Investigation of anti-neuronal antibodies and disparity in central hypersomnias

STUDY OBJECTIVES

Microbial antigens can elicit an immune response leading to the production of autoantibodies cross-reacting with autoantigens. Still, their clinical significance in human sera in the context of brain diseases is unclear. Therefore, assessment of natural autoantibodies reacting with their neuropeptides may elucidate the autoimmune etiology of central hypersomnias. The study aims to determine whether serum autoantibody levels differ in patients with different types of central hypersomnias (narcolepsy type 1 and 2, NT1 and NT2; idiopathic hypersomnia, IH) and healthy controls and if the differences could suggest the participation of autoantibodies in disease pathogenesis.

METHODS

Sera from 91 patients with NT1, 27 with NT2, 46 with IH, and 50 healthy controls were examined for autoantibodies against assorted neuropeptides. Participants were screened using questionnaires related to sleep disorders, quality of life, and mental health conditions. In addition, serum biochemical parameters and biomarkers of microbial penetration through the intestinal wall were determined.

RESULTS

A higher prevalence of autoantibodies against neuropeptides was observed only for alpha-melanocytes-stimulating hormone (α-MSH) and neuropeptide glutamic acid-isoleucine (NEI), which differed slightly among diagnoses. Patients with both types of narcolepsy exhibited signs of microbial translocation through the gut barrier. According to the questionnaires, patients diagnosed with NT2 or IH had subjectively worse life quality than patients with NT1. Patients displayed significantly lower levels of bilirubin and creatinine and slightly higher alkaline phosphatase values than healthy controls.

CONCLUSIONS

Overall, serum anti-neuronal antibodies prevalence is rare, suggesting that their participation in the pathophysiology of concerned sleep disorders is insignificant. Moreover, their levels vary slightly between diagnoses indicating no major diagnostic significance.

Guardians of Rest? Investigating the gut microbiota in central hypersomnolence disorders

In recent years, there has been an increased interest in elucidating the influence of the gut microbiota on sleep physiology. The gut microbiota affects the central nervous system by modulating neuronal pathways through the neuroendocrine and immune system, the hypothalamus-pituitary-adrenal axis, and various metabolic pathways. The gut microbiota can also influence circadian rhythms. In this study, we observed the gut microbiota composition of patients suffering from narcolepsy type 1, narcolepsy type 2, and idiopathic hypersomnia. We did not observe any changes in the alpha diversity of the gut microbiota among patient groups and healthy controls. We observed changes in beta diversity in accordance with Jaccard dissimilarities between the control group and groups of patients suffering from narcolepsy type 1 and idiopathic hypersomnia. Our results indicate that both these patient groups differ from controls relative to the presence of rare bacterial taxa. However, after adjustment for various confounding factors such as BMI, age, and gender, there were no statistical differences among the groups. This indicates that the divergence in beta diversity in the narcolepsy type 1 and idiopathic hypersomnia groups did not arise due to sleep disturbances. This study implies that using metabolomics and proteomics approaches to study the role of microbiota in sleep disorders might prove beneficial.

Magnetic susceptibility changes in the brainstem reflect REM sleep without atonia severity in isolated REM sleep behavior disorder

REM sleep without atonia (RWA) is the hallmark of isolated REM sleep behavior disorder (iRBD) and is caused by neurodegeneration of brainstem structures. Previously, quantitative susceptibility mapping (QSM) was shown to detect microstructural tissue changes in neurodegenerative diseases. The goal of the study was to compare brainstem magnetic susceptibility (MS) in iRBD and controls using the voxel-based QSM approach and to examine the association between brainstem MS and severity of RWA in iRBD. Sixty iRBD patients and 41 healthy controls were included in the study. Phasic, tonic, mixed RWA and SINBAR score was quantified. QSM maps were reconstructed with QSMbox software from a multi-gradient-echo sequence acquired at 3T MRI system and normalized using a custom T1 template. Voxel-based analysis with age and gender as covariates was performed using a two-sample t-test model for between-group comparison and using a linear regression model for association with the RWA parameters. Statistical maps were generated using threshold free cluster enhancement with p-value p < 0.05, corrected for family wise error. Compared to controls, the iRBD group had higher MS in bilateral substantia nigra (SN), red nucleus and the ventral tegmental area. MS positively correlated with iRBD duration in the right pedunculotegmental nucleus and white matter of caudal mesencephalic and pontine tegmentum and with phasic RWA in bilateral SN. QSM was able to detect MS abnormalities in several brainstem structures in iRBD. Association of MS levels in the brainstem with the intensity of RWA suggests that increased iron content in SN is related to RWA severity.

Sleep-related rhythmic movements and rhythmic movement disorder beyond early childhood

INTRODUCTION

Sleep-related rhythmic movements (SRRMs) are common in young children and become less prevalent with increasing age. When SRRMs significantly interfere with sleep and/or affect daytime functioning, potentially resulting in injury, rhythmic movement disorder (SRRMD) is diagnosed.

OBJECTIVE

The aim of our study was to assess clinical comorbidities, types of SRRMs, sleep stage/wakefulness distribution during night, and age-dependence of these parameters.

MATERIAL AND METHODS

In sum, 45 patients (age range 1-26 years, mean age 10.56 ± 6.4 years, 29 men) were clinically examined for SRRMs or SRRMD. Nocturnal polysomnography (PSG) was recorded in 38 patients. To evaluate clinical and sleep comorbidity, the cohort of 38 patients was divided according to age into four groups: (1) younger than 5 years (N = 7), (2) 5-9 years (N = 12), (3) 10-14 years (N = 11), and (4) ≥ 15 years (N = 8).

RESULTS

A clear relationship between perinatal risk factors and developmental disorders (attention deficit hyperactivity disorder - ADHD, specific learning disability) was found which extended population prevalence at least five times. A total of 62 recordings were evaluated in 38 patients; SRRMs were found in PSG in 31 of 38 patients (82%). No age-dependent correlation between type of SRRMs and sleep stage/wakefulness distribution during the night was observed. However, when all recordings were correlated together, rolling stereotypes occurred more frequently in REM sleep, and rocking stereotypes in superficial NREM sleep.

CONCLUSION

Developmental disorders and perinatal risk factors were connected with SRRMs and SRRMD in children and young adults. Rolling movements were significantly associated with REM stage and rocking stereotypes with superficial NREM sleep, independent of age.

Simultaneous tonic and phasic REM sleep without atonia best predicts early phenoconversion to neurodegenerative disease in idiopathic REM sleep behavior disorder

Study Objectives

Rapid eye movement (REM) sleep without atonia (RWA) is the main polysomnographic feature of idiopathic REM sleep behavior disorder (iRBD) and is considered to be a promising biomarker predicting conversion to manifested synucleinopathy. Besides conventionally evaluated tonic, phasic and any RWA, we took into consideration also periods, when phasic and tonic RWA appeared simultaneously and we called this activity “mixed RWA.” The study aimed to evaluate different types of RWA, to reveal the most relevant biomarker to the conversion.

Methods

A total of 55 patients with confirmed iRBD were recruited with mean follow-up duration 2.3 ± 0.7 years. Scoring of RWA was based on Sleep Innsbruck Barcelona rules. Positive phenocoversion was ascertained according to standard diagnostic criteria during follow-up. Receiver operator characteristic analysis was applied to evaluate predictive performance of different RWA types.

Results

A total of nine patients (16%) developed neurodegenerative diseases. Yearly phenoconversion rate was 5.5%. Significantly higher amounts of mixed (p = 0.009), tonic (p = 0.020), and any RWA (p = 0.049) were found in converters. Optimal cutoffs differentiating the prediction were 16.4% (sensitivity 88.9; specificity 69.6) for tonic, 4.4% (sensitivity 88.9; specificity 60.9) for mixed, and 36.8% (sensitivity 77.8; specificity 65.2) for any RWA. With area under the curve (AUC) 0.778, mixed RWA has proven to be the best predictive test followed by tonic (AUC 0.749) and any (AUC 0.710).

Conclusions

Mixed, tonic and any RWA may serve as biomarkers predicting the conversion into neurodegenerative disease in iRBD. The best predictive value lies within mixed RWA, thus it should be considered as standard biomarker.

Childhood narcolepsy and autism spectrum disorders: four case reports

BACKGROUND

Childhood narcolepsy is associated with various emotional, behavioural and cognitive dysfunctions as well as with psychiatric and neurodevelopmental disorders: anxiety, depression, attention deficit hyperactivity disorder and psychosis. A relationship between these conditions is unclear - comorbidity or similar pathophysiological mechanisms can be suggested.

OBJECTIVE

We reported four children with narcolepsy type 1 (NT1) and autism spectrum disorder (ASD) - Asperger syndrome (AS).

RESULTS AND CONCLUSION

To the best of our knowledge co-occurrence of NT1 and AS has not been described in the literature as noted in this report.

Childhood parasomnia--a disorder of sleep maturation?

BACKGROUND

Childhood parasomnias are believed to be a benign disorder due to immaturity of some neural circuits, synapses and receptors. The aim of our study was to explore a possible connection with other neurological developmental disorders.

METHODS

72 children (mean age 9.9 ± 5.0 years, 47 boys) were clinically examined and 88 nocturnal v-PSG and 22 v-EEG recordings were evaluated. The most frequent diagnostic findings were: sleepwalking in 24 children, confusional arousal in 21, sleep terror in 8, groaning and enuresis each in 7, non-specific arousal disorder in 4 patients, and REM-related parasomnia in only one child. For statistical evaluation chi-square test, the two-sample t-test and Mann-Whitney rank test were used.

RESULTS

Perinatal risk history was found in 38% of the cohort. Developmental disorders were diagnosed in 30 children (41.7%), more frequently in combinations with: attention-hyperactivity disorder (30.6%), dyslexia and dysgraphia (13.9%), developmental dysphasia (9.7%), mild motor and/or intellectual dysfunction (6.9%). Abnormal movements in sleep, some of them also regarded as developmental, were diagnosed in 37 children (51.4%). Sleep-related breathing disorders were found in 29 patients (40.3%) -snoring (29.2%) and/or sleep apnea (11.1%). Only 16.7% had no comorbidity. Most of the children (60%) showed 2 or 3, exceptionally up to 5 comorbidities. Children, in whom no parasomnia was found in close relatives, had a mild but non-significant earlier onset of the disease (4.4 ± 4.0 against 6.3 ± 4.3 years).

CONCLUSION

Childhood parasomnias are frequently associated with perinatal risk factors and developmental comorbidities, and can be regarded as a disorder of sleep maturation.

Clinical features of childhood narcolepsy. Can cataplexy be foretold?

BACKGROUND

Narcolepsy is a life-long disease characterized by abnormal regulation of the sleep-wake cycle and increased penetration of rapid eye movement (REM) sleep. In children, narcolepsy without cataplexy is more frequently seen than in adults. The aim of our study was to evaluate clinical and polysomnographic parameters to verify if cataplexy appearing later in life can be foretold.

METHODS

30 patients (12 boys), who contracted narcolepsy before the age of 18, were enrolled. All underwent clinical examination, nocturnal polysomnography (PSG), multiple sleep latency test (MSLT), HLA-DQB1∗0602 testing and, most of them Epworth Sleepiness Scale (ESS) rating. The Mann-Whitney rank and Fisher's tests were used for statistical analysis.

RESULTS

Narcolepsy without cataplexy (NwC) was diagnosed in 40% of the patients. The mean age at the first symptoms was 14.0 ± 3.0, at diagnosis 15.6 ± 3.1 years. Narcolepsy was accompanied by hypnagogic hallucinations in 15 and sleep paralysis in 12 patients. Frequent symptoms were sleep inertia during awakening, REM behavior symptoms, behavioral and serious school problems. BMI was higher in patients with narcolepsy-cataplexy (N-C). A high ESS score was indicative of excessive daytime sleepiness (17.1 ± 2.5). Mean MSLT sleep latency was 4.0 ± 3.1 min with 3.2 ± 1.4 sleep onset REM periods (SOREMs) with no difference between the two study groups. HLA typing revealed no differences either. The N-C group showed a higher degree of wakefulness and superficial non-REM (NREM) stage 1 with a lower NREM stage 3 during PSG.

CONCLUSION

Narcolepsy in childhood leaves very little scope for the prediction of cataplexy later in life.

Long lasting complex nocturnal hallucinations during Osmotic Release Oral System (OROS) methylphenidate treatment in a 7-year old girl

We report a case of a girl with Attention deficit hyperactivity disorder (ADHD) and Oppositional defiant disorder (ODD) who experienced a 3-hour episode of nocturnal complex bizarre visual hallucinations when treated with 18 mg Osmotic Release Oral System (OROS) methylphenidate (MPH). Nocturnal polysomnography performed two weeks later revealed REM sleep reduction (17%) and fragmentation . Two episodes of confusional arousals were recorded. This finding is typical of parasomnia associated with NREM sleep - disorder of arousal. We hypothesize that this preexisting sleep impairment represents a factor of vulnerability to MPH sleep side effects. In our search of literature, we found no report of nocturnal hallucination alone during treatment with stimulants.

REM behavior disorder (RBD) can be one of the first symptoms of childhood narcolepsy

More than one in three adult patients suffering from narcolepsy-cataplexy experience rapid eye movement (REM) behavior disorder (RBD), while RBD in childhood is extremely rare. We present the cases of two girls (aged 9 and 7 years old) with narcolepsy-cataplexy, in whom RBD was one of the first symptoms of the disease. The coincidence of RBD was seen by nocturnal video-polysomnography (v-PSG), and narcolepsy was diagnosed from short sleep latency and multiple sleep onset REMs (SOREMs) during a multiple sleep latency test (MSLT). Both girls were human leukocyte antigen (HLA)-DQB1 *0602 positive, and their cerebrospinal fluid (CSF) hypocretin level (Hcrt-1) was extremely low.