Experimentally induced arousals do not elicit periodic leg motor activity during sleep in normal subjects

The genetic etiology of periodic limb movement in sleep

STUDY OBJECTIVES

Periodic limb movement in sleep is a common sleep phenotype characterized by repetitive leg movements that occur during or before sleep. We conducted a genome-wide association study (GWAS) of periodic limb movements in sleep (PLMS) using a joint analysis (i.e., discovery, replication, and joint meta-analysis) of four cohorts (MrOS, the Wisconsin Sleep Cohort Study, HypnoLaus, and MESA), comprised of 6843 total subjects.

METHODS

The MrOS study and Wisconsin Sleep Cohort Study (N = 1745 cases) were used for discovery. Replication in the HypnoLaus and MESA cohorts (1002 cases) preceded joint meta-analysis. We also performed LD score regression, estimated heritability, and computed genetic correlations between potentially associated traits such as restless leg syndrome (RLS) and insomnia. The causality and direction of the relationships between PLMS and RLS was evaluated using Mendelian randomization.

RESULTS

We found 2 independent loci were significantly associated with PLMS: rs113851554 (p = 3.51 × 10-12, β = 0.486), an SNP located in a putative regulatory element of intron eight of MEIS1 (2p14); and rs9369062 (p = 3.06 × 10-22, β = 0.2093), a SNP located in the intron region of BTBD9 (6p12); both of which were also lead signals in RLS GWAS. PLMS is genetically correlated with insomnia, risk of stroke, and RLS, but not with iron deficiency. Pleiotropy adjusted Mendelian randomization analysis identified a causal effect of RLS on PLMS.

CONCLUSIONS

Because PLMS is more common than RLS, PLMS may have multiple causes and additional studies are needed to further validate these findings.

Trazodone affects periodic leg movements and chin muscle tone during sleep less than selective serotonin reuptake inhibitor antidepressants in children

STUDY OBJECTIVES

To test the hypothesis that children taking trazodone have less leg movements during sleep (LMS) and higher rapid eye movement (REM) sleep atonia than children taking selective serotonin reuptake inhibitors (SSRIs) but more than normal controls.

METHODS

Fifteen children (9 girls and 6 boys, mean age 11.7 years, standard deviation [SD] 3.42) taking trazodone (median dosage 50 mg/d, range 25-200 mg) for insomnia and 19 children (11 girls and 8 boys, mean age 13.7 years, SD 3.07) taking SSRIs for depression, anxiety, or both were consecutively recruited, as well as an age- and sex-matched group of 25 control children (17 girls and 8 boys, mean age 13.7 years, SD 3.11). LMS were scored and a series of parameters was calculated, along with the analysis of their time structure. The Atonia Index was then computed for each non-REM sleep stage and for REM sleep.

RESULTS

Children taking trazodone exhibited slightly higher leg movement indices than controls but lower than those found in children taking SSRIs and their time structure was different. Chin electromyogram atonia in all sleep stages was not significantly altered in children taking trazodone but was decreased in children taking SSRIs, especially during non-REM sleep.

CONCLUSIONS

In children, SSRIs but not trazodone are associated with a significantly increased number of LMS, including periodic LMS, and increased chin tone in all sleep stages. The assessment of periodic limb movement disorder and REM sleep without atonia might not be accurate when children are taking SSRIs because of their significant impact.

CITATION

DelRosso LM, Mogavero MP, Bruni O, Schenck CH, Fickenscher A, Ferri R. Trazodone affects periodic leg movements and chin muscle tone during sleep less than selective serotonin reuptake inhibitor antidepressants in children. J Clin Sleep Med. 2022;18(12):2829-2836.

Experimental Models to Study End-Organ Morbidity in Sleep Apnea: Lessons Learned and Future Directions

Sleep apnea (SA) is a very prevalent sleep breathing disorder mainly characterized by intermittent hypoxemia and sleep fragmentation, with ensuing systemic inflammation, oxidative stress, and immune deregulation. These perturbations promote the risk of end-organ morbidity, such that SA patients are at increased risk of cardiovascular, neurocognitive, metabolic and malignant disorders. Investigating the potential mechanisms underlying SA-induced end-organ dysfunction requires the use of comprehensive experimental models at the cell, animal and human levels. This review is primarily focused on the experimental models employed to date in the study of the consequences of SA and tackles 3 different approaches. First, cell culture systems whereby controlled patterns of intermittent hypoxia cycling fast enough to mimic the rates of episodic hypoxemia experienced by patients with SA. Second, animal models consisting of implementing realistic upper airway obstruction patterns, intermittent hypoxia, or sleep fragmentation such as to reproduce the noxious events characterizing SA. Finally, human SA models, which consist either in subjecting healthy volunteers to intermittent hypoxia or sleep fragmentation, or alternatively applying oxygen supplementation or temporary nasal pressure therapy withdrawal to SA patients. The advantages, limitations, and potential improvements of these models along with some of their pertinent findings are reviewed.

Interaktionen schlafbezogener Atmungsstörungen mit Vorhofflimmern

Hintergrund

Vorhofflimmern (VHF) ist die häufigste Herzrhythmusstörung. Sowohl die zentrale als auch die obstruktive Schlafapnoe interagieren mit dieser Erkrankung. Intermittierende Hypoxie, oxidativer Stress, wiederkehrende Aufwachreaktionen, intrathorakale Druckveränderungen und atriales Remodeling können im Rahmen einer schlafbezogenen Atmungsstörung (SBAS) zu VHF führen.

Ziel

Dieser Artikel stellt die komplexen Zusammenhänge und Erkenntnisse jüngster Forschungen bezüglich SBAS und VHF sowie die Therapiemöglichkeiten dar.

Material und Methoden

Es erfolgten eine Literaturrecherche von Original- und Übersichtsartikeln sowie Metaanalysen, die zwischen 1963 und 2020 in der PubMed-Datenbank veröffentlicht wurden.

Ergebnisse

Die Erkenntnisse der Studien weisen auf einen bidirektionalen kausalen Zusammenhang zwischen SBAS und VHF hin. Die pathophysiologischen Auswirkungen der obstruktiven und zentralen Schlafapnoe auf VHF sind unterschiedlich. Die Studien, die die Effekte einer Therapie der SBAS auf das Rezidivrisiko von VHF nach Intervention (Kardioversion oder Pulmonalvenenisolation) untersuchen, ergeben bisher kein eindeutiges Bild.

Diskussion

Bisherige Studien bestätigen multiple Interaktionen zwischen SBAS und VHF. Aufgrund widersprüchlicher Ergebnisse hinsichtlich der Effekte einer positiven Atemwegsdrucktherapie auf das Rezidivrisiko von VHF nach Interventionen sind weitere Studien nötig.

Periodic limb movements in sleep are followed by increases in EEG activity, blood pressure, and heart rate during sleep

Purpose

Periodic limb movements in sleep (PLMS) are related to arousal, sympathetic activation, and increases in blood pressure (BP), but whether they are part of the arousal process or causative of it is unclear. Our objective was to assess the temporal distribution of arousal-related measures around PLMS.

Methods

Polysomnographic recordings of six patients with restless legs syndrome were analyzed. We analyzed 15 PLMS, plus three 5-s epochs before and after each movement, for every patient. Mean values per epoch of blood pressure (BP), heart rate (HR), and electroencephalographic (EEG) power were calculated. For each patient, six 5-s epochs of undisturbed sleep were analyzed as controls.

Results

Alpha + beta EEG power, systolic BP, and HR were significantly increased following PLMS. The EEG power and HR increases were noticed in the first epoch after PLMS, whereas that of systolic BP was observed in the second and third epochs following a PLMS. No significant changes occurred in the epochs of undisturbed sleep.

Conclusions

The results suggest that PLMS are followed by arousal-related nervous system events. Given the high frequency of PLMS throughout the night, they could be a potential risk factor for nocturnal arrhythmias and hypertension, in addition to causing sleep deprivation.

Periodic limb movements during REM sleep in multiple sclerosis: a previously undescribed entity

BACKGROUND

There are few studies describing periodic limb movement syndrome (PLMS) in rapid eye movement (REM) sleep in patients with narcolepsy, restless legs syndrome, REM sleep behavior disorder, and spinal cord injury, and to a lesser extent, in insomnia patients and healthy controls, but no published cases in multiple sclerosis (MS). The aim of this study was to investigate PLMS in REM sleep in MS and to analyze whether it is associated with age, sex, disability, and laboratory findings.

METHODS

From a study of MS patients originally published in 2011, we retrospectively analyzed periodic limb movements (PLMs) during REM sleep by classifying patients into two subgroups: PLM during REM sleep greater than or equal to ten per hour of REM sleep (n=7) vs less than ten per hour of REM sleep (n=59). A univariate analysis between PLM and disability, age, sex, laboratory findings, and polysomnographic data was performed.

RESULTS

MS patients with more than ten PLMs per hour of REM sleep showed a significantly higher disability measured by the Kurtzke expanded disability status scale (EDSS) (P=0.023). The presence of more than ten PLMs per hour of REM sleep was associated with a greater likelihood of disability (odds ratio 22.1; 95% confidence interval 3.5-139.7; P<0.0001), whereas there were no differences in laboratory and other polysomnographic findings.

CONCLUSION

PLMs during REM sleep were not described in MS earlier, and they are associated with disability measured by the EDSS.

Change in heart rate variability precedes the occurrence of periodic leg movements during sleep: an observational study

BACKGROUND

Several reports have described that individual periodic leg movements during sleep (PLMS) activities are associated with autonomic nervous system activity occurring shortly before each PLMS activity. Nevertheless, no study has investigated dynamic changes of autonomic nervous system activity before the onset of PLMS. This study detected changes in heart rate variability (HRV) at the onset of the period with PLMS using complex demodulation method.

METHODS

This study enrolled 14 patients diagnosed as having idiopathic PLMS disorder (PLMD). In periods with and without PLMS during sleep stage 2, HRV-related variables and the spectral power of fluctuation of a high frequency (HF) band (FHFB) were analyzed and compared. The changes of those parameters during transition from the period without PLMS to that with PLMS were explored.

RESULTS

Spectral power in the low frequency (LF) band and very low frequency (VLF) band were higher in the period with PLMS. Additionally, the average frequency in FHFB was higher. The frequency in this band fluctuated during the period with PLMS with remarkable elevation of FHFB. Moreover, spectral powers in FHFB, LF, and VLF were remarkably elevated shortly before the beginning of the period with PLMS (FHFB, -65 s; LF, -53 s; and VLF, -45 s).

CONCLUSIONS

Elevation of sympathetic nervous system activity and mean frequency fluctuation in an HF band can occur several tens of seconds before the period with PLMS. Dynamic changes in the autonomic nervous system activity might be related to the vulnerability to PLMS occurrence during the night.