four of four patients had HLA-DRB1*1001 and HLA-DQB1*0501 alleles. All patients had antibodies (mainly IgG4) against IgLON5, a neuronal cell adhesion molecule. Only one of the 298 controls, who had progressive supranuclear palsy, had IgLON5 antibodies. Neuropathology showed neuronal loss and extensive deposits of hyperphosphorylated tau mainly involving the tegmentum of the brainstem and hypothalamus in the two patients studied.

INTERPRETATION

IgLON5 antibodies identify a unique non-REM and REM parasomnia with sleep breathing dysfunction and pathological features suggesting a tauopathy.

FUNDING

Fondo de Investigaciones Sanitarias, Centros de Investigación Biomédica en Red de enfermedades neurodegenerativas (CIBERNED) and Respiratorias (CIBERES), Ministerio de Economía y Competitividad, Fundació la Marató TV3, and the National Institutes of Health.

Atypical sleep in ventilated patients: empirical electroencephalography findings and the path toward revised ICU sleep scoring criteria

OBJECTIVES

Standard sleep scoring criteria may be unreliable when applied to critically ill patients. We sought to quantify typical and atypical polysomnographic findings in critically ill patients and to begin development and reliability testing of methodology to characterize the atypical polysomnographic tracings that confound standard sleep scoring criteria.

DESIGN

Prospective convenience sample.

SETTING

Two academic, tertiary care medical centers.

PATIENTS

Thirty-seven critically ill, mechanically ventilated, medical ICU patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Mechanically ventilated subjects were monitored by continuous polysomnography. After noting frequent atypical polysomnographic findings (i.e., lack of stage N2 markers, the presence of polymorphic delta, burst suppression, or isoelectric electroencephalography), attempts to use standard sleep scoring criteria alone were abandoned. Atypical polysomnographic findings were characterized and used to develop a modified scoring system. Polysomnographic data were scored manually via this revised scoring scheme. Of 37 medical ICU patients enrolled, 36 experienced atypical sleep, which accounted for 85% of all recorded data, with 5.1% normal sleep and 9.4% wake. Coupling observed patient arousal levels with polysomnographic characteristics revealed that standard polysomnographic staging criteria did not reliably determine the presence or absence of sleep. Rapid eye movement occurred in only five patients (14%). The revised scoring system incorporating frequently seen atypical characteristics yielded very high interrater reliability (weighted κ = 0.80; bootstrapped 95% CI, [0.48, 0.89]).

CONCLUSIONS

Analysis of polysomnographic data revealed profound deficiencies in standard scoring criteria due to a predominance of atypical polysomnographic findings in ventilated patients. The revised scoring scheme proved reliable in sleep staging and may serve as a building block in future work.

Daytime alertness in Parkinson's disease: potentially dose-dependent, divergent effects by drug class

Many patients with idiopathic Parkinson's disease experience difficulties maintaining daytime alertness. Controversy exists regarding whether this reflects effects of antiparkinsonian medications, the disease itself, or other factors such as nocturnal sleep disturbances. In this study we examined the phenomenon by evaluating medicated and unmedicated Parkinson's patients with objective polysomnographic measurements of nocturnal sleep and daytime alertness. Patients (n = 63) underwent a 48-hour laboratory-based study incorporating 2 consecutive nights of overnight polysomnography and 2 days of Maintenance of Wakefulness Testing. We examined correlates of individual differences in alertness, including demographics, clinical features, nocturnal sleep variables, and class and dosage of anti-Parkinson's medications. Results indicated that, first, relative to unmediated patients, all classes of dopaminergic medications were associated with reduced daytime alertness, and this effect was not mediated by disease duration or disease severity. Second, the results showed that increasing dosages of dopamine agonists were associated with less daytime alertness, whereas higher levels of levodopa were associated with higher levels of alertness. Variables unrelated to the Maintenance of Wakefulness Test defined daytime alertness including age, sex, years with diagnosis, motor impairment score, and most nocturnal sleep variables. Deficits in objectively assessed daytime alertness in Parkinson's disease appear to be a function of both the disease and the medications and their doses used. The apparent divergent dose-dependent effects of drug class in Parkinson's disease are anticipated by basic science studies of the sleep/wake cycle under different pharmacological agents.