Periodic Limb Movements and White Matter Hyperintensities in First-Ever Minor Stroke or High-Risk Transient Ischemic Attack

Association of Periodic Limb Movements and Obstructive Sleep Apnea With Risk of Cardiovascular Disease and Mortality

BACKGROUND

Obstructive sleep apnea is a well-established risk factor for cardiovascular disease (CVD). Recent studies have also linked periodic limb movements during sleep to CVD. We aimed to determine whether periodic limb movements during sleep and obstructive sleep apnea are independent or synergistic factors for CVD events or death.

METHODS AND RESULTS

We examined data from 1049 US veterans with an apnea-hypopnea index (AHI) <30 events/hour. The primary outcome was incident CVD or death. Cox proportional hazards regression assessed the relationships between the AHI, periodic limb movement index (PLMI), and the AHI×PLMI interaction with the primary outcome. We then examined whether AHI and PLMI were associated with primary outcome after adjustment for age, sex, race and ethnicity, obesity, baseline risk of mortality, and Charlson Comorbidity Index. During a median follow-up of 5.1 years, 237 of 1049 participants developed incident CVD or died. Unadjusted analyses showed an increased risk of the primary outcome with every 10-event/hour increase in PLMI (hazard ratio [HR], 1.08 [95% CI, 1.05-1.13]) and AHI (HR, 1.17 [95% CI, 1.01- 1.37]). Assessment associations of AHI and PLMI and their interaction with the primary outcome revealed no significant interaction between PLMI and AHI. In fully adjusted analyses, PLMI, but not AHI, was associated with an increased risk of primary outcome: HR of 1.05 (95% CI, 1.00-1.09) per every 10 events/hour. Results were similar after adjusting with Framingham risk score.

CONCLUSIONS

Our study revealed periodic limb movements during sleep as a risk factor for incident CVD or death among those who had AHI <30 events/hour, without synergistic association between periodic limb movements during sleep and obstructive sleep apnea.

Obstructive sleep apnea in those with idiopathic intracranial hypertension undergoing diagnostic in-laboratory polysomnography

RATIONALE

The association of obstructive sleep apnea (OSA) with idiopathic intracranial hypertension (IIH) remains unclear, and few studies have used objective in-laboratory polysomnography (PSG) data. Thus, we used PSG data to examine the: 1) association between OSA, and its severity, with IIH and 2) sex differences in OSA severity in those with and without IIH.

METHODS

We retrospectively analyzed diagnostic PSG data from January 2015 to August 2023 for patients who were diagnosed with IIH by a neuro-ophthalmologist using the modified Dandy criteria. We selected three age, sex, and body mass index (BMI) matched controls for each IIH patient. We examined potential associations of IIH with OSA using regression. Sex differences were analyzed using ANOVA.

RESULTS

Of 3482 patients who underwent PSG, we analyzed 78 IIH patients (16 males) and 234 matched controls (48 males). Five (6.4 %) IIH and 39 (16.7 %) control patients had OSA, defined as AHI≥15. After adjusting for age, sex, BMI, and comorbidities, IIH was negatively associated with the presence of OSA (OR 0.29, 95%CI 0.10-0.87, p = 0.03). However, models that adjusted for acetazolamide use, with or without comorbidities, showed no significant relationship with OSA (OR 0.31, p = 0.20). Males with IIH had a significantly higher age (p = 0.020), OSA severity (p = 0.032), and arousal index (p = 0.046) compared to females with IIH.

CONCLUSIONS

IIH treated with acetazolamide was not an independent risk factor for OSA presence or severity. The presence of IIH treated with acetazolamide likely does not warrant routine screening for OSA, but related risk factors may identify appropriate patients.

The multifaceted aspects of sleep and sleep-wake disorders following stroke

Sleep-wake disorders (SWD) are acknowledged risk factors for both ischemic stroke and poor cardiovascular and functional outcome after stroke. SWD are frequent following stroke, with sleep apnea (SA) being the most frequent SWD affecting more than half of stroke survivors. While sleep disturbances and SWD are frequently reported in the acute phase, they may persist in the chronic phase after an ischemic stroke. Despite the frequency and risk associated with SWD following stroke, screening for SWD remains rare in the clinical setting, due to challenges in the assessment of post-stroke SWD, uncertainty regarding the optimal timing for their diagnosis, and a lack of clear treatment guidelines (i.e., when to treat and the optimal treatment strategy). However, little evidence support the feasibility of SWD treatment even in the acute phase of stroke and its favorable effect on long-term cardiovascular and functional outcomes. Thus, sleep health recommendations and SWD treatment should be systematically embedded in secondary stroke prevention strategy. We therefore propose that the management of SWD associated with stroke should rely on a multidisciplinary approach, with an integrated diagnostic, treatment, and follow-up strategy. The challenges in the field are to improve post-stroke SWD diagnosis, prognosis and treatment, through a better appraisal of their pathophysiology and temporal evolution.

Impact of sleep chronotype on in-laboratory polysomnography parameters

Morningness-eveningness preference, also known as chronotype, is the tendency for a person to sleep during certain hours of the day and is broadly categorised into morning and evening types. In-laboratory polysomnography (iPSG) is the gold-standard to assess sleep, however, an individual's chronotype is not accounted for in current protocols, which may confound collected sleep data. The objective of our study was to assess if chronotype had an association with sleep physiology. Patients who completed the diagnostic iPSG and the Morningness-Eveningness Questionnaire (MEQ), which categorises patients into morning type, neither or evening type, were assessed. Multivariable linear regression models were used to assess if chronotype was associated with sleep quality, duration, and physiology during iPSG. The study sample included 2612 patients (mean age of 53.6 years, 48% male) recruited during 2010-2015. Morning type, compared with neither type, was significantly associated with an increase in total sleep time and rapid eye movement (REM) sleep, and a decrease in sleep onset latency and the arousal index. Evening type, compared with neither type, was significantly associated with a decrease in total sleep time, sleep efficiency, and REM sleep, and an increase in sleep onset latency and wake after sleep onset. Additionally, iPSG lights out time was significantly different between the different chronotypes. Overall, a morningness chronotype was associated with favourable sleep quality and duration while an eveningness chronotype was associated with reduced sleep quality. Our study quantifies the association of chronotype with iPSG metrics and suggests that laboratory protocols should consider chronotype in their evaluations.

Periodic limb movements in sleep are linked to decreased hippocampus and amygdala volumes in the population-based BiDirect Study

STUDY OBJECTIVES

Even though numerous studies indicate that sleep disorders are associated with altered brain morphology, MRI studies focusing on periodic limb movements in sleep (PLMS) are scarce. Our aim was to investigate the association of PLMS with global and regional gray matter volumes as well as white matter hyperintensity (WMH) volume.

METHODS

One hundred and eighty-nine subjects (57.0 ± 7.8 years, women: 50.5%) of the population-based BiDirect Study underwent a single-night polysomnography (PSG). Standard criteria of the American Academy of Sleep Medicine were applied to evaluate sleep characteristics and calculate the PLMS index (PLMSI). T1w and FLAIR images were acquired with cerebral MRI at 3 Tesla. Voxel-based morphometry was performed to determine the total gray matter volume as well as the volume of cortical segments and subcortical gray matter areas using SPM12 and CAT12. The WMH volume was quantified with the Brain Intensity AbNormality Classification Algorithm. The independent relationship between MRI markers and PLMSI was analyzed using multivariable linear regression with adjustment for age, sex, body mass index, intracranial volume, PSG scorer, PSG device, sleep apnea, and the use of antidepressants.

RESULTS

PLMSI was not significantly related to global gray matter volume and WMH volume. However, significant inverse associations of the PLMSI with the volume of the hippocampus (left and right hemisphere) and left amygdala were observed.

CONCLUSIONS

A significant relationship between a higher PLMSI and lower volumes of the hippocampus and amygdala was found among the participants of the BiDirect Study. Since these associations are based on exploratory analyses, further replications are required before drawing firm conclusions.

[Periodic limb movements in sleep and cerebral small vessel disease progression: a prospective cohort study]

OBJECTIVE

To determine the predictive role of periodic limb movements in sleep (PLMS) in cerebral small vessel disease (cSVD) progression rate.

MATERIAL AND METHODS

Fifty patients with cSVD, aged 60-75 y.o., were enrolled. The study protocol included MRI assessment of white matter hyperintensities (WMH), nocturnal actigraphy and cognitive assessment. Depending on the PLMS, the main (PLM index ≥15) and the control (PLM index <15) groups were formed. The second visit was carried out in one year follow-up period, the examination consisted of brain MRI and cognitive assessment under the same protocol. ANCOVA was performed to determine if PLMS influence the degree of MRI- and neuropsychological changes.

RESULTS

A significant effect of PLMS on the increase in the volume of WMH was revealed, both in the form of an increase in the index by more than 15 movements per hour (p=0.03), and quantitatively in the form of a connection with the index value (p=0.048). The influence of PLMS on the progression of cognitive dysfunction has not been found, however, it has been shown that the presence of PLMS is associated with lesions in the deep white matter (r=0.42, p<0.0001), and the results of neuropsychological tests are associated with lesions in the periventricular and juxtacortical WMH (p < 0.05 for each test).

CONCLUSION

PLMS predict WMH progression in cSVD.

Relationship between gastroesophageal reflux disease and objective sleep quality

STUDY OBJECTIVES

To objectively characterize (1) the relationship between gastroesophageal reflux disease (GERD) and sleep quality, and (2) the influence of sleep position on this relationship, using in-laboratory polysomnography.

METHODS

We retrospectively analyzed first-night diagnostic in-laboratory polysomnography data for 3411 patients (median age 55 years; 48% male). Medication use and medical condition data were obtained through self-reported questionnaires. Associations between sleep quality and the presence of GERD, and the influence of sleep position on these associations, were analyzed using multivariable linear regression models.

RESULTS

After adjusting for age, sex, body mass index, and relevant comorbidities, GERD was associated with a 3.0% decrease in sleep efficiency, 8.8-minute increase in wake after sleep onset, 24.4-minute increase in rapid eye movement (REM) latency, 13.4-minute decrease in total sleep time, 1.4% decrease in %REM sleep, and 1.5% increase in %N3 sleep. Having both GERD and the majority of sleep on the right side was associated with an 8.6% decrease in sleep efficiency, 27.5-minute increase in wake after sleep onset, 35.6-minute decrease in total sleep time, 2.1% decrease in %REM sleep, and 3.5% increase in %N3 sleep. Having both GERD and the majority of sleep on the left side was associated with an 8.7-minute increase in sleep onset latency.

CONCLUSIONS

GERD is associated with an impairment in objective sleep quality. These associations were more pronounced in right-sided sleep and mostly ameliorated in left-sided sleep. Physicians should recognize the potential for poor sleep quality in patients with GERD and the effect of body position on this relationship.

CITATION

Gurges P, Murray BJ, Boulos MI. Relationship between gastroesophageal reflux disease and objective sleep quality. J Clin Sleep Med. 2022;18(12):2731-2738.

Sleep medicine: Practice, challenges and new frontiers

Sleep medicine is an ambitious cross-disciplinary challenge, requiring the mutual integration between complementary specialists in order to build a solid framework. Although knowledge in the sleep field is growing impressively thanks to technical and brain imaging support and through detailed clinic-epidemiologic observations, several topics are still dominated by outdated paradigms. In this review we explore the main novelties and gaps in the field of sleep medicine, assess the commonest sleep disturbances, provide advices for routine clinical practice and offer alternative insights and perspectives on the future of sleep research.

Association of Periodic Limb Movements with Medication Classes: A Retrospective Cohort Study

OBJECTIVE

To investigate the association between various medication classes and the periodic limb movement index (PLMI) in a clinical cohort of adults who completed in-laboratory polysomnography.

METHODS

A single, diagnostic, overnight, in-laboratory polysomnogram was completed for 3,488 patients consecutively referred from 2010-2015 to determine the PLMI. Medication use and medical comorbidities were collected through patient questionnaires. Associations between medication classes and the PLMI were ascertained using multivariable ordinal logistic regression models.

RESULTS

The median age of the cohort was 56.0 years (48.2% male). After adjusting for age, sex, body mass index, relevant comorbidities, and sleep parameters, the use of selective serotonin reuptake inhibitors (SSRIs) (OR = 1.52) and serotonin-norepinephrine reuptake inhibitors (SNRIs) (OR = 1.99) were associated with an increased PLMI. Conversely, gabapentinoids (OR = 0.71), stimulants (OR = 0.52), benzodiazepines (OR = 0.79), and dopamine agonists (OR = 0.38) were associated with a decreased PLMI. A non-statistically significant trend for a decreased PLMI with neuroleptic use was observed. No significant associations were found between the PLMI and the use of antihypertensives, statins, tricyclic antidepressants, bupropion, anticoagulants, antiplatelets, modafinil, and antihistamines.

CONCLUSION

The use of SSRIs and SNRIs was associated with an elevated PLMI while the use of gabapentinoids, stimulants, benzodiazepines, and dopamine agonists was associated with a decreased PLMI. These results can assist physicians in managing PLMs and invite further research into the relationship between PLMs and medications with the modulating effects of dose, formulation type, and time of administration.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that SSRIs and SNRIs are associated with an elevated PLMI while gabapentinoids, stimulants, benzodiazepines, and dopamine agonists are associated with a decreased PLMI.

Stroke-related restless legs syndrome: Clinical and anatomo-functional characterization of an emerging entity

BACKGROUND AND PURPOSE

Stroke-related restless legs syndrome (sRLS) secondary to ischemic lesions is an emerging entity and an interesting condition, but there are limited available data to help us further understand its underlying pathways. In this study, we characterized sRLS clinically, neuroanatomically and functionally.

METHODS

Consecutive patients hospitalized in the Stroke Unit of the University Hospital of Strasbourg were assessed clinically and electrophysiologically for sRLS characteristics. They underwent brain magnetic resonance imaging for the neuroanatomical study of involved structures, and received functional evaluations with ¹⁸ F-FDG (2-deoxy-2-[fluorine-18]fluoro-D-glucose) positron emission tomography (PET) for glucose consumption, ¹²³ I-FP-CIT ([123]I-2beta-carbometoxy-3beta-[4-iodophenyl]-N-[3-fluoropropyl]nortropane) single-photon emission computed tomography for dopamine reuptake and PET with ¹⁸ F-FDOPA ((3,4-dihydroxy-6-[18]F-fluoro-l-phenylalanine) for presynaptic dopaminergic synthesis.

RESULTS

Sixteen patients with sRLS, eight women and eight men, aged 41-81 years, were included. The clinical characteristics of sRLS and idiopathic RLS were similar. Most patients presented with bilateral and symmetric de novo RLS. Eight patients had infarction in the lenticulostriate area (middle cerebral artery and internal carotid arteria). The body of the caudate nucleus was most commonly affected. Seven patients had sRLS secondary to ventral brainstem infarction (perforating branches of the basilar arteria) affecting the pons in six patients and the medulla oblongata in one patient. Both the corticospinal tract and the cortico-pontocerebellar fibres were lesioned in all patients with brainstem stroke. One patient had infarction in the left posterior cerebellar vermis and occipital area (posterior cerebral artery and superior cerebellar artery). Isotopic explorations showed a significantly increased dopaminergic tone in the striatum ipsilateral to lenticulostriate infarction. Dopamine fixation was normal in patients with stroke outside of the lenticulostriate area.

CONCLUSIONS

Clinicians should be aware of the characteristics of sRLS for the appropriate diagnosis and treatment of this condition.

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.

Periodic Limb Movements Syndrome in Patients With Cerebral Small Vessel Disease: Protocol for a Prospective Observational Study

Background: Cerebrovascular diseases are the leading cause of cognitive decline and dementia. Therefore, the investigation of the potential ways to slow down the disease progression is an important research field. Periodic limb movements in sleep (PLMS) are known to be associated with transient changes in heart rate and blood pressure. These changes might influence the course of cerebral small vessel disease (cSVD). Nevertheless, the clinical significance of PLMS, particularly its influence on cardiovascular diseases course, is still controversial and underinvestigated.

Methods/design: Patients from 60 to 75 years old diagnosed with cSVD will undergo nocturnal polysomnography. Subjects with apnea/hypopnea index under 5 will be enrolled. Sleep quality and daytime functioning will be assessed at baseline with self-reported questionnaires. Brain MRI and cognitive assessment will be performed at baseline and in the 2-year follow-up. Progression of cSVD markers and cognitive dysfunction will be compared between patients with PLMS index (PLMI) equal to or more than 15 movements per hour of sleep and controls (PLMI <15/h).

Discussion: The negative role of PLMS in cSVD progression and related cognitive decline is expected. We suppose that patients with PLMS tend to worsen in cognitive performance more rapidly than age-, gender-, and comorbidity-matched controls. We also expect them to have more rapid white matter hyperintensities and other cSVD marker progression. The limitations of the study protocol are the short follow-up period, the absence of a treatment group, and inability to make a conclusion about causality.

Sleep in Neurologic Disorders

Sleep is a complex brain state with fundamental relevance for cognitive functions, synaptic plasticity, brain resilience, and autonomic balance. Sleep pathologies may interfere with cerebral circuit organization, leading to negative consequences and favoring the development of neurologic disorders. Conversely, the latter can interfere with sleep functions. Accordingly, assessment of sleep quality is always recommended in the diagnosis of patients with neurologic disorders and during neurorehabilitation programs. This review investigates the complex interplay between sleep and brain pathologies, focusing on diseases in which the association with sleep disturbances is commonly overlooked and whereby major benefits may derive from their proper management.

A potential role for zinc in restless legs syndrome

STUDY OBJECTIVES

Evaluate serum and brain noniron metals in the pathology and genetics of restless legs syndrome (RLS).

METHODS

In two independent studies (cohorts 1 and 2), in which subjects either remained on medications or tapered off medications, we analyzed serum levels of iron, calcium, magnesium, manganese, copper, and zinc both in RLS patients and controls, and assessed the prevalence of the MEIS1 and BTBD9 risk alleles previously established through genome-wide association studies. Human brain sections and a nematode genetic model were also quantified for metal levels using mass spectrometry.

RESULTS

We found a significant enrichment for the BTBD9 risk genotype in the RLS affected group compared to control (p = 0.0252), consistent with previous literature. Serum (p = 0.0458 and p = 0.0139 for study cohorts 1 and 2, respectively) and brain (p = 0.0413) zinc levels were significantly elevated in the RLS patients versus control subjects.

CONCLUSION

We show for the first time that serum and brain levels of zinc are elevated in RLS. Further, we confirm the BTBD9 genetic risk factor in a new population, although the zinc changes were not significantly associated with risk genotypes. Zinc and iron homeostasis are interrelated, and zinc biology impacts neurotransmitter systems previously linked to RLS. Given the modest albeit statistically significant increase in serum zinc of ~20%, and the lack of association with two known genetic risk factors, zinc may not represent a primary etiology for the syndrome. Further investigation into the pathogenetic role that zinc may play in restless legs syndrome is needed.

Treating Restless Legs Syndrome Was Associated With Low Risk of Cardiovascular Disease: A Cohort Study With 3.4 Years of Follow-Up

Background Restless legs syndrome (RLS) is associated with higher cardiovascular disease (CVD) risk. However, it remains unknown whether treatment of RLS lowers the cardiovascular risk associated with RLS. Methods and Results All data were collected retrospectively, but subjects were prospectively followed forward in time to determine outcomes of interest. We used the Truven Health MarketScan Commercial Claims and Encounters database from January 1, 2006, through December 31, 2014. Participants were 169 393 individuals, which included 24 199 nonpregnant participants with an RLS diagnosis (16 694 receiving treatments for RLS and 7505 without treatment) during 2006 to 2008 and 145 194 age- and sex-matched participants without RLS. All participants were free of CVD before January 1, 2009 (analysis baseline). Incident CVD cases (myocardial infarction, angina, stroke, atrial fibrillation, and heart failure) were identified. We adjusted for potential confounders, such as presence of chronic conditions and medication use. We identified 16 574 incident CVD cases during 2009 to 2014. Relative to the non-RLS group, the adjusted hazard ratio (HR) for future CVD was 1.26 (95% CI, 1.20-1.32) (P<0.001) for the RLS with treatment group, and 1.53 (95% CI, 1.42-1.65) (P<0.001) for the RLS without treatment group. Significant lower CVD risk was observed for all different RLS treatments, including dopaminergics, anticonvulsants, benzodiazepines, and opiates (adjusted HRs range, 0.71-0.84; P<0.001 for all), except for ergot-dopamine use. Conclusions RLS was associated with higher future CVD risk. However, RLS was associated with statistically significantly less future cardiovascular risk in RLS patients with treatment than in those without treatment.

Actigraphic detection of periodic limb movements: development and validation of a potential device-independent algorithm. A proof of concept study

STUDY OBJECTIVES

We propose a unique device-independent approach to analyze long-term actigraphy signals that can accurately quantify the severity of periodic limb movements in sleep (PLMS).

METHODS

We analyzed 6-8 hr of bilateral ankle actigraphy data for 166 consecutively consenting patients who simultaneously underwent routine clinical polysomnography. Using the proposed algorithm, we extracted 14 time and frequency features to identify PLMS. These features were then used to train a Naïve-Bayes learning tool which permitted classification of mild vs. severe PLMS (i.e. periodic limb movements [PLM] index less than vs. greater than 15 per hr), as well as classification for four PLM severities (i.e. PLM index < 15, between 15 and 29.9, between 30 and 49.9, and ≥50 movements per hour).

RESULTS

Using the proposed signal analysis technique, coupled with a leave-one-out cross-validation method, we obtained a classification accuracy of 89.6%, a sensitivity of 87.9%, and a specificity of 94.1% when classifying a PLM index less than vs. greater than 15 per hr. For the multiclass classification for the four PLM severities, we obtained a classification accuracy of 85.8%, with a sensitivity of 97.6%, and a specificity of 84.8%.

CONCLUSIONS

Our approach to analyzing long-term actigraphy data provides a method that can be used as a screening tool to detect PLMS using actigraphy devices from various manufacturers and will facilitate detection of PLMS in an ambulatory setting.

Inconsistent Classification of Mild Stroke and Implications on Health Services Delivery

OBJECTIVE

To conduct a scoping review on classifications of mild stroke based on stroke severity assessments and/or clinical signs and symptoms reported in the literature.

DATA SOURCES

Electronic searches of PubMed, PsycINFO (Ovid), and Cumulative Index to Nursing and Allied Health (CINAHL-EBSCO) databases included keyword combinations of mild stroke, minor stroke, mini stroke, mild cerebrovascular, minor cerebrovascular, transient ischemic attack, or TIA.

STUDY SELECTION

Inclusion criteria were limited to articles published between January 2003 and February 2018. Inclusion criteria included studies (1) with a definition of either mild or minor stroke, (2) written in English, and (3) with participants aged 18 years and older. Animal studies, reviews, dissertations, blogs, editorials, commentaries, case reports, newsletters, drug trials, and presentation abstracts were excluded.

DATA EXTRACTION

Five reviewers independently screened titles and abstracts for inclusion and exclusion criteria. Two reviewers independently screened each full-text article for eligibility. The 5 reviewers checked the quality of the included full-text articles for accuracy. Data were extracted by 2 reviewers and verified by a third reviewer.

DATA SYNTHESIS

Sixty-two studies were included in the final review. Ten unique definitions of mild stroke using stroke severity assessments were discovered, and 10 different cutoff points were used. The National Institutes of Health Stroke Scale was the most widely used measure to classify stroke severity. Synthesis also revealed variations in classification of mild stroke across publication years, time since stroke, settings, and medical factors including imaging, medical indicators, and clinical signs and symptoms.

CONCLUSIONS

Inconsistencies in the classification of mild stroke are evident with varying use of stroke severity assessments, measurement cutoff scores, imaging tools, and clinical or functional outcomes. Continued work is necessary to develop a consensus definition of mild stroke, which directly affects treatment receipt, referral for services, and health service delivery.

Prevalence and correlates of periodic limb movements in OSA and the effect of CPAP therapy

OBJECTIVE

We sought to assess the prevalence, correlates, and consequences of periodic limb movements of sleep (PLMS) in persons with obstructive sleep apnea (OSA) and the effect (worsening or improvement) of continuous positive airway pressure (CPAP) therapy on PLMS in a large prospective multicenter randomized controlled trial.

METHODS

We performed retrospective analyses of data from the Apnea Positive Pressure Long-term Efficacy Study, a prospective multicenter randomized controlled trial. A total of 1,105 persons with OSA enrolled in this study underwent a polysomnographic investigation at baseline, another one for CPAP titration, and another study 6 months after randomization to either active CPAP or sham CPAP.

RESULTS

Of all participants, 19.7% had PLM index (PLMI) ≥10/hour, 14.8% had PLMI ≥15/hour, 12.1% had PLMI ≥20/hour, 9.3% had PLMI ≥25/hour, and 7.5% had PLMI ≥30/hour. The odds of having a PLMI ≥10 were higher in older participants (odds ratio [OR] 1.03, p < 0.001), men (OR 1.63. p = 0.007), those using antidepressants (OR 1.48. p = 0.048), and those with higher caffeine use (OR 1.01, p = 0.04). After controlling for OSA and depression, PLMS were associated with increased sleep latency, reduced sleep efficiency, and reduced total sleep time. No significant relationships were noted between PLMS frequency and subjective sleepiness (Epworth Sleepiness Scale score) or objective sleepiness (Maintenance of Wakefulness Test). There was no differential effect of CPAP in comparison to sham CPAP on PLMS after 6 months of therapy.

CONCLUSIONS

PLMS are common in patients with OSA and are associated with a significant reduction in sleep quality over and above that conferred by OSA. Treatment with CPAP does not affect the severity of PLMS.

Impaired endothelial function may predict treatment response in restless legs syndrome

While dopaminergic dysfunction is believed to be a crucial role in restless legs syndrome (RLS), changes in peripheral microvasculature system such as peripheral hypoxia and altered skin temperature, have been found. This study aimed to investigate whether patients with RLS would have a cerebral and peripheral endothelial dysfunction, and this may have association with treatment responsiveness. We evaluated cerebral endothelial function using breath-holding index (BHI) on transcranial Doppler in bilateral middle cerebral artery (MCA), posterior cerebral artery (PCA) and basilar artery (BA) and peripheral endothelial function using brachial flow-mediated dilation (FMD) in 34 patients with RLS compared with age and sex-matched controls. The values of BHI in both MCA and BA were significantly lower in RLS group than control group. The values of FMD also were significantly lower in RLS patients. There was a weak correlation between BHI and FMD (p = 0.038 in Rt MCA, p = 0.032 in Lt MCA, p = 0.362 in BA) in RLS, but not in controls. BHI differed according to treatment responsiveness. (p < 0.005). Our study suggests that RLS patients have poorer cerebral and peripheral endothelial function than controls, showing an underlying mechanism of RLS and further evidence of a possible association between RLS and cardiovascular disease.

Sleep and Stroke: New Updates on Epidemiology, Pathophysiology, Assessment, and Treatment

PURPOSE OF REVIEW

This review aims to discuss the most recent data on sleep disorders and stroke, highlighting relevant findings for the practicing neurologist or health providers who encounter patients with sleep disorders and stroke.

RECENT FINDINGS

Sleep apnea and abnormal sleep duration have the strongest association with stroke risk. Possible mechanisms include non-dipping of blood pressure during sleep, hypoxemia or reoxygenation leading to sympathetic activation, hypertension, atrial fibrillation and impaired cerebral hemodynamics. Treatment studies suggest that continuous positive airway pressure (CPAP) for sleep apnea could improve primary prevention of stroke, but data is equivocal for secondary prevention. However, CPAP could improve functional outcomes after stroke.

SUMMARY

Sleep disorders present an opportunity to improve stroke risk and functional outcomes. However, new strategies are needed to determine the patients at high-risk who would most likely benefit from targeted care. Novel methods for phenotyping sleep disorders could provide personalized stroke care to improve clinical outcomes and public health strategies.

Sleep disorders and the risk of stroke

INTRODUCTION

Stroke is a major cause of disability and death in the United States and across the world, and the incidence and prevalence of stroke are expected to rise significantly due to an aging population. Obstructive sleep apnea, an established independent risk factor for stroke, is a highly prevalent disease that is estimated to double the risk of stroke. It remains uncertain whether non-apnea sleep disorders increase the risk of stroke. Areas covered: This paper reviews the literature describing the association between incident stroke and sleep apnea, rapid eye movement sleep behavior disorder, restless legs syndrome, periodic limb movements of sleep, insomnia, and shift work. Expert commentary: Trials of continuous positive airway pressure for stroke prevention in sleep apnea patients have been largely disappointing, but additional trials that target populations not yet optimally studied are needed. Self-reported short and long sleep duration may be associated with incident stroke. However, abnormal sleep duration may be a marker of chronic disease, which may itself be associated with incident stroke. The relationship between non-apnea sleep disorders and incident stroke deserves further attention. Identification of specific non-apnea sleep disorders or sleep problems that convey an increased risk for stroke may provide novel targets for stroke prevention.

Sleep Disturbances as a Risk Factor for Stroke

Sleep, a vital process of human being, is carefully orchestrated by the brain and consists of cyclic transitions between rapid eye movement (REM) and non-REM (NREM) sleep. Autonomic tranquility during NREM sleep is characterized by vagal dominance and stable breathing, providing an opportunity for the cardiovascular-neural axis to restore homeostasis, in response to use, distress or fatigue inflicted during wakefulness. Abrupt irregular swings in sympathovagal balance during REM sleep act as phasic loads on the resting cardiovascular system. Any causes of sleep curtailment or fragmentation such as sleep restriction, sleep apnea, insomnia, periodic limb movements during sleep, and shift work, not only impair cardiovascular restoration but also impose a stress on the cardiovascular system. Sleep disturbances have been reported to play a role in the development of stroke and other cardiovascular disorders. This review aims to provide updated information on the role of abnormal sleep in the development of stroke, to discuss the implications of recent research findings, and to help both stroke clinicians and researchers understand the importance of identification and management of sleep pathology for stroke prevention and care.

Basal sympathetic predominance in periodic limb movements in sleep after continuous positive airway pressure

PURPOSE

This study investigated the basal autonomic regulation in patients with obstructive sleep apnea (OSA) showing periodic limb movements in sleep (PLMS) emerging after therapy with continuous positive airway pressure (CPAP).

METHODS

Data of patients with OSA undergoing a first polysomnography for diagnosis and a second polysomnography for therapy with CPAP were reviewed. Patients with OSA showing PLMS on the first polysomnography were excluded. By using heart rate variability analysis, epochs without any sleep events and continuous effects from the second polysomnography were retrospectively analyzed.

RESULTS

Of 125 eligible patients, 30 with PLMS after therapy with CPAP (PLMS group) and 30 not showing PLMS on both polysomnography (non-PLMS group) were randomly selected for the analysis. No significant differences in the demographic characteristics and variables of polysomnographies were identified between the groups. Although one trend of low root mean square of successive differences (RMSSD) between intervals of adjacent normal heart beats (NN intervals) in the PLMS group was observed, patients in the PLMS group had significantly low normalized high-frequency (n-HF) and high-frequency (HF) values, but high normalized low frequency (n-LF) and high ratio of LF to HF (LF/HF ratio). After adjustment for confounding variables, PLMS on the second polysomnography was significantly associated with RMSSD (β = - 6.7587, p = 0.0338), n-LF (β = 0.0907, p = 0.0148), n-HF (β = - 0.0895, p = 0.0163), log LF/HF ratio (β = 0.4923, p = 0.0090), and log HF (β = - 0.6134, p = 0.0199).

CONCLUSIONS

Patients with OSA showing PLMS emerging after therapy with CPAP may have a basal sympathetic predominance with potential negative cardiovascular effects.