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Wagle Shukla A. Reduction of neuronal hyperexcitability with modulation of T-type calcium channel or SK channel in essential tremor. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 163:335-355. [PMID: 35750369 DOI: 10.1016/bs.irn.2022.02.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Essential tremor is one of the most prevalent movement disorders. Propranolol and primidone are the first-line pharmacological therapies. They provide symptomatic control in less than 50% of patients. Topiramate, alprazolam, clonazepam, gabapentin, and botulinum toxin injections are the next line of treatments. These medications lead to modest improvements and are therefore commonly used as add-on agents. Surgical therapies, including deep brain stimulation (DBS) surgery and focused ultrasound beam targeted to the thalamus, are considered for treating tremor refractory to medications and lead to greater than 75% improvements in tremor symptoms. However, DBS is a costly and an invasive procedure; some patients report tolerance to benefits. Focused ultrasound therapy leading to brain lesions is associated with a possibility for permanent clinical deficits. Therefore, research efforts to develop the next generation of oral medications with greater benefits and lesser adverse effects are warranted. There is considerable evidence that the increased functions of calcium channels (P/Q-type and T-type channels) and reduced functions of calcium-activated potassium channels (SK channels) located in the neuronal membranes lead to tremor oscillations. Consequently, many new pharmacological studies have targeted these channels to leverage better clinical outcomes. The current review will discuss the pathophysiology, the specific importance of these channels, and the early clinical experience of using compounds targeting these channels to treat essential tremor.
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Affiliation(s)
- Aparna Wagle Shukla
- Department of Neurology, Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, United States.
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Primidone Intolerance in Essential tremor: Is it More than Just Age? Tremor Other Hyperkinet Mov (N Y) 2021; 11:57. [PMID: 35070493 PMCID: PMC8719469 DOI: 10.5334/tohm.672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 12/21/2021] [Indexed: 11/20/2022] Open
Abstract
Background: There are few medications for the treatment of essential tremor (ET). One of these, primidone, which is one of only two front-line agents, is associated with considerable adverse drug reactions (ADRs). It is unclear why some primidone-treated ET patients develop ADRs whereas others do not, and why these ADRs seem to be more prevalent in ET patients than primidone-treated patients with epilepsy. Objective: To review several possible explanations underlying the above-referenced differences. Methods: A literature search was conducted in PubMed in October 2021. Studies reporting the ADRs of primidone in different neurological conditions were comprehensively reviewed. Discussion: Although there were no head-to-head data, a review of the previous studies on ET and epilepsy patients indicates that the former is relatively more intolerant to primidone. Moreover, not all ET patients develop ADR of similar nature or severity. We discuss several potential mechanisms for this variability in the intolerance to primidone. These include: (i) older age (ET vs. epilepsy patients), (ii) cross-tolerance to primidone in patients with epilepsy, (iii) neurobiological (GABA-related) abnormalities associated with ET. Conclusion: We speculate that there are several possible explanations for primidone intolerance in ET. These possibilities should be tested in future studies, and we propose the roadmap for designing these studies. It is of value to obtain detailed insight into these complex issues because primidone remains one of the few frontline anti-tremor medications in ET. Answers to issues we have raised in this article could facilitate more customized formulation of primidone in ET patients.
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Abstract
Established medications that improve tremor include beta-adrenergic antagonists, primidone, topiramate, and ethanol. Less consistent efficacy is reported with many other medications, usually antiepileptic drugs. A number of investigational medications, including T-type calcium channel blockers and allosteric gamma-aminobutyric acid-A modulators, are being developed for tremor. Deep brain stimulation techniques continues to be refined and focused ultrasound thalamotomy now offers an incisionless surgical option. Finally a number of peripheral electrical and mechanical devices are under development for tremor.
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Affiliation(s)
- William George Ondo
- Movement Disorders-Methodist Neurological Institute, Weill Cornel Medical School, 6560 Fannin Suite 1002, Houston, TX 77025, USA.
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Alonso-Navarro H, García-Martín E, Agúndez JA, Jiménez-Jiménez FJ. Current and Future Neuropharmacological Options for the Treatment of Essential Tremor. Curr Neuropharmacol 2020; 18:518-537. [PMID: 31976837 PMCID: PMC7457404 DOI: 10.2174/1570159x18666200124145743] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/31/2019] [Accepted: 01/23/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Essential Tremor (ET) is likely the most frequent movement disorder. In this review, we have summarized the current pharmacological options for the treatment of this disorder and discussed several future options derived from drugs tested in experimental models of ET or from neuropathological data. METHODS A literature search was performed on the pharmacology of essential tremors using PubMed Database from 1966 to July 31, 2019. RESULTS To date, the beta-blocker propranolol and the antiepileptic drug primidone are the drugs that have shown higher efficacy in the treatment of ET. Other drugs tested in ET patients have shown different degrees of efficacy or have not been useful. CONCLUSION Injections of botulinum toxin A could be useful in the treatment of some patients with ET refractory to pharmacotherapy. According to recent neurochemical data, drugs acting on the extrasynaptic GABAA receptors, the glutamatergic system or LINGO-1 could be interesting therapeutic options in the future.
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Affiliation(s)
| | | | | | - Félix J. Jiménez-Jiménez
- Address correspondence to this author at the Section of Neurology, Hospital Universitario del Sureste, Arganda del Rey, Madrid, Spain; Tel: +34636968395; Fax: +34913280704; E-mails: ;
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Abstract
Essential tremor is one of the most common movement disorders in adults and can affect both children and adults. An updated consensus statement in 2018 redefined essential tremor as an isolated action tremor present in bilateral upper extremities for at least three years. Tremor may also be present in other locations, commonly the neck or the vocal cords. Patients with additional neurologic symptoms are now categorized as "essential tremor plus." Additional clinical features associated with the condition include but are not limited to cognitive impairment, psychiatric disorders, and hearing loss. When treatment is needed, propranolol and primidone are considered first line treatments. Patients who are severely affected are often offered deep brain stimulation. Although the ventral intermediate nucleus of the thalamus is the traditional surgical target, the caudal zona incerta is also being studied as a possible superior alternative. Magnetic resonance imaging guided high intensity focused ultrasound is a newer surgical alternative that may be ideal for patients with substantial medical comorbidities. Current research explores novel oral treatments, chemodenervation, and noninvasive neuromodulation for treatment of essential tremor.
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Affiliation(s)
- Vicki Shanker
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
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Ferreira JJ, Mestre TA, Lyons KE, Benito-León J, Tan EK, Abbruzzese G, Hallett M, Haubenberger D, Elble R, Deuschl G. MDS evidence-based review of treatments for essential tremor. Mov Disord 2019; 34:950-958. [PMID: 31046186 DOI: 10.1002/mds.27700] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 03/25/2019] [Accepted: 03/27/2019] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Essential tremor is one of the most prevalent movement disorders. Many treatments for essential tremor have been reported in clinical practice, but it is uncertain which options have the most robust evidence. The International Parkinson and Movement Disorder Society commissioned a task force on tremor to review clinical studies of treatments for essential tremor. OBJECTIVES To conduct an evidence-based review of current pharmacological and surgical treatments for essential tremor, using standardized criteria defined a priori by the International Parkinson and Movement Disorder Society. METHODS We followed the recommendations of the International Parkinson and Movement Disorder Society Evidence Based Medicine Committee. RESULTS Sixty-four studies of pharmacological and surgical interventions were included in the review. Propranolol and primidone were classified as clinically useful, similar to Topiramate, but only for doses higher than 200 mg/day. Alprazolam and botulinum toxin type A were classified as possibly useful. Unilateral Ventralis intermedius thalamic DBS, radiofrequency thalamotomy, and MRI-guided focused ultrasound thalamotomy were considered possibly useful. All the above recommendations were made for limb tremor in essential tremor. There was insufficient evidence for voice and head tremor as well as for the remaining interventions. CONCLUSION Propranolol, primidone, and topiramate (>200 mg/day) are the pharmacological interventions in which the data reviewed robustly supported efficacy. Their safety profile and patient preference may guide the prioritization of these interventions in clinical practice. MRI-guided focused ultrasound thalamotomy was, for the first time, assessed and was considered to be possibly useful. There is a need to improve study design in essential tremor and overcome the limitation of small sample sizes, cross-over studies, short-term follow-up studies, and use of nonvalidated clinical scales. © 2019 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Joaquim J Ferreira
- Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Portugal.,CNS-Campus Neurológico Sénior, Torres Vedras, Portugal
| | - Tiago A Mestre
- Parkinson's Disease and Movement Disorders Center, Division of Neurology, Department of Medicine, The Ottawa Hospital Research Institute, Brain and Mind Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Kelly E Lyons
- Parkinson's Disease and Movement Disorder Center, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Julián Benito-León
- Department of Neurology, University Hospital 12 de Octubre; Center of Biomedical Network Research on Neurodegenerative diseases (CIBERNED), Department of Medicine, Faculty of Medicine, Complutense University, Madrid, Spain
| | - Eng-King Tan
- National Neuroscience Institute, Duke NUS Medical School, Singapore
| | - Giovanni Abbruzzese
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal Child Health, University of Genoa-IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Mark Hallett
- Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Dietrich Haubenberger
- Clinical Trials Unit, Office of the Clinical Director, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Rodger Elble
- Department of Neurology, Southern Illinois University School of Medicine, Springfield, Illinois, USA
| | - Günther Deuschl
- Department of Neurology, Universitätsklinikum Schleswig-Holstein, Kiel Campus, Christian Albrechts University Kiel, Kiel, Germany
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Schaefer SM, Vives Rodriguez A, Louis ED. Brain circuits and neurochemical systems in essential tremor: insights into current and future pharmacotherapeutic approaches. Expert Rev Neurother 2017; 18:101-110. [PMID: 29206482 DOI: 10.1080/14737175.2018.1413353] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
INTRODUCTION There are few medications that are available for the treatment of essential tremor (ET) and they are only moderately effective. Areas covered: Data were obtained from a PubMed search. Original articles, review articles, and clinical guidelines were included. Two disease models for ET have been proposed: 1) the olivary model, which attributes ET to a pathological pacemaker in the inferior olivary nucleus, and 2) the cerebellar degeneration model, which postulates that ET originates in the cerebellum and could be related to deficient or abnormal Purkinje cell (PC) output. Underlying biochemical dysfunction in T-type calcium channels (T-tCaC) may loosely be linked to the first model and deficiency/abnormality in γ-aminobutyric acid (GABA) neurotransmission, to the second. Expert commentary: Human data points robustly to the role of GABA in ET. Numerous medications that target the GABA system have been tried, with variable success. Given the many different types of GABA-ergic neurons, and the multitude of GABAA receptor subtypes, a given medication could have competing/cancelling effects. It would seem that influencing GABA receptors broadly is not as effective as targeting certain GABAA receptor subtypes. Future research should seek to identify molecular candidates that have a more targeted effect within the GABA system.
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Affiliation(s)
- Sara M Schaefer
- a Department of Neurology , Yale School of Medicine, Yale University , New Haven , CT , USA
| | - Ana Vives Rodriguez
- a Department of Neurology , Yale School of Medicine, Yale University , New Haven , CT , USA
| | - Elan D Louis
- a Department of Neurology , Yale School of Medicine, Yale University , New Haven , CT , USA.,b Department of Chronic Disease Epidemiology , Yale School of Public Health, Yale University , New Haven , CT , USA.,c Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine , Yale University , New Haven , CT , USA
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Postural hand tremor and incident hypertension in young to middle-aged adults: the Bogalusa heart study. J Hypertens 2017; 34:1273-8. [PMID: 27136316 DOI: 10.1097/hjh.0000000000000963] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Hand tremor and blood pressure (BP) are both increased by adrenergic stimulation and reduced by β-blockade, indicating that they may share a common underlying pathophysiology. METHODS We prospectively examined the relationship between postural hand tremor and incident hypertension in a community-based cohort of 715 (184 blacks and 531 whites) adults without hypertension and not using medications to control tremor (e.g. β-blockers). At baseline, tremor was measured with participants holding a laser pointer aimed at a sheet of Polaroid film 8 feet away with arm outstretched for 8 s in a darkened room, and characterized by the width of the circle diameter encompassing all exposures and enumeration of exposure dots in the same area. Incident hypertension was defined as new elevation of BP (SBP ≥ 140 or DBP ≥ 90 mmHg, based on an average of six readings over two visits) or antihypertensive medication use. RESULTS During a median follow-up of 6.4 years, 198 (69 blacks and 129 whites) participants developed hypertension. Tremor measurements (by quartile) were positively associated with incident hypertension after adjustment for baseline demographics, lifestyle characteristics, and BP. There was significant interaction by race (P = 0.01). Among whites, tremor was positively associated with incident hypertension [hazard ratio highest vs. lowest quartile: 2.50 (95% confidence interval: 1.40-4.48) dot method and 3.24 (1.78-5.90) circular method; both P trend <0.01]. Among blacks, tremor was not associated with hypertension. CONCLUSION In this community-based cohort, postural hand tremor was strongly associated with the risk of incident hypertension among whites and merits further study as a potential indicator of risk for hypertension.
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Effect of Primidone on Dentate Nucleus γ-Aminobutyric Acid Concentration in Patients With Essential Tremor. Clin Neuropharmacol 2016; 39:24-8. [PMID: 26757316 DOI: 10.1097/wnf.0000000000000127] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES It is not known whether current use of the medication primidone affects brain γ-aminobutyric acid (GABA) concentrations. This is an important potential confound in studies of the pathophysiology of essential tremor (ET), one of the most common neurological diseases. We compared GABA concentrations in the dentate nucleus in 6 ET patients taking primidone versus 26 ET patients not taking primidone. METHODS (1)H magnetic resonance spectroscopy was performed using a 3.0-T Siemens Tim Trio scanner. The MEGA-PRESS J-editing sequence was used for GABA detection in 2 cerebellar volumes of interest (left and right) that included the dentate nucleus. RESULTS The right dentate GABA concentration was similar in the 2 groups (2.21 ± 0.46 [on primidone] vs 1.93 ± 0.39 [not on primidone], P = 0.15), as was the left dentate GABA concentration (1.61 ± 0.35 [on primidone] vs 1.67 ± 0.34 [not on primidone], P = 0.72). The daily primidone dose was not associated with either right or left dentate GABA concentrations (P = 0.89 and 0.76, respectively). CONCLUSIONS We did not find a difference in dentate GABA concentrations between 6 ET patients taking daily primidone and 26 ET patients not taking primidone. Furthermore, there was no association between daily primidone dose and dentate GABA concentration. These data suggest that it is not necessary to exclude ET patients on primidone from magnetic resonance spectroscopy studies of dentate GABA concentration, and if assessment of these concentrations was to be developed as a biomarker for ET, primidone usage would not confound interpretation of the results.
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Ondo W. Essential Tremor: What We Can Learn from Current Pharmacotherapy. Tremor Other Hyperkinet Mov (N Y) 2016; 6:356. [PMID: 26989572 PMCID: PMC4790207 DOI: 10.7916/d8k35tc3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 12/17/2015] [Indexed: 04/07/2023] Open
Abstract
BACKGROUND The pathophysiology of essential tremor, especially at the cellular level, is poorly understood. Although no drug has been specifically designed to treat essential tremor, several medications improve tremor, and others worsen it. Studying the mechanism of actions of these medications can help our understanding of tremor pathophysiology and contribute to future rational drug design. METHODS We reviewed literature, concentrating on mechanisms of action, of various medications that mitigate tremor. RESULTS Many medications have multiple mechanisms of actions, making simple correlations difficult. Medications that increase the duration of opening of gamma-aminobutyric acid (GABA)-A receptors are most consistently associated with tremor improvement. Interestingly, drugs that increase GABA availability have not been associated with improved tremor. Other mechanisms possibly associated with tremor improvement include antagonism of alpha-2 delta subunits associated with calcium channels, inhibition of carbonic anhydrase, and inhibition of the synaptic vesicle protein 2A. Drugs that block voltage-gaited sodium channels do not affect tremor. The ideal beta-adrenergic blocker requires B2 affinity (non-cardiac selective), has no sympathomimetic properties, does not require membrane stabilization properties, and may benefit from good central nervous system penetration. DISCUSSION To date, serendipitous observations have provided most of our understanding of tremor cellular physiology. Based on similarities to currently effective drugs or rational approximations and inferences, several currently available agents should be considered for tremor trials.
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Affiliation(s)
- William Ondo
- Methodist Neurological Institute, Houston, TX, USA
- *To whom correspondence should be addressed. E-mail:
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Apartis E, Jedynak CP. Tremori. Neurologia 2014. [DOI: 10.1016/s1634-7072(14)66663-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Louis ED. 'Essential tremor' or 'the essential tremors': is this one disease or a family of diseases? Neuroepidemiology 2013; 42:81-9. [PMID: 24335621 DOI: 10.1159/000356351] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 10/10/2013] [Indexed: 12/14/2022] Open
Abstract
There is accumulating evidence that the entity referred to as 'essential tremor' (ET) is not a single disease. It may be a family of diseases better referred to as 'the ETs'. This review will summarize the following evidence: (1) the presence of etiological heterogeneity; (2) the heterogeneity of findings in postmortem studies, thus suggesting several diseases; (3) the recent discussion that age of onset may be an important marker of disease heterogeneity; (4) the clinical expansion of the concept of ET in recent years to include a broader range of tremor phenomenology, other motor features (gait ataxia), other involuntary movements (dystonia), and nonmotor features (cognitive problems, psychiatric problems), some of which could be primary; (5) the heterogeneity of pharmacological response profiles and clinical progression, and (6) the association of ET with Parkinson's disease, Alzheimer's disease, and possibly progressive supranuclear palsy, with the possibility that some ET patients are more predisposed to develop one of these. © 2013 S. Karger AG, Basel.
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Affiliation(s)
- Elan D Louis
- GH Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, N.Y., USA
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[Essential tremor: update]. Med Clin (Barc) 2013; 140:128-33. [PMID: 22995841 DOI: 10.1016/j.medcli.2012.07.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 07/02/2012] [Accepted: 07/05/2012] [Indexed: 11/23/2022]
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Zappia M, Albanese A, Bruno E, Colosimo C, Filippini G, Martinelli P, Nicoletti A, Quattrocchi G. Treatment of essential tremor: a systematic review of evidence and recommendations from the Italian Movement Disorders Association. J Neurol 2012; 260:714-40. [DOI: 10.1007/s00415-012-6628-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 07/12/2012] [Accepted: 07/12/2012] [Indexed: 10/28/2022]
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Dalvi A. Medical Treatment of Tremor. Dis Mon 2011; 57:135-41. [DOI: 10.1016/j.disamonth.2011.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Deuschl G, Raethjen J, Hellriegel H, Elble R. Treatment of patients with essential tremor. Lancet Neurol 2011; 10:148-61. [PMID: 21256454 DOI: 10.1016/s1474-4422(10)70322-7] [Citation(s) in RCA: 230] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Benito-León J, Louis ED. Management of essential tremor, including medical and surgical approaches. HANDBOOK OF CLINICAL NEUROLOGY 2011; 100:449-456. [PMID: 21496601 DOI: 10.1016/b978-0-444-52014-2.00034-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Essential tremor (ET) is one of the most common neurological disorders among adults. For many years, ET was viewed as a benign monosymptomatic condition, characterized by a kinetic arm tremor, yet over the last 10 years, a growing body of evidence suggests that this disorder is a progressive condition that is heterogeneous. Tremor may have a negative impact on health-related quality of life in some patients. Pharmacotherapy is initiated when the tremor interferes with the patient's ability to perform daily activities or when the tremor becomes embarrassing or affects health-related quality of life. For severe tremor, deep-brain stimulation of the thalamus may improve function.
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Affiliation(s)
- Julián Benito-León
- Department of Neurology, University Hospital "12 de Octubre" and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
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Abstract
Essential tremor (ET) is one of the most common movement disorders in the world. Despite this, only one medication (propranolol) is approved by the Food and Drug Administration (FDA) to treat it. Fortunately, recent studies have identified some additional medications as treatment of ET. Surgical procedures, such as deep brain stimulation of the ventral intermediate nucleus of the thalamus, offer treatment for refractory tremor. The epidemiology, pathogenesis, and medical and surgical treatment of ET will be discussed in this paper.
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Affiliation(s)
- Theresa A Zesiewicz
- Department of Neurology, Parkinson Research Foundation, James A. Haley Veterans Administration Hospital, University of South Florida, Tampa, FL, USA
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Abstract
Essential tremor (ET) is a common, often familial, movement disorder characterized by tremor of the limbs, head, and voice. Epidemiological surveys indicate that up to 5% of the adult population has ET, and 5-30% of adults with ET report symptom onset during childhood. There is, however, little published regarding ET in the pediatric population, and no prospective studies targeted specifically to children. Retrospective studies from subspecialty movement disorder clinics indicate that childhood-onset ET is usually hereditary, begins at a mean age of 6 years, and affects boys three times as often as girls. While ET occasionally results in disability during childhood, only one-quarter of children seeing a neurologist for ET require pharmacotherapy. Small case series suggest that propranolol is effective in approximately 50% of children with ET, but controlled treatment trials are lacking.
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Affiliation(s)
- Joseph Ferrara
- Parkinson Disease Center and Movement Disorders Clinic, Department of Neurology, Baylor College of Medicine, Houston, Texas 77030, USA
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Abstract
Tremor in childhood is not commonly described in the literature; but it is also likely underappreciated. The etiology of childhood tremor encompasses a wide variety of pathologic processes. Tremor may occur in isolation, or in association with other neurologic findings or systemic disorders. This article aims to provide an overview of tremorogenic mechanisms with respect to neuroanatomy and neurophysiology, particularly as they relate to children. Classification of tremors, diagnostic entities in childhood, and treatment will also be discussed. With improved recognition and characterization of childhood tremors, we may gain a better understanding of the pathophysiology of the disease and determine more age-appropriate treatment strategies.
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Affiliation(s)
- Stephanie Keller
- Department of Pediatrics, Division of Child Neurology, University of Alabama at Birmingham, The Children's Hospital of Alabama, Birmingham, AL 35233, USA.
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Louis ED, Benito-León J, Bermejo-Pareja F. Philadelphia Geriatric Morale Scale in essential tremor: a population-based study in three Spanish communities. Mov Disord 2008; 23:1435-40. [PMID: 18512746 DOI: 10.1002/mds.22124] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Essential tremor (ET) is associated with both functional disability and depression. Each could contribute to a poor sense of well-being and low morale. We hypothesized that morale would be lower in ET cases than controls. Using a population-based, cross-sectional design, morale was assessed in 187 ET cases and 561 matched controls living in three communities in central Spain using the Philadelphia Geriatric Center Morale Scale (PGCMS) (range = 0 [low morale]-17), which included three-dimensions of psychological well-being: agitation, lonely dissatisfaction, and attitude toward own aging. The PGCMS score was lower in ET cases than controls (9.41 +/- 3.21 vs. 10.39 +/- 2.92, P < 0.001), as were the Agitation subscore (3.17 +/- 1.71 vs. 3.78 +/- 1.67, P< 0.001) and Lonely Dissatisfaction subscore (3.75 +/- 1.34 vs. 4.02 +/- 1.24, P < 0.05). Nearly one-half of the ET cases were classified as having low morale compared with only one-third of controls (P = 0.006). In a linear regression analysis adjusting for demographic factors and multiple comorbid conditions, ET cases had a lower log PGCMS score than controls (P < 0.001). Exclusion of participants on antidepressant medication did not change the results. Our results indicate that morale is significantly lower in community-dwelling ET cases than in matched controls. This lower morale could in part be a proxy for mild, untreated depression. It therefore seems important to detect and then possibly treat this problem to improve the psychological well-being of patients with this disease.
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Affiliation(s)
- Elan D Louis
- G.H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
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Nguyen HV, Ngian V, Cordato D, Shen Q, Chan DKY. Quality of life in a random sample of community dwelling older patients with essential tremor. Acta Neurol Scand 2007; 116:289-92. [PMID: 17883423 DOI: 10.1111/j.1600-0404.2007.00863.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
STUDY OBJECTIVE - Nested case-control study aimed to assess the quality of life of community dwelling participants aged 65 years or over with newly diagnosed Essential Tremor (ET). METHODS AND RESULTS - Thirty-two participants with newly diagnosed ET and 32 age and gender matched controls were administered the Rand-SF36 quality of life questionnaire. Medical co-morbidities were also assessed in the two groups. Results - Participants with ET had significantly lower scores in the physical function, role limitation because of physical function, role limitation as a result of emotional problem, pain, and energy/vitality subscales of the Rand-SF36 when compared with controls. CONCLUSIONS - Older patients with newly diagnosed ET have poorer quality of life than their community dwelling counterparts without ET.
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Affiliation(s)
- H V Nguyen
- Department of Aged Care and Rehabilitation, Bankstown Hospital, Sydney, NSW, Australia.
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Abstract
Essential tremor (ET) is among the most common neurologic disorders. The traditional view of this disorder as a benign, monosymptomatic, familial condition is being replaced by a more complex view of ET as perhaps a family of diseases with etiologic, clinical, and pathologic heterogeneity. This article discusses the major clinical features of ET and approaches to its diagnosis and treatment.
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Affiliation(s)
- Elan D Louis
- Department of Neurology, College of Physicians and Surgeons, Columbia University, 710 West 168th Street, New York, NY 10032, USA.
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Benito-León J, Louis ED. Essential tremor: emerging views of a common disorder. ACTA ACUST UNITED AC 2006; 2:666-78; quiz 2p following 691. [PMID: 17117170 DOI: 10.1038/ncpneuro0347] [Citation(s) in RCA: 194] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Accepted: 09/15/2006] [Indexed: 11/08/2022]
Abstract
Essential tremor (ET) is the most prevalent tremor disorder. ET has traditionally been viewed as a monosymptomatic disorder characterized by a kinetic arm tremor, but this definition is gradually being replaced. The clinical spectrum has come to include several motor features, including tremor and ataxia, and several non-motor features, including possible cognitive impairment and personality disturbances. Postmortem studies are revealing several different patterns of pathology. The emerging view is that ET might be a family of diseases, unified by the presence of kinetic tremor, but further characterized by etiological, clinical and pathological heterogeneity. Effective pharmacological treatments for the disorder remain limited, although new insights into disease mechanisms might result in more-effective therapies. In addition, recent investigations of environmental toxicants that might be linked to ET open the way towards primary disease prevention through a reduction in exposure to these factors.
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Rincon F, Louis ED. Benefits and risks of pharmacological and surgical treatments for essential tremor: disease mechanisms and current management. Expert Opin Drug Saf 2006; 4:899-913. [PMID: 16111452 DOI: 10.1517/14740338.4.5.899] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Essential tremor (ET) is a neurological disease (and possibly a family of diseases) whose most recognisable feature is an action tremor of the hands and occasionally of the voice and head. Current data support the view that CNS gamma-amino-butyric acid (GABA)-ergic mechanisms may underlie ET and that the tremor may be further modulated by peripheral (muscle) adrenoreceptors. Potential pharmacotherapeutic options, targeted to influence the activity of the neurotransmitter GABA within the CNS and the peripheral adrenergic receptors, are part of the current armamentarium to treat ET. As such, primidone and propranolol remain the mainstays of the therapy for ET. Intramuscular injections of botulinum toxin A may play a role in the treatment of voice and head tremor. Surgical options, which are reserved for patients with severe, medically-refractory tremor, provide adequate tremor control in the majority of patients. As with other progressive neurological disorders of late life, the ability to use neuroprotective medications to intervene in the developing disease to either slow or halt the progression of the pathological process, would involve an understanding of underlying disease mechanisms. The understanding of these mechanisms in ET is limited and further study of these mechanisms is critical for the development of such therapies.
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Affiliation(s)
- Fred Rincon
- Department of Neurology, Columbia University, College of Physicians and Surgeons, New York, NY, USA
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Lyons KE, Pahwa R, Comella CL, Eisa MS, Elble RJ, Fahn S, Jankovic J, Juncos JL, Koller WC, Ondo WG, Sethi KD, Stern MB, Tanner CM, Tintner R, Watts RL. Benefits and risks of pharmacological treatments for essential tremor. Drug Saf 2003; 26:461-81. [PMID: 12735785 DOI: 10.2165/00002018-200326070-00003] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Essential tremor can cause significant functional disability in some patients. The arms are the most common body part affected and cause the most functional disability. The treatment of essential tremor includes medications, surgical options and other forms of therapy. Presently there is no cure for essential tremor nor are there any medications that can slow the progression of tremor. Treatment for essential tremor is recommended if the tremor causes functional disability. If the tremor is disabling only during periods of stress and anxiety, propranolol and benzodiazepines can be used during those periods when the tremor causes functional disability. The currently available medications can improve tremor in approximately 50% of the patients. If the tremor is disabling, treatment should be initiated with either primidone or propranolol. If either primidone or propranolol do not provide adequate control of the tremor, then the medications can be used in combination. If patients experience adverse effects with propranolol, occasionally other beta-adrenoceptor antagonists (such as atenolol or metoprolol) can be used. If primidone and propranolol do not provide adequate control of tremor, occasionally the use of benzodiazepines (such as clonazepam) can provide benefit. Other medications that may be helpful include gabapentin or topiramate. If a patient has disabling head or voice tremor, botulinum toxin injections into the muscles may provide relief from the tremor. Botulinum toxin in the hand muscles for hand tremor can result in bothersome hand weakness and is not widely used. There are other medications that have been tried in essential tremor and have questionable efficacy. These drugs include carbonic anhydrase inhibitors (e.g. methazolamide), phenobarbital, calcium channel antagonists (e.g. nimodipine), isoniazid, clonidine, clozapine and mirtazapine. If the patient still has disabling tremor after medication trials, surgical options are usually considered. Surgical options include thalamotomy and deep brain stimulation of the thalamus. These surgical options provide adequate tremor control in approximately 90% of the patients. Surgical morbidity and mortality for these procedures is low. Deep brain stimulation and thalamotomy have been shown to have comparable efficacy but fewer complications have been reported with deep brain stimulation. In patients undergoing bilateral procedures deep brain stimulation of the thalamus is the procedure of choice to avoid adverse effects seen with bilateral ablative procedures. The use of medication and/or surgery can provide adequate tremor control in the majority of the patients.
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Affiliation(s)
- Kelly E Lyons
- University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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Abstract
Essential tremor (ET) is the most prevalent tremor syndrome. It commonly affects the hands, head, voice, and other body parts. Appropriate management begins with correct diagnosis. Primidone and propranolol are the first-line medications for the treatment for ET, but several other medications may also provide benefit. In patients with medically refractory tremor, alternative therapies, including surgery or injections of botulinum toxin, may be considered.
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Affiliation(s)
- Theresa A Zesiewicz
- Parkinson's Disease and Movement Disorders Center and Department of Neurology, University of South Florida, Harborside Medical Tower, 4 Columbia Drive, Suite 410, Tampa, FL 33606, USA.
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O'Suilleabhain P, Dewey RB. Randomized trial comparing primidone initiation schedules for treating essential tremor. Mov Disord 2002; 17:382-6. [PMID: 11921128 DOI: 10.1002/mds.10083] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Early side effects are common when primidone is used to treat essential tremor, with as many as one-third of patients failing to tolerate the tablets. Lower doses can be prescribed initially using a suspension formulation. We suspected suspension initiation would result in fewer early side effects, allow better acclimatization, and improve compliance. Forty patients with essential tremor were randomized to begin primidone treatment using either 2.5 mg doses in the suspension form or 25 mg doses in the tablet form. Doses gradually increased over 3 weeks to 150 mg/day. This was a double-blind, double-dummy trial. Medication cessation due to side effects was designated the primary end-point. Four patients in the suspension group and two in the tablet group dropped out due to early side effects, resulting in a relative risk of 1.9 (95% confidence interval 0.4 to 9.2). Side effects in the first 48 hours of treatment were equally common, affecting seven subjects in each group. Treatment benefits were the same in both groups. We concluded that use of a very low initial dose and a graduated titration schedule in suspension formulation did not appear to improve primidone tolerability. If anything, compliance tended to be worse when compared with the tablet formulation, though the study was under-powered to reject the null hypothesis of equivalence.
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Affiliation(s)
- Padraig O'Suilleabhain
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
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Affiliation(s)
- E D Louis
- Gertrude H. Sergievsky Center and the Department of Neurology, Columbia University, New York, USA.
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Abstract
Tremor is classified according to anatomic distribution among body parts, and by frequency and amplitude during rest, postural maintenance, movement, intention, and the performance of specific tasks. Key historical features include age at onset, progression over time, family history, exacerbating and remitting factors and behaviors, response to alcohol and medications, and additional neurological signs and symptoms. Accurate diagnosis is a critical factor in predicting the natural history and response to treatment.
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Affiliation(s)
- T A Zesiewicz
- Parkinson's Disease and Movement Disorders Center, Department of Neurology, Department of Pharmacology and Experimental Therapeutics, University of South Florida, Tampa, Florida, USA
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Louis ED, Barnes L, Wendt KJ, Ford B, Sangiorgio M, Tabbal S, Lewis L, Kaufmann P, Moskowitz C, Comella CL, Goetz CC, Lang AE. A teaching videotape for the assessment of essential tremor. Mov Disord 2001; 16:89-93. [PMID: 11215599 DOI: 10.1002/1531-8257(200101)16:1<89::aid-mds1001>3.0.co;2-l] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
UNLABELLED Teaching videotapes, developed to aid in the evaluation of several movement disorders, have not been used in essential tremor research. As part of the Washington Heights-Inwood Genetic Study of Essential Tremor (WHIGET), we developed a reliable and valid tremor rating scale. Because this rating scale is currently being used by investigators at other centers, we developed a teaching videotape to aid in the consistent application of this scale. OBJECTIVE To develop a teaching videotape for a revised version of the WHIGET Tremor Rating Scale and to assess the interrater agreement among raters who used this videotape to rate tremor. METHODS The revised WHIGET Tremor Rating Scale was used to rate action tremor from 0 to 4 during six tests: arm extension, pouring, drinking, using a spoon, finger-to-nose, and drawing spirals. A 22-minute teaching videotape was developed that includes a 29-item educational section and a self-assessment section consisting of 20 examples of tremor ratings chosen by the two WHIGET study neurologists. Eight raters, including senior movement disorder specialists, movement disorder fellows, general neurologists, and a movement disorder nurse practitioner, independently viewed the videotape and rated tremor during the self-assessment section. Interobserver reliability was assessed with weighted kappa statistics (kappa(w)). RESULTS Eight raters each rated 20 items (160 ratings total). Total kappa(w) was 0.97 (nearly perfect agreement). Interrater reliability was as follows: kappa(w) = 0.99 (movement disorder specialists), kappa(w) = 0.98 (movement disorder fellows), and kappa(w) = 0.97 (general neurologists); all kappa(w) were nearly perfect. CONCLUSIONS This teaching videotape may be used to improve the uniform application of the revised WHIGET Tremor Rating Scale by raters with various levels of experience in movement disorders.
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Affiliation(s)
- E D Louis
- Department of Neurology, Columbia University, New York, New York, USA
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Sasso E, Perucca E, Fava R, Calzetti S. Quantitative comparison of barbiturates in essential hand and head tremor. Mov Disord 1991; 6:65-8. [PMID: 2005924 DOI: 10.1002/mds.870060112] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The tremorolytic effects of primidone and phenobarbital in essential tremor of hands and head were compared in a double-blind, placebo-controlled trial. Quantitative measurements of tremor were obtained in 15 patients by means of an accelerometric method. Only primidone proved to be superior to placebo in reducing hand tremor, suggesting that its tremorolytic effectiveness is largely dependent on the parent drug rather than its metabolite phenobarbital. Head tremor tended to improve only in three out of six patients with both primidone and phenobarbital, but, likely due to the small number of affected patients, the effect failed to reach statistical significance.
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Affiliation(s)
- E Sasso
- Institute of Neurology, University of Parma, Italy
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Martines C, Gatti G, Sasso E, Calzetti S, Perucca E. The disposition of primidone in elderly patients. Br J Clin Pharmacol 1990; 30:607-11. [PMID: 2291873 PMCID: PMC1368252 DOI: 10.1111/j.1365-2125.1990.tb03820.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
1. The pharmacokinetics and metabolism of primidone at steady-state were studied in 10 elderly patients aged 70-81 years and eight control subjects aged 18-26 years. 2. Primidone half-lives and clearance values (mean +/- s.d.) were similar in the elderly and in the young (12.1 +/- 4.6 vs 14.7 +/- 3.5 h and 34.8 +/- 9.0 vs 33.2 +/- 7.2 ml h-1 kg-1 respectively. 3. The serum concentrations of the metabolites phenylethylmalonamide (PEMA) and phenobarbitone relative to those of parent drug were higher in the elderly than in the young, the difference being significant (P less than 0.01) in the case of PEMA. 4. The renal clearances of primidone, phenobarbitone and PEMA were moderately decreased in the elderly but this reduction was statistically significant only for PEMA. Elderly patients excreted a reduced proportion of unchanged primidone and an increased proportion of PEMA in urine. 5. Ageing is associated with a greater accumulation of PEMA, which is unlikely to have a major clinical significance.
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Affiliation(s)
- C Martines
- Department of Internal Medicine and Therapeutics, University of Pavia, Italy
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