Review of the role of the endogenous opioid and melanocortin systems in the restless legs syndrome.

Restless legs syndrome (RLS) is responsive to opioid, dopaminergic and iron-based treatments. Receptor blocker studies in RLS patients suggest that the therapeutic efficacy of opioids is specific to the opioid receptor and mediated indirectly through the dopaminergic system. An RLS autopsy study reveals decreases in endogenous opioids, ß-endorphin and perhaps Met-enkephalin in the thalamus of RLS patients. A total opioid receptor knock-out (mu, delta and kappa) and a mu-opioid receptor knock-out mouse model of RLS show circadian motor changes akin to RLS and, although both models show sensory changes, the mu-opioid receptor knock mouse shows circadian sensory changes closest to those seen in idiopathic RLS. Both models show changes in striatal dopamine, anaemia and low serum iron. However, only in the total receptor knock-out mouse do we see the decreases in serum ferritin that are normally found in RLS. There are also decreases in serum iron when wild-type mice are administered a mu-opioid receptor blocker. In addition, the mu-opioid receptor knock-out mouse also shows increases in striatal zinc paralleling similar changes in RLS. Adrenocorticotropic hormone and α-melanocyte stimulating hormone are derived from pro-opiomelanocortin as is ß-endorphin. However, they cause RLS-like symptoms and periodic limb movements when injected intraventricularly into rats. These results collectively suggest that an endogenous opioid deficiency is pathogenetic to RLS and that an altered melanocortin system may be causal to RLS as well.

Hyperactivity in patients with narcolepsy and idiopathic hypersomnia: an exploratory study.

Introduction: Patients with either Idiopathic Hypersomnia or Narcolepsy demonstrate excessive daytime somnolence (EDS) with resultant inattention mimicking Attention Deficit Hyperactivity Disorder (ADHD). Patients with ADHD also often express sleep problems including EDS. Thus, patients with ADHD and patients with idiopathic hypersomnia or narcolepsy may share inattention and daytime drowsiness as common features. However, it is not known whether EDS patients with idiopathic hypersomnia or narcolepsy also have increased movement (hyperactivity) like ADHD patients, the determination of which is the purpose of this study. Methods: We studied 12 patients (7 Narcolepsy type 2 and 5 Idiopathic Hypersomnia) with EDS as shown by Multiple Sleep Latency Test which served as the gold standard for entry into the study. Twelve subjects without symptoms of EDS served as the control group. None of the participants had a previous history of ADHD. Each participant underwent a one-hour session laying at 45 degrees with surveys about the need to move and actigraphy as an objective measure of movement. Results: Sleep-disordered patients with EDS reported more symptoms of inattention and hyperactivity on the ADHD Self-Report Scale. At each of the time points patients with EDS had a clear trend to express the need to move more than controls on the Suggested Immobilization Test (SIT). For the total 60 minutes, a large effect size for the need to move during the SIT test was found between patients and controls (Cohen's d = 0.61, p=0.01). Patients with EDS did not express a need to move more to combat drowsiness than controls, nor did actigraphy show any difference in objective movement between patients and controls during the SIT. Conclusion: Patients with EDS express inattention and a need to move more than controls. However, hyperactivity was not verified by objective measurement, nor did the EDS patients express a need to move to combat drowsiness more than controls. Thus, a hypothesis to be further tested, is whether narcolepsy and idiopathic hypersomnia may be more a model of the inattentive form of ADHD rather than the combined or inattentive/hyperactive form of ADHD. Further studies are needed to explore the relationship between EDS and hyperactivity.

Exploring the role of the endogenous opiate system in the pathogenesis of anemia in an opiate receptor knock-out model of Restless Legs Syndrome.

Restless Legs Syndrome (RLS) is characterized by bothersome leg discomfort accompanied by an urge to move to obtain relief and symptoms are worse at night and on lying down. There is at least partial and temporary relief with activity. It is also an opioid responsive disorder, often accompanied by iron deficiency with or without anemia, and inflammation may be a precipitating factor in some cases. We created two in-vivo opiate receptor knock out mouse models of RLS - a triple opiate receptor knock-out mouse and a mu opiate receptor knock-out mouse. Both sets of animals were restless during the sleep period as is also true of RLS. Both of our knockout models showed statistically significantly decreased Hemoglobin and Hematocrit indicating anemia and both models showed statistically significant decreases in serum iron suggestive of either iron deficiency anemia or inflammatory anemia. The rest of the hematologic studies were not consistent enough to determine which of these two types of anemia was present in either model. An additional experiment in normal wild type mice showed a statistically significant decrease in serum iron when an opiate receptor blocker was used. To our knowledge this is the first demonstration that deficiency of endogenous opioids might play a role in the production of anemia. Our hypothesis is that an intact endogenous opiate system is necessary for red cell homeostasis. The presence of opioid receptors both on red blood cells and on various immunologically based white blood cells suggest mechanisms by which deficiency in the endogenous opiate system could cause anemia of either the iron deficiency or inflammatory types. The administration of opioid agonists or antagonists to iron deficient cultures of red blood cell precursors is a next step in determining the role of the endogenous opiate system in the maintenance of red cell homeostasis and in the possible prevention of iron deficiency or inflammatory anemia where iron dysregulation is key.

Prevalence of objective excessive daytime sleepiness in a cohort of patients with mild obstructive sleep apnea.

STUDY OBJECTIVES: Obstructive sleep apnea (OSA) is common, yet the relationship between mild OSA and excessive daytime sleepiness (EDS) is unclear. Our objective was to determine the prevalence of objective EDS in a population with mild OSA using the mean sleep latency (MSL) from the multiple sleep latency test (MSLT). METHODS: We retrospectively analyzed 1205 consecutive patients who underwent a polysomnography and a following day MSLT at a single sleep center. Adult patients who met criteria for mild OSA with an apnea-hypopnea index of 5 to <15 events/h were identified, and the percentage of patients with a MSL ≤ 8 min was determined. Sleep study and demographic variables were examined to evaluate predictors of objective EDS. RESULTS: Of 155 patients with mild OSA, objective EDS was found in 36% (56/155) with an average MSL of 5.6 ± 2.1 min in the objectively sleepy patients. Objectively sleepy patients with mild OSA had greater total sleep time (411.6 ± 48.9 vs. 384.5 ± 61.7 min, p = 0.004), increased sleep efficiency (84.9 ± 9.7 vs. 79.7 ± 12.7%, p = 0.01), and decreased wake after sleep onset time (53.0 ± 36.9 vs. 67.4 ± 46.1 min, p = 0.04) compared to patients with mild OSA but without objective EDS, with total sleep time being an independent predictor of MSL (p = 0.006). The Epworth Sleepiness Scale (ESS) weakly correlated with objective EDS (ρ = - 0.169, p = 0.03). CONCLUSIONS: There is a large subgroup of patients with mild OSA patients who have objective sleepiness. This may represent an ideal subgroup to target for future studies examining the effect of treatment in mild OSA. Additionally, the ESS was a poor predictor of this subgroup with mild OSA and objective EDS.

Restless Legs Syndrome Shows Increased Silent Postmortem Cerebral Microvascular Disease With Gliosis.

Background Patients with restless legs syndrome (RLS) have increased silent microvascular disease by magnetic resonance imaging. However, there has been no previous autopsy confirmation of these magnetic resonance imaging findings. RLS is also frequently associated with inflammatory and immunologically mediated medical disorders. The postmortem cortex in patients with RLS was therefore evaluated for evidence of microvascular and immunological changes. Methods and Results Ten microvascular injury samples of precentral gyrus in 5 patients with RLS (3 men, 2 women; mean age, 81 years) and 9 controls (2 men, 7 women; mean age, 90 years) were studied by hematoxylin and eosin stains in a blinded fashion. None of the subjects had a history of stroke or neurologic insults. In a similar manner, the following immunohistochemistry stains were performed: (1) glial fibrillary acidic protein (representing gliosis, reactive change of glial cells in response to damage); (2) CD3 (a T-cell marker); (3) CD19 (a B-cell marker); (4) CD68 (a macrophage marker); and (5) CD117 (a mast cell marker). Patients with RLS had significantly greater silent microvascular disease (P=0.015) and gliosis (P=0.003). T cells were increased in RLS compared with controls (P=0.009) and tended to colocalize with microvascular disease (P=0.003). Other markers did not differ. There was no correlation between microvascular lesion load and RLS severity or duration. Conclusions Patients with RLS had statistically significantly more silent cerebral microvascular disease and gliosis than controls compatible with previous magnetic resonance imaging studies and with studies showing a link between RLS and hypertension, clinical stroke, and cardiovascular disease. T-cell invasion may be a secondary phenomenon.

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

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

Sleep Medicine Milestones 2.0: designed for our field.

NONE: The Accreditation Council for Graduate Medical Education published the first sleep medicine milestones in 2015. However, these milestones were the same among all internal medicine fellowship programs; they were not specific to the specialty. Based on stakeholder feedback, the Accreditation Council for Graduate Medical Education called for the creation of specialty-specific milestones. Herein, we outline the history of Accreditation Council for Graduate Medical Education reporting milestones; the identification of knowledge, skills, and attitudes that define the practice of sleep medicine; and the creation of the supplemental guide and sleep medicine-specific milestones (Sleep Medicine Milestones 2.0) to assess developmental progression during fellowship training.

Restless legs syndrome is increased in postural orthostatic tachycardia syndrome.

STUDY OBJECTIVES: Postural orthostatic tachycardia syndrome (POTS) and restless legs syndrome (RLS) are both characterized by sleep disturbance along with autoimmune/inflammatory features and autonomic dysfunction. However, to our knowledge, there has been no direct study looking at the prevalence of RLS in patients with POTS patients compared with healthy participants (controls). METHODS: Ninety-six physician-diagnosed patients with POTS (89 female and 7 male) and 130 controls (99 female and 31 male) were administered the Cambridge Hopkins questionnaire. Participants who were diagnosed with probable or definite RLS on the Cambridge Hopkins questionnaire were then contacted to determine the severity of RLS with the International Restless Legs Scale. RESULTS: More patients with POTS (15 of 96; 15.6%) than controls (6 of 130; 4.6%) were diagnosed with probable or definite RLS on the Cambridge Hopkins questionnaire (P = .0048). A sensitivity analysis with only female respondents yielded similar results. RLS severity was in the moderate range (12.23 ± 9.22). CONCLUSIONS: There is a higher prevalence of RLS in patients with POTS patients compared with controls. This association may have to do with shared increased inflammatory/autoimmune load and autonomic dysfunction.

A potential role for zinc in restless legs syndrome.

STUDY OBJECTIVES: Evaluate serum and brain noniron metals in the pathology and genetics of restless legs syndrome (RLS). METHODS: In two independent studies (cohorts 1 and 2), in which subjects either remained on medications or tapered off medications, we analyzed serum levels of iron, calcium, magnesium, manganese, copper, and zinc both in RLS patients and controls, and assessed the prevalence of the MEIS1 and BTBD9 risk alleles previously established through genome-wide association studies. Human brain sections and a nematode genetic model were also quantified for metal levels using mass spectrometry. RESULTS: We found a significant enrichment for the BTBD9 risk genotype in the RLS affected group compared to control (p = 0.0252), consistent with previous literature. Serum (p = 0.0458 and p = 0.0139 for study cohorts 1 and 2, respectively) and brain (p = 0.0413) zinc levels were significantly elevated in the RLS patients versus control subjects. CONCLUSION: We show for the first time that serum and brain levels of zinc are elevated in RLS. Further, we confirm the BTBD9 genetic risk factor in a new population, although the zinc changes were not significantly associated with risk genotypes. Zinc and iron homeostasis are interrelated, and zinc biology impacts neurotransmitter systems previously linked to RLS. Given the modest albeit statistically significant increase in serum zinc of ~20%, and the lack of association with two known genetic risk factors, zinc may not represent a primary etiology for the syndrome. Further investigation into the pathogenetic role that zinc may play in restless legs syndrome is needed.

Characterization of genetic and phenotypic heterogeneity of obstructive sleep apnea using electronic health records.

BACKGROUND: Obstructive sleep apnea (OSA) is defined by frequent episodes of reduced or complete cessation of airflow during sleep and is linked to negative health outcomes. Understanding the genetic factors influencing expression of OSA may lead to new treatment strategies. Electronic health records (EHRs) can be leveraged to both validate previously reported OSA-associated genomic variation and detect novel relationships between these variants and comorbidities. METHODS: We identified candidate single nucleotide polymorphisms (SNPs) via systematic literature review of existing research. Using datasets available at Geisinger (n = 39,407) and Vanderbilt University Medical Center (n = 24,084), we evaluated associations between 40 previously implicated SNPs and OSA diagnosis, defined using clinical codes. We also evaluated associations between these SNPs and OSA severity measures obtained from sleep reports at Geisinger (n = 6571). Finally, we used a phenome-wide association study approach to help reveal pleiotropic genetic effects between OSA candidate SNPs and other clinical codes and laboratory values available in the EHR. RESULTS: Most previously reported OSA candidate SNPs showed minimal to no evidence for associations with OSA diagnosis or severity in the EHR-derived datasets. Three SNPs in LEPR, MMP-9, and GABBR1 validated for an association with OSA diagnosis in European Americans; the SNP in GABBR1 was associated following meta-analysis of results from both clinical populations. The GABBR1 and LEPR SNPs, and one additional SNP, were associated with OSA severity measures in European Americans from Geisinger. Three additional candidate OSA SNPs were not associated with OSA-related traits but instead with hyperlipidemia and autoimmune diseases of the thyroid. CONCLUSIONS: To our knowledge, this is one of the largest candidate gene studies and one of the first phenome-wide association studies of OSA genomic variation. Results validate genetic associates with OSA in the LEPR, MMP-9 and GABBR1 genes, but suggest that the majority of previously identified genetic associations with OSA may be false positives. Phenome-wide analyses provide evidence of mediated pleiotropy. Future well-powered genome-wide association analyses of OSA risk and severity across populations with diverse ancestral backgrounds are needed. The comprehensive nature of the analyses represents a platform for informing future work focused on understanding how genetic data can be useful to informing treatment of OSA and related comorbidities.

Application of a novel actigraphy algorithm to detect movement and sleep/wake patterns in children with autism spectrum disorder.

OBJECTIVE: Actigraphy is a non-intrusive method of recording rest/activity cycles as well as a surrogate for sleep/wake activity. Standard actigraphy analysis is limited in ascribing discrete movement events to wake status during sleep. We applied a novel algorithm to overnight actigraphy data recorded simultaneously with video polysomnography-electroencephalography (video PSG-EEG) to determine its ability to define movement and sleep/wake patterns in children with autism spectrum disorder (ASD) and age-comparable typically developing (TD) controls. METHODS: A previously published novel algorithm uses mathematical endpoints to analyze actigraphy data without assumptions about sleep/wake status, and smooths data using moving windows of increasing length. Nighttime activity level "S" events (S1-S5) determined by this algorithm (n = 273) were identified in 15 children ages 3-10 years (nine with ASD and six TD) who wore an AW2 Spectrum Actiwatch (Philips Respironics) while undergoing simultaneous video PSG-EEG. Data were analyzed to identify the time each activity level "S" event occurred, video movement events (movements captured by video and scored based on level of severity), and sleep/wake status defined by PSG-EEG. The relationships among activity level "S" events, video movement events, and sleep/wake status were analyzed statistically. RESULTS: Activity level "S" events, the presence and severity of video movement events, and sleep-wake status, were significantly associated. These associations were present in both participants with ASD and those who were typically developing. CONCLUSION: This actigraphy algorithm shows promise for detecting nighttime movements and sleep/wake status and warrants further study in larger datasets of neurotypical children and those with neurodevelopmental disorders.

Spinal Cord Stimulation in Patients With Chronic Pain and Restless Legs Syndrome: A Case Report.

Restless legs syndrome can be a debilitating condition that affects a patient's ability to function and their quality of life. Neuromodulation may represent a potential option for nonpharmacological management of restless legs syndrome. We present 3 patients who have a chronic pain diagnosis and medically refractory restless legs syndrome that warranted neuromodulation. After neuromodulation, all 3 patients had improvement in their restless legs syndrome symptoms and were taking less pain medication, and 2 out of 3 had significantly improved functionality at short-term follow-up. This case series suggests that spinal cord stimulation may be a viable nonpharmacological treatment option for medically refractory restless legs syndrome.

Improvement of Neuropathy Symptoms With Treatment of Obstructive Sleep Apnea in a Patient With Charcot-Marie-Tooth Disease.

ABSTRACT: This is a case report describing a 53-year-old woman with Charcot-Marie-Tooth disease, obstructive sleep apnea, and a 6-year history of numbness in bilateral upper extremities, feet, and in the trunk that resolved with initiation of continuous positive airway pressure for her obstructive sleep apnea.

Refining duration and frequency thresholds of restless legs syndrome diagnosis criteria.

OBJECTIVE: This study assesses the prevalence of restless legs syndrome (RLS) using DSM-5 criteria and determines what is the most appropriate threshold for the frequency and duration of RLS symptoms. METHODS: The Sleep-EVAL knowledge base system queried the interviewed subjects on life, sleeping habits, and health. Questions on sleep and mental and organic disorders (DSM-5, ICD-10) were also asked. A representative sample of 19,136 noninstitutionalized individuals older than 18 years living in the United States was interviewed through a cross-sectional telephone survey. The participation rate was 83.2%. RESULTS: The prevalence of the 4 leg symptoms describing RLS occurring at least 1 d/wk varied between 5.7% and 12.3%. When the frequency was set to at least 3 d/wk, the prevalence dropped and varied between 1.8% and 4.5% for the 4 leg symptoms. Higher frequency of leg symptoms was associated with greater distress and impairment with a marked increase at 3 d/wk. Symptoms were mostly chronic, lasting for more than 3 months in about 97% of the cases. The prevalence of RLS according to DSM-5 was 1.6% (95% confidence interval 1.4%-1.8%) when frequency was set at 3 d/wk. Stricter criteria for frequency of restless legs symptoms resulted in a reduction of prevalence of the disorder. The prevalence was further reduced when clinical impact was taken into consideration. CONCLUSIONS: In order to avoid inflation of case rates and to identify patients in whom treatment is truly warranted, using a more conservative threshold of 3 times or greater per week appears the most appropriate.

Depth and Distribution of Symptoms in Restless Legs Syndrome/ Willis-Ekbom Disease.

STUDY OBJECTIVES: To determine the depth and distribution of sensory discomfort in idiopathic restless legs syndrome/Willis-Ekbom disease (RLS) and RLS concurrent with other leg conditions, specifically peripheral neuropathy, sciatica, leg cramps, and arthritis. METHODS: RLS subjects (n = 122) were divided into 71 idiopathic RLS and 51 RLS-C, or Comorbid, groups. All subjects were examined by an RLS expert, answered standardized RLS questionnaires, and received a body diagram to draw the location and depth of their symptoms. RESULTS: Age was 63.04 ± 12.84 years, with 77 females and 45 males. All patients had lower limb involvement and 43/122 (35.25%) also had upper limb involvement. Of the 122 subjects, 42.62% felt that the RLS discomfort was only deep, 9.84% felt that the discomfort was only superficial, and 47.54% felt both superficial and deep discomfort. There were no defining characteristics in depth or distribution of RLS sensations that differentiated those patients with idiopathic RLS from those patients with RLS associated with other comorbid leg conditions. The sensation of arthritis was felt almost exclusively in the joints and not in the four quadrants of the leg, whereas the exact opposite was true of RLS sensations. CONCLUSIONS: Depth and distribution cannot be used as a discriminative mechanism to separate out idiopathic RLS from RLS comorbid with other leg conditions. Although seen in clinical practice, the total absence of patients with non-painful RLS only in the joints in the current study attests to the rarity of this presentation and raises the possibility of misdiagnosis under these circumstances. We recommend that such patients not be admitted to genetic or epidemiological studies.

Restless Legs Syndrome: Current Concepts about Disease Pathophysiology.

BACKGROUND: In the past few decades, much has been learned about the pathophysiology of restless legs syndrome (RLS). Investigators have studied neuropathology, imaging, electrophysiology, and genetics of RLS, identifying brain regions and biological systems affected in RLS. This manuscript will review RLS pathophysiology literature, examining the RLS state through consideration of the neuroanatomy, then the biological, organ, and genetic systems. METHODS: Pubmed (1966 to April 2016) was searched for the term "restless legs syndrome" cross-referenced with "pathophysiology," "pathogenesis," "pathology," or "imaging." English language papers were reviewed. Studies that focused on RLS in relation to another disease were not reviewed. RESULTS: Although there are no gross structural brain abnormalities in RLS, widespread brain areas are activated, including the pre- and post-central gyri, cingulate cortex, thalamus, and cerebellum. Pathologically, the most consistent finding is striatal iron deficiency in RLS patients. A host of other biological systems are also altered in RLS, including the dopaminergic, oxygen-sensing, opioid, glutamatergic, and serotonergic systems. Polymorphisms in genes including BTBD9 and MEIS1 are associated with RLS. DISCUSSION: RLS is a neurologic sensorimotor disorder that involves pathology, most notably iron deficiency, in motor and sensory brain areas. Brain areas not subserving movement or sensation such as the cingulate cortex and cerebellum are also involved. Other biological systems including the dopaminergic, oxygen-sensing, opioid, glutamatergic, and serotonergic systems are involved. Further research is needed to determine which of these anatomic locations or biological systems are affected primarily, and which are affected in a secondary response.

A Pilot Study Assessing the Effects of Pallidal Deep Brain Stimulation on Sleep Quality and Polysomnography in Parkinson's Patients.

OBJECTIVE: Deep Brain Stimulation (DBS) is an established adjunctive surgical intervention to treat poorly controlled motor symptoms in Parkinson's disease (PD). Both surgical targets (the subthalamic nucleus and globus pallidus) have proven equally efficacious in treating motor symptoms but unique differences may exist in effects on nonmotor symptoms. Sleep dysfunction, a common disabling symptom in PD, has only been examined directly in the subthalamic target, demonstrating some beneficial changes in sleep quality. We aimed to explore sleep changes after pallidal stimulation; hypothesizing similar benefits would be seen. METHODS: We performed a prospective nonblinded clinical trial evaluating sleep in five PD patients already slated for pallidal DBS pre and six months postimplantation using validated sleep surveys and polysomnograms (PSGs). Surveys included the Epworth sleepiness scale, PD sleep scale, Insomnia severity index (ISI), and RLS severity scale. RESULTS: Most patients had notable improvements in sleep quality as measured by PSG metrics such as sleep efficiency and latency to sleep but they did not reach statistical significance. Most surveys reflected an improvement as well with the ISI scale showing the most promising trend post pallidal DBS (14.4 ± 7.02 vs. 9.0 ± 2.55; p = 0.07). CONCLUSION: In this small pilot trial, pallidal DBS failed to demonstrate statistically significant improvements in sleep metrics postimplantation but did reveal improving trends in several PSG measures including sleep efficiency and latency to sleep onset as well as sleep survey scores. A larger, blinded clinical trial is needed to more definitively determine whether pallidal DBS may benefit sleep.

Silent Cerebral Small Vessel Disease in Restless Legs Syndrome.

STUDY OBJECTIVES: Growing literature suggests that patients with restless legs syndrome (RLS) may be at increased risk for hypertension, heart disease, and stroke. Cerebral small vessel disease (SVD) is a known risk factor for clinical stroke. This study evaluated silent cerebral SVD by MRI in patients with RLS, in the absence of a history of previous clinical stroke or known stroke risk factors and taking into account disease duration. METHODS: Fifty-three patients with RLS < 10 y were prospectively recruited along with 44 with RLS > 10 y and 74 normal controls. A magnetic resonance imaging study was obtained from all subjects and scans were analyzed for area and volume of SVD. RESULTS: There was a significant increase in SVD area in the entire group of RLS patients compared to controls (P = 0.036); this was almost entirely driven by the group with RLS > 10 y. SVD area and volume were significantly increased in patients with RLS > 10 y with respect to both controls (P < 0.0001 and P < 0.0014, respectively) and RLS < 10 y (P < 0.00022 and P < 0.003, respectively). Age, duration of RLS, and the interaction of age and duration of RLS were independent predictors of SVD disease. Duration of RLS was an independent predictor of the burden of cerebral SVD (area P < 0.00012 and volume P < 0.0025), whereas sex and insomnia were not. CONCLUSION: RLS duration should be taken into account when analyzing the association between RLS and cerebrovascular disease; our data support the hypothesis that a long-lasting RLS and its accompanying periodic limb movements in sleep are a risk factor for silent SVD and perhaps for the development of clinical stroke.

Objective Sleep Assessments in Patients with Postural Tachycardia Syndrome using Overnight Polysomnograms.

STUDY OBJECTIVES: Patients with postural tachycardia syndrome (POTS) commonly complain of fatigue, unrefreshing sleep, daytime sleepiness, and diminished quality of life. The study objective was to assess objective sleep quality in POTS patients using overnight polysomnography. METHODS: We studied 16 patients with POTS and 15 healthy control subjects performing daytime autonomic functions tests and overnight polysomnography at the Vanderbilt Clinical Research Center. RESULTS: There were no significant differences in the objective sleep parameters including sleep efficiency, sleep onset latency, wake time after sleep onset, REM latency, percentage of time spent in N1, N2, N3, and REM sleep, arousal index, apnea-hypopnea index, or periodic leg movement index in POTS patients as compared with healthy control subjects. There were significant negative correlations between sleep efficiency and the change in HR from supine to stand (rs = -0.527; p = 0.036). CONCLUSIONS: POTS patients do not have significant differences in objective sleep parameters as compared to control subjects based on overnight polysomnograms. Activation of the sympathetic nervous system may contribute significantly to the hyper arousal state and worsening of subjective estimates of sleep quality as previously reported in POTS patients.