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

Sleep Deficiency in Obstructive Sleep Apnea

Sleep deficiency in patients with obstructive sleep apnea (OSA) includes abnormal quality, timing and duration of sleep, and the presence of other comorbid conditions. These include insomnia, circadian misalignment disorders, and periodic limb movements of sleep, among others. The co-occurrence of these conditions with OSA likely plays a role in pathogenesis, clinical presentation, and management of OSA. Considering these conditions and their treatment in evaluating sleep deficiency in OSA may help improve patient outcomes. However, future research is needed to understand the intersection between OSA and these disorders.

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.

Positional Obstructive Sleep Apnea and Periodic Limb Movements During Sleep: A Large Multicenter Study

OBJECTIVES

The relationships among positional obstructive sleep apnea (POSA), obstructive sleep apnea (OSA), and periodic limb movements during sleep (PLMS) remain unclear. We investigated these relationships with respect to the severity of OSA and explored the underlying mechanisms.

METHODS

We retrospectively reviewed 6,140 eligible participants who underwent full-night diagnostic polysomnography at four clinical centers over a 5-year period, utilizing event-synchronized analysis. We evaluated the periodic limb movement index (PLMI) and the periodic limb movement with arousal index (PLMAI). The impacts of POSA on the PLMI, PLMAI, and PLMS were analyzed in relation to the severity of OSA.

RESULTS

The mean PLMI, the mean PLMAI, and the prevalence of PLMS were significantly lower in participants with severe OSA compared to the mild and moderate OSA groups. The mean PLMI among those with mild OSA exceeded that of control participants. Furthermore, the mean PLMI (4.8±12.7 vs. 2.6±9.8 events/hr, P<0.001), the mean PLMAI (0.9±3.7 vs. 0.5±3.3 events/hr, P<0.001), and the prevalence of PLMS (11% vs. 5.3%, P<0.001) were higher in patients with POSA than in those with non-positional OSA. This PLMS finding was particularly pronounced among those with severe OSA (odds ratio [OR], 1.554; 95% confidence interval [CI], 1.065-2.267) and was less evident in the mild (OR, 0.559; 95% CI, 0.303-1.030) and moderate (OR, 1.822; 95% CI, 0.995-3.339) groups.

CONCLUSION

Patients with POSA, especially those with severe OSA, exhibit a comparatively high prevalence of PLMS. In cases involving prominent PLMS, the diagnosis and treatment of POSA and OSA should be considered.

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

Background

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.

Methods

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).

Results

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.

Conclusion

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.

The relationship between periodic limb movement during sleep and dyslipidaemia in patients with obstructive sleep apnea

Periodic limb movements during sleep and obstructive sleep apnea are both associated with increased sympathetic tone, and have been proposed as risk factors for heart diseases and, in particular, cardiovascular disease. As sympathetic system activation may lead to dyslipidaemia, periodic limb movements during sleep could be an additional risk factor for cardiovascular disease in patients with obstructive sleep apnea. The aim of the study was to determine whether the presence of periodic limb movements during sleep affects serum lipid levels in obstructive sleep apnea. Total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, non- high-density lipoprotein cholesterol and triglyceride levels were investigated in 4138 patients with obstructive sleep apnea in the European Sleep Apnea Database (ESADA) cohort, divided into those with periodic limb movements during sleep index ≥ 15 per hr (n = 628) and controls (n = 3510). ANCOVA adjusted for age, sex, body mass index, apnea-hypopnea index, alcohol intake, smoking status, diabetes, insomnia and study site was used to assess differences in lipids between periodic limb movements during sleep and controls. Patients with periodic limb movements during sleep (24% female, 54.4 ± 12.1 years, body mass index 31.9 ± 5.8 kg m-2 , apnea-hypopnea index 36.7 ± 25.4 per hr) had higher triglyceride (1.81 ± 1.04 versus 1.69 ± 0.90 mmol L-1 , p = 0.002) and lower high-density lipoprotein cholesterol (1.19 ± 0.34 versus 1.24 ± 0.37 mmol L-1 , p = 0.002) levels, whilst there was no difference in either total cholesterol (4.98 ± 1.10 versus 4.94 ± 1.07 mmol L-1 ), low-density lipoprotein cholesterol (3.04 ± 0.96 versus 2.98 ± 0.98 mmol L-1 ) or non- high-density lipoprotein cholesterol (3.78 ± 1.10 versus 3.70 ± 1.05 mmol L-1 ) concentrations (all p > 0.05). The results remained unchanged after most sensitivity analyses. Patients with obstructive sleep apnea with periodic limb movements during sleep had more prevalent cardiovascular disease (11% versus 6%, p < 0.01). Periodic limb movements during sleep in obstructive sleep apnea is associated with dyslipidaemia independently of important confounders. Our results highlight periodic limb movements during sleep as an additional risk factor for cardiovascular disease in obstructive sleep apnea.

Polysomnographic findings in the ultra-rare McLeod syndrome: further documentation of sleep apnea as a possible feature

STUDY OBJECTIVES

McLeod syndrome is a very rare multisystemic neurodegenerative disease linked to mutations in the XK gene. It has cardiac, neurologic, and neuromuscular manifestations and shares similarities with Huntington's disease. The aim of this study was to evaluate sleep patterns of patients affected by McLeod syndrome.

METHODS

This retrospective case series of four males who underwent diagnostic polysomnography (mean age 53.8 ± 2.5 years) includes self-reported and objective evaluation of sleep using the Epworth Sleepiness Scale, genetic tests, documentation of clinical course and features, and laboratory-based full-night attended video-polysomnography.

RESULTS

In three out of four patients, an Epworth Sleepiness Scale score ≥ 7 was evident. The average apnea-hypopnea index was 45.0 ± 19.0, with predominantly obstructive phenotype in three patients and predominant central events (central sleep apnea syndrome) in one patient. A significantly increased periodic limb movement index during sleep was observed in all patients. All patients tolerated continuous positive airway pressure or pressure controlled therapy.

CONCLUSIONS

Polysomnography of all patients confirmed sleep apnea syndrome as a feature of McLeod syndrome. Three patients were diagnosed with obstructive sleep apnea and one with central sleep apnea syndrome. In addition, periodic limb movement index was increased in all patients.

CITATION

Dieter M, Kevin P, Tobias V, et al. Polysomnographic findings in the ultra-rare McLeod syndrome: further documentation of sleep apnea as a possible feature. J Clin Sleep Med. 2024;20(3):339-344.

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.

Sex-specific patterns of discomfort in patients with restless legs syndrome

STUDY OBJECTIVES

Sex differences in the prevalence of restless legs syndrome (RLS) have been reported, with a higher prevalence in women than in men. However, sex differences in clinical presentation remain unclear. We aimed to investigate the phenotypic differences in patients with RLS between sexes by comparing clinical presentations, iron status, polysomnographic parameters, and treatment.

METHODS

We retrospectively evaluated 614 patients (225 men, 389 women) diagnosed with RLS. To enhance the robustness of the study, an age-matched control group of 179 men and 286 women without sleep disorders was also included. Information on demographics and sleep-related questionnaires were collected. Iron status was evaluated using blood samples, and polysomnography was performed to evaluate periodic leg movements and comorbid sleep disorders.

RESULTS

Our analysis revealed no sex difference in the severity of RLS but a difference in the pattern of symptoms. Women had more frequent symptoms of pain and awakening during sleep, while men had more common motor symptoms (both self-reported symptoms and periodic leg movement on polysomnography). Women with RLS also had lower iron parameters and received more frequent iron supplementation therapy than men. In contrast to women with RLS, who presented higher sleep disturbances and depressive mood, men with RLS had a higher risk of comorbidities such as hypertension and cardiovascular disease. These sex differences were notably more pronounced than in the control group.

CONCLUSIONS

This study suggests that sex differences exist in RLS phenotypes, and clinicians should consider these differences for treatment.

CITATION

Kim J, Kim JR, Park HR, Joo EY. Sex-specific patterns of discomfort in patients with restless legs syndrome. J Clin Sleep Med. 2024;20(2):253-259.

Obstructive sleep apnea and periodic limb movement in children: is there really an association?

PURPOSE

Periodic limb movements (PLMs) can be found isolated or related to other sleep disorders, as Obstructive Sleep Apnea (OSA). Nevertheless, this association was described before the proposal for modification of the World Association of Sleep Medicine (WASM), which incorporated major changes modifying the definition of respiratory-related leg movements (RRLM) so that the relationship between OSA and PLM could be affected.

METHODS

A total of 131 PSG were studied (children with ages from 5 to 12 years old), all referred because of a suspicion of sleep-disordered breathing (65 children were diagnosed of OSA, and 66 presented snoring but no sleep apnea). Leg movements were manually scored according to both 2006 and 2016 WASM/IRLSSG criteria.

RESULTS

According to 2006 WASM rules, statistical differences were found, not only for PLM index (p 0.002), but all indexes. Nevertheless, according to new 2016 WASM rules, no statistical differences were found for PLM index (p 0.677), non-REM PLM index (p 0.299), REM PLM index (P 0.511) or PLM with arousal index (p 0.180), between OSA and non-OSA group. Positive correlation between PLM and RRLM have been found with both set of rules. The percentage of children with PLM>5/h is higher when using the prior PLM scoring criteria developed in 2006 (38.93%) versus the updated PLM scoring criteria (19.08%).

CONCLUSION

The lack of association when using the new WASM/IRLSSG scoring rules together with the absence of a previous clear etiopathology explanation may suggest that the association between OSA and PLM might be indeed overestimated and that, perhaps, it really did not exist.

Temporal association between leg movements and respiratory events in patients with obstructive sleep apnea: description and differences between the AASM and WASM scoring criteria

PURPOSE

To describe the temporal association between leg movements (LMs) and respiratory events in patients with obstructive sleep apnea (OSA), and to quantify the difference in scoring respiratory-related leg movement (RRLM) between the American Academy of Sleep Medicine (AASM) criterion and the criterion recommended by the World Association of Sleep Medicine (WASM).

METHODS

Patients with OSA who presented with > 10 LMs of any type per hour of sleep were included in this study. For each participant, RRLMs were scored using both the AASM criterion and the recommended WASM criterion. The occurrence of LMs in relation to respiratory events and the difference in scoring RRLM between the AASM criterion and the criterion recommended by the WASM were quantified.

RESULTS

In 32 patients enrolled, mean age was 48.1 ± 11.0 years and 78% were men. LMs were significantly more frequent after respiratory events, followed by before respiratory events, and were rare during respiratory events (P < 0.01). Compared with the AASM criterion, more LMs were classified as RRLMs based on the recommended WASM criterion (P = 0.01).

CONCLUSION

LMs are more frequent after respiratory events than before and during respiratory events, and more LMs are scored as RRLMs based on the recommended WASM criterion than based on the AASM criterion.

The accuracy and difference of scoring rules and methods to score respiratory event-related leg movements in obstructive sleep apnea patients

OBJECTIVE

To compare manual scoring: 1) to the American Academy of Sleep Medicine (AASM) auto-scoring rules. 2) to the AASM and World Association of Sleep Medicine (WASM) rules, and evaluate the accuracy of the AASM and WASM for respiratory event-related limb movements (RRLM) in diagnostic and continuous positive airway pressure (CPAP) titration polysomnography (PSG).

METHODS

We retrospectively, re-scored diagnostic and CPAP titration PSGs of 16 patients with obstructive sleep apnea (OSA), using manual re-scoring by the AASM (mAASM) and WASM (mWASM) criteria for RRLM, periodic limb movements during sleep (PLMS), and limb movements (LM), which were compared to auto-scoring by the AASM (aAASM).

RESULTS

In diagnostic PSG, significant differences were found in LMs (p < 0.05), RRLM (p = 0.009) and the mean duration of PLMS sequences (p = 0.013). In CPAP titration PSG, there was a significant difference in RRLM (p = 0.008) and PLMS with arousal index (p = 0.036). aAASM underestimated LM and RRLM, especially in severe OSA. Changes in RRLM and PLMS with arousal index between diagnostic and titration PSG were significantly different between aAASM and mAASM, but there was no significant difference between scoring by mAASM and mWASM. The ratio of PLMS and RRLM changes between diagnostic and CPAP titration PSG was 0.257 in mAASM and 0.293 in mWASM.

CONCLUSIONS

In addition to the overestimation of RRLM by mAASM compared to aAASM, mAASM may also be more sensitive than aAASM in detecting RRLM changes in the titration PSG. Despite intuitive differences in the definition of RRLM between AASM and WASM rules, RRLM results between mAASM and mWASM were not significant and about 30% of RRLMs might be scored as PLMS by both scoring rules.

Periodic limb movements during sleep and risk of hypertension: A systematic review

BACKGROUND

Several studies suggest an association between periodic limb movements during sleep (PLMS) and hypertension; however, a systematic evaluation of this relationship is lacking.

METHODS

We conducted a systematic review and meta-analysis of observational studies that reported odds ratio, relative risk, hazard ratio, or standardized incidence ratio, comparing the risk of hypertension in persons with PLMS (defined by the level of periodic limb movements per hour of sleep depended on individual studies) versus those without PLMS. After assessing heterogeneity and bias, the pooled risk ratio and 95% confidence intervals (CIs) were determined using a random-effect, generic inverse variance method of DerSimonian and Laird.

RESULTS

Out of 572 potentially relevant articles, six eligible studies were included in the data analysis. Studies (6 cross-sectional) included 8949 participants. The statistical heterogeneity of this study was insignificant, with an I² of 0%. A funnel plot and Egger's regression asymmetry test showed no publication bias with P-value ≥0.05. The pooled risk ratio of hypertension in patients with PLMS was 1.26 (95% CI, 1.12-1.41).

CONCLUSIONS

Our analysis demonstrates an increased hypertension risk among patients with PLMS. Prospective or interventional studies are needed to confirm this association.

More than sleepiness: prevalence and relevance of nonclassical symptoms of obstructive sleep apnea

PURPOSE OF REVIEW

The purpose of this review is to describe the nonclassical symptoms and manifestations occurring in patients with obstructive sleep apnea (OSA), both from a standpoint of prevalence and in terms of clinical relevance. Particular emphasis will be given to nightmares, comorbid insomnia, restless legs syndrome and periodic limb movement disorder, bruxism, morning headache, nocturia, acid reflux, chronic cough and dysphagia.

RECENT FINDINGS

A review of the recent literature suggests that nonclassical symptoms have a high prevalence, are underestimated, and can interact with quality of life. Although these disturbances may occur together by mere coincidence, they may interact reciprocally. However, the degree of symptoms is not always correlated with OSA severity.

SUMMARY

OSA is a heterogeneous disease with variable clinical manifestations. This review highlights the need for detailed evaluation of patients with OSA to diagnose other important sleep disorders and clinical manifestations, given their frequent association.

Sleep Bruxism Contributes to Motor Activity Increase during Sleep in Apneic and Nonapneic Patients-A Polysomnographic Study

Background: Jaw motor activity (MA) in sleep bruxism (SB) has been demonstrated to accompany lower limb movements. However, it remains unknown whether SB activity coexists with other types of movements and what the possible underlying mechanisms of such temporal coexistence are. In obstructive sleep apnea (OSA), increased movement activity is also reported, including SB activity; however, no studies have compared MA in apneic and nonapneic SB patients. Aim: This cross-sectional study focused on the phenomenon of “big body movements” in patients with either SB or OSA (or both) and intended to identify the primary factors contributing to their appearance, using polysomnography (PSG) recording. Methods: A whole-night videoPSG was carried out in 287 participants, and 124 apneic and 146 nonapneic participants were selected for the study. In both groups, participants were further divided into no SB, moderate SB, and severe SB (SSB) subgroups based on their bruxism episode index (BEI). MA was recorded using a built-in sensor of the central PSG unit located on the participant’s chest during the examination. Results: The presence of SB was related to the higher intensity of MA in both apneic and nonapneic participants, though in general the MA level was higher in apneic participants, with the highest level observed in SSB apneic participants. Conclusions: SB might contribute to MA. The prevalence of SB might be higher in nonapneic patients due to phasic and mixed SB activity, whereas the SB phenotype seems to be less relevant in apneic patients. SB activity is likely to increase MA in non-REM 1 sleep.

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.

Changes in Periodic Limb Movements of Sleep After the Use of Continuous Positive Airway Pressure Therapy: A Meta-Analysis

Background

Both obstructive sleep apnea (OSA) and periodic limb movements of sleep (PLMS) are common in the sleep laboratory. The severity of OSA can be improved by using continuous positive airway pressure (CPAP). However, increasing evidence has shown an elevated periodic limb movement index (PLMI) in patients with OSA who use CPAP, although the pathophysiology is still unknown. This meta-analysis aimed to investigate changes in PLMS after using CPAP and the potential pathophysiology of these changes.

Methods

Clinical trials in adult humans investigating the comorbidity between PLMS and CPAP were identified and analyzed using random-effects model meta-analysis.

Results

This meta-analysis included 14 studies comprising 2,938 patients with OSA. The PLMI was significantly increased after using CPAP with a difference in means of 1.894 (95% confidence interval = 0.651-3.138, p = 0.003). Subgroup analysis showed that CPAP was only significantly associated with an increase in PLMI in the patients without PLMS at baseline (p = 0.045) and in those with a baseline body-mass index <30 kg/m2 (p = 0.045). The use of CPAP, apnea-hypopnea index, and arousal index were positively correlated with changes in PLMI.

Conclusion

These characteristics may serve as qualitative predictive indicators of changes in PLMI after CPAP usage. Further analysis of the quantitative relationships between PLMI and the predictive indicators may be warranted.

Trial Registration

PROSPERO (registration number: CRD42021252635).

Sleep Deficiency in Obstructive Sleep Apnea

Sleep deficiency in patients with obstructive sleep apnea includes abnormal quality, timing, and duration of sleep, and the presence of other comorbid conditions. These include insomnia, circadian misalignment disorders, and periodic limb movements of sleep. The co-occurrence of these conditions with obstructive sleep apnea likely plays a role in the pathogenesis, clinical presentation, and management of obstructive sleep apnea. Considering these conditions and their treatment in evaluating sleep deficiency in obstructive sleep apnea may help to improve patient outcomes. However, future research is needed to understand the intersection between obstructive sleep apnea and these disorders.

Associations of diabetes mellitus and hypertension with adherence to continuous positive airway pressure therapy in male patients with obstructive sleep apnea

Methods

We conducted a retrospective study among 497 male patients with OSA on CPAP therapy. Participants with pretreatment Apnea-Hypopnea Index (AHI) data based on overnight polysomnographic recordings completed a questionnaire. Adherence data for CPAP therapy were collected using a smart card system. We classified CPAP use of ≥4 hours per night and ≥70% of nights as good adherence; other CPAP use was categorized as poor adherence. Logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for poor adherence to CPAP therapy in the hypertension and diabetes mellitus groups, compared with the no comorbidity group, adjusting for body mass index, duration of CPAP therapy, AHI, and Epworth Sleepiness Scale score.

Results

In the no comorbidity, hypertension, and diabetes mellitus groups, 43.4%, 44.7%, and 56.0%, respectively, had poor adherence to CPAP therapy. Being in the diabetes mellitus group was significantly associated with poor adherence to CPAP therapy (OR=1.86, 95% CI: 1.18-2.92, p=0.007); there was no association for the hypertension group.

Conclusion

Our results indicate that comorbidity of diabetes mellitus is associated with poor adherence to CPAP therapy in male patients with OSA.

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.

Periodic limb movements during sleep: a narrative review

Objective

Using narrative review techniques, this paper evaluates the evidence for separable underlying patho-mechanisms of periodic limb movements (PLMs) to separable PLM motor patterns and phenotypes, in order to elucidate potential new treatment modalities.

Background

Periodic limb movement disorder (PLMD) is estimated to occur in 5–8% of the paediatric population and 4–11% of the general adult population. Due to significant sleep fragmentation, PLMD can lead to functional impairment, including hyperactivity and delayed language development in children, and poor concentration and work performance in adults. Longitudinal data demonstrate that those with PLMD are at greater risk of depression and anxiety, and a 4-fold greater risk of developing dementia. PLMD has been extensively studied over the past two decades, and several key insights into the genetic, pathophysiological, and neural correlates have been proposed. Amongst these proposals is the concept of separable PLM phenotypes, proposed on the basis of nocturnal features such as the ratio of limb movements and distribution throughout the night. PLM phenotype and presentation, however, varies significantly depending on the scoring utilized and the nocturnal features examined, across age, and co-morbid clinical conditions. Furthermore, associations between these phenotypes with major neurologic and psychiatric disorders remain controversial.

Methods

In order to elucidate potential divergent biological pathways that may help clarify important new treatment modalities, this paper utilizes narrative review and evaluates the evidence linking PLM motor patterns and phenotypes with hypothesised underlying patho-mechanisms. Distinctive, underlying patho-mechanisms include: a pure motor mechanism originating in the spinal cord, iron deficiency, dopamine system dysfunction, thalamic glutamatergic hyperactivity, and a more cortical-subcortical interplay. In support of the latter hypothesis, PLM rhythmicity appears tightly linked to the microarchitecture of sleep, not dissimilarly to the apnoeic/hypopneic events seen in obstructive sleep apnea (OSA).

Conclusions

This review closes with a proposal for greater investigation into the identification of potential, divergent biological pathways. To do so would require prospective, multimodal imaging clinical studies which may delineate differential responses to treatment in restless legs syndrome (RLS) without PLMS and PLMS without RLS. This could pave the way toward important new treatment modalities.

Periodic limb movements during sleep are associated with poor health-related quality of life in patients with obstructive sleep apnea

PURPOSE

The clinical significance of the comorbidity of periodic limb movements during sleep (PLMS) in sleep-disordered breathing remains unclear. This study aimed to determine whether or not the presence of PLMS is related to depressed mood and poor quality of life in subjects with obstructive sleep apnea (OSA).

METHODS

We defined PLMS as a periodic leg movement index of > 15/h. Scores for the Medical Outcomes Study Short Form Health Survey and Beck Depression Inventory were assessed with multiple logistic or linear regression analyses.

RESULTS

Of 1370 subjects with OSA, a prevalence of PLMS was 14.1%. Older age, men, and obesity were positively associated with PLMS. PLMS occurred in 17%, 15%, and 12% of mild, moderate, and severe subjects with OSA, respectively. Severe OSA was less likely to be associated with PLMS than mild OSA. PLMS negatively correlated with physical and mental component summary scores of the health survey but not with Beck Depression Inventory scores after controlling for confounding variables. PLMS were significantly associated with poor sleep architecture on polysomnography. However, the relationship between PLMS and disturbed sleep was no longer significant after adjusting for age.

CONCLUSIONS

Health-related quality of life, including physical and mental health but not depressive symptoms, was worse in subjects with OSA and PLMS than in those without PLMS.

Different scoring rules for respiratory event-related leg movements: effects on the prevalence of periodic limb movements during sleep and their association with depressive symptoms in patients with obstructive sleep apnea

BACKGROUND

We compared the prevalence of periodic leg movements during sleep (PLMS) according to two different scoring rules of the American Academy of Sleep Medicine (AASM) 2012 and World Association of Sleep Medicine (WASM) 2016 and determined their association with depressed mood in patients with obstructive sleep apnea (OSA).

METHODS

PLMS, defined as a periodic leg movements index of >15, were diagnosed on a diagnostic and continuous positive airway pressure (CPAP) titration polysomnography using the AASM 2012 and WASM 2016 rules. The Beck Depression Inventory (BDI) and Epworth Sleepiness Scale (ESS) were used, and multiple regression analyses were performed.

RESULTS

Among 160 OSA patients, the proportion with PLMS scored by the WASM 2016 criteria was significantly higher than that scored by the AASM 2012 criteria in a diagnostic study (20.6% vs. 16.3%, respectively; P = 0.016) but not in CPAP titration study and only in patients with severe OSA. In adjusted models, PLMS were positively associated with BDI scores and a BDI of ≥10 on both diagnostic and CPAP titration studies when scored by the WASM 2016. By contrast, when scored by the AASM 2012, PLMS were associated with BDI scores (but not BDI of ≥10) only in a CPAP titration study.

CONCLUSIONS

There are significant differences in the prevalence of PLMS and their association with depressed mood depending on the scoring rules in patients with OSA. The current AASM scoring criteria underestimate the prevalence of PLMS, and PLMS are more likely associated with depressed mood according to the WASM scoring criteria.

Clinical characteristics of periodic limb movements during sleep categorized by continuous positive airway pressure titration polysomnography in patients with obstructive sleep apnea

PURPOSE

The presence of periodic limb movements during sleep (PLMS) varies among patients with obstructive sleep apnea (OSA) undergoing treatment with continuous positive airway pressure (CPAP). The factors associated with this variation are unknown.

METHODS

PLMS were defined as a periodic leg movements index of > 15/h. Patients with OSA and PLMS were categorized into four groups depending on diagnostic and CPAP titration polysomnography (PSG). A multinomial logistic regression analysis was performed using a non-PLMS group as the reference category.

RESULTS

This study included 861 patients with OSA who underwent a full-night CPAP titration PSG. The proportions of the subjects with PLMS on both PSGs (persistent PLMS), those with CPAP-emergent PLMS, and those with CPAP-resolved PLMS were 12.9%, 9.2%, and 3.9%, respectively. Compared with the non-PLMS group, the persistent group was more likely to be of older age and male sex and has a higher body mass index and restless legs syndrome (RLS). Patients in the CPAP-emergent group were also older and more likely to have RLS as well as more severe apnea. Patients in the CPAP-resolved group were more likely to be women, of older age, have a higher body mass index, but less severe apnea.

CONCLUSIONS

PLMS elicited by CPAP are more likely to occur in older patients with more severe sleep apnea and comorbid RLS, whereas OSA patients in which PLMS resolve after CPAP are more likely to be women and have milder sleep apnea. Persistent PLMS share clinical characteristics with PLMS in general population.

Low Arousal Threshold: A Potential Bridge Between OSA and Periodic Limb Movements of Sleep

OBJECTIVE

Periodic Limb Movements of Sleep (PLMS) is a poorly understood comorbidity with close association to Obstructive Sleep Apnea (OSA). The mechanistic link between the two is unclear. Recent studies on the latter have uncovered low respiratory arousal threshold as an important non-anatomical cause of the disorder. This study sought to investigate whether periodic limb movements are associated with the low respiratory arousal threshold (ArTH) in OSA.

METHODS

Retrospective data on 720 OSA patients (mean age = 47.0) who underwent Polysomnography (PSG) were collected. Using PLMS diagnostic criteria of PLMS index ≥ 15, patients were divided into the OSA-PLMS group (n=95) and the OSA-only group (n=625). Binary logistic regression analysis was used to examine the correlation between PLMS and the presence of low ArTH, classified using a predicted tool (developed by Edward et al) requiring meeting at least two of the three criteria: apnea-hypopnea index (AHI) < 30/h, nadir oxygen saturation (SaO2) > 82.5%, and fraction of hypopneas > 58.3%. The resulting model was validated in the external MrOS database.

RESULTS

The patients in the OSA-PLMS group tend to be older, with a higher prevalence of hypertension, diabetes, and stroke. PLMS was associated with age, diabetes, oxygen desaturation index, and low respiratory arousal threshold (OR=8.78 (4.73-16.30), p<0.001). When validated against the MrOS database, low ArTH remained a significant predictor of PLMS with an odds ratio of 1.33 (1.08-1.64, p = 0.009).

CONCLUSION

This is the first study that demonstrated a strong correlation between PLMS and low respiratory arousal threshold. This suggests a possible mechanistic link between the physical manifestation of PLMS and the non-anatomical low arousal threshold phenotype in OSA.