Periodic limb movements in sleep and periodic limb movement disorder

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.

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.

Polysomnographic phenotyping of obstructive sleep apnea and its implications in mortality in Korea

Conventionally, apnea–hypopnea index (AHI) is used to define and categorize the severity of obstructive sleep apnea. However, routine polysomnography (PSG) includes multiple parameters for assessing the severity of obstructive sleep apnea. The goal of this study is to identify and categorize obstructive sleep apnea phenotypes using unsupervised learning methods from routine PSG data. We identified four clusters from 4,603 patients by using 29 PSG variable and arranged according to their mean AHI. Cluster 1, spontaneous arousal (mean AHI = 8.52/h); cluster 2, poor sleep and periodic limb movements (mean AHI = 12.16/h); cluster 3, hypopnea (mean AHI = 38.60/h); and cluster 4, hypoxia (mean AHI = 69.66/h). Conventional obstructive sleep apnea classification based on apnea–hypopnea index severity showed no significant difference in cardiovascular or cerebrovascular mortality (Log rank P = 0.331), while 4 clusters showed an overall significant difference (Log rank P = 0.009). The risk of cardiovascular or cerebrovascular mortality was significantly increased in cluster 2 (hazard ratio = 6.460, 95% confidence interval 1.734–24.073) and cluster 4 (hazard ratio = 4.844, 95% confidence interval 1.300–18.047) compared to cluster 1, which demonstrated the lowest mortality. After adjustment for age, sex, body mass index, and underlying medical condition, only cluster 4 showed significantly increased risk of mortality compared to cluster 1 (hazard ratio = 7.580, 95% confidence interval 2.104–34.620). Phenotyping based on numerous PSG parameters gives additional information on patients’ risk evaluation. Physicians should be aware of PSG features for further understanding the pathophysiology and personalized treatment.

Actimetry-Documented Persistent Periodic Limb Movements During EEG-Confirmed Deep General Anesthesia: A Case Report

Motor activity during general anesthesia (GA) without neuromuscular blockade is often interpreted as reflecting insufficient anesthesia. Here we present the case of an octogenarian undergoing deep sclerectomy with opioid-sparing electroencephalography (EEG)-guided anesthesia. Periodic leg movements (PLM) appeared during ongoing surgery while the patient's raw EEG displayed a pattern of deep anesthesia, evidenced by burst suppression. Recognizing PLM in the context of opioid-sparing GA is of importance for anesthesiologists, as deep anesthesia is not necessarily associated with a decrease in motor activity.

Periodic Limb Movements in Sleep is Associated with Increased Mortality

OBJECTIVE

To elucidate the association between periodic limb movements in sleep (PLMS) and mortality.

METHODS

Nocturnal polysomnographic recordings of 1,344 subjects obtained from 1995 to 2008 were reviewed. The subjects were divided into four groups based on PLMS and insomnia: reference group (PLMS≤5), insomnia group (PLMS≤5 with insomnia symptoms), 5<PLMS≤15 group, and the PLMS>15 group. We searched each subject's Identification Number in the death records from the Statistics of Korea, the national bureau of statistics, to determine deaths in the cohort that occurred prior to December, 2013. Cox-proportional hazard regression and Kaplan-Meier survival curve analyses were used to compare mortality among the four groups.

RESULTS

Hazard ratios (HRs) in the 5<PLMS≤15 and PLMS>15 groups were significantly higher than that in the reference group before adjusting for age and gender [HR, 3.37; 95% confidence interval (CI), 1.73-6.55; p<0.001; HR, 5.77; 95% CI, 3.24-10.29; p<0.001]. Only the PLMS>15 group had a higher mortality rate than that in the reference group after adjusting for age, gender, and sleep efficiency (HR, 1.99; 95% CI, 1.06-2.21; p=0.033).

CONCLUSION

These results suggest that PLMS may be associated with increased mortality.

The Semiology of Tics, Tourette's, and Their Associations

Gilles de la Tourette syndrome (GTS) is a prototypical neuropsychiatric disorder breaking the boundary of disciplinary dualism between neurology and psychiatry. The diagnosis of GTS is clinical and, in most cases, straightforward. Tics as a hallmark of GTS are usually easy to recognize and distinguish from other movement disorders as fragmented, repetitive, exaggerated movements resembling normal motor behavior, but appearing out of context. In complex cases, knowledge on additional characteristics and signs as, for example, tic distribution, suggestibility, voluntary tic inhibition, and presence of echo- or paliphenomena might further aid clinical diagnosis. However, although defining GTS, tics are rarely the main issue. The presence of comorbidities and coexisting psychopathologies often hampers normal development and negatively affects quality of life. Their recognition and treatment is paramount. Here, we review existing literature and provide a comprehensive update on the multifarious aspects of the movement disorder and neuropsychiatry of GTS. We also provide a list of associated movement disorders known to occur in GTS patients and discuss differential diagnoses to be considered in atypical cases. We finally comment on available treatment options.

Lisuride reduces involuntary periodic leg movements in spinocerebellar ataxia type 2 patients

Periodic leg movements (PLMs) are a common sleep disorder in spinocerebellar ataxia type 2 (SCA2) being associated to higher disease severity and altered sleep patterns. To assess the efficacy and safety of lisuride for the treatment of PLMs in SCA2 patients, an open-label clinical trial was conducted in 12 SCA2 patients suffering from PLMs associated to other subjective sleep complaints. All subjects received 0.1 mg of oral lisuride daily for 4 weeks. Primary outcome measure was the change of PLMs index. Changes in the subjective sleep quality, other polysomnographical sleep parameters, Scale for the Assessment and Rating of Ataxia score, and saccadic velocity were assessed as secondary outcome parameters. Safety assessments included hemoglobin, hematocrit, cholesterol, creatinine, and TGP. A significant decrease in both the PLMs index and R stage latency were observed during the treatment, associated to subjective improvement of frequent awakenings, early insomnia, restless leg syndrome, and nocturnal limb paresthesias in most cases. Ataxia score and saccadic pathology were unchanged. No significantly adverse events were observed. Our study suggests the efficacy of dopamine agonist therapy in the treatment of PLMs in SCA2, improving various subjective sleep complaints. These findings serve to promote the adequate management of sleep-related disorders in SCA2, which could improve the life quality of the patients.

Clinical correlates of periodic limb movements in sleep in Parkinson's disease

OBJECTIVE

The aim of the current study was to investigate the frequency of periodic limb movements in sleep (PLMS) in Parkinson's disease (PD) and their impact on nocturnal sleep and daytime functioning.

METHODS

Forty-five PD patients (mean age 68.5 ± 8.7 years; 32 males) underwent one night of polysomnography (PSG). Clinical assessment and questionnaires evaluating sleep disturbance and quality of life (QoL) were completed. Patients were divided into two groups based on their PLMS index (PLMSI): PLMSI ≥ 15 (PLMS+) and PLMSI <15 (PLMS-).

RESULTS

There were 26 (57.8%) PD patients in the PLMS+group and 19 (42.2%) patients in the PLMS-group. Subjective assessment revealed an association between PLMS+status and greater PD symptom severity, more subjective sleep disturbance, and decreased QoL. All patients showed poor sleep, and no significant group differences were detected on PSG measures.

CONCLUSION

We observed that PLMS occurred frequently in PD and increased with more severe PD. Although PLMS did not affect objective sleep, it was associated with increased sleep complaints and reduced QoL. Overall, our findings support the association between PLMS and PD as well as the clinical relevance of sleep disturbances in PD.

Stretching before sleep reduces the frequency and severity of nocturnal leg cramps in older adults: a randomised trial

QUESTION

In adults who experience nocturnal leg cramps, does stretching of the calf and hamstring muscles each day just before sleep reduce the frequency and severity of the cramps?

DESIGN

A randomised trial with concealed allocation and intention-to-treat analysis.

PARTICIPANTS

Eighty adults aged over 55 years with nocturnal leg cramps who were not being treated with quinine.

INTERVENTION

The experimental group performed stretches of the calf and hamstring muscles nightly, immediately before going to sleep, for six weeks. The control group performed no specific stretching exercises. Both groups continued other usual activities.

OUTCOME MEASURES

Participants recorded the frequency of nocturnal leg cramps in a daily diary. Participants also recorded the severity of the pain associated with nocturnal leg cramps on a 10-cm visual analogue scale. Adverse events were also recorded.

RESULTS

All participants completed the study. At six weeks, the frequency of nocturnal leg cramps decreased significantly more in the experimental group, mean difference 1.2 cramps per night (95% CI 0.6 to 1.8). The severity of the nocturnal leg cramps had also decreased significantly more in the experimental group than in the control group, mean difference 1.3 cm (95% CI 0.9 to 1.7) on the 10-cm visual analogue scale.

CONCLUSION

Nightly stretching before going to sleep reduces the frequency and severity of nocturnal leg cramps in older adults.

TRIAL REGISTRATION

NCT01421628.

A comprehensive review of spinocerebellar ataxia type 2 in Cuba

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant cerebellar ataxia characterized by a progressive cerebellar syndrome associated to saccadic slowing, peripheral neuropathy, cognitive disorders, and other multisystem features. SCA2 is caused by the abnormal expansion of cytosine-adenine-guanine triplet repeats in the encoding region of the ATXN2 gene and therefore the expression of toxic polyglutamine expansions in the ataxin 2 protein, which cause progressive neuronal death of Purkinje cells in the cerebellum and several pontine, mesencephalic, and thalamic neurons among other cells. Worldwide, SCA2 is the second most frequent type of spinocerebellar ataxia, only surpassed by SCA3. Nevertheless, in Holguin, Cuba, the disease reaches the highest prevalence, resulting from a putative foundational effect. This review discusses the most important advances in the genotypical and phenotypical studies of SCA2, highlighting the comprehensive characterization reached in Cuba through clinical, neuroepidemiological, neurochemical, and neurophysiological evaluation of SCA2 patients and pre-symptomatic subjects, which has allowed the identification of new disease biomarkers and therapeutical opportunities. These findings provide guidelines, from a Cuban viewpoint, for the clinical management of the disease, its diagnosis, genetic counseling, and therapeutical options through rehabilitative therapy and/or pharmacological options.

Ropinirole in restless legs syndrome and periodic limb movement disorder

Restless legs syndrome and periodic limb movement disorder of sleep are now recognized as prevalent, distinct, yet overlapping disorders affecting all age groups. Although delineation of the mechanisms underlying these disorders continues to be the focus of very intense research efforts, it has become apparent that there is a prominent role for dopaminergic agents in the clinical management of these patients. Among the various dopaminergic drugs, ropinirole has undergone relatively intense and critical scrutiny, and appears to provide a safe and efficacious treatment option for patients with these two conditions. The more recent development of a controlled formulation for this drug is likely to yield additional benefits such as improved adherence and reduced fluctuations in daytime and nighttime symptoms. However, there is not enough evidence at this time to support such assumption.

Sleep disorders frequency in post-polio syndrome patients caused by periodic limb movements

Post-polio syndrome (PPS) in individuals with polio longer than 15 years is characterized by weakness and/or muscle fatigue, deficit of deglutition and breath and periodic limb movements (PLM) during sleep. We undertook a review of 99 patients with PPS, and assessed the frequency of PLM through polysomnographic recordings at our sleep disorders unit. The total number of PLM, total time of sleep (TTS), efficiency of sleep (EfS), awaking index (AI) and apnea-hypopnea index (AHI) were analyzed. Sixteen patients presented PLM in excess of 5 for the entire night. When comparing these with the group without PLM, a correlation was found (p=0.001). Significant difference was found for the correlation of the parameters: IAH, ID, TTS and EfS when compared the two groups. There is a close relationship between PPS and PLM.

Periodic limb movements both in non-REM and REM sleep: relationships between cerebral and autonomic activities

OBJECTIVE

To investigate the temporal relationship between cerebral and autonomic activities before and during periodic limb movements in NREM and REM sleep (PLMS).

METHODS

Patterns of EEG, cardiac and muscle activities associated with PLMS were drawn from polysomnographic recordings of 14 outpatients selected for the presence of PLMS both in NREM and REM sleep. PLMS were scored during all sleep stages from tibial EMG. Data from a bipolar EEG channel were analyzed by wavelet transform. Heart rate (HR) was evaluated from the electrocardiogram. EEG, HR and EMG activations were detected as transient increase of signal parameters and examined by analysis of variance and correlation analysis independently in NREM and REM sleep. Homologous parameters in REM and NREM sleep were compared by paired t-test.

RESULTS

The autonomic component, expressed by HR increase, took place before the motor phenomenon both in REM and NREM sleep, but it was significantly earlier during NREM. In NREM sleep, PLM onset was heralded by a significant activation of delta-EEG, followed by a progressive increase of all the other bands. No significant activations of delta EEG were found in REM sleep. HR and EEG activations positively correlated with high frequency EEG activations and negatively (in NREM) with slow frequency ones.

CONCLUSIONS

Our findings suggested a heralding role for delta band only in NREM sleep and for HR during both NREM and REM sleep. Differences in EEG and HR activation between REM and NREM sleep and correlative data suggested a different modulation of the global arousal response.

SIGNIFICANCE

In this study, time-frequency analysis and advanced statistical methods enabled an accurate comparison between brain and autonomic changes associated to PLM in NREM and REM sleep providing indications about interaction between autonomic and slow and fast EEG components of arousal response.

[The neuropathology of sleep in human neurodegenerative diseases]

The neuropathology of human sleep remains an ill-defined issue. The data concerning the main structures of human brain areas involved, or supposed to be implicated, in sleep organisation are reviewed. Five levels of organisation can be schematically recognized: (i) the ascending arousal system, (ii) the non REM and REM systems (iii) regulated by hypothalamic areas, (iv) and the biological clock, (v) modulated by a number of "allostatic" influences. These are briefly described, with emphasis on the location of structures involved in humans, and on the recently revised concepts. Current knowledge on the topography of lesions associated with the main sleep disorders in degenerative diseases is recalled, including REM sleep behavior disorders, restless legs syndrome and periodic leg movements, sleep apneas, insomnia, excessive daily sleepiness, secondary narcolepsy and disturbed sleep-wake rhythms. The lesions of sleep related structures observed in early and late stages of four degenerative diseases are then reviewed. Two synucleinopathies (Lewy lesions associated disorders, including Parkinson's disease and Dementia with Lewy bodies, and Multiple System Atrophy) and two tauopathies (Progressive Supranuclear Palsy and Alzheimer's disease) are dealt with. The distribution of lesions usually found in affected patients fit with that expected from the prevalence of different sleep disorders in these diseases. This confirms the current opinion that these disorders depend on the distribution of lesions rather than on their biochemical nature. Further studies might throw insight on the mechanism of normal and pathological sleep in humans, counterpart of the increasing knowledge provided by animal models. Specially designed prospective clinicopathological studies including peculiar attention to sleep are urgently needed.