Periodic Limb Movement Index Research Articles

The Validation of the SOMNOwatch™ Actigraphy System for Periodic Limb Movements in Sleep Assessment.

There is a growing body of evidence regarding the clinical significance of PLMS, and this movement disorder is of concern in both clinical and scientific contexts. Leg actigraphy is a convenient and promising method for screening periodic limb movements in sleep (PLMSs). This study aims to demonstrate the reliability of the SOMNOwatch™ actigraph for detecting periodic limb movements in sleep. Twenty-eight patients, referred to a sleep laboratory for various sleep problems, underwent nocturnal polysomnography with simultaneous one-sided actigraphy using the SOMNOwatch™ actigraph. Recordings of leg movements obtained from both methods were manually scored, calculating the periodic limb movement index (PLMI). The agreement between the methods was assessed through correlation analysis and event-by-event comparison. The correlation between the PLMI derived from PSG and SOMNOwatch™ was high and statistically significant (r = 0.98, p < 0.0001). The SOMNOwatch™ demonstrated a sensitivity of 86.7% and a specificity of 92.3% in detecting PLMS. Similarly, for detecting patients with a PLMI equal to or greater than 15, the sensitivity was 85.7%, and the specificity was 95.2%.

Polysomnographic and clinical characteristics of sleep apnea headache patients.

Sleep apnea headache can be defined as a persistent, widespread, throbbing headache that occurs recurrently, is not accompanied by any additional symptoms after waking up, and usually resolves within four hours. Diagnosis of the condition requires confirmation through polysomnography with an apnea-hypopnea index of at least 5, indicating the presence of obstructive sleep apnea syndrome (OSAS). While sleep apnea headaches are common in 10-15% of individuals with OSAS, morning headaches are experienced by 5% of this population. The aim of this study is to examine both polysomnographic and clinical features associated with sleep apnea headache in individuals confirmed to have OSAS by polysomnography. The study was conducted in the sleep center of University of Health Science, Erenköy Mental and Nervous Disease Training and Research Hospital. We have examined the clinical and polysomnographic data of the patients with sleep apnea headache (SAH) diagnosed according to IHS-3 criteria retrospectively and grouped the patients as mild, moderate and severe OSAS. Patients with morning headache except sleep apnea headache and under PAP titration treatment were excluded. The differences between the sleep macro structures of patients with (WSAH) and without sleep apnea headache (WOSAH) were examined. The WSAH group consisted of 384 participants and the control group (WOSAH) consisted of 294 participants The mean age was 46.29 ± 12.18 and 45.08 ± 12.62 years, respectively. Patients in the WSAH group had significantly higher scores on the Epworth Sleepiness Scale (ESS) (p = 0.004) and higher periodic limb movement index (PLMI) (p = 0.014) compared to the WOSAH group. WSAH patients exhibited shorter wake times after sleep onset (WASO) and lower scores on the sleep quality index, in contrast to WOSAH patients. Additionally, within the WSAH group, there was a negative correlation between age and several sleep parameters, including total sleep parameters. A positive correlation was observed between sleep duration (p = 0.009), waking up after sleep (p = 0.043), sleep efficiency (p = 0.001) and apnea-hypopnea index (AHI) (p = 0.018). Additionally, ESS scores were positively correlated with AHI and total awake time (p = 0.000 and p = 0.008, respectively), while negatively correlated with stage N3 sleep percentage and mean minimum oxygen level (p = 0.001 and p = 0.020, respectively) in the WSAH group. The causes and possible mechanisms of sleep apnea headache are not fully clarified and the underlying processes are not fully understood. Sleep apnea headaches appear to be related to disturbances in nocturnal sleep. Dysregulation in regions that modulate sleep and nociception may be one possible mechanism.

The paradoxical impact of periodic limb movements on isolated REM sleep behavior disorder patients.

Recently, the α-synuclein origin and connectome model described two types of Parkinson's disease: "brain-first" and "body-first" subtypes. We aimed to investigate the role of periodic limb movements during sleep (PLMS) in identifying these subtypes starting from a prodromal stage of α-synucleinopathies. 191 patients with isolated REM sleep behavior disorder (iRBD) underwent video-polysomnography (vPSG), questionnaires, clinical interview, and neuropsychological battery. Patients who presented PLMS index (PLMSi) > 15 were compared with patients presenting PLMSi ≤ 15 on clinical questionnaires, vPSG, and neuropsychological domains with age as a covariate. Correlations were performed between PLMSi and vPSG and neuropsychological domains in both groups of iRBD. 48.2% of patients presented PLMSi > 15. iRBD subgroup with PLMSi > 15 performed better than the iRBD subgroup with PLMSi ≤ 15 in the executive function domain. In patients with PLMSi > 15 negative correlations were observed between PLMSi and some neuropsychological domains (memory, language, and executive function). Moreover, this subgroup was older and their PLMSi was positively correlated with wake-after-sleep onset and inversely correlated with total sleep time and sleep efficiency, suggesting a detrimental effect of PLM on sleep also in this cohort. Patients with PLMSi > 15 are characterized by a more preserved cognitive status, despite a more disrupted sleep. PLMSi could be explored in longitudinal studies concerning the "brain-first" and "body-first" model.

Development and Validation of Machine Learning Models to Predict Postoperative Delirium Using Clinical Features and Polysomnography Variables.

Background: Delirium affects up to 50% of patients following high-risk surgeries and is associated with poor long-term prognosis. This study employed machine learning to predict delirium using polysomnography (PSG) and sleep-disorder questionnaire data, and aimed to identify key sleep-related factors for improved interventions and patient outcomes. Methods: We studied 912 adults who underwent surgery under general anesthesia at a tertiary hospital (2013-2024) and had PSG within 5 years of surgery. Delirium was assessed via clinical diagnoses, antipsychotic prescriptions, and psychiatric consultations within 14 days postoperatively. Sleep-related data were collected using PSG and questionnaires. Machine learning predictions were performed to identify postoperative delirium, focusing on model accuracy and feature importance. Results: This study divided the 912 patients into an internal training set (700) and an external test set (212). Univariate analysis identified significant delirium risk factors: midazolam use, prolonged surgery duration, and hypoalbuminemia. Sleep-related variables such as fewer rapid eye movement (REM) episodes and higher daytime sleepiness were also linked to delirium. An extreme gradient-boosting-based classification task achieved an AUC of 0.81 with clinical variables, 0.60 with PSG data alone, and 0.84 with both, demonstrating the added value of PSG data. Analysis of Shapley additive explanations values highlighted important predictors: surgery duration, age, midazolam use, PSG-derived oxygen saturation nadir, periodic limb movement index, and REM episodes, demonstrating the relationship between sleep patterns and the risk of delirium. Conclusions: The artificial intelligence model integrates clinical and sleep variables and reliably identifies postoperative delirium, demonstrating that sleep-related factors contribute to its identification. Predicting patients at high risk of developing postoperative delirium and closely monitoring them could reduce the costs and complications associated with delirium.

Effects of transcranial magnetic stimulation on sleep quality in fibromyalgia: A double-blind randomized clinical trial

ObjectivesThe aim of the current study was to assess the therapeutic impact of repeated low frequency repetitive transcranial magnetic stimulation (rTMS) over the right dorsolateral prefrontal cortex (rDLPFC) on sleep problems in patients with fibromyalgia. MethodsForty two patients with fibromyalgia who had sleep difficulties were randomly assigned to receive either real or sham rTMS treatment. Patients received 20 treatment sessions (5 sessions per week) in which 1200 rTMS pulses were applied over the rDLPFC using a frequency of 1 Hz and an intensity of 120 % of the resting motor threshold. All participants were evaluated at baseline, and then 1 month and 3 months after treatment using the Fibromyalgia Impact Questionnaire (FIQ), Pittsburgh Sleep Quality Index (PSQI), Medical Outcomes Study Sleep Scale (MOS-SS) and polysomnography (PSG). ResultsThere were significant time (pre, 1month, and 3 months)X group (real versus sham group) interactions in all 3 clinical rating scales; FIQ (Df = 1.425, F = 237.645, P = 0.001), PSQI (Df = 2, F = 64.005, P = 0.001), MOS-SS (Df = 2, F = 28.938, P = 0.001) due to the fact that the real group improved significantly more over time than the sham group. Similarly, the real group improved more on the PSG parameters than the sham group. The effect sizes were large both in the rating scales and PSG, indicating a substantial clinical improvement. Correlation as an exploratory analysis between the changes (pre - post 3 months) in MOS-SS and PLMs index (/h) showed significant negative correlation (r = −0.643, P = 0.002). Conclusions20 sessions of LF-rTMS over rDLPFC can improve sleep quality in both subjective (PSQI and MOSS) as well as objective (PSG) rating scales.

Exploring sex differences in periodic leg movements during sleep across the lifespan of patients with restless legs syndrome

BackgroundRestless legs syndrome (RLS) and periodic leg movements during sleep (PLMS) are prevalent sleep disorders with significant implications for health and well-being. While previous research has highlighted sex-related disparities in RLS and PLMS prevalence, comprehensive understanding of these differences across the lifespan remains limited. This study aims to explore sex differences in RLS and PLMS across diverse age groups, spanning ages 2 to over 80 years, and to investigate the underlying mechanisms influenced by sex hormones. MethodsA retrospective analysis was conducted on drug-free patients diagnosed with RLS, including 95 females (age range: 2–83.2 years) and 89 males (age range: 2–79.5 years). Polysomnographic recordings were analyzed to assess leg movement activity, including PLMS index and Periodicity index. ResultsA more rapid increase in PLMS index was observed in women starting before age 10, plateauing lower than men until around age 55. An increase in women occurred after 55, lasting over a decade, while in men, PLMS index continued to rise after 75. Conversely, Periodicity index displayed a simpler pattern, increasing progressively from prepuberty to around 35 in males and 45–50 in females. Females maintained a slightly higher Periodicity index than males for over a decade after this age. ConclusionThese findings underscore the complex interplay between sex hormones, age, and sleep disorders, highlighting the need for tailored approaches to diagnosis and management across diverse demographic cohorts. Further research is warranted to elucidate the underlying mechanisms and develop targeted interventions to optimize sleep health outcomes.

Polysomnography parameters in a large cohort of people with multiple sclerosis

BackgroundDisordered and disturbed sleep is quite common among people with multiple sclerosis (PwMS). It is associated with fatigue one of most disabling symptoms in MS. This study aims at comparing polysomnographic (PSG) sleep parameters in a large single cohort of PwMS from a single center to that of the published norms. Hence establishing PSG parameters in PwMS. MethodsThis is a retrospective review of 299 consecutive adult PwMS who were seen and evaluated with an overnight PSG at a Comprehensive MS Care Center between 11/19/2001 to 9/17/2014. Data extracted from the PSG included Total Sleep Time (TST), sleep efficiency (SE), sleep onset latency (SOL), Relative REM latency, total apnea-hypopnea indices (AHI), spontaneous arousal indices (AI), total periodic leg movements indices (PLMI) and, sleep architecture metrics including percentage spent in stages N1/N2, N3, and REM. ResultsPwMS, compared to normative data, had, on average, 85.9 min shorter TST (p < 0.001), 27.3 min longer SOL (p < 0.0001), 62.1 min longer REM latency (p < 0.0001), 10.7 % lower SE (p < 0.0001), 16.4 % more N1/N2 (p < 0.0001) and 11.4 % less N3 (p < 0.0001). REM latency The prevalence of Obstructive Sleep Apnea (OSA) was high at 60.7 % and the mean AHI was higher by 11.1 events per hour (p < 0.0001). ConclusionsThis study establishes PSG parameters in the largest PwMS cohort reported to date. It is important to be vigilant of sleep complaints in PwMS. Future prospective large single cohort studies with standardized methods are needed to further understand sleep disturbances in PwMS as well as their causes and implications.

Distinctive sleep complaints and polysomnographic findings in antibody subgroups of autoimmune limbic encephalitis

IntroductionSleep disturbances are being increasingly recognized in association with autoimmune encephalitis (AIE). We investigated the prevalence of sleep-related symptoms and polysomnographic features of patients with AIE and the long-term outcomes in these patients in a multi-center, prospective study from Turkey.MethodsWe prospectively evaluated patients with definite AIE in a common database including demographics, AIE-related and sleep-related symptomatology. Maximum and latest modified Rankin scores (mRS) and Liverpool Outcome Score (LOS) were noted.ResultsOf 142 patients, 87 patients (61.3%) fulfilled the criteria for definite AIE (mean age, 46.8+18.8 years; 51.7% women; mean disease duration, 21.0+38.4 months). 78.9% of patients had at least one or more new onset or worsened sleep-related symptomatology: insomnia (55.3%), excessive daytime sleepiness (EDS, 28.0%), sleep apnea (18.7%), REM sleep behavior disorder (RBD, 17.3%), restless legs syndrome (10.7%) and oneiric stupor (9.3%). Sleep efficiency, N3 and REM sleep were decreased and N1 sleep was increased in patients with Ab[+] AIE. LOS points were highest in those with insomnia and sleep apnea, and lowest in those with EDS, RBD and oneiric stupor. RBD and sleep apnea were more common in anti-LG1 Ab[+] group than anti-NMDAR Ab[+] group. Index of periodic leg movements was highest in anti-LG1 Ab[+] group. Patients with EDS and oneiric stupor had more common memory problems. Maximum and latest mRS scores were positively correlated with EDS and oneiric stupor. EDS, RBD and oneiric stupor were negatively correlated with LOS points.ConclusionOur study emphasizes the presence and importance of early diagnosis of sleep disturbances in AIE in regard to their deteriorative influences on disease prognosis.

Periodic limb movements during sleep in children with neuromuscular disease or cerebral palsy – An important potential contributor to sleep-related morbidity

ObjectivesPoor sleep is frequently reported in children with neuromuscular diseases (NMD) and cerebral palsy (CP) however breathing disorders during sleep are often the clinical focus. Periodic limb movements (PLMs) have an increased prevalence in adults with NMD and may contribute to sleep disturbance in this population. We assessed the prevalence of PLMs in children with NMD or CP. MethodsRetrospective review of polysomnography (PSG) with leg electromyography in children age 1–18 years with NMD (including Duchenne muscular dystrophy, myotonic dystrophy, spinal muscular atrophy) or CP performed at a paediatric sleep centre 2004–2022. ResultsLeg electromyography was available in at least 1 PSG in 239 children (125 NMD, 114 CP), and in 2 PSGs in 105 children (73 NMD, 32 CP). At initial PSG, 72 (30 %) were female with a median age 9y and respiratory disturbance index 3.5/h (interquartile range 1.3–9.9/h). Elevated PLM index (PLMI; >5/h) occurred in 9.6 % of each of the CP and NMD groups, quantified by initial PSG. Overall, PLMI increased from baseline (median 0, maximum 33/h) to follow-up (median 0, maximum 55.8/h; p < 0.05). In those with an elevated PLMI, arousal percentage attributable to PLMs was up to 25 % (median 7.5 %). ConclusionsElevated PLMI occurred at a higher prevalence in children with NMD and CP than reported in other clinic-referred paediatric populations. It is important that PLMs are not overlooked as identification and treatment may help improve sleep outcomes. Further research is required to understand the pathophysiology and consequences of PLMs specifically in this population.

Polysomnographically Defined Restless Sleep Disorder and Periodic Limb Movements during Sleep in Children Born Prematurely.

Children born prematurely (<37 weeks' gestation) are at increased risk of perinatal complications, comorbidities, and iron deficiency. Iron deficiency is associated with restless legs syndrome and periodic limb movement disorder. In this study, we assessed the prevalence of restless sleep disorder (RSD) and elevated periodic limb movements during sleep (PLMS) in children born prematurely who underwent polysomnography. A retrospective chart review of sleep studies was conducted in children aged 1-18 years (median age 4 years) with a history of premature birth. Children with genetic syndrome, airway surgery, or tracheostomy were excluded. Three groups were compared: children with PLMS index >5, children with RSD, and children with neither elevated PLMS index nor RSD. During the study, 2577 sleep studies were reviewed. Ninety-two studies fit our criteria and were included in the analysis. The median age at birth was 31 weeks, and the interquartile range (IQR) was 27-34 weeks. A total of 32 (34.8%) children were referred for restless sleep and 55 (59.8%) for snoring. After polysomnography, 18% were found to have a PLMS index >5/h, and 14% fit the criteria for restless sleep disorder (RSD). There were no statistically significant differences in PSG parameters among the children with RSD, PLMS, and the remaining group, except for lower obstructive apnea/hypopnea index (Kruskal-Wallis ANOVA 8.621, p = 0.0135) in the RSD group (median 0.7, IQR 0.3-0.9) than in the PLMS (median 1.7, IQR 0.7-3.5) or the non-RSD/non-PLMS (median 2.0, IQR 0.8-4.5) groups. There was an elevated frequency of RSD and elevated PLMS in our cohort of children born prematurely. Children born prematurely are at higher risk of iron deficiency which can be a contributor factor to sleep -related movement disorders. These results add new knowledge regarding the prevalence of RSD and PLMS in these children.

Large muscle group movements during sleep in restless leg syndrome: neurophysiological and clinical implications.

Recently, criteria have been drawn up for large muscle group movements during sleep (LMM), defined as movements lasting for 3-45 seconds in adults, which are often accompanied by changes in sleep stage, arousals, and increases in heart rate. The aim of this study was to characterize LMM in restless legs syndrome (RLS) in order to better evaluate their impact on the neurophysiology of the disorder and, therefore, the possible clinical implications. Consecutive, drug-free patients diagnosed with RLS and controls, aged 18 years or more, were retrospectively enrolled. Leg movement activity-short-interval (SILMS), periodic (PLMS), and isolated (ISOLMS) leg movements during sleep-and LMM were detected and scored. In total, 100 patients and 67 controls were recruited. All movement measures were significantly higher in RLS. A significant positive correlation was found between LMM and ISOLMS index but not PLMS index in both groups. LMM index showed a significant negative correlation with total sleep time, sleep efficiency, and percentage of sleep stages N3 and R, as well as a significant positive correlation with the number of awakenings, and percentage of sleep stages N1 and N2 only in patients with RLS. No significant correlation was found between either LMM or PLMS index and RLS severity. Different types of movements, including SILMS, ISOLMS, and LMM, play somewhat distinct roles in sleep neurophysiology in RLS. Notably, LMM, a newly recognized category of movements, demonstrates associations with sleep architecture instability and fragmentation, arousals, and awakenings, suggesting potential clinical implications.

Periodic limb movements in patients with suspected obstructive sleep apnea without comorbid conditions.

Periodic limb movement disorder (PLMD) and obstructive sleep apnea (OSA) are overlapping clinical syndromes with common risk factors. However, current literature has failed to establish a clear pathophysiological link between them. Thus, little is known about periodic limb movements (PLM) in otherwise healthy patients with suspected OSA. We performed a retrospective analysis of 112 patients (age: 44.5 ± 12.0 years, 14.3% female) with suspected OSA who underwent full night polysomnography for the first time. Patients with chronic diseases of any kind, recent infections, malignancies, or daily or regular use of any type of medication were excluded. Group comparisons were made based on the severity of OSA (using the apnea hypopnea index, AHI) or the periodic limb movement index (PLMI). Both, PLMI and the total number of periodic limb movements during sleep (PLMS), showed a significant increase in patients with severe OSA. In addition, AHI and apnea index (AI) were significantly higher in patients with PLMI >15/h, with a similar trend for hypopnea index (HI) (p < 0.001, p < 0.001, and p > 0.05, respectively). PLMI was significantly positive correlated with AHI, AI, and HI (r = 0.392, p < 0.001; r = 0.361, p < 0.001; and r = 0.212, p < 0.05, respectively). Patients with PLMI >15/h were significantly older (p < 0.001). There was no significant association between body mass index (BMI) and PLMI >15/h. We found a significant association between the severity of OSA and PLM in our study population with suspected OSA but without other comorbidities. PLMI and PLMS were significantly increased in patients with severe OSA. Future prospective studies with larger collectives should verify the presented results and should include mechanistic aspects in their evaluation.

Manual scoring of periodic limb movements in children: is it still necessary?

ObjectiveAlthough manual scoring has been classically considered the gold standard to identify periodic leg movements (PLM), it is a very time consuming and expensive process, also subject to variability in interpretation. In the last decades, different authors have observed reasonably good agreement between automated PSG scoring algorithms and manual scoring in adults, according to established criteria. We aim to compare the automatic software analysis of our polysomnogram with the manual staging in children with sleep-disordered breathing. MethodsWe performed a semiautomatic method, in which an experienced technician watched the video recording and removed from the automatic analysis those movements that did not correspond to true candidate leg movement (LM). ResultsA total of 131 PSGs were studied; applying the established criteria, 65 children were diagnosed of obstructive sleep apnea, and 66 presented snoring but with no sleep apnea. The mean age was 6.7 years (±1.7) and twenty-five children (19.08 %) had a PLMI >5/h. Statistical differences were found not only for PLMI (manual: 2.20 (0.7, 4.1) vs automatic (6.4 (3.85,9.5); p < 0.001), but for almost of all indexes assessed between the automatic and the manual scoring analysis. The level of concordance was only moderate for PLM index (0.63 [0.51–0.72]); showing that, unlike the articles published in the adult population, automatic analysis is not accurate in children and, manually or semi-automatically analysis as ours need to be done. ConclusionIt seems that PLM detection algorithm might work accurately but, the real need would be a true LM detection algorithm.

0695 Residual Periodic Limb Movement Index After CPAP Titration Is Correlated with Hypoxemia

0695 Residual Periodic Limb Movement Index After CPAP Titration Is Correlated with Hypoxemia

Elevated periodic limb movement index is associated with hypoxemia in children with early onset scoliosis.

Patients with early onset scoliosis are at high risk of sleep disordered breathing, sleep disruption, and adverse consequences of poor sleep. In this study, we aim to assess the prevalence of periodic limb movements of sleep in a cohort of children with early onset scoliosis and identify factors that correlate with the presence of periodic limb movements. This is a retrospective chart review of 40 patients with EOS (ages 1-17years) who underwent a PSG from 2003 through 2019. Data collected included age, sex, and polysomnography parameters. Descriptive statistics were used: independent T test and Pearson correlation. The average age was 9.6years (SD 5.2); 22 were female. Eleven patients (27.5%) had elevated periodic limb movement index (PLMI) (≥ 5). Those with PLMI ≥ 5 had arousal index of 15.4 (SD 7.2) and those with normal PLMI having an arousal index of 9.4 (SD 4.9); this reached statistical significance (p < 0.05). Those with elevated PLMI spent 4.9 (SD 8.3) minutes with saturations below 88%, while those with normal PLMI spent 1.0 (SD 1.8); this was statistically significant. There was a moderate positive correlation between arousal index, hypoxemia, and PLMI. The study suggests that children with early onset scoliosis have higher frequency of periodic limb movements during sleep, and these may be correlated with increased arousal and with hypoxemia.

Compromised Dynamic Cerebral Autoregulation in Patients with Restless Legs Syndrome.

Restless legs syndrome (RLS) is a prevalent sensorimotor nervous system disorder in patients accompanied with insomnia, blood pressure fluctuation, and sympathetic dysfunction. These symptoms may disrupt cerebral hemodynamics. Dynamic cerebral autoregulation (dCA) describes the temporary response of cerebrovascular system to abrupt fluctuations in blood pressure, which keep cerebral blood flow stable and serve as a marker of cerebrovascular system ability. This research aimed to assess dCA in RLS patients. In this study, RLS patients were recruited and subsequently classified into four groups (mild, moderate, severe, and very severe) based on the International RLS Rating Scale (IRLS). Healthy controls matched for age and sex were enrolled. All participants were evaluated dCA by assessing phase difference (PD). A portion of patients with RLS was reassessed for dCA after one month of medication therapy (pramipexole [0.125 mg/day] and gabapentin [300 mg/day]). There were altogether 120 patients with RLS and 30 controls completed the polysomnography and dCA assessment. PD was lower in the moderate, severe, and very severe RLS groups than that in the controls and mild RLS groups. Periodic limb movement index (PLMI), arousal index, and IRLS all showed a linear correlation with PD in RLS patients. Additionally, PD increased in RLS patients after therapy. The dCA was compromised in moderate, severe, and very severe RLS patients and was negatively correlated with the IRLS, arousal index, and PLMI. After 1 month of therapy, dCA improved in RLS patients.

Clinical features, polysomnography, and genetics association study of restless legs syndrome in clinic based Chinese patients: A multicenter observational study

Study objectivesTo systemically describe the clinical features, polysomnography (PSG) finding, laboratory tests and single-nucleotide polymorphisms (SNPs) in a clinic based Chinese primary restless legs syndrome (RLS) population. MethodsThis observational study, conducted from January 2020 to October 2021 across 22 sleep labs in China, recruited 771 patients diagnosed with RLS following the 2014 RLSSG criteria. Clinical data, PSG testing, and laboratory examination and SNPs of patients with RLS were collected. A total of 32 SNPs in 24 loci were replicated using the Asian Screening Array chip, employing data from the Han Chinese Genomes Initiative as controls. ResultsIn this study with 771 RLS patients, 645 had primary RLS, and 617 has DNA available for SNP study. Among the 645 primary RLS, 59.7% were women. 33% had a family history of RLS, with stronger familial influence in early-onset cases. Clinical evaluations showed 10.4% had discomfort in body parts other than legs. PSG showed that 57.1% of RLS patients had periodic leg movement index (PLMI) of >5/h and 39.1% had PLMI >15/h, respectively; 73.8% of RLS patients had an Apnea-Hypopnea Index (AHI) > 5/h, and 45.3% had an AHI >15/h. The laboratory examinations revealed serum ferritin levels <75 ng/ml in 31.6%, and transferrin saturation (TSAT) of <45% in 88.7% of RLS patients. Seven new SNPs in 5 genes showed a significant allelic association with Chinese primary RLS, with one previously reported (BTBD9) and four new findings (TOX3, PRMT6, DCDC2C, NOS1). ConclusionsChinese RLS patients has specific characters in many aspects. A high family history with RLS not only indicates strong genetic influence, but also reminds us to consider the familial effect in the epidemiological study. Newly developed sequencing technique with large samples remains to be done.

An expedited model for identifying potential patients with periodic leg movements.

Periodic leg movements during sleep (PLMS) may have crucial consequences in adults. This study aimed to identify baseline characteristics, symptoms, or questionnaires that could help to identify sleep-disordered breathing patients with significant PLMS. Patients aged 20-80 years who underwent polysomnography for assessing sleep disturbance were included. Various factors such as sex, age, body measurements, symptoms, apnea-hypopnea index (AHI), and sleep quality scales were analysed to determine the presence of PLMS. The study included 1480 patients with a mean age of 46.4 ± 13.4 years, among whom 110 (7.4%) had significant PLMS with a PLM index of 15 or higher. There were no significant differences observed in terms of sex or BMI between patients with and without significant PLMS. However, the odds ratios (OR) for PLMS were 4.33, 4.41, and 4.23 in patients who were aged over 50 years, had insomnia, or had an ESS score of less than 10, respectively. Notably, the OR increased up to 67.89 times in patients who presented with all three risk factors. Our analysis identified significant risk factors for PLMS: age over 50, self-reported insomnia, and lower daytime sleepiness levels. These findings aid in identifying potential PLMS patients, facilitating confirmatory examinations and managing associated comorbidities.

Coexistence of periodic limb movements during sleep with restless legs syndrome and its association with hypertension in Japanese patients

BackgroundCaucasian patients with restless legs syndrome (RLS) frequently exhibit periodic limb movements during sleep (PLMS), which may increase the risk of hypertension. We evaluated the positivity rate of PLMS and factors associated with positivity in Japanese patients with RLS, and tested whether the complications of PLMS are associated with the presence of hypertension. MethodsWe retrospectively investigated polysomnographic data and the presence or absence of hypertension in patients with RLS. Patients with systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg or those taking antihypertensive medication were categorized as the group with hypertension. ResultsAmong 468 patients, 200 (42.7%) had periodic limb movement index (PLMI) values ≥ 15/h and 108 (23.1%) met the criteria of positivity for hypertension. Multiple logistic regression analysis revealed that only higher age was significantly associated with PLMI values ≥ 15/h. Multiple linear regression analyses of factors associated with an increased PLMI also showed that increased PLMI was significantly correlated with higher age and male sex, but not with the international restless legs scale scores. Multiple logistic regression analysis also revealed that higher age and body mass index, not PLMI values ≥ 15/h, were significantly associated with the presence of hypertension. ConclusionThe PLMS-positivity rate may be lower in Japanese patients with RLS than in Caucasian patients, and it increases with age and male sex, but not with the severity of the disorder. Furthermore, PLMS complications were not associated with the risk of hypertension in Japanese patients with RLS.

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

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. 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. 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.