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Walters AS, Zee PC. Why the worsening at rest and worsening at night criteria for Restless Legs Syndrome are listed separately: review of the circadian literature on RLS and suggestions for future directions. Front Neurol 2023; 14:1153273. [PMID: 37181571 PMCID: PMC10172647 DOI: 10.3389/fneur.2023.1153273] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 04/03/2023] [Indexed: 05/16/2023] Open
Abstract
The field of circadian research on Restless Legs Syndrome (RLS) and periodic limb movements (PLMs) is reviewed in general. RLS has five obligatory criteria for diagnosis: (1) an urge to move the legs often accompanied by uncomfortable leg sensations; (2) symptoms are worse at rest, i.e., lying or sitting; (3) there is a least partial and temporary relief of symptoms by activity, e.g., walking or stretching or bending the legs; (4) symptoms are worse later in the day or at night; and (5) mimics of RLS such as leg cramps and positional discomfort should be excluded by history and physical. In addition, RLS is frequently accompanied by PLMs, either periodic limb movements of sleep (PLMS) as determined by polysomnography or periodic limb movements while awake (PLMW) as determined by the suggested immobilization test (SIT). Since the criteria for RLS were based upon clinical experience only, an early question after the development of the criteria was whether criteria 2 and 4 were the same or different phenomena. In other words, were RLS patients worse at night only because they were lying down, and were RLS patients worse lying down only because it was night? Early circadian studies performed during recumbency at different times of the day suggest that the uncomfortable sensations, PLMS, and PLMW as well as voluntary movement in response to leg discomfort follow a similar circadian pattern with worsening at night independent of body position and independent of sleep timing or duration. Other studies demonstrated that RLS patients get worse when sitting or lying down independent of the time of day. These studies as a whole suggest that the worsening at rest and the worsening at night criteria for RLS are related but separate phenomena and that criteria 2 and 4 for RLS should be kept separate based upon the circadian studies, as had been the case previously based upon clinical grounds alone. To more fully prove the circadian rhythmicity of RLS, studies should be conducted to see if bright light shifts the signs and symptoms of RLS to a different circadian time in concert with circadian markers.
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Affiliation(s)
- Arthur S. Walters
- Department of Neurology, Division of Sleep Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
- *Correspondence: Arthur S. Walters
| | - Phyllis C. Zee
- Division of Sleep Medicine, Department of Neurology and Center for Circadian and Sleep Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
- Phyllis C. Zee
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2
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Kenar SG, Dirik EB, Tutal Gursoy G, Kayali N, Bilen S. F wave in restless legs syndrome, as an electrophysiological response of clinical relief. Neurol Res 2022; 44:719-725. [DOI: 10.1080/01616412.2022.2042123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
| | | | | | - Nuriye Kayali
- Neurology Department of Ankara City Hospital, Ankara, Turkey
| | - Sule Bilen
- Neurology Department of Ankara City Hospital, Ankara, Turkey
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3
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Gossard TR, Trotti LM, Videnovic A, St Louis EK. Restless Legs Syndrome: Contemporary Diagnosis and Treatment. Neurotherapeutics 2021; 18:140-155. [PMID: 33880737 PMCID: PMC8116476 DOI: 10.1007/s13311-021-01019-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/28/2021] [Indexed: 12/12/2022] Open
Abstract
Restless legs syndrome (RLS) is characterized by an uncomfortable urge to move the legs while at rest, relief upon movement or getting up to walk, and worsened symptom severity at night. RLS may be primary (idiopathic) or secondary to pregnancy or a variety of systemic disorders, especially iron deficiency, and chronic renal insufficiency. Genetic predisposition with a family history is common. The pathogenesis of RLS remains unclear but is likely to involve central nervous system dopaminergic dysfunction, as well as other, undefined contributing mechanisms. Evaluation begins with a thorough history and examination, and iron measures, including ferritin and transferrin saturation, should be checked at presentation and with worsened symptoms, especially when augmentation develops. Augmentation is characterized by more intense symptom severity, earlier symptom occurrence, and often, symptom spread from the legs to the arms or other body regions. Some people with RLS have adequate symptom control with non-pharmacological measures such as massage or temperate baths. First-line management options include iron-replacement therapy in those with evidence for reduced body-iron stores or, alternatively, with prescribed gabapentin or pregabalin, and dopamine agonists such as pramipexole, ropinirole, and rotigotine. Second-line therapies include intravenous iron infusion in those who are intolerant of oral iron and/or those having augmentation with intense, severe RLS symptoms, and opioids including tramadol, oxycodone, and methadone. RLS significantly impacts patients' quality of life and remains a therapeutic area sorely in need of innovation and a further pipeline of new, biologically informed therapies.
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Affiliation(s)
- Thomas R Gossard
- Mayo Center for Sleep Medicine, 200 First Street SW, Rochester, MN, 55905, USA
| | | | | | - Erik K St Louis
- Mayo Center for Sleep Medicine, 200 First Street SW, Rochester, MN, 55905, USA.
- Departments of Neurology and Clinical and Translational Research, Mayo Clinic Southwest Wisconsin, La Crosse, Wisconsin, USA.
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4
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Nardone R, Sebastianelli L, Versace V, Brigo F, Golaszewski S, Pucks-Faes E, Saltuari L, Trinka E. Contribution of transcranial magnetic stimulation in restless legs syndrome: pathophysiological insights and therapeutical approaches. Sleep Med 2020; 71:124-134. [PMID: 32088150 DOI: 10.1016/j.sleep.2019.12.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 12/10/2019] [Accepted: 12/11/2019] [Indexed: 01/06/2023]
Abstract
Transcranial magnetic stimulation (TMS) may offer a reliable means to characterize significant pathophysiologic and neurochemical aspects of restless legs syndrome (RLS). Namely, TMS has revealed specific patterns of changes in cortical excitability and plasticity, in particular dysfunctional inhibitory mechanisms and sensorimotor integration, which are thought to be part of the pathophysiological mechanisms of RLS rather than reflect a non-specific consequence of sleep architecture alteration. If delivered repetitively, TMS is able to transiently modulate the neural activity of the stimulated and connected areas. Some studies have begun to therapeutically use repetitive TMS (rTMS) to improve sensory and motor disturbances in RLS. High-frequency rTMS applied over the primary motor cortex or the supplementary motor cortex, as well as low-frequency rTMS over the primary somatosensory cortex, seem to have transient beneficial effects. However, further studies with larger patient samples, repeated sessions, an optimized rTMS setup, and clinical follow-up are needed in order to corroborate preliminary results. Thus, we performed a systematic search of all the studies that have used TMS and rTMS techniques in patients with RLS.
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Affiliation(s)
- Raffaele Nardone
- Department of Neurology, Franz Tappeiner Hospital, Merano, Italy; Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; Spinal Cord Injury and Tissue Regeneration Center, Salzburg, Austria; Karl Landsteiner Institut für Neurorehabilitation und Raumfahrtneurologie, Salzburg, Austria.
| | - Luca Sebastianelli
- Department of Neurorehabilitation, Hospital of Vipiteno, Vipiteno, Italy; Research Unit for Neurorehabilitation South Tyrol, Bolzano, Italy
| | - Viviana Versace
- Department of Neurorehabilitation, Hospital of Vipiteno, Vipiteno, Italy; Research Unit for Neurorehabilitation South Tyrol, Bolzano, Italy
| | - Francesco Brigo
- Department of Neurology, Franz Tappeiner Hospital, Merano, Italy; Department of Neuroscience, Biomedicine and Movement Science, University of Verona, Italy
| | - Stefan Golaszewski
- Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; Karl Landsteiner Institut für Neurorehabilitation und Raumfahrtneurologie, Salzburg, Austria
| | | | - Leopold Saltuari
- Department of Neurorehabilitation, Hospital of Vipiteno, Vipiteno, Italy; Research Unit for Neurorehabilitation South Tyrol, Bolzano, Italy; Department of Neurology, Hochzirl Hospital, Zirl, Austria
| | - Eugen Trinka
- Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; Centre for Cognitive Neurosciences Salzburg, Salzburg, Austria; University for Medical Informatics and Health Technology, UMIT, Hall in Tirol, Austria
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5
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Didato G, Di Giacomo R, Rosa GJ, Dominese A, de Curtis M, Lanteri P. Restless Legs Syndrome across the Lifespan: Symptoms, Pathophysiology, Management and Daily Life Impact of the Different Patterns of Disease Presentation. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:E3658. [PMID: 32456058 PMCID: PMC7277795 DOI: 10.3390/ijerph17103658] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 05/17/2020] [Accepted: 05/18/2020] [Indexed: 12/14/2022]
Abstract
Restless legs syndrome is a common but still underdiagnosed neurologic disorder, characterized by peculiar symptoms typically occurring in the evening and at night, and resulting in sleep disruption and daily functioning impairment. This disease can affect subjects of all age ranges and of both sexes, manifesting itself with a broad spectrum of severity and deserving special attention in certain patient categories, in order to achieve a correct diagnosis and an effective treatment. The diagnosis of restless legs syndrome can be challenging in some patients, especially children and elderly people, and an effective treatment might be far from being easy to achieve after some years of drug therapy, notably when dopaminergic agents are used. Moreover, the pathophysiology of this disorder offers an interesting example of interaction between genetics and the environment, considering strong iron metabolism involvement and its interaction with recognized individual genetic factors. Therefore, this syndrome allows clinicians to verify how lifespan and time can modify diagnosis and treatment of a neurological disorder.
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Affiliation(s)
- Giuseppe Didato
- Clinical and Experimental Epileptology and Sleep Disorders Unit, Foundation IRCCS Carlo Besta Neurological Institute, Via Celoria 11, 20133 Milan, Italy; (R.D.G.); (G.J.R.); (A.D.); (M.d.C.)
| | - Roberta Di Giacomo
- Clinical and Experimental Epileptology and Sleep Disorders Unit, Foundation IRCCS Carlo Besta Neurological Institute, Via Celoria 11, 20133 Milan, Italy; (R.D.G.); (G.J.R.); (A.D.); (M.d.C.)
| | - Giuseppa Jolanda Rosa
- Clinical and Experimental Epileptology and Sleep Disorders Unit, Foundation IRCCS Carlo Besta Neurological Institute, Via Celoria 11, 20133 Milan, Italy; (R.D.G.); (G.J.R.); (A.D.); (M.d.C.)
- Neurology Unit, University Hospital of Ferrara, 44100 Ferrara, Italy
| | - Ambra Dominese
- Clinical and Experimental Epileptology and Sleep Disorders Unit, Foundation IRCCS Carlo Besta Neurological Institute, Via Celoria 11, 20133 Milan, Italy; (R.D.G.); (G.J.R.); (A.D.); (M.d.C.)
| | - Marco de Curtis
- Clinical and Experimental Epileptology and Sleep Disorders Unit, Foundation IRCCS Carlo Besta Neurological Institute, Via Celoria 11, 20133 Milan, Italy; (R.D.G.); (G.J.R.); (A.D.); (M.d.C.)
| | - Paola Lanteri
- Neurophysiopathology Unit, Foundation IRCCS Carlo Besta Neurological Institute, 20133 Milan, Italy;
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Türkoglu ŞA, Bolac ES, Yildiz S, Kalaycioglu O, Yildiz N. Presynaptic inhibition in restless legs syndrome. Int J Neurosci 2020; 131:213-219. [PMID: 32108535 DOI: 10.1080/00207454.2020.1737048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Introduction: Restless legs syndrome (RLS) is a condition that particularly urges at night in resting and causes the need to move the legs. Although the pathophysiology has not yet been clarified, dopamine and iron metabolism and spinal cord pathologies are blamed for causing the condition. There are few studies on spinal reflex mechanisms on RLS. In the present study, we aimed to investigate the role of presynaptic inhibition (PreI) in the spinal cord in RLS.Methods: Fourteen patients with RLS and 14 controls with similar demographic characteristics were included in the study. Soleus muscle H-reflex (Ht) investigation was performed for subjects whose electrophysiologic investigation was normal. The Ht response was conditioned to the stimulation of the common peroneal nerve (CPN) (Hc). The test and conditioned stimulation intervals were kept between 10 ms, 20 ms, 30 ms, 40 ms, 50 ms, 75 ms, 100 ms, 150 ms and 200 ms. In each inter-stimulus interval, nonparametric repeat measurement evaluations were conducted with the percentage value of Hc/Ht. The Hc/Ht values of the study and control groups in the same intervals were compared separately.Results: A significant decrease was detected in Hc values in the control group in the repeat measurement values at 20 ms and 100 ms inter-stimulus intervals; however, there was not decrease in any intervals in the patient's group.Conclusion: The absence of any decrease in Hc reflexes for 20-100 ms intervals revealed that discernible PreI was vanished in RLS patients.
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Affiliation(s)
- Şule Aydin Türkoglu
- Department of Neurology, Abant İzzet Baysal University Faculty of Medicine, Bolu, Turkey
| | - Elif Sultan Bolac
- Department of Neurology, Abant İzzet Baysal University Faculty of Medicine, Bolu, Turkey
| | - Serpil Yildiz
- Department of Neurology, Abant İzzet Baysal University Faculty of Medicine, Bolu, Turkey
| | - Oya Kalaycioglu
- Biostatistics Unit, Abant İzzet Baysal University Faculty of Medicine, Bolu, Turkey
| | - Nebil Yildiz
- Department of Neurology, Abant İzzet Baysal University Faculty of Medicine, Bolu, Turkey
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7
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Abnormal Circadian Modification of A δ-Fiber Pathway Excitability in Idiopathic Restless Legs Syndrome. Pain Res Manag 2019; 2019:5408732. [PMID: 31827655 PMCID: PMC6885267 DOI: 10.1155/2019/5408732] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 10/06/2019] [Accepted: 10/16/2019] [Indexed: 11/17/2022]
Abstract
Restless legs syndrome (RLS) is characterized by unpleasant sensations generally localized to legs, associated with an urge to move. A likely pathogenetic mechanism is a central dopaminergic dysfunction. The exact role of pain system is unclear. The purpose of the study was to investigate the nociceptive pathways in idiopathic RLS patients. We enrolled 11 patients (mean age 53.2 ± 19.7 years; 7 men) suffering from severe, primary RLS. We recorded scalp laser-evoked potentials (LEPs) to stimulation of different sites (hands and feet) and during two different time conditions (daytime and nighttime). Finally, we compared the results with a matched control group of healthy subjects. The Aδ responses obtained from patients did not differ from those recorded from control subjects. However, the N1 and the N2-P2 amplitudes' night/day ratios after foot stimulation were increased in patients, as compared to controls (N1: patients: 133.91 ± 50.42%; controls: 83.74 ± 34.45%; p = 0.016; Aδ-N2-P2: patients: 119.15 ± 15.56%; controls: 88.42 ± 23.41%; p = 0.003). These results suggest that RLS patients present circadian modifications in the pain system, which are not present in healthy controls. Both sensory-discriminative and affective-emotional components of pain experience show parallel changes. This study confirms the structural integrity of Aδ nociceptive system in idiopathic RLS, but it also suggests that RLS patients present circadian modifications in the pain system. These findings could potentially help clinicians and contribute to identify new therapeutic approaches.
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8
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Yang H, Wang L, Li X, Wang K, Hou Y, Zhang X, Chen Z, Liu C, Yin C, Wu S, Huang Q, Lin Y, Bao Y, Chen Y, Wang Y. A study for the mechanism of sensory disorder in restless legs syndrome based on magnetoencephalography. Sleep Med 2018; 53:35-44. [PMID: 30414507 DOI: 10.1016/j.sleep.2018.07.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 07/03/2018] [Accepted: 07/05/2018] [Indexed: 10/28/2022]
Abstract
In spite of the relatively high incidence rate, the etiology and pathogenesis of restless legs syndrome (RLS) are still unclear. Long-term drug treatments fail to achieve satisfying curative effects, which is reflected by rebound and augmentation of related symptoms. An electrophysiological endophenotype experiment was done to investigate the mechanism of somatosensory disorder among RLS patients. Together with 15 normal subjects as the control group, with comparable ages and genders to the RLS patients, 15 primitive RLS patients were scanned by Magnetoencephalography (MEG) under natural conditions; furthermore, the somatosensory evoked magnetic field (SEF) with single and paired stimuli, was also measured. Compared to the control group, the SEF intensities of RLS patients' lower limbs were higher, and the paired-pulse depression (PPD) for SEF in RLS patients was attenuated. It was also revealed by time-frequency analysis of somatosensory induced oscillation (SIO) in RLS patients, that 93.3% of somatosensory induced Alpha (8-12 Hz) oscillations were successfully elicited, while 0% somatosensory induced Gamma (30-55 Hz) oscillations were elicited; which was significantly different from the control group. Additionally, in RLS patients exhibit increased excitability of the sensorimotor cortex, a remarkable abnormality existing in early somatosensory gating control (GC) and an attenuated inhibitory interneuron network, which consequently results in a compensatory mechanism through which RLS patients increase their attention-driven lower limb sensory gating control via somatosensory-induced Alpha (8-12 Hz) oscillation. This hyperexcitability, partially due to an electrocortical disinhibition, may have an important therapeutical implication, and become an important target of neuromodulatory interventions.
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Affiliation(s)
- Haoxiang Yang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Li Wang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Xin Li
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Kun Wang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Yue Hou
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Xiating Zhang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Zheng Chen
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Chunyan Liu
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Chunli Yin
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Siqi Wu
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Qian Huang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Yicong Lin
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Yan Bao
- Department of Nuclear Magnetic Resonance, Guang'anmen Hospital, Chinese Academy of Chinese Medical Sciences, Beijing, 100053, China
| | - Yuanyuan Chen
- Department of Nuclear Magnetic Resonance, Guang'anmen Hospital, Chinese Academy of Chinese Medical Sciences, Beijing, 100053, China
| | - Yuping Wang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China; The Beijing Key Laboratory of Neuromodulation, Beijing, 100053, China; Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China.
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9
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Ku J, Lee YS, Chang HW, Earley CJ, Allen RP, Cho YW. Diurnal variation of default mode network in patients with restless legs syndrome. Sleep Med 2018; 41:1-8. [DOI: 10.1016/j.sleep.2017.09.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 08/16/2017] [Accepted: 09/20/2017] [Indexed: 01/22/2023]
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de Paiva JPQ, Magalhães SC, do Prado GF, Eckeli AL, Kaelin-Lang A, Conforto AB. The duration of the cortical silent period is not abnormal in Restless Legs Syndrome/Willis-Ekbom Disease. J Neurol Sci 2017; 375:35-42. [PMID: 28320166 DOI: 10.1016/j.jns.2016.12.066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 11/28/2016] [Accepted: 12/28/2016] [Indexed: 12/14/2022]
Abstract
OBJECTIVE To compare the duration of the cortical silent period (CSP) measured in a hand muscle in subjects with primary Restless Legs Syndrome (RLS/WED) and controls, using four different methods of analysis. METHODS The CSP to transcranial magnetic stimulation of the dominant motor cortex was assessed in the abductor digiti minimi of 33 subjects with RLS/WED and 24 controls. CSP duration was measured by an automated and three visually-guided methods. RESULTS There were significant differences between absolute values of CSP duration according to the method of analysis. However, irrespectively of the method used for CSP assessment, no differences were found between measurements performed in subjects with RLS/WED and subjects from the control group. CONCLUSIONS Absolute values of CSP durations analyzed by different methods should not be directly compared, because significantly different results can be obtained from the same data set. SIGNIFICANCE The CSP assessed from a hand muscle is unlikely to be a biomarker of primary RLS/WED. Our results highlight the importance of standardizing the definition of CSP onset and offset, as well as of describing in detail the methodology chosen to record and measure CSP duration, in order to enable comparisons between studies.
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Affiliation(s)
- Joselisa Péres Queiroz de Paiva
- Hospital Israelita Albert Einstein, Edifício Josef Féher (Bloco A), 2° subsolo, Av. Albert Einstein, 627/701, São Paulo, SP, Brazil CEP: 05652-900.
| | - Samir Câmara Magalhães
- Hospital Israelita Albert Einstein, Edifício Josef Féher (Bloco A), 2° subsolo, Av. Albert Einstein, 627/701, São Paulo, SP, Brazil CEP: 05652-900.
| | - Gilmar Fernandes do Prado
- Universidade Federal de São Paulo, Departamento de Neurologia e Neurocirurgia, Rua Claúdio Rossi, 394, São Paulo, SP, Brazil CEP: 01547-000.
| | - Alan Luiz Eckeli
- Hospital das Clínicas da Faculdade de Medicina, Departamento de Neurociências e Ciências do Comportamento, Divisão de Neurologia, Hospital das Clinicas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil CEP: 14.048-900.
| | - Alain Kaelin-Lang
- Neurocenter of Southern Switzerland, LBN - Laboratory for Biomedical Neurosciences, 6900 Lugano, Switzerland.
| | - Adriana Bastos Conforto
- Hospital Israelita Albert Einstein, Edifício Josef Féher (Bloco A), 2° subsolo, Av. Albert Einstein, 627/701, São Paulo, SP, Brazil CEP: 05652-900; Hospital das Clínicas da Faculdade de Medicina, Departamento de Neurologia e Núcleo de Apoio à Pesquisa em Neurociência Aplicada (NAPNA), Universidade de São Paulo, São Paulo, SP, Brazil CEP: 05403-010.
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11
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Lanza G, Bachmann CG, Ghorayeb I, Wang Y, Ferri R, Paulus W. Central and peripheral nervous system excitability in restless legs syndrome. Sleep Med 2017; 31:49-60. [PMID: 27745789 DOI: 10.1016/j.sleep.2016.05.010] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/24/2016] [Accepted: 05/30/2016] [Indexed: 02/07/2023]
Abstract
Neurophysiological techniques have been applied in restless legs syndrome (RLS) to obtain direct and indirect measures of central and peripheral nervous system excitability, as well as to probe different neurotransmission pathways. Data converge on the hypothesis that, from a pure electrophysiological perspective, RLS should be regarded as a complex sensorimotor disorder in which cortical, subcortical, spinal cord, and peripheral nerve generators are all involved in a network disorder, resulting in an enhanced excitability and/or decreased inhibition. Although the spinal component may have dominated in neurophysiological assessment, possibly because of better accessibility compared to the brainstem or cerebral components of a hypothetical dysfunction of the diencephalic A11 area, multiple mechanisms, such as reduced central inhibition and abnormal peripheral nerve function, contribute to the pathogenesis of RLS similarly to some chronic pain conditions. Dopamine transmission dysfunction, either primary or triggered by low iron and ferritin concentrations, may also bridge the gap between RLS and chronic pain entities. Further support of disturbed central and peripheral excitability in RLS is provided by the effectiveness of nonpharmacological tools, such as repetitive transcranial magnetic stimulation and transcutaneous spinal direct current stimulation, in transiently modulating neural excitability, thereby extending the therapeutic repertoire. Understanding the complex interaction of central and peripheral neuronal circuits in generating the symptoms of RLS is mandatory for a better refinement of its therapeutic support.
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Affiliation(s)
- Giuseppe Lanza
- Sleep Research Center, I.R.C.C.S. "Oasi Maria SS.", Troina, Italy.
| | | | - Imad Ghorayeb
- Department of Clinical Neurophysiology, CHU de Bordeaux, Bordeaux, France; CNRS, INCIA, CNRS UMR 5287, Université de Bordeaux, Bordeaux, France
| | - Yuping Wang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Raffale Ferri
- Sleep Research Center, I.R.C.C.S. "Oasi Maria SS.", Troina, Italy
| | - Walter Paulus
- Department of Clinical Neurophysiology, University Medical Center, Georg August University Göttingen, Göttingen, Germany
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12
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Gunduz A, Metin B, Metin SZ, Poyraz BC, Karadeniz D, Kiziltan G, Kiziltan ME. Lower limb flexor reflex: Comparisons between drug-induced akathisia and restless legs syndrome. Neurosci Lett 2017; 641:40-44. [PMID: 28115240 DOI: 10.1016/j.neulet.2017.01.042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 01/15/2017] [Accepted: 01/17/2017] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND OBJECTIVE Akathisia is characterized by restlessness and crawling sensations similar to restless legs syndrome (RLS). Long latency flexor reflex (LLFR) which has helped to advance RLS pathophysiology has never been investigated in akathisia. Due to the clinical commonalities of akathisia and RLS, we investigated the behavior of LLFR in patients with akathisia aiming to understand pathophysiology of akathisia. PATIENTS AND METHODS Seven patients with neuroleptic-induced akathisia, 12 drug-naïve patients with primary RLS and 17 healthy subjects were prospectively enrolled in the study. LLFR was recorded from unilateral tibialis anterior (TA) and long head of biceps femoris (BF) muscles after stimulating the sole by trains of electrical stimuli. We measured amplitude, latency, duration, presence of response and compared between three groups. RESULTS One-way ANOVA showed mean durations of early and late responses recorded over TA were the longest in akathisia group compared to both RLS group and healthy subjects (p=0.012). The spatial spread of LLFR in akathisia patients was comparable to those of healthy subjects whereas presence of response on BF was significantly less in akathisia than RLS group. CONCLUSIONS Our findings indicate increased excitability of LLFR pathway in akathisia group. These findings are probably due to lack of inhibition originated in regions other than those known to downregulate in RLS.
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Affiliation(s)
- Aysegul Gunduz
- Department of Neurology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey.
| | - Baris Metin
- Department of Neurology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey; Department of Psychology, Uskudar University, Istanbul, Turkey
| | - Sinem Zeynep Metin
- Department of Psychiatry, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey; Department of Psychology, Uskudar University, Istanbul, Turkey
| | - Burc Cagri Poyraz
- Department of Psychiatry, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Derya Karadeniz
- Department of Neurology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Gunes Kiziltan
- Department of Neurology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Meral E Kiziltan
- Department of Neurology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
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13
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Cho YW, Kang MS, Kim KT, Do SY, Lim JG, Lee SY, Motamedi GK. Quantitative sensory test for primary restless legs syndrome/Willis–Ekbom disease using the current perception threshold test. Sleep Med 2017; 30:19-23. [DOI: 10.1016/j.sleep.2016.03.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 02/02/2016] [Accepted: 03/01/2016] [Indexed: 10/22/2022]
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14
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Seddigh R, Keshavarz-Akhlaghi AA. Improvement of restless legs syndrome by nabat: a case series and new hypotheses for research. JOURNAL OF COMPLEMENTARY & INTEGRATIVE MEDICINE 2016; 13:91-95. [PMID: 26841448 DOI: 10.1515/jcim-2014-0069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 10/09/2015] [Indexed: 06/05/2023]
Abstract
BACKGROUND Although many hypotheses have been suggested, the pathophysiology of restless legs syndrome (RLS) has not been fully understood. In this case series, we describe eleven cases with RLS whose symptoms subsided by the use of crystallized sucrose. This kind of sugar, known as nabat, is used in traditional Iranian medicine. METHODS Case series. RESULTS All patients felt relief 30-60 min after taking 100 grams of dissolved nabat. CONCLUSIONS Sucrose seems to carry a special benefit for patients with RLS, and it provides evidence for growing literature demonstrating the different underlying mechanisms of RLS. Possible causes for this concurrence are also discussed.
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15
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Sharon D. Nonpharmacologic Management of Restless Legs Syndrome (Willis-Ekbom Disease). Sleep Med Clin 2015; 10:263-78, xiii. [DOI: 10.1016/j.jsmc.2015.05.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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16
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Abstract
Restless leg syndrome/Willis-Ekbom disease has brain iron deficiency that produces excessive dopamine and known genetic risks, some of which contribute to the brain iron deficiency. Dopamine treatments work temporarily but may eventually produce further postsynaptic down-regulation and worse restless leg syndrome. This article includes sections focused on pathophysiologic findings from each of these areas: genetics, cortical-spinal excitability, and iron and dopamine.
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Affiliation(s)
- Richard P Allen
- Department of Neurology, Johns Hopkins University, Asthma & Allergy Building, 1B76b, 5501 Hopkins Bayview Boulevard, Baltimore, MD 21224, USA.
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17
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Magalhães SC, Kaelin-Lang A, Sterr A, do Prado GF, Eckeli AL, Conforto AB. Transcranial magnetic stimulation for evaluation of motor cortical excitability in restless legs syndrome/Willis-Ekbom disease. Sleep Med 2015; 16:1265-73. [PMID: 26429756 DOI: 10.1016/j.sleep.2015.03.018] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Revised: 02/27/2015] [Accepted: 03/29/2015] [Indexed: 11/30/2022]
Abstract
There is no consensus about mechanisms underlying restless legs syndrome (RLS), also known as Willis-Ekbom disease (WED). Cortical excitability may be abnormal in RLS. Transcranial magnetic stimulation (TMS) can provide insight about cortical excitability. We reviewed studies about measures of excitability to TMS in RLS. Original studies published between January 1999 and January 2015 were searched in PubMed, Scopus, and Web of Science databases. Inclusion criteria were as follows: original studies involving primary RLS in patients from both sexes and ages between 18 and 85 years; TMS protocols clearly described; and they were written in English, in peer-reviewed journals. Fifteen manuscripts were identified. TMS protocols were heterogeneous across studies. Resting motor threshold, active motor threshold, and amplitudes of motor-evoked potentials were typically reported to be normal in RLS. A reduction in short-interval intracortical inhibition (SICI) was the most consistent finding, whereas conflicting results were described in regard to short-interval intracortical facilitation and the contralateral silent period. Decreased SICI can be reversed by treatment with dopaminergic agonists. Plasticity in the motor cortex and sensorimotor integration may be disrupted. TMS may become a useful biomarker of responsiveness to drug treatment in RLS. The field can benefit from increases in homogeneity and sizes of samples, as well as from decrease in methodological variability across studies.
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Affiliation(s)
| | | | | | | | - Alan Luiz Eckeli
- Hospital das Clínicas da Faculdade de Medicina da USP, Ribeirão Preto, São Paulo, Brazil
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18
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Lanza G, Cantone M, Lanuzza B, Pennisi M, Bella R, Pennisi G, Ferri R. Distinctive patterns of cortical excitability to transcranial magnetic stimulation in obstructive sleep apnea syndrome, restless legs syndrome, insomnia, and sleep deprivation. Sleep Med Rev 2015; 19:39-50. [PMID: 24849846 DOI: 10.1016/j.smrv.2014.04.001] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 01/25/2014] [Accepted: 04/03/2014] [Indexed: 02/07/2023]
Abstract
Altered responses to transcranial magnetic stimulation (TMS) in obstructive sleep apnea syndrome (OSAS), restless legs syndrome (RLS), insomnia, and sleep-deprived healthy subjects have been reported. We have reviewed the relevant literature in order to identify eventual distinctive electrocortical profiles based on single and paired-pulse TMS, sensorimotor modulation, plasticity-related and repetitive TMS measures. Although obtained from heterogeneous studies, the detected changes might be the result of the different pathophysiological substrates underlying OSAS, RLS, insomnia and sleep deprivation rather than reflect the general effect of non-specific sleep loss and instability. OSAS tends to exhibit an increased motor cortex inhibition, which is reduced in RLS; intracortical excitability seems to be in favor of an "activating" profile in chronic insomnia and in sleep-deprived healthy individuals. Abnormal plasticity-related TMS phenomena have been demonstrated in OSAS and RLS. This review provides a perspective of TMS techniques by further understanding the role of neurotransmission pathways and plastic remodeling of neuronal networks involved in common sleep disorders. TMS might be considered a valuable tool in the assessment of sleep disorders, the evaluation of the effect of therapy and the design of non-pharmacological approaches.
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Affiliation(s)
- Giuseppe Lanza
- Department of Neurology I.C., Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Via Conte Ruggero, 73, 94018 Troina, EN, Italy.
| | - Mariagiovanna Cantone
- Department of Neurology I.C., Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Via Conte Ruggero, 73, 94018 Troina, EN, Italy
| | - Bartolo Lanuzza
- Department of Neurology I.C., Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Via Conte Ruggero, 73, 94018 Troina, EN, Italy
| | - Manuela Pennisi
- Department of Chemistry, University of Catania, Viale Andrea Doria, 6, 95125 Catania, Italy
| | - Rita Bella
- Department "G.F. Ingrassia", Section of Neurosciences, University of Catania, Via Santa Sofia, 78, 95123 Catania, Italy
| | - Giovanni Pennisi
- Department "G.F. Ingrassia", Section of Neurosciences, University of Catania, Via Santa Sofia, 78, 95123 Catania, Italy
| | - Raffaele Ferri
- Department of Neurology I.C., Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Via Conte Ruggero, 73, 94018 Troina, EN, Italy
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19
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Abad VC, Guilleminault C. Pharmacological treatment of sleep disorders and its relationship with neuroplasticity. Curr Top Behav Neurosci 2015; 25:503-53. [PMID: 25585962 DOI: 10.1007/7854_2014_365] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Sleep and wakefulness are regulated by complex brain circuits located in the brain stem, thalamus, subthalamus, hypothalamus, basal forebrain, and cerebral cortex. Wakefulness and NREM and REM sleep are modulated by the interactions between neurotransmitters that promote arousal and neurotransmitters that promote sleep. Various lines of evidence suggest that sleep disorders may negatively affect neuronal plasticity and cognitive function. Pharmacological treatments may alleviate these effects but may also have adverse side effects by themselves. This chapter discusses the relationship between sleep disorders, pharmacological treatments, and brain plasticity, including the treatment of insomnia, hypersomnias such as narcolepsy, restless legs syndrome (RLS), obstructive sleep apnea (OSA), and parasomnias.
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Affiliation(s)
- Vivien C Abad
- Psychiatry and Behavioral Science-Division of Sleep Medicine, Stanford University School of Medicine, Palo Alto, CA, USA
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20
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Ferri R, Cosentino FI, Manconi M, Rundo F, Bruni O, Zucconi M. Increased electroencephalographic high frequencies during the sleep onset period in patients with restless legs syndrome. Sleep 2014; 37:1375-81. [PMID: 25083018 PMCID: PMC4096207 DOI: 10.5665/sleep.3934] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES To analyze the electroencephalographic (EEG) spectral content in untreated patients with restless legs syndrome (RLS) during the sleep onset period (SOP) and during the quiet wakefulness preceding sleep, in order to test the hypothesis that a state of hyperarousal might be present during the SOP with RLS. SETTING Sleep Research Centre. PATIENTS Twenty-seven untreated consecutive patients with RLS (mean age = 53.6 y), 11 untreated consecutive patients with primary insomnia (mean age = 58.9 y), and 14 normal controls (mean age = 50.3 y). METHODS SOP was defined as the 10-min period centered with the occurrence of the first sleep spindle in the EEG, and then subdivided into SOP-1 (period of 5 min before the first spindle) and SOP-2 (period of 5 min following). Leg movements occurring during SOP were counted and used as a covariate in the statistical analysis. Also, one period of 1 min of artifact-free quiet wakefulness after lights off was identified. EEG spectral analysis was run during these periods using the C3/A2 or C4/A1 channel. MEASUREMENTS AND RESULTS Increased EEG alpha and beta bands and/or beta/delta ratio in RLS versus normal controls, during both wakefulness preceding sleep and SOP (both parts SOP-1 and SOP-2) were found, which were, however, smaller than the increases found in patients with insomnia. CONCLUSION The results of this study support the hypothesis of the presence of a state of hyperarousal in restless legs syndrome (RLS) during the sleep onset period. Treatment for RLS might need to take these findings into consideration. CITATION Ferri R, Cosentino FI, Manconi M, Rundo F, Bruni O, Zucconi M. Increased electroencephalographic high frequencies during the sleep onset period in patients with restless legs syndrome.
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Affiliation(s)
- Raffaele Ferri
- Department of Neurology IC, Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Troina, Italy
| | - Filomena I.I. Cosentino
- Department of Neurology IC, Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Troina, Italy
| | - Mauro Manconi
- Sleep and Epilepsy Center, Neurocenter of Southern Switzerland, Civic Hospital (EOC) of Lugano, Lugano, Switzerland
| | - Francesco Rundo
- Department of Neurology IC, Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Troina, Italy
| | - Oliviero Bruni
- Department of Social and Developmental Psychology, Faculty of Medicine and Psychology, Sapienza University, Rome, Italy
| | - Marco Zucconi
- Sleep Disorders Center, Department of Neurology, Scientific Institute and University Ospedale San Raffaele, Vita-Salute University, Institute and Ospedale San Raffaele, Milan, Italy
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21
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Jung JS, Lee HJ, Cho CH, Kang SG, Yoon HK, Park YM, Moon JH, Yang HJ, Song HM, Kim L. Association between restless legs syndrome and CLOCK and NPAS2 gene polymorphisms in schizophrenia. Chronobiol Int 2014; 31:838-44. [PMID: 24824748 DOI: 10.3109/07420528.2014.914034] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Previous studies have suggested that there is a genetic basis to restless legs syndrome (RLS) development. Occurrence of antipsychotic-induced RLS could also be due to differences in genetic susceptibility. We investigated whether CLOCK and NPAS2 gene polymorphisms are associated with RLS in schizophrenic patients on antipsychotics because RLS symptoms usually manifest during the evening and night. We assessed symptoms of RLS in 190 Korean schizophrenic patients on antipsychotics and divided the subjects into two groups according to the International Restless Legs Syndrome Study Group diagnostic criteria: (i) subjects who met all the criteria and (ii) the remaining subjects who did not meet all the criteria. We found a significant difference in the number of subjects with different genotype and allele carrier frequencies for the CLOCK gene (rs2412646) between the two groups (p = 0.031 and 0.010, respectively). Distribution of CLOCK haplotypes (rs2412646-rs1801260) was significantly different between schizophrenic patients with and without RLS (p = 0.021). However, the distributions of allelic, genotypic, and haplotypic variants of NPAS2 (rs2305160 and rs6725296) were not significantly different between the two groups. Our results suggest that CLOCK polymorphisms are associated with increased susceptibility of schizophrenic patients to RLS. We hypothesize that RLS in schizophrenia patients treated with antipsychotics may be a very mild akathisia that manifests during the night and is under control of circadian oscillation.
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Affiliation(s)
- Jin-Sook Jung
- Department of Psychiatry, College of Medicine, Korea University , Seoul , South Korea
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Nardone R, Höller Y, Brigo F, Tezzon F, Golaszewski S, Trinka E. Transcranial magnetic stimulation and sleep disorders: pathophysiologic insights. Sleep Med 2013; 14:1047-58. [PMID: 24051115 DOI: 10.1016/j.sleep.2013.04.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 04/28/2013] [Accepted: 04/30/2013] [Indexed: 01/15/2023]
Abstract
The neural mechanisms underlying the development of the most common intrinsic sleep disorders are not completely known. Therefore, there is a great need for noninvasive tools which can be used to better understand the pathophysiology of these diseases. Transcranial magnetic stimulation (TMS) offers a method to noninvasively investigate the functional integrity of the motor cortex and its corticospinal projections in neurologic and psychiatric diseases. To date, TMS studies have revealed cortical and corticospinal dysfunction in several sleep disorders, with cortical hyperexcitability being a characteristic feature in some disorders (i.e., the restless legs syndrome) and cortical hypoexcitability being a well-established finding in others (i.e., obstructive sleep apnea syndrome narcolepsy). Several research groups also have applied TMS to evaluate the effects of pharmacologic agents, such as dopaminergic agent or wake-promoting substances. Our review will focus on the mechanisms underlying the generation of abnormal TMS measures in the different types of sleep disorders, the contribution of TMS in enhancing the understanding of their pathophysiology, and the potential diagnostic utility of TMS techniques. We also briefly discussed the possible future implications for improving therapeutic approaches.
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Affiliation(s)
- Raffaele Nardone
- Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; Department of Neurology, Franz Tappeiner Hospital, Merano, Italy.
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Recurrent CSPs after Transcranial Magnetic Stimulation of Motor Cortex in Restless Legs Syndrome. Neurol Res Int 2012; 2012:628949. [PMID: 23213521 PMCID: PMC3507135 DOI: 10.1155/2012/628949] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 10/20/2012] [Accepted: 10/20/2012] [Indexed: 11/21/2022] Open
Abstract
Aims. The aim of this study was to investigate the motor control and central silent period (CSP) in restless legs syndrome (RLS). Methods. Transcranial magnetic stimulation was focused on the dominant and nondominant hemispheric areas of motor cortex in six subjects with RLS and six controls. The responses were recorded on the contralateral abductor digiti minimi (ADM) and tibialis anterior (TA) muscles with intramuscular needle electrodes. Results. No significant differences were found in the motor conduction or central motor conduction time, in the latency, or in the duration of the CSPs between or within the groups, but multiple CSPs were observed in both groups. The number of the CSPs was significantly higher in both ADMs and in the dominant TA (P ≤ 0.01) in the RLS group compared to the controls. Conclusion. Descending motor pathways functioned correctly in both groups. The occurrence of the recurrent CSPs predominantly in the RLS group could be a sign of a change of function in the inhibitory control system. Further research is needed to clarify the role of the intramuscular recording technique and especially the role of the subcortical generators in the feedback regulation of the central nervous system in RLS.
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