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Silvani A, Ghorayeb I, Manconi M, Li Y, Clemens S. Putative Animal Models of Restless Legs Syndrome: A Systematic Review and Evaluation of Their Face and Construct Validity. Neurotherapeutics 2023; 20:154-178. [PMID: 36536233 PMCID: PMC10119375 DOI: 10.1007/s13311-022-01334-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2022] [Indexed: 12/24/2022] Open
Abstract
Restless legs syndrome (RLS) is a sensorimotor disorder that severely affects sleep. It is characterized by an urge to move the legs, which is often accompanied by periodic limb movements during sleep. RLS has a high prevalence in the population and is usually a life-long condition. While its origins remain unclear, RLS is initially highly responsive to treatment with dopaminergic agonists that target D2-like receptors, in particular D2 and D3, but the long-term response is often unsatisfactory. Over the years, several putative animal models for RLS have been developed, mainly based on the epidemiological and neurochemical link with iron deficiency, treatment efficacy of D2-like dopaminergic agonists, or genome-wide association studies that identified risk factors in the patient population. Here, we present the first systematic review of putative animal models of RLS, provide information about their face and construct validity, and report their role in deciphering the underlying pathophysiological mechanisms that may cause or contribute to RLS. We propose that identifying the causal links between genetic risk factors, altered organ functions, and changes to molecular pathways in neural circuitry will eventually lead to more effective new treatment options that bypass the side effects of the currently used therapeutics in RLS, especially for long-term therapy.
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Affiliation(s)
- Alessandro Silvani
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum - University of Bologna, Ravenna Campus, Ravenna, Italy
| | - Imad Ghorayeb
- Département de Neurophysiologie Clinique, Pôle Neurosciences Cliniques, CHU de Bordeaux, Bordeaux, France
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, Université de Bordeaux, Bordeaux, France
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, CNRS, Bordeaux, France
| | - Mauro Manconi
- Sleep Medicine Unit, Neurocenter of Southern Switzerland, EOC, Ospedale Civico, Lugano, Switzerland
- Department of Neurology, University Hospital, Inselspital, Bern, Switzerland
- Faculty of Biomedical Sciences, Università della Svizzera Italiana, Lugano, Switzerland
| | - Yuqing Li
- Department of Neurology, College of Medicine, Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, USA
| | - Stefan Clemens
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, USA.
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Wang XX, Feng Y, Tan EK, Ondo WG, Wu YC. Stroke-related restless legs syndrome: epidemiology, clinical characteristics and pathophysiology. Sleep Med 2022; 90:238-248. [DOI: 10.1016/j.sleep.2022.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/23/2022] [Accepted: 02/01/2022] [Indexed: 12/24/2022]
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Restless Legs Syndrome: Known Knowns and Known Unknowns. Brain Sci 2022; 12:brainsci12010118. [PMID: 35053861 PMCID: PMC8773543 DOI: 10.3390/brainsci12010118] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 01/09/2022] [Accepted: 01/12/2022] [Indexed: 02/06/2023] Open
Abstract
Although restless legs syndrome (RLS) is a common neurological disorder, it remains poorly understood from both clinical and pathophysiological perspectives. RLS is classified among sleep-related movement disorders, namely, conditions characterized by simple, often stereotyped movements occurring during sleep. However, several clinical, neurophysiological and neuroimaging observations question this view. The aim of the present review is to summarize and query some of the current concepts (known knowns) and to identify open questions (known unknowns) on RLS pathophysiology. Based on several lines of evidence, we propose that RLS should be viewed as a disorder of sensorimotor interaction with a typical circadian pattern of occurrence, possibly arising from neurochemical dysfunction and abnormal excitability in different brain structures.
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Vlasie A, Trifu S, Lupuleac C, Kohn B, Cristea M. Restless legs syndrome: An overview of pathophysiology, comorbidities and therapeutic approaches (Review). Exp Ther Med 2021; 23:185. [PMID: 35069866 PMCID: PMC8764906 DOI: 10.3892/etm.2021.11108] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 08/05/2021] [Indexed: 11/06/2022] Open
Affiliation(s)
- Andrei Vlasie
- Department of Psychiatry, ‘Prof. Dr. Alexandru Obregia’ Clinical Hospital of Psychiatry, Bucharest 041914, Romania
| | - Simona Trifu
- Department of Clinical Neurosciences, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest 020021, Romania
| | - Cristiana Lupuleac
- Department of Psychiatry, ‘Prof. Dr. Alexandru Obregia’ Clinical Hospital of Psychiatry, Bucharest 041914, Romania
| | - Bianca Kohn
- Department of Psychiatry, ‘Prof. Dr. Alexandru Obregia’ Clinical Hospital of Psychiatry, Bucharest 041914, Romania
| | - Mihai Cristea
- Department of Morphological Sciences, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest 020021, Romania
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Katunina EA, Titova NV, Katunin DA, Bagmanyan SD, Pogorova AR. [Restless legs syndrome]. Zh Nevrol Psikhiatr Im S S Korsakova 2021; 121:106-113. [PMID: 33728859 DOI: 10.17116/jnevro2021121021106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Restless legs syndrome (RLS) is seen widely in clinical practice. RLS commonly occurs at night time and presents with unpleasant or uncomfortable sensations in the legs that causes an urge to move them. This article describes the epidemiology, risk factors and pathophysiology of RLS. There is a detailed description of clinical presentations, diagnostic criteria and also management of RLS.
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Affiliation(s)
- E A Katunina
- Pirogov Russian National Research Medical University, Moscow, Russia.,Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
| | - N V Titova
- Pirogov Russian National Research Medical University, Moscow, Russia.,Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
| | - D A Katunin
- Pirogov Russian National Research Medical University, Moscow, Russia.,Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
| | - S D Bagmanyan
- Pirogov Russian National Research Medical University, Moscow, Russia
| | - A R Pogorova
- Pirogov Russian National Research Medical University, Moscow, Russia
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Colzato LS, Zhang W, Brandt MD, Stock AK, Beste C. Cognitive profile in Restless Legs Syndrome: A signal-to-noise ratio account. CURRENT RESEARCH IN NEUROBIOLOGY 2021; 2:100021. [PMID: 36246509 PMCID: PMC9559071 DOI: 10.1016/j.crneur.2021.100021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 07/05/2021] [Accepted: 07/29/2021] [Indexed: 11/19/2022] Open
Abstract
Restless legs syndrome (RLS) is a common neurological disorder characterized by a sensorimotor condition, where patients feel an uncontrollable urge to move the lower limbs in the evening and/or during the night. RLS does not only have a profound impact on quality of life due to the disturbed night-time sleep, but there is growing evidence that untreated or insufficiently managed RLS might also cause cognitive changes in patients affected by this syndrome. It has been proposed that RLS is caused by alterations in the signal-to-noise ratio (SNR) and in dopamine (DA) neurotransmission in the nervous system. Based on this evidence, we propose the “SNR-DA hypothesis” as an explanation of how RLS could affect cognitive performance. According to this hypothesis, variations/reductions in the SNR underlie RLS-associated cognitive deficits, which follow an inverted U-shaped function: In unmedicated patients, low dopamine levels worsen the SNR, which eventually impairs cognition. Pharmacological treatment enhances DA levels in medicated patients, which likely improves/normalizes the SNR in case of optimal doses, thus restoring cognition to a normal level. However, overmedication might push patients past the optimal point on the inverted U-shaped curve, where an exaggerated SNR potentially impairs cognitive performance relying on cortical noise such as cognitive flexibility. Based on these assumptions of SNR alterations, we propose to directly measure neural noise via “1/f noise” and related metrics to use transcranial random noise stimulation (tRNS), a noninvasive brain stimulation method which manipulates the SNR, as a research tool and potential treatment option for RLS. Restless legs syndrome (RLS) is a common neurological disorder. RLS is caused by alterations in the SNR ratio and in DA neurotransmission. The SNR- DA hypothesis how RLS affects cognitive performance is presented.
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Affiliation(s)
- Lorenza S. Colzato
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Germany
- Cognitive Psychology, Faculty of Psychology, Shandong Normal University, Jinan, China
- University Neuropsychology Center, Faculty of Medicine, TU Dresden, Germany
| | - Wenxin Zhang
- Cognitive Psychology, Faculty of Psychology, Shandong Normal University, Jinan, China
| | - Moritz D. Brandt
- Department of Neurology, University Hospital, Technische Universität Dresden, Dresden, Germany
- German Center for Neurodegenerative Diseases (DZNE) Dresden, Dresden, Germany
| | - Ann-Kathrin Stock
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Germany
- University Neuropsychology Center, Faculty of Medicine, TU Dresden, Germany
- Biopsychology, Faculty of Psychology, TU Dresden, Dresden, Germany
| | - Christian Beste
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Germany
- Cognitive Psychology, Faculty of Psychology, Shandong Normal University, Jinan, China
- University Neuropsychology Center, Faculty of Medicine, TU Dresden, Germany
- Corresponding author. Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine of the TU Dresden, Germany Schubertstrasse 42, D-01309, Dresden, Germany.
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Leclair-Visonneau L, Vecchierini MF, Schröder C, Charley Monaca C. French Consensus: How to diagnose restless legs syndrome. Rev Neurol (Paris) 2018; 174:508-514. [PMID: 30049562 DOI: 10.1016/j.neurol.2018.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 04/16/2018] [Accepted: 06/05/2018] [Indexed: 11/30/2022]
Abstract
Correct diagnosis of restless legs syndrome (RLS) is essential to patient care and treatment. Diagnosis is most often clinical and based on diagnostic criteria: the need to move the legs accompanied to varying degrees by unpleasant sensations, predominantly during the evening and improved by movement. In rare cases, clinical examination is insufficient and a polysomnography is necessary. Once a positive diagnosis has been made, a neurological examination and an assessment of iron status are required. The severity of the RLS must be evaluated to determine whether a specific treatment is necessary. Before treatment, it is essential to ensure that a definite diagnosis of RLS has been made and the phenotype characterised. This enables a personal treatment plan and limits the risk of augmentation syndrome.
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Affiliation(s)
- L Leclair-Visonneau
- Inserm CIC-04, Inserm U1235, université de Nantes, laboratoire d'explorations fonctionnelles, CHU de Nantes, CHU-Hotel Dieu, 1, place Alexis-Ricordeau, 44093 Nantes, France
| | - M-F Vecchierini
- Sleep Center Hôtel-Dieu, place Jean-Paul II, 1, parvis Notre-Dame, 75004 Paris, France
| | - C Schröder
- Child, Adolescent Psychiatry Service, Psychiatry Pole, Mental Health, Addiction, Strasbourg Teaching Hospitals, Strasbourg University, 1, place de l'Hôpital, 67091 Strasbourg cedex, France; CNRS UPR 3212, Team 9, Institute of Cellular, Integrative Neurosciences (INCI), 5, rue Blaise-Pascal, 67084 Strasbourg cedex, France
| | - C Charley Monaca
- Inserm UMR 1171, Clinical Neurophysiology, Teaching Hospital, Lille University, 1, place de Verdun, 59045 Lille cedex, France.
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Ferini-Strambi L, Carli G, Casoni F, Galbiati A. Restless Legs Syndrome and Parkinson Disease: A Causal Relationship Between the Two Disorders? Front Neurol 2018; 9:551. [PMID: 30087647 PMCID: PMC6066514 DOI: 10.3389/fneur.2018.00551] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 06/19/2018] [Indexed: 11/13/2022] Open
Abstract
Restless Legs Syndrome/Willis-Ekbom Disease (RLS/WED) is a common sleep related movement disorder that can be idiopathic or occurs in comorbidity with other medical conditions such as polyneuropathy, iron deficiency anemia, multiple sclerosis, hypertension and cardiovascular diseases. In recent years, a growing body of literature investigated the association between RLS/WED and Parkinson's Disease (PD). Several questions regarding the comorbidity between these two disorders are still unanswered. If the insurgence of RLS/WED may precede the onset of PD, or if RLS/WED could represent a secondary condition of PD and if impaired dopaminergic pathway may represent a bridge between these two conditions are still debatable issues. In this review, we critically discuss the relationship between RLS/WED and PD by reviewing cross sectional and longitudinal studies, as well as the role of dopamine in these disorders. A twofold interpretation have to be taken into account: dopaminergic therapy may have a crucial role in the development of RLS/WED in PD patients or RLS/WED can be conceived as an early manifestation of PD rather than a risk factor. Several studies showed a high prevalence of RLS/WED in PD patients and several findings related to dopaminergic and iron alterations in both disorders, however up to now it is difficult to find a point of agreement between studies. A greater number of systematic and strongly controlled longitudinal studies as well as basic pathophysiological investigations particularly in RLS/WED are needed to clarify this complex relationship.
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Affiliation(s)
- Luigi Ferini-Strambi
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Neurology - Sleep Disorders Center, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy
| | - Giulia Carli
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Neurology - Sleep Disorders Center, Milan, Italy
| | - Francesca Casoni
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Neurology - Sleep Disorders Center, Milan, Italy
| | - Andrea Galbiati
- Department of Clinical Neurosciences, IRCCS San Raffaele Scientific Institute, Neurology - Sleep Disorders Center, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy
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Koo BB, Bagai K, Walters AS. Restless Legs Syndrome: Current Concepts about Disease Pathophysiology. TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2016; 6:401. [PMID: 27536462 PMCID: PMC4961894 DOI: 10.7916/d83j3d2g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/07/2016] [Indexed: 01/31/2023]
Abstract
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.
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Affiliation(s)
- Brian B Koo
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA; Department of Neurology, Connecticut Veterans Affairs Health System, West Haven, CT, USA; Yale Center for Neuroepidemiology & Clinical Neurological Research, New Haven, CT, USA
| | - Kanika Bagai
- Department of Neurology, Vanderbilt University, Nashville, TN, USA
| | - Arthur S Walters
- Department of Neurology, Vanderbilt University, Nashville, TN, USA
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Leon-Sarmiento FE, Peckham E, Leon-Ariza DS, Bara-Jimenez W, Hallett M. Auditory and Lower Limb Tactile Prepulse Inhibition in Primary Restless Legs Syndrome: Clues to Its Pathophysiology. J Clin Neurophysiol 2016; 32:369-74. [PMID: 26241246 DOI: 10.1097/wnp.0000000000000196] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The resting sensory discomfort transiently relieved upon movement of the affected area in restless legs syndrome suggests that sensorimotor integration mechanisms, specifically gating, may be altered in the disease. The authors sought to determine the effects of prepulse auditory and tactile stimulation applied to lower limbs on the blink reflex of patients with restless legs syndrome and healthy subjects. Seventeen patients with restless legs syndrome and 17 age- and sex-matched healthy controls were investigated. Auditory stimuli and tactile lower limb stimulation were applied as prepulses. The R2 response of the blink reflex induced by electrical stimulation applied to the right supraorbital nerve was selected as the test stimulus. Time intervals between prepulses and response-eliciting stimuli were 40, 70, 90, 110, and 200 milliseconds. There were no differences in either the auditory or tactile prepulse conditions between patients and controls and no differences between these measures within subject groups. We concluded that the tactile lower limb and the auditory prepulse effects on the brainstem interneurons mediating the blink reflex share common neural pathways. Because forebrain interneurons mediate these prepulse effects, they are likely not involved in the disordered sensorimotor interaction of restless legs syndrome.
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Affiliation(s)
- Fidias E Leon-Sarmiento
- *Human Motor Control Section, NINDS, National Institutes of Health, Bethesda, Maryland, U.S.A.; †Smell and Taste Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, U.S.A.; ‡Mediciencias Research Group, Unicolciencias/Universidad Nacional, Bogota, Colombia; and §Faculty of Health, Universidad de Santander (UDES), Bucaramanga, Colombia
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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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Earley CJ, Connor J, Garcia-Borreguero D, Jenner P, Winkelman J, Zee PC, Allen R. Altered brain iron homeostasis and dopaminergic function in Restless Legs Syndrome (Willis-Ekbom Disease). Sleep Med 2014; 15:1288-301. [PMID: 25201131 DOI: 10.1016/j.sleep.2014.05.009] [Citation(s) in RCA: 189] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 05/15/2014] [Accepted: 05/27/2014] [Indexed: 12/31/2022]
Abstract
Restless legs syndrome (RLS), also known as Willis-Ekbom Disease (WED), is a sensorimotor disorder for which the exact pathophysiology remains unclear. Brain iron insufficiency and altered dopaminergic function appear to play important roles in the etiology of the disorder. This concept is based partly on extensive research studies using cerebrospinal fluid (CSF), autopsy material, and brain imaging indicating reduced regional brain iron and on the clinical efficacy of dopamine receptor agonists for alleviating RLS symptoms. Finding causal relations, linking low brain iron to altered dopaminergic function in RLS, has required however the use of animal models. These models have provided insights into how alterations in brain iron homeostasis and dopaminergic system may be involved in RLS. The results of animal models of RLS and biochemical, postmortem, and imaging studies in patients with the disease suggest that disruptions in brain iron trafficking lead to disturbances in striatal dopamine neurotransmission for at least some patients with RLS. This review examines the data supporting an iron deficiency-dopamine metabolic theory of RLS by relating the results from animal model investigations of the influence of brain iron deficiency on dopaminergic systems to data from clinical studies in patients with RLS.
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Affiliation(s)
- Christopher J Earley
- Department of Neurology, The Johns Hopkins Bayview Medical Center, Baltimore, MD, USA.
| | - James Connor
- Department of Neurosurgery, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | | | - Peter Jenner
- Neurodegenerative Diseases Research Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King's College, London, UK
| | - John Winkelman
- Brigham and Women's Hospital Sleep Health Center, Brighton, MA, USA
| | - Phyllis C Zee
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Richard Allen
- Department of Neurology, The Johns Hopkins Bayview Medical Center, Baltimore, MD, USA
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Jiménez-Jiménez FJ, Alonso-Navarro H, Martínez C, Zurdo M, Turpín-Fenoll L, Millán J, Adeva-Bartolomé T, Cubo E, Navacerrada F, Calleja M, Plaza-Nieto JF, Pilo-de-la-Fuente B, Arroyo-Solera M, Rojo-Sebastián A, Rubio L, Agúndez JAG, García-Martín E. Dopamine receptor D3 (DRD3) gene rs6280 variant and risk for restless legs syndrome. Sleep Med 2013; 14:382-4. [PMID: 23312624 DOI: 10.1016/j.sleep.2012.11.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 11/04/2012] [Accepted: 11/20/2012] [Indexed: 11/18/2022]
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DeAndrade MP, Johnson RL, Unger EL, Zhang L, van Groen T, Gamble KL, Li Y. Motor restlessness, sleep disturbances, thermal sensory alterations and elevated serum iron levels in Btbd9 mutant mice. Hum Mol Genet 2012; 21:3984-92. [PMID: 22678064 DOI: 10.1093/hmg/dds221] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Restless legs syndrome (RLS), also known as Willis-Ekbom disease, is a sensory-motor neurological disorder with a circadian component. RLS is characterized by uncomfortable sensations in the extremities, generally at night or during sleep, which often leads to an uncontrollable urge to move them for relief. Recently, genomic studies identified single-nucleotide polymorphisms in BTBD9, along with three other genes, as being associated with a higher risk of RLS. Little is known about the function of BTBD9 or its potential role in the pathophysiology of RLS. We therefore examined a line of Btbd9 mutant mice we recently generated for phenotypes similar to symptoms found in RLS patients. We observed that the Btbd9 mutant mice had motor restlessness, sensory alterations likely limited to the rest phase, and decreased sleep and increased wake times during the rest phase. Additionally, the Btbd9 mutant mice had altered serum iron levels and monoamine neurotransmitter systems. Furthermore, the sensory alterations in the Btbd9 mutant mice were relieved using ropinirole, a dopaminergic agonist widely used for RLS treatment. These results, taken together, suggest that the Btbd9 mutant mice model several characteristics similar to RLS and would therefore be the first genotypic mouse model of RLS. Furthermore, our data provide further evidence that BTBD9 is involved in RLS, and future studies of the Btbd9 mutant mice will help shine light on its role in the pathophysiology of RLS. Finally, our data argue for the utility of Btbd9 mutant mice to discover and screen novel therapeutics for RLS.
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Affiliation(s)
- Mark P DeAndrade
- Interdisciplinary Program in Biomedical Sciences and Department of Neurology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
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Bliwise DL, Trotti LM, Yesavage JA, Rye DB. Periodic leg movements in sleep in elderly patients with Parkinsonism and Alzheimer's disease. Eur J Neurol 2012; 19:918-23. [PMID: 22340757 PMCID: PMC3351548 DOI: 10.1111/j.1468-1331.2012.03673.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Periodic leg movements in sleep (PLMS) are non-epileptiform, repetitive movements of the lower limbs that have been associated with apparent dopamine deficiency. We hypothesized that elderly patients with a disease characterized primarily by dopamine depletion (Parkinsonism) would have higher rates of PLMS than age-matched controls or a different neurodegenerative condition not primarily involving a hypodopaminergic state, Alzheimer's disease (AD). METHODS We compared rates of PLMS derived from in-laboratory overnight polysomnography in patients with Parkinsonism (n = 79), AD (n = 28), and non-neurologically impaired, community-based controls (n = 187). RESULTS Patients with Parkinsonism not receiving levodopa had significantly higher rates of PLMS than did patients with Parkinsonism receiving levodopa as well as higher rates than seen in AD and controls. Other medications did not appear to exert the pronounced effect of levodopa on PLMS in this Parkinsonian patient population. The symptom of leg kicking was reported more frequently in Parkinsonism and was associated with higher rates of PLMS. Caregiver reported leg kicking was unrelated to PLMS in AD. CONCLUSIONS Results are broadly compatible with a dopaminergic hypothesis for PLMS in Parkinsonism. The clinical significance of the negative findings in patients with AD requires further investigation.
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Affiliation(s)
- D L Bliwise
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA.
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Earley CJ, Kuwabara H, Wong DF, Gamaldo C, Salas R, Brasic J, Ravert HT, Dannals RF, Allen RP. The dopamine transporter is decreased in the striatum of subjects with restless legs syndrome. Sleep 2011; 34:341-7. [PMID: 21358851 DOI: 10.1093/sleep/34.3.341] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
STUDY OBJECTIVES Prior studies, all using SPECT techniques, failed to find any differences for dopamine transporter (DAT) in restless legs syndrome (RLS) subjects. The distinct pharmacokinetic properties associated with SPECT-determined DAT along with rapid biodynamic changes in DAT may, however, have missed membrane-bound DAT differences. The current studies assessed real-time DAT binding potentials (BP) in striatum of RLS patients using (11)C-methylphenidate and PET techniques. DESIGN RLS medications were stopped at least 11 days prior to the PET study. Clinical severity of RLS was also assessed. PET scans were performed at 2 different times of day (starting at 08:30 and 19:30) in separate groups of subjects. The primary outcome measure was total striatal DAT BP. PARTICIPANTS Thirty-six patients with primary RLS and 34 age- and gender-matched controls. RESULTS RLS subjects had significantly lower DAT binding in the striatum compared to controls on both the Day and the Night scans. DAT was decreased in putamen and caudate but not the ventral striatum of RLS subjects. There were no diurnal differences in DAT for the total group or for control and RLS separately. DAT BP did not correlate with any clinical measures of RLS. CONCLUSION The current study found a significant decrease in DAT BP in two independent studies. These results when viewed along with prior RLS SPECT and autopsy studies of DAT, and cell culture studies with iron deficiency and DAT, suggest that membrane-bound striatal DAT, but not total cellular DAT, may be decreased in RLS.
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Affiliation(s)
- Christopher J Earley
- Department of Neurology, Division of Nuclear Medicine, Johns Hopkins University, Baltimore, MD, USA.
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Earley CJ, Allen RP, Hening W. Restless legs syndrome and periodic leg movements in sleep. HANDBOOK OF CLINICAL NEUROLOGY 2011; 99:913-48. [PMID: 21056236 DOI: 10.1016/b978-0-444-52007-4.00015-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Abstract
Restless legs syndrome (RLS) is characterized by a compelling, often insatiable, need to move the legs, accompanied by unpleasant sensations located mainly in the ankles and calves. Because symptoms are brought on by inactivity, distress intrudes upon everyday, sedentary activities such as plane travel, car rides, and attending school, meetings, or the theatre. Symptoms show a diurnal preference for the evening and night, so disruption of sleep onset or maintenance is particularly common. RLS is associated with both lower ratings of quality of life and higher rates of cardiovascular disease. Four common genetic loci associating to RLS have recently been identified, but the molecular pathways by which they increase risk for RLS have yet to be determined. Both sensory (RLS) and motor (periodic limb movements of sleep) symptoms are responsive to dopaminergic medications, yet clear delineation of dopaminergic pathology has not emerged. Brain iron is reduced in many, but not all, patients with RLS. First-line treatment for RLS includes agents acting at D(2) and D(3) dopamine receptors.
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Connor JR, Wang XS, Allen RP, Beard JL, Wiesinger JA, Felt BT, Earley CJ. Altered dopaminergic profile in the putamen and substantia nigra in restless leg syndrome. Brain 2009; 132:2403-12. [PMID: 19467991 DOI: 10.1093/brain/awp125] [Citation(s) in RCA: 233] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Restless leg syndrome (RLS) is a sensorimotor disorder. Clinical studies have implicated the dopaminergic system in RLS, while others have suggested that it is associated with insufficient levels of brain iron. To date, alterations in brain iron status have been demonstrated but, despite suggestions from the clinical literature, there have been no consistent findings documenting a dopaminergic abnormality in RLS brain tissue. In this study, the substantia nigra and putamen were obtained at autopsy from individuals with primary RLS and a neurologically normal control group. A quantitative profile of the dopaminergic system was obtained. Additional assays were performed on a catecholaminergic cell line and animal models of iron deficiency. RLS tissue, compared with controls, showed a significant decrease in D2R in the putamen that correlated with severity of the RLS. RLS also showed significant increases in tyrosine hydroxylase (TH) in the substantia nigra, compared with the controls, but not in the putamen. Both TH and phosphorylated (active) TH were significantly increased in both the substantia nigra and putamen. There were no significant differences in either the putamen or nigra for dopamine receptor 1, dopamine transporters or for VMAT. Significant increases in TH and phosphorylated TH were also seen in both the animal and cell models of iron insufficiency similar to that from the RLS autopsy data. For the first time, a clear indication of dopamine pathology in RLS is revealed in this autopsy study. The results suggest cellular regulation of dopamine production that closely matches the data from cellular and animal iron insufficiency models. The results are consistent with the hypothesis that a primary iron insufficiency produces a dopaminergic abnormality characterized as an overly activated dopaminergic system as part of the RLS pathology.
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Affiliation(s)
- James R Connor
- Department of Neurosurgery, Penn State College of Medicine, Hershey, PA 17033-0850, USA.
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Trenkwalder C, Kohnen R, Allen RP, Benes H, Ferini-Strambi L, Garcia-Borreguero D, Hadjigeorgiou GM, Happe S, Högl B, Hornyak M, Klein C, Nass A, Montagna P, Oertel WH, O'Keeffe S, Paulus W, Poewe W, Provini F, Pramstaller PP, Sieminski M, Sonka K, Stiasny-Kolster K, de Weerd A, Wetter TC, Winkelmann J, Zucconi M. Clinical trials in restless legs syndrome--recommendations of the European RLS Study Group (EURLSSG). Mov Disord 2008; 22 Suppl 18:S495-504. [PMID: 17530666 DOI: 10.1002/mds.21538] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The European Restless Legs Syndrome (RLS) Study Group (EURLSSG) is an association of European RLS experts who are actively involved in RLS research. A major aim of the Study Group is the development and continuous improvement of standards for diagnosis and treatment of RLS. Several members developed study designs and evaluation methods in investigator-initiated trials early in the 1990s, and all members have since contributed to many pivotal and nonpivotal drug trials for the treatment of RLS. The recommendations on clinical investigations of pharmacological treatment of RLS patients summarize the group's expertise and knowledge acquired through clinical trials. The recommendations primarily address how to plan and conduct confirmatory, randomized clinical studies in patients with idiopathic RLS. Advice is presented for the diagnosis of RLS and clinical and polysomnographic inclusion and exclusion criteria. Primary and secondary endpoints for an evaluation of efficacy are based on a critical description of validated methods for both short- and long-term trials, also in special populations (children, pregnant women, elderly patients). The recommendations include the assessment of augmentation. Finally, general issues including the evaluation of safety and tolerability, as well as specific neurological and cardiovascular risks and sleep attacks/daytime somnolence, are discussed. The aim of these recommendations is to support research groups or pharmaceutical companies in the design of optimized study protocols.
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Affiliation(s)
- Claudia Trenkwalder
- Paracelsus-Elena Hospital, Center of Parkinsonism and Movement Disorders, Klinikstr. 16, 34128 Kassel, Germany.
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Allen RP, Connor JR, Hyland K, Earley CJ. Abnormally increased CSF 3-Ortho-methyldopa (3-OMD) in untreated restless legs syndrome (RLS) patients indicates more severe disease and possibly abnormally increased dopamine synthesis. Sleep Med 2008; 10:123-8. [PMID: 18226951 DOI: 10.1016/j.sleep.2007.11.012] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2007] [Revised: 11/08/2007] [Accepted: 11/13/2007] [Indexed: 12/14/2022]
Abstract
BACKGROUND Abnormally high CSF 3-OMD occurs frequently for RLS patients indicating either increased l-dopa synthesis, limitations in l-dopa decarboxylation or increased MAT/COMT activity, or some combination of these. Increased tyrosine hydroxylase activity was found on both the RLS autopsy and the rodent iron-deprivation model of RLS, suggesting increased DA synthesis in RLS. We, therefore, hypothesized elevated 3-OMD in RLS results from increased DA synthesis and that this should occur accordingly with increased HVA. It would then also reflect both the more severe iron insufficiency pathology of RLS and greater clinical severity, shown by the objective measure of PLMS/hr. METHODS Patients off RLS medications and matched controls had lumbar punctures at either 10 a.m. or 10 p.m.; RLS patients were grouped by normal or abnormally high 3-OMD (>10 nmol/l). RESULTS Forty-nine RLS patients (30 high, 19 normal 3-OMD) and 36 age- and gender-matched controls, analyzed separately by time of CSF collection, did not significantly differ in age or gender. RLS patients with high 3-OMD had significantly higher CSF HVA, while those with normal 3-OMD had consistently lower CSF HVA than controls. CSF ferritin was consistently lower compared to controls for the high 3-OMD but not the normal 3-OMD RLS patients. The PLMS/hr was significantly higher for RLS patients with high compared to normal 3-OMD, indicating high 3-OMD patients had more severe RLS. CONCLUSIONS Abnormal elevation in 3-OMD for RLS patients may reflect increased dopamine synthesis for more severe but perhaps not mild RLS. These differences in the putative dopamine pathology of RLS may indicate different phases or expression of RLS biology or different underlying disease processes.
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Affiliation(s)
- Richard P Allen
- Johns Hopkins University, School of Medicine, Department of Neurology, Asthma & Allergy Building, 1B76B 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA.
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Simple Sleep-Related Movement Disorders of Childhood Including Benign Sleep Myoclonus of Infancy, Rhythmic Movement Disorder, and Childhood Restless Legs Syndrome and Periodic Limb Movements in Sleep. Sleep Med Clin 2007. [DOI: 10.1016/j.jsmc.2007.05.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Zhao H, Zhu W, Pan T, Xie W, Zhang A, Ondo WG, Le W. Spinal cord dopamine receptor expression and function in mice with 6-OHDA lesion of the A11 nucleus and dietary iron deprivation. J Neurosci Res 2007; 85:1065-76. [PMID: 17342757 DOI: 10.1002/jnr.21207] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
It is suggested that dysfunction of the diencephalospinal dopaminergic (DAergic) pathway may cause restless legs syndrome. We examined the mRNA and protein levels as well as DA receptor subtypes function within the lumbar spinal cord of an RLS animal model. C57BL/6 male mice with or without iron deprivation were lesioned with 6-hydroxydopamine (6-OHDA) in the bilateral A11 nuclei. Locomotor behaviors were observed. DA concentration, mRNA, and protein levels of D1, D2, and D3 receptors in the lumbar spinal cords were analyzed, and the specific binding of D1, D2, and D3 receptors was determined using [(3)H]SCH23390, [(3)H]Spiperone, and [(3)H]PD128907 radioligands respectively. The behavioral tests showed that the locomotor activities were increased significantly in the mice treated with iron-deficiency (ID) diet and 6-OHDA lesions, which were reversed by the D2/D3 agonist ropinirole. DA in the spinal cord was decreased significantly by 6-OHDA lesioning in A11. D2/D3 mRNA and protein levels as well as their binding capacity in the spinal cord were decreased significantly by 6-OHDA lesions. ID with 6-OHDA lesions produced a synergistic greater decrease of D2 binding. Although ID increased D1 mRNA and protein expression in the spinal cord, it did not significantly change D1 receptor binding. The present study suggests that ID and 6-OHDA lesions in A11 nuclei differentially altered the D1, D2, and D3 receptors expression and binding capacity in the lumbar spinal cord of RLS animal model, which was accompanied by changes in locomotor activities.
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Affiliation(s)
- Hongru Zhao
- Department of Neurology, Baylor College of Medicine, Houston, Texas 77030, USA
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Baier PC, Trenkwalder C. Circadian variation in restless legs syndrome. Sleep Med 2007; 8:645-50. [PMID: 17383937 DOI: 10.1016/j.sleep.2006.10.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Revised: 10/09/2006] [Accepted: 10/26/2006] [Indexed: 11/30/2022]
Abstract
Restless legs syndrome (RLS) is a clinical disorder that currently is not characterized by a uniform pathophysiologiocal definition. The diagnosis of RLS requires circadian variation in symptoms, although no pathophysiological basis has been verified. Clinical observations and research studies confirm the variation in symptoms, of both sensory and motor components, over the course of the day. This contribution reviews the current literature on circadian variation in RLS and discusses potential intrinsic and extrinsic causes.
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Affiliation(s)
- P C Baier
- Department of Clinical Neurophysiology, Georg August University of Göttingen, Göttingen, Germany.
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Tackenberg B, Metz A, Unger M, Schimke N, Passow S, Hoeffken H, Hoffmann GF, Müller U, Nolte D, Oertel WH, Eggert K, Möller JC. Nigrostriatal dysfunction in X-linked dystonia-parkinsonism (DYT3). Mov Disord 2007; 22:900-2. [PMID: 17377924 DOI: 10.1002/mds.21462] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Abstract
Ropinirole is an original nonergoline dopamine agonist indicated for the treatment of Parkinson's disease. However, recent developments in the study of restless legs syndrome have demonstrated another role for this drug. The symptoms of restless legs syndrome are responsive to dopaminergic agents such as ropinirole. The dosage of ropinirole needed to treat the symptoms of restless legs syndrome appears to be much smaller than what is necessary for Parkinson's disease therapy. The liver is primarily responsible for the metabolism of ropinirole, which has an elimination half-life of approximately 6 h. Ropinirole is generally well tolerated, with no serious adverse effects. Clinical studies have indicated that ropinirole can effectively reduce the motor symptoms of restless legs syndrome and improve overall sleep quality.
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Affiliation(s)
- Rajdeep S Kakar
- Department of Psychiatry and Behavioral Sciences, Stanford University Center of Excellence for Sleep Disorders Research, Stanford Sleep Disorders Center, 401 Quarry Road, Palo Alto, CA 94305, USA
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Earley CJ, Hyland K, Allen RP. Circadian changes in CSF dopaminergic measures in restless legs syndrome. Sleep Med 2006; 7:263-8. [PMID: 16564215 DOI: 10.1016/j.sleep.2005.09.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Revised: 09/06/2005] [Accepted: 09/17/2005] [Indexed: 10/24/2022]
Abstract
BACKGROUND AND PURPOSE Restless legs syndrome (RLS) has a circadian component with symptoms being prominent at night. The dopaminergic (DAergic) system, which plays a role in RLS, entails circadian changes that parallel RLS symptom changes. The aim of this study was to look for relative and diurnal differences in DAergic activity. PATIENTS AND METHODS All RLS subjects were treated prior to their enrollment in the study but were all drug-free for at least 2 weeks prior to evaluation. Cerebrospinal fluid (CSF) collected at 10 p.m. was used to determine DA-related co-factors and metabolites. These were compared to CSF values collected in a previous study at 10 a.m. RESULTS The only significant finding from the 10 p.m. samples (30 RLS; 22 control) was increased 3-ortho-methyldopa (3OMD) for RLS compared to controls. A comparison of the 10 p.m. to 10 a.m. values (16 RLS; 9 controls) showed small, non-significant diurnal changes for controls but large diurnal changes in tetrahydrobiopterin (BH4), HVA:5HIAA ratio and 3OMD for RLS, with the 10 a.m. sample showing increases in all three CSF factors compared to the 10 p.m. sample. CONCLUSIONS The greater diurnal changes in RLS suggest greater fluctuations than normal in DAergic circadian dynamics. The increased 3OMD concentration in the absence of concurrent exogenous levodopa (l-dopa) suggests changes in synthesis or metabolism of l-dopa in RLS.
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Affiliation(s)
- Christopher J Earley
- Department of Neurology, Johns Hopkins Bayview Medical Center, Johns Hopkins School of Medicine, Baltimore, MD 21224, USA.
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Martínez-Rodríguez JE, Santamaria J. CSF markers in sleep neurobiology. Clin Chim Acta 2005; 362:12-25. [PMID: 15992787 DOI: 10.1016/j.cccn.2005.05.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2005] [Revised: 05/23/2005] [Accepted: 05/24/2005] [Indexed: 11/19/2022]
Abstract
The cerebrospinal fluid has been used in the study of normal and pathological conditions of the central nervous system for more than a century. CSF analysis has also been applied to the study of sleep and its disorders but methodological aspects have often limited the results. The discovery of the hypocretin system (also known as orexin system) and its involvement in the pathophysiology of narcolepsy has opened a new field in the diagnosis of hypersomnia by CSF analysis and has revived the interest on this subject in sleep medicine. Older and new lines of research involving CSF measurement of hypocretin and other neurotransmitters in sleep and its disorders are reviewed.
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Affiliation(s)
- Jose E Martínez-Rodríguez
- Neurology Service, Hospital Clínic de Barcelona and Institut d'Investigació Biomédica August Pi i Sunyer (IDIBAPS), C/Villarroel 170, Spain.
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Abstract
Restless legs syndrome (RLS) is clinically defined as an urge to move the legs with or without paresthesia, worsening of symptoms with rest and transient improvement with activity, and worsening of symptoms in the evening and night. This is often genetic but may also occur in the setting of iron deficiency, uremia, pregnancy, neuropathy, and possibly other conditions. The pathology is probably related to central nervous system iron dysregulation. Effective treatments include dopaminergics and narcotics. Recent advances in our understanding of RLS clinical presentation, epidemiology, etiology, and treatment will be discussed.
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Barrière G, Cazalets JR, Bioulac B, Tison F, Ghorayeb I. The restless legs syndrome. Prog Neurobiol 2005; 77:139-65. [PMID: 16300874 DOI: 10.1016/j.pneurobio.2005.10.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Revised: 10/19/2005] [Accepted: 10/21/2005] [Indexed: 10/25/2022]
Abstract
The restless legs syndrome (RLS) is one of the commonest neurological sensorimotor disorders at least in the Western countries and is often associated with periodic limb movements (PLM) during sleep leading to severe insomnia. However, it remains largely underdiagnosed and its underlying pathogenesis is presently unknown. Women are more affected than men and early-onset disease is associated with familial cases. A genetic origin has been suggested but the mode of inheritance is unknown. Secondary causes of RLS may share a common underlying pathophysiology implicating iron deficiency or misuse. The excellent response to dopaminegic drugs points to a central role of dopamine in the pathophysiology of RLS. Iron may also represent a primary factor in the development of RLS, as suggested by recent pathological and brain imaging studies. However, the way dopamine and iron, and probably other compounds, interact to generate the circadian pattern in the occurrence of RLS and PLM symptoms remains unknown. The same is also the case for the level of interaction of the two compounds within the central nervous system (CNS). Recent electrophysiological and animals studies suggest that complex spinal mechanisms are involved in the generation of RLS and PLM symptomatology. Dopamine modulation of spinal reflexes through dopamine D3 receptors was recently highlighted in animal models. The present review suggests that RLS is a complex disorder that may result from a complex dysfunction of interacting neuronal networks at one or several levels of the CNS and involving numerous neurotransmitter systems.
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Affiliation(s)
- G Barrière
- Laboratoire de Neurophysiologie, UMR-CNRS 5543, Université Bordeaux 2, Bordeaux, France
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Abstract
PURPOSE OF REVIEW In the review period since February 2004 a number of papers have been published that make significant contributions to the current understanding of the epidemiology, clinical assessment, pathophysiology and treatment of restless legs syndrome. Those with the most significant findings were selected and will be reviewed. RECENT FINDINGS Several epidemiological studies about restless legs syndrome have become available in the review period. A new susceptibility locus for restless legs syndrome has been reported. Neuropathological studies have provided profound insights into the key role of iron regulation in the pathophysiology of restless legs syndrome. Several randomized, double-blind, placebo-controlled studies have demonstrated that dopamine agonists are efficacious in the treatment of restless legs syndrome. A few pilot treatment studies with intravenous iron have been performed. SUMMARY In this paper, recent advances in the field of restless legs syndrome are reviewed. Special emphasis is placed on pathophysiology and treatment. Restless legs syndrome is still an underdiagnosed disorder. The evidence basis for its treatment has been considerably increased in the review period.
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Affiliation(s)
- Birgit Högl
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.
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Papapetropoulos S, Mash DC. Psychotic symptoms in Parkinson’s disease. J Neurol 2005; 252:753-64. [PMID: 15999234 DOI: 10.1007/s00415-005-0918-5] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Revised: 11/12/2004] [Accepted: 02/24/2005] [Indexed: 10/25/2022]
Abstract
Psychotic symptoms are common in Parkinson's disease (PD) and occur in at least 20% of medication-treated patients. Benign visual hallucinations usually appear earlier, while malignant hallucinations, confusional states, delusions, paranoid beliefs, agitation, and delirium become more frequent with disease progression. Virtually all antiparkinsonian drugs may produce psychotic symptoms. Cognitive impairment, increased age, disease duration and severity, depression, and sleep disorders have been consistently identified as independent risk factors for their development. Although the precise pathoetiologic mechanisms remain unknown, we review evidence that links ventral dopaminergic pathway dysfunction (overactivity) together with the involvement of other neurotransmitter system imbalances as likely contributors. The clinical importance of the proposed mechanism is that successful management of psychotic symptoms in PD may rely on a multitarget approach to restore neurotransmitter imbalances rather than focusing exclusively on the dopaminergic dysfunction.
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Affiliation(s)
- Spiridon Papapetropoulos
- Department of Neurology, University of Miami, School of Medicine, Room 4004, 1501 NW 9th Avenue, Miami FL 33136, USA.
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