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Handforth A, Singh RP, Kosoyan HP, Kadam PA. A Role for GABA A Receptor β3 Subunits in Mediating Harmaline Tremor Suppression by Alcohol: Implications for Essential Tremor Therapy. Tremor Other Hyperkinet Mov (N Y) 2024; 14:20. [PMID: 38681506 PMCID: PMC11049614 DOI: 10.5334/tohm.834] [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] [Received: 10/27/2023] [Accepted: 03/31/2024] [Indexed: 05/01/2024] Open
Abstract
Background Essential tremor patients may find that low alcohol amounts suppress tremor. A candidate mechanism is modulation of α6β3δ extra-synaptic GABAA receptors, that in vitro respond to non-intoxicating alcohol levels. We previously found that low-dose alcohol reduces harmaline tremor in wild-type mice, but not in littermates lacking δ or α6 subunits. Here we addressed whether low-dose alcohol requires the β3 subunit for tremor suppression. Methods We tested whether low-dose alcohol suppresses tremor in cre-negative mice with intact β3 exon 3 flanked by loxP, and in littermates in which this region was excised by cre expressed under the α6 subunit promotor. Tremor in the harmaline model was measured as a percentage of motion power in the tremor bandwidth divided by overall motion power. Results Alcohol, 0.500 and 0.575 g/kg, reduced harmaline tremor compared to vehicle-treated controls in floxed β3 cre- mice, but had no effect on tremor in floxed β3 cre+ littermates that have β3 knocked out. This was not due to potential interference of α6 expression by the insertion of the cre gene into the α6 gene since non-floxed β3 cre+ and cre- littermates exhibited similar tremor suppression by alcohol. Discussion As α6β3δ GABAA receptors are sensitive to low-dose alcohol, and cerebellar granule cells express β3 and are the predominant brain site for α6 and δ expression together, our overall findings suggest alcohol acts to suppress tremor by modulating α6β3δ GABAA receptors on these cells. Novel drugs that target this receptor may potentially be effective and well-tolerated for essential tremor. Highlights We previously found with the harmaline essential tremor model that GABAA receptors containing α6 and δ subunits mediate tremor suppression by alcohol. We now show that β3 subunits in α6-expressing cells, likely cerebellar granule cells, are also required, indicating that alcohol suppresses tremor by modulating α6β3δ extra-synaptic GABAA receptors.
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Affiliation(s)
- Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Ram P. Singh
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Hovsep P. Kosoyan
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Pournima A. Kadam
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, USA
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McGurrin P, Norato G, Thompson-Westra J, McCrossin G, Lines E, Lungu C, Pandey S, Tinaz S, Voller B, Ramchandani V, Hallett M, Haubenberger D. Objective response to ethanol in essential tremor: results from a standardized ethanol challenge study. Ann Clin Transl Neurol 2024; 11:156-168. [PMID: 38087917 PMCID: PMC10791018 DOI: 10.1002/acn3.51943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 10/29/2023] [Indexed: 01/17/2024] Open
Abstract
BACKGROUND AND OBJECTIVES Ethanol has been reported to improve tremor severity in approximately two thirds of patients with essential tremor (ET), but the accuracy of that proportion is not certain and the mechanism of action is unknown. The goal of this study was to investigate alcohol response on tremor by applying an a priori objective response definition and subsequently to describe the responder rate to a standardized ethanol dose in a cohort of 85 ET patients. A secondary analysis evaluated other tremor and nontremor features, including demographics, tremor intensity, breath alcohol concentration, nontremor effects of alcohol, self-reported responder status to ethanol, and prior ethanol exposure. METHODS This was a prospective, open-label, single-dose challenge of oral ethanol during which motor and nonmotor measurements were obtained starting immediately prior to ethanol administration and subsequently every 20 min for 120 min. We defined tremor reduction as a 35% decline in power in the patient's tremor frequency recorded during spiral drawing 60 min after ethanol administration. RESULTS In total, 80% of patients were considered alcohol responsive using our objective definition. Responder status and change in the objective tremor metrics were significantly correlated with the change in breath alcohol concentration levels after ethanol administration, but no other relationships to nontremor metrics were found. DISCUSSION A high percentage of patients actually respond to acute ethanol. However, their self-reported response does not correlate well with their objective response. Objective response correlates with breath alcohol level but not with sedation, indicating a specific effect of ethanol on tremor.
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Affiliation(s)
- Patrick McGurrin
- Office of the Senior Vice President and Provost, University of Maryland, College Park, Maryland, USA
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Gina Norato
- Office of the Clinical Director, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Johanna Thompson-Westra
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
- Department of Family Medicine, University of Colorado Anschutz, Aurora, Colorado, USA
| | - Gayle McCrossin
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
- Department of Rehabilitation Medicine, Office of Strategic Research, Applied Physiology and Exercise Science Lab, National Institutes of Health, Bethesda, Maryland, USA
| | - Emily Lines
- Department of Family Medicine, University of Colorado Anschutz, Aurora, Colorado, USA
| | - Codrin Lungu
- Division of Clinical Research, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Sanjay Pandey
- Department of Neurology and Stroke Medicine, Amrita Hospital, Faridabad, India
| | - Sule Tinaz
- Department of Neurology, Yale School of Medicine, New Haven, Connecticut, USA
| | | | - Vijay Ramchandani
- Human Psychopharmacology Laboratory, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland, USA
| | - Mark Hallett
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Dietrich Haubenberger
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
- Office of the Clinical Director, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
- Department of Neurosciences, University of San Diego California, La Jolla, California, USA
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Handforth A, Kosoyan HP, Kadam PA, Singh RP. Alcohol and Ganaxolone Suppress Tremor via Extra-Synaptic GABA A Receptors in the Harmaline Model of Essential Tremor. Tremor Other Hyperkinet Mov (N Y) 2023; 13:18. [PMID: 37214542 PMCID: PMC10198231 DOI: 10.5334/tohm.760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 05/06/2023] [Indexed: 05/24/2023] Open
Abstract
Background A long-standing question is why essential tremor often responds to non-intoxicating amounts of alcohol. Blood flow imaging and high-density electroencephalography have indicated that alcohol acts on tremor within the cerebellum. As extra-synaptic δ-subunit-containing GABAA receptors are sensitive to low alcohol levels, we wondered whether these receptors mediate alcohol's anti-tremor effect and, moreover, whether the δ-associated GABAA receptor α6 subunit, found abundantly in the cerebellum, is required. Methods We tested the hypotheses that low-dose alcohol will suppress harmaline-induced tremor in wild-type mice, but not in littermates lacking GABAA receptor δ subunits, nor in littermates lacking α6 subunits. As the neurosteroid ganaxolone also activates extra-synaptic GABAA receptors, we similarly assessed this compound. The harmaline mouse model of essential tremor was utilized to generate tremor, measured as a percentage of motion power in the tremor bandwidth (9-16 Hz) divided by background motion power at 0.25-32 Hz. Results Ethanol, 0.500 and 0.575 g/kg, and ganaxolone, 7 and 10 mg/kg, doses that do not impair performance in a sensitive psychomotor task, reduced harmaline tremor compared to vehicle-treated controls in wild-type mice but failed to suppress tremor in littermates lacking the δ or the α6 GABAA receptor subunit. Discussion As cerebellar granule cells are the predominant brain site intensely expressing GABAA receptors containing both α6 and δ subunits, these findings suggest that this is where alcohol acts to suppress tremor. It is anticipated that medications designed specifically to target α6βδ-containing GABAA receptors may be effective and well-tolerated for treating essential tremor. Highlights How does alcohol temporarily ameliorate essential tremor? This study with a mouse model found that two specific kinds of GABA receptor subunits were needed for alcohol to work. As receptors with both these subunits are found mainly in cerebellum, this work suggests this is where alcohol acts to suppress tremor.
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Affiliation(s)
- Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - Hovsep P. Kosoyan
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - Pournima A. Kadam
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - Ram P. Singh
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
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Huang YH, Lee MT, Hsueh HY, Knutson DE, Cook J, Mihovilovic MD, Sieghart W, Chiou LC. Cerebellar α6GABA A Receptors as a Therapeutic Target for Essential Tremor: Proof-of-Concept Study with Ethanol and Pyrazoloquinolinones. Neurotherapeutics 2023; 20:399-418. [PMID: 36696034 PMCID: PMC10121996 DOI: 10.1007/s13311-023-01342-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2022] [Indexed: 01/26/2023] Open
Abstract
Ethanol has been shown to suppress essential tremor (ET) in patients at low-to-moderate doses, but its mechanism(s) of action remain unknown. One of the ET hypotheses attributes the ET tremorgenesis to the over-activated firing of inferior olivary neurons, causing synchronic rhythmic firings of cerebellar Purkinje cells. Purkinje cells, however, also receive excitatory inputs from granule cells where the α6 subunit-containing GABAA receptors (α6GABAARs) are abundantly expressed. Since ethanol is a positive allosteric modulator (PAM) of α6GABAARs, such action may mediate its anti-tremor effect. Employing the harmaline-induced ET model in male ICR mice, we evaluated the possible anti-tremor effects of ethanol and α6GABAAR-selective pyrazoloquinolinone PAMs. The burrowing activity, an indicator of well-being in rodents, was measured concurrently. Ethanol significantly and dose-dependently attenuated action tremor at non-sedative doses (0.4-2.4 g/kg, i.p.). Propranolol and α6GABAAR-selective pyrazoloquinolinones also significantly suppressed tremor activity. Neither ethanol nor propranolol, but only pyrazoloquinolinones, restored burrowing activity in harmaline-treated mice. Importantly, intra-cerebellar micro-injection of furosemide (an α6GABAAR antagonist) had a trend of blocking the effect of pyrazoloquinolinone Compound 6 or ethanol on harmaline-induced tremor. In addition, the anti-tremor effects of Compound 6 and ethanol were synergistic. These results suggest that low doses of ethanol and α6GABAAR-selective PAMs can attenuate action tremor, at least partially by modulating cerebellar α6GABAARs. Thus, α6GABAARs are potential therapeutic targets for ET, and α6GABAAR-selective PAMs may be a potential mono- or add-on therapy.
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Affiliation(s)
- Ya-Hsien Huang
- Department and Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, No. 1, Jen-Ai Rd., Section 1, Taipei, 10051, Taiwan
| | - Ming Tatt Lee
- Department and Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, No. 1, Jen-Ai Rd., Section 1, Taipei, 10051, Taiwan
- Faculty of Pharmaceutical Sciences, UCSI University, Kuala Lumpur, 56000, Malaysia
| | - Han-Yun Hsueh
- Department and Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, No. 1, Jen-Ai Rd., Section 1, Taipei, 10051, Taiwan
| | - Daniel E Knutson
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, 53211, USA
| | - James Cook
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, 53211, USA
| | | | - Werner Sieghart
- Center for Brain Research, Department of Molecular Neurosciences, Medical University Vienna, Vienna, 1090, Austria
| | - Lih-Chu Chiou
- Department and Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, No. 1, Jen-Ai Rd., Section 1, Taipei, 10051, Taiwan.
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan.
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, 40402, Taiwan.
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Heimburg T. The thermodynamic soliton theory of the nervous impulse and possible medical implications. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2022; 173:24-35. [PMID: 35640761 DOI: 10.1016/j.pbiomolbio.2022.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 05/05/2022] [Accepted: 05/22/2022] [Indexed: 06/15/2023]
Abstract
The textbook picture of nerve activity is that of a propagating voltage pulse driven by electrical currents through ion channel proteins, which are gated by changes in voltage, temperature, pressure or by drugs. All function is directly attributed to single molecules. We show that this leaves out many important thermodynamic couplings between different variables. A more recent alternative picture for the nerve pulse is of thermodynamic nature. It considers the nerve pulse as a soliton, i.e., a macroscopic excited region with properties that are influenced by thermodynamic variables including voltage, temperature, pressure and chemical potentials of membrane components. All thermodynamic variables are strictly coupled. We discuss the consequences for medical treatment in a view where one can compensate a maladjustment of one variable by adjusting another variable. For instance, one can explain why anesthesia can be counteracted by hydrostatic pressure and decrease in pH, suggest reasons why lithium over-dose may lead to tremor, and how tremor is related to alcohol intoxication. Lithium action as well as the effect of ethanol and the anesthetic ketamine in bipolar patients may fall in similar thermodynamic patterns. Such couplings remain obscure in a purely molecular picture. Other fields of application are the response of nerve activity to muscle stretching and the possibility of neural stimulation by ultrasound.
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Affiliation(s)
- T Heimburg
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100, Copenhagen Ø, Denmark.
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Santos de Alencar S, Crippa JAS, Brito MCM, Pimentel ÂV, Cecilio Hallak JE, Tumas V. A single oral dose of cannabidiol did not reduce upper limb tremor in patients with essential tremor. Parkinsonism Relat Disord 2021; 83:37-40. [PMID: 33465546 DOI: 10.1016/j.parkreldis.2021.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/13/2020] [Accepted: 01/04/2021] [Indexed: 10/22/2022]
Abstract
Essential tremor (ET) is a common clinical syndrome characterized by action tremors affecting both upper limbs that can compromise manual tasks' execution and impair functional and social performance. The primary pharmacological treatment is symptomatic, but effective medicines are somewhat limited. There is a clear need to find new effective therapies for the treatment of ET. Cannabidiol (CBD) is a modulator of CB1 receptor and CB1 agonists can reduce tremors in experimental models. We hypothesized that a single acute CBD intake would reduce tremors in ET patients. We performed a randomized, controlled, double-blind, crossover study on 19 patients with ET. They were 10 males and 9 females, had mean 63 years of age, and mean 23 years of disease duration and had insufficient control of their tremors with the usual pharmacological treatment. They ingested a single oral dose of CBD (300 mg) or placebo in two experimental sessions performed 2-weeks apart. Patients were evaluated immediately before and after oral ingestion (60 min and 210 min), using the Fahn-Tolosa-Marin clinical scale. There was no carryover effect. There were no significant differences in upper limb tremors score, specific motor task tremor scores (writing and drawing/pouring) or clinical impression of change after treatment with placebo or CBD. In conclusion, a single 300 mg oral dose of CBD had no significant effect on the severity of upper limb tremors of ET patients. Our findings did not exclude the possibility that chronic treatment with CBD could have a symptomatic effect.
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Affiliation(s)
| | - José Alexandre S Crippa
- Department of Neurosciences and Behavior, Ribeirão Preto Medical School, University of São Paulo, Brazil.
| | | | - Ângela V Pimentel
- Ribeirão Preto Medical School Hospital, University of São Paulo, Brazil.
| | | | - Vitor Tumas
- Department of Neurosciences and Behavior, Ribeirão Preto Medical School, University of São Paulo, Brazil.
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Abstract
Patients with essential tremor, vocal tremor, torticollis, myoclonus-dystonia and posthypoxic myoclonus often benefit in a surprisingly rapid and robust manner from ingestion of a modest amount of alcohol (ethanol). Despite considerable investigation, the mechanism of ethanol’s ability to produce this effect remains a mystery. In this paper, we review the pharmacology of ethanol and its analogue GHB (or sodium oxybate), summarize the published literature of alcohol-responsive hyperkinetic movement disorders, and demonstrate videos of patients we have treated over the last fifteen years with either an ethanol challenge or with chronic sodium oxybate therapy. We then propose a novel explanation for this phenomenon—namely, that ingestion of modest doses of ethanol (or sodium oxybate) normalizes the aberrant motor networks underling these disorders. We propose that alcohol and its analogues improve clinical symptoms and their physiologic correlate by restoring the normal firing pattern of the major outflow pathways of the cerebellum (the Purkinje cells and deep cerebellar nuclei), We present evidence to support this hypothesis in animal models and in affected patients, and suggest future investigations to test this model.
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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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Cao H, Thompson-Westra J, Hallett M, Haubenberger D. The response of the central and peripheral tremor component to octanoic acid in patients with essential tremor. Clin Neurophysiol 2018; 129:1467-1471. [PMID: 29678370 DOI: 10.1016/j.clinph.2018.03.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 02/26/2018] [Accepted: 03/10/2018] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To investigate the effect of octanoic acid (OA) on the peripheral component of tremor, as well as OA's differential effects on the central and peripheral tremor component in essential tremor (ET) patients. METHODS We analyzed postural tremor accelerometry data from a double-blind placebo-controlled cross-over study evaluating the effect of 4 mg/kg OA in ET. The weighted condition was used to identify tremor power for both the central and peripheral tremor components. Exploratory non-parametric statistical analyses were used to describe the relation between the central and peripheral component of tremor power. RESULTS A peripheral tremor component was identified in 4 out of 18 subjects. Tremor power was reduced after OA administration in both the central and the peripheral tremor component. There was a positive correlation of tremor power between the central and peripheral component, both after placebo and OA. CONCLUSIONS When present, the peripheral component was closely related to the central tremor component. We hypothesize that the magnitude of the peripheral mechanical component of tremor is determined by that of the central component. SIGNIFICANCE Both central and peripheral component of tremor are reduced after OA, with the central component providing the energy driving the peripheral component.
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Affiliation(s)
- Hongmei Cao
- Department of Neurology, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, 277 Yanta Western Road, Xi'an 710061, China; National Institute of Neurological Disorders and Stroke, National Institutes of Health, 9000 Rockville Pike, Building 10, Bethesda, MD 20892, USA
| | - Johanna Thompson-Westra
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, 9000 Rockville Pike, Building 10, Bethesda, MD 20892, USA
| | - Mark Hallett
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, 9000 Rockville Pike, Building 10, Bethesda, MD 20892, USA
| | - Dietrich Haubenberger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, 9000 Rockville Pike, Building 10, Bethesda, MD 20892, USA.
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Knowledge gaps and research recommendations for essential tremor. Parkinsonism Relat Disord 2016; 33:27-35. [PMID: 27769649 DOI: 10.1016/j.parkreldis.2016.10.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 08/29/2016] [Accepted: 10/01/2016] [Indexed: 12/17/2022]
Abstract
Essential tremor (ET) is a common cause of significant disability, but its etiologies and pathogenesis are poorly understood. Research has been hampered by the variable definition of ET and by non-standardized research approaches. The National Institute of Neurological Disorders and Stroke (USA) invited experts in ET and related fields to discuss current knowledge, controversies, and gaps in our understanding of ET and to develop recommendations for future research. Discussion focused on phenomenology and phenotypes, therapies and clinical trials, pathophysiology, pathology, and genetics. Across all areas, the need for collaborative and coordinated research on a multinational level was expressed. Standardized data collection using common data elements for genetic, clinical, neurophysiological, and pathological studies was recommended. Large cohorts of patients should be studied prospectively to collect bio-samples, characterize the natural history of the clinical syndrome including patient-oriented outcomes, investigate potential etiologies of various phenotypes, and identify pathophysiological mechanisms. In particular, cellular and system-level mechanisms of tremor oscillations should be elucidated because they may yield effective therapeutic targets and biomarkers. A neuropathology consortium was recommended to standardize postmortem analysis and further characterize neuropathological observations in the cerebellum and elsewhere. Furthermore, genome-wide association studies on large patient cohorts (>10,000 patients) may allow the identification of common genes contributing to risk, and whole exome or genome sequencing may enable the identification of genetic risk and causal mutations in cohorts and well-characterized families.
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Silva D, Matias C, Bourne S, Nagel S, Machado A, Lobel D. Effects of chronic alcohol consumption on long-term outcomes of thalamic deep brain stimulation for essential tremor. J Clin Neurosci 2016; 31:142-6. [PMID: 27401226 DOI: 10.1016/j.jocn.2016.03.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 03/08/2016] [Indexed: 11/28/2022]
Abstract
The prevalence of essential tremor (ET) is about 4% above 40years of age. Chronic alcohol consumption is present in around 20% of patients with ET. Our objective was to identify whether chronic alcohol consumption was associated with a negative effect on tremor outcome after thalamic deep brain stimulation (DBS) in ET patients. We conducted a retrospective chart review, from January 2005 to December 2012, from which 23 patients who had ventral intermediate nucleus (Vim)-DBS surgery for ET were identified. Seven patients had a positive history of chronic alcohol consumption. We defined as chronic alcohol users those patients with a habit of drinking alcohol every day in order to suppress tremor. In the overall group of 23 patients, there was a reduction in the median tremor score from 8 pre-operatively, to 1 post-operatively (p<0.0001). The alcohol consumers group experienced a reduction in the median tremor score from 6 pre-operatively to 0 post-operatively (p=0.03). The non-alcohol consumers group had a reduction in the median tremor score from 8 pre-operatively to 1.7 post-operatively (p<0.0001). Both groups of patients experienced significant benefit from thalamic DBS. A larger study may reveal statistically significant differences between subgroups.
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Affiliation(s)
- Danilo Silva
- Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic, OH 44124, USA.
| | - Caio Matias
- Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic, OH 44124, USA
| | - Sarah Bourne
- Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic, OH 44124, USA
| | - Sean Nagel
- Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic, OH 44124, USA
| | - Andre Machado
- Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic, OH 44124, USA
| | - Darlene Lobel
- Center for Neurological Restoration, Department of Neurosurgery, Neurological Institute, Cleveland Clinic, OH 44124, USA
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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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Kahathuduwa CN, Weerasinghe VS, Dassanayake TL, Priyadarshana R, Dissanayake AL, Perera C. Task-specific kinetic finger tremor affects the performance of carrom players. J Sports Sci 2015; 34:923-8. [PMID: 26280452 DOI: 10.1080/02640414.2015.1078487] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
We aimed to determine the effect of task-specific kinetic finger tremor, as indexed by surface electromyography (EMG), on the accuracy of a carrom stroke. Surface EMG of extensor digitorum communis muscle of the playing arm was recorded during rest, isometric contraction and stroke execution in 17 male carrom players with clinically observed finger tremor and 18 skill- and age-matched controls. Log-transformed power spectral densities (LogPSDs) of surface EMG activity (signifying tremor severity) at a 1-s pre-execution period correlated with angular error of the stroke. LogPSDs in 4-10 Hz range were higher in players with tremor than controls during pre-execution (P < 0.001), but not during the resting state (P = 0.067). Pre-execution tremor amplitude correlated with angular deviation (r = 0.45, P = 0.007). For the first time, we document a task-specific kinetic finger tremor in carrom players. This finger tremor during the immediate pre-execution phase appears to be a significant determinant of stroke accuracy.
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Affiliation(s)
- Chanaka N Kahathuduwa
- a Department of Physiology, Faculty of Medicine , University of Peradeniya , Sri Lanka.,b Department of Nutritional Sciences , Texas Tech University , Lubbock , TX , USA
| | - Vajira S Weerasinghe
- a Department of Physiology, Faculty of Medicine , University of Peradeniya , Sri Lanka
| | - Tharaka L Dassanayake
- a Department of Physiology, Faculty of Medicine , University of Peradeniya , Sri Lanka.,c School of Psychology , The University of Newcastle , Australia
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Sharifi S, Nederveen AJ, Booij J, van Rootselaar AF. Neuroimaging essentials in essential tremor: a systematic review. NEUROIMAGE-CLINICAL 2014; 5:217-31. [PMID: 25068111 PMCID: PMC4110352 DOI: 10.1016/j.nicl.2014.05.003] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 05/03/2014] [Accepted: 05/05/2014] [Indexed: 01/04/2023]
Abstract
Background Essential tremor is regarded to be a disease of the central nervous system. Neuroimaging is a rapidly growing field with potential benefits to both diagnostics and research. The exact role of imaging techniques with respect to essential tremor in research and clinical practice is not clear. A systematic review of the different imaging techniques in essential tremor is lacking in the literature. Methods We performed a systematic literature search combining the terms essential tremor and familial tremor with the following keywords: imaging, MRI, VBM, DWI, fMRI, PET and SPECT, both in abbreviated form as well as in full form. We summarize and discuss the quality and the external validity of each study and place the results in the context of existing knowledge regarding the pathophysiology of essential tremor. Results A total of 48 neuroimaging studies met our search criteria, roughly divided into 19 structural and 29 functional and metabolic studies. The quality of the studies varied, especially concerning inclusion criteria. Functional imaging studies indicated cerebellar hyperactivity during rest and during tremor. The studies also pointed to the involvement of the thalamus, the inferior olive and the red nucleus. Structural studies showed less consistent results. Discussion and conclusion Neuroimaging techniques in essential tremor give insight into the pathophysiology of essential tremor indicating the involvement of the cerebellum as the most consistent finding. GABAergic dysfunction might be a major premise in the pathophysiological hypotheses. Inconsistencies between studies can be partly explained by the inclusion of heterogeneous patient groups. Improvement of scientific research requires more stringent inclusion criteria and application of advanced analysis techniques. Also, the use of multimodal neuroimaging techniques is a promising development in movement disorders research. Currently, the role of imaging techniques in essential tremor in daily clinical practice is limited. We conducted a systematic review of neuroimaging studies in essential tremor. Cerebellar involvement is the most consistent finding. GABAergic dysfunction is worthwhile investigating more intensively. We encourage multimodal neuroimaging focussing on brain networks.
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Affiliation(s)
- Sarvi Sharifi
- Department of Neurology, Academic Medical Center, Amsterdam, The Netherlands ; Brain Imaging Center, Academic Medical Center, Amsterdam, The Netherlands
| | - Aart J Nederveen
- Brain Imaging Center, Academic Medical Center, Amsterdam, The Netherlands ; Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Jan Booij
- Brain Imaging Center, Academic Medical Center, Amsterdam, The Netherlands ; Department of Nuclear Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - Anne-Fleur van Rootselaar
- Department of Neurology, Academic Medical Center, Amsterdam, The Netherlands ; Brain Imaging Center, Academic Medical Center, Amsterdam, The Netherlands
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Rajput AH, Rajput A. Medical treatment of essential tremor. J Cent Nerv Syst Dis 2014; 6:29-39. [PMID: 24812533 PMCID: PMC3999812 DOI: 10.4137/jcnsd.s13570] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 03/10/2014] [Accepted: 03/12/2014] [Indexed: 11/05/2022] Open
Abstract
Essential tremor (ET) is the most common pathological tremor characterized by upper limb action-postural tremor (PT)/kinetic tremor (KT). There are no specific neuropathological or biochemical abnormalities in ET. The disability is consequent to amplitude of KT, which may remain mild without handicap or may become disabling. The most effective drugs for sustained tremor control are propranolol and primidone. Symptomatic drug treatment must be individualized depending on the circumstances that provoke the tremor-related disability. Broad guidelines for treatment are discussed in this review. Patients may be treated intermittently only on stressful occasions with propranolol, clonazepam, or primidone monotherapy, or an alcoholic drink. Those with persistently disabling tremor need continued treatment.
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Affiliation(s)
- Ali H Rajput
- University of Saskatchewan, Canada
- Saskatoon Health Region, Canada
| | - Alex Rajput
- University of Saskatchewan, Canada
- Saskatoon Health Region, Canada
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Haubenberger D, Nahab FB, Voller B, Hallett M. Treatment of essential tremor with long-chain alcohols: still experimental or ready for prime time? Tremor Other Hyperkinet Mov (N Y) 2014; 4:tre-04-211-4673-2. [PMID: 24587968 PMCID: PMC3918508 DOI: 10.7916/d8rx991r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 12/31/2013] [Indexed: 12/30/2022] Open
Abstract
AIM To review current literature on long-chain alcohols and their derivatives as novel pharmacotherapy for the treatment of essential tremor (ET). BACKGROUND Currently available and recommended pharmacotherapies for ET are often limited by suboptimal treatment effects, frequent adverse effects, and drug interactions. While ethanol is reported to profoundly decrease tremor severity in the majority of patients with ET, preclinical experience suggests that long-chain alcohols such as 1-octanol might lead to a comparable tremor reduction without ethanol's typical side effects of sedation and intoxication. Here, we review the literature on the first clinical trials on 1-octanol and its metabolite octanoic acid (OA) for the treatment of ET. METHODS The literature on preclinical and clinical trials on long-chain alcohols as well as OA was reviewed and summarized, and an outlook given on next phases of development. DISCUSSION 1-octanol was demonstrated to be safe and effective in a double-blind, placebo-controlled low-dose trial, and open-label data showed excellent tolerability and dose-dependent efficacy up to 128 mg/kg. Despite 1-octanol's efficacy, its future viability as an effective therapy is limited by its pharmacological properties that require large volumes to be orally administered. Pharmacokinetic data indicate that OA is the active metabolite of 1-octanol. Preclinical efficacy data for OA are positive, and human pilot data demonstrated excellent safety as well as efficacy in secondary outcome measures of tremor amplitudes. OA also has more favorable pharmacological properties for drug delivery; hence, OA may be worth developing as a pharmaceutical.
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Affiliation(s)
- Dietrich Haubenberger
- Department of Neurology, Medical University of Vienna, Vienna, Austria
- Human Motor Control Section, Medical Neurology Branch, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Fatta B. Nahab
- Movement Disorders Center, Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
| | - Bernhard Voller
- Department of Neurology, Medical University of Vienna, Vienna, Austria
- Human Motor Control Section, Medical Neurology Branch, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Mark Hallett
- Human Motor Control Section, Medical Neurology Branch, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
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Voller B, Lines E, McCrossin G, Artiles A, Tinaz S, Lungu C, Hallett M, Haubenberger D. Alcohol challenge and sensitivity to change of the Essential Tremor Rating Assessment Scale. Mov Disord 2013; 29:555-8. [PMID: 24123358 DOI: 10.1002/mds.25667] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 07/20/2013] [Accepted: 08/12/2013] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND The ability of the Essential Tremor (ET) Rating Assessment Scale (TETRAS) to detect changes in tremor severity is unknown. METHODS Fifteen adult ET patients received a single oral ethanol dose calculated to reach 0.05 g/dL breath alcohol content (brAC). Effects were investigated independently with accelerometry and TETRAS. RESULTS Accelerometry data were log-transformed and a cumulative score logACC(R+L) was calculated. Correlation between logACC(R+L) and TETRAS was significant. TETRAS and accelerometry showed a significant effect of time point using repeated-measures analysis of variance. The difference between baseline and each of the following six time points as well as the correlation of TETRAS with brAC were significant. The calculated minimum detectable change of TETRAS was 8.9% and the effect size was d = 4.75 (95% confidence interval: 3.60-5.90). CONCLUSION We demonstrated sensitivity to change of the TETRAS performance scale after a therapeutic intervention, which further establishes its potential for use in both clinical and research settings.
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Affiliation(s)
- Bernhard Voller
- Human Motor Control Section, Medical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA; Department of Neurology, Medical University of Vienna, Vienna, Austria
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Cohort study of prevalence and phenomenology of tremor in dementia with Lewy bodies. J Neurol 2013; 260:1731-42. [PMID: 23400498 PMCID: PMC3705145 DOI: 10.1007/s00415-013-6853-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 01/21/2013] [Accepted: 01/22/2013] [Indexed: 10/27/2022]
Abstract
To study prevalence, specific patterns and response to treatment of tremor in dementia with Lewy bodies (DLB), in comparison with other tremulous disorders prevalence, qualitative and quantitative features of tremor were studied in an incident cohort of 67 dopaminergic treatment naive DLB, 111 Parkinson's Disease (PD) and 34 Essential Tremor (ET) patients. Tremulous DLB patients (tDLB) were compared with tremulous PD (tPD) and ET patients and followed for 2 years. Double blind placebo-controlled acute drug challenge with L-Dopa and alcohol was performed in all ET, 24 tDLB and 27 tPD. Effects of dopaminergic chronic treatment in all tDLB and tPD patients and primidone in 8 tDLB were also assessed. Tremor occurred in 44.76 % of DLB patients. The tDLB patients presented a complex pattern of mixed tremors, characterized by rest and postural/action tremor, including walking tremor and standing overflow in 50 % tDLB. Standing tremor with overflow was characteristic of tDLB (p < 0.001). Head tremor was more frequent in tDLB than tPD and ET (p = 0.001). The tDLB tremors were reduced by acute and chronic dopaminergic treatments (p < 0.01) but not by alcohol or primidone. Tremor occurs commonly in DLB patients with a complex mixed tremor pattern which shows a significant response to acute and chronic dopaminergic treatments. Recognizing that there is a clinical category of tremulous DLB may help the differential diagnosis of tremors.
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Zoethout RWM, Iannone R, Bloem BR, Palcza J, Murphy G, Chodakewitz J, Buntinx A, Gottesdiener K, Marsilio S, Rosen L, van Dyck K, Louis ED, Cohen AF, Schoemaker RC, Tokita S, Sato N, Koblan KS, Hargreaves RH, Renger J, van Gerven JMA. The effects of a novel histamine-3 receptor inverse agonist on essential tremor in comparison to stable levels of alcohol. J Psychopharmacol 2012; 26:292-302. [PMID: 21335358 DOI: 10.1177/0269881111398685] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Essential tremor (ET) is a common movement disorder. Animal studies show that histaminergic modulation may affect the pathological processes involved in the generation of ET. Histamine-3 receptor inverse agonists (H3RIA) have demonstrated attenuating effects on ET in the harmaline rat model. In this double-blind, three-way cross-over, single-dose, double-dummy study the effects of 25 mg of a novel H3RIA (MK-0249) and a stable alcohol level (0.6 g L(-1)) were compared with placebo, in 18 patients with ET. Tremor was evaluated using laboratory tremorography, portable tremorography and a clinical rating scale. The Leeds Sleep Evaluation Questionnaire (LSEQ) and a choice reaction time (CRT) test were performed to evaluate potential effects on sleep and attention, respectively. A steady state of alcohol significantly diminished tremor as assessed by laboratory tremorography, portable tremorography and clinical ratings compared with placebo. A high single MK-0249 dose was not effective in reducing tremor, but caused significant effects on the LSEQ and the CRT test. These results suggest that treatment with a single dose of MK-0249 does not improve tremor in alcohol-responsive patients with ET, whereas stable levels of alcohol as a positive control reproduced the commonly reported tremor-diminishing effects of alcohol.
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Affiliation(s)
- R W M Zoethout
- Centre for Human Drug Research, Leiden, the Netherlands.
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de Haas SL, Zoethout RWM, Van Dyck K, De Smet M, Rosen LB, Murphy MG, Gottesdiener KM, Schoemaker RC, Cohen AF, van Gerven JMA. The effects of TPA023, a GABAAα2,3 subtype-selective partial agonist, on essential tremor in comparison to alcohol. J Psychopharmacol 2012; 26:282-91. [PMID: 21890585 DOI: 10.1177/0269881111415731] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Essential tremor (ET) is a relatively frequent neurological disorder that responds in some patients to gamma-aminobutyric acid A (GABA(A)) agonists such as the benzodiazepines. Partial subtype-selective GABA(A) agonists may have an improved side effect profile compared to non-selective GABA(A) agonists. However, it is unknown which GABA(A) subtypes are involved in the therapeutic effects of benzodiazepines in ET. The effects of 2 mg TPA023, a GABA(A) α2,3 subtype-selective partial agonist, on ET were compared to the effects of a stable alcohol level (0.6 g/L) and placebo in nine patients with ET. Tremor evaluation included laboratory accelerometry and a performance-based scale. Additional measurements were performed to evaluate other effects on the central nervous system (CNS). Alcohol significantly diminished tremor symptoms in the postural and kinetic condition, as assessed by laboratory accelerometry, but the performance-based rating scale was unaffected. Tremor was also reduced after TPA023 treatment in the kinetic condition, albeit not significantly. Additionally, TPA023 decreased saccadic peak velocity, while alcohol decreased subjective feelings of alertness. This study showed that alcohol reduced maximum tremor power, as assessed by laboratory accelerometry, unlike TPA023, which decreased tremor symptoms to some extent but not significantly. This study showed that treatment with an α2,3 subunit-selective GABA(A) partial agonist was less effective than a stable level of alcohol in reducing ET symptoms. These results provide no support for a therapeutic role of TPA023 in the suppression of ET symptoms.
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Affiliation(s)
- S L de Haas
- Centre for Human Drug Research, Leiden, the Netherlands
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Knudsen K, Lorenz D, Deuschl G. A clinical test for the alcohol sensitivity of essential tremor. Mov Disord 2011; 26:2291-5. [PMID: 22021159 DOI: 10.1002/mds.23846] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 05/13/2011] [Accepted: 05/23/2011] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND The objective of the study was to develop a simple diagnostic test for alcohol sensitivity of essential tremor patients. Here we describe the controlled measurements of tremor severity after alcohol ingestion and the practicability of using it as a home test. METHODS Ten patients were tested for alcohol sensitivity under controlled conditions in the laboratory (blood alcohol, quantitative tremor recordings, modified Fahn scale, visual analog scale, Archimedes spirals), and 15 patients were instructed to perform an alcohol test at home (visual analog scale, Archimedes spirals) following an adapted dosage of alcohol. RESULTS The time course of the antitremor effect showed significant improvement of up to 50% in both groups for all the outcome parameters. Tremor deteriorated after 3 hours. A quarter of the patients noticed the alcohol effect for the first time during the test. CONCLUSIONS Alcohol is an effective drug for essential tremor. Its effect is only short-lived and exhibits a rebound after > 3 hours and the next morning. We propose this essential tremor home test as a diagnostic tool to confirm the alcohol sensitivity of essential tremor.
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Affiliation(s)
- Karina Knudsen
- Department of Neurology, Christian-Albrechts-University, Kiel, Germany
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Haubenberger D, Kalowitz D, Nahab FB, Toro C, Ippolito D, Luckenbaugh DA, Wittevrongel L, Hallett M. Validation of digital spiral analysis as outcome parameter for clinical trials in essential tremor. Mov Disord 2011; 26:2073-80. [PMID: 21714004 DOI: 10.1002/mds.23808] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 04/21/2011] [Accepted: 04/28/2011] [Indexed: 11/08/2022] Open
Abstract
Essential tremor, one of the most prevalent movement disorders, is characterized by kinetic and postural tremor affecting activities of daily living. Spiral drawing is commonly used to visually rate tremor intensity, as part of the routine clinical assessment of tremor and as a tool in clinical trials. We present a strategy to quantify tremor severity from spirals drawn on a digitizing tablet. We validate our method against a well-established visual spiral rating method and compare both methods on their capacity to capture a therapeutic effect, as defined by the change in clinical essential tremor rating scale after an ethanol challenge. Fifty-four Archimedes spirals were drawn using a digitizing tablet by nine ethanol-responsive patients with essential tremor before and at five consecutive time points after the administration of ethanol in a standardized treatment intervention. Quantitative spiral tremor severity was estimated from the velocity tremor peak amplitude after numerical derivation and Fourier transformation of pen-tip positions. In randomly ordered sets, spirals were scored by seven trained raters, using Bain and Findley's 0 to 10 rating scale. Computerized scores correlated with visual ratings (P < 0.0001). The correlation was significant at each time point before and after ethanol (P < 0.005). Quantitative ratings provided better sensitivity than visual rating to capture the effects of an ethanol challenge (P < 0.05). Using a standardized treatment approach, we were able to demonstrate that spirography time-series analysis is a valid, reliable method to document tremor intensity and a more sensitive measure for small effects than currently available visual spiral rating methods.
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Affiliation(s)
- Dietrich Haubenberger
- Human Motor Control Section, Medical Neurology Branch, NINDS/NIH, Bethesda, Maryland, USA.
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Mostile G, Jankovic J. Alcohol in essential tremor and other movement disorders. Mov Disord 2010; 25:2274-84. [DOI: 10.1002/mds.23240] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Boecker H, Weindl A, Brooks DJ, Ceballos-Baumann AO, Liedtke C, Miederer M, Sprenger T, Wagner KJ, Miederer I. GABAergic dysfunction in essential tremor: an 11C-flumazenil PET study. J Nucl Med 2010; 51:1030-5. [PMID: 20554735 DOI: 10.2967/jnumed.109.074120] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
UNLABELLED Essential tremor is the most common movement disorder, but the underlying pathophysiology is not well understood. A primary overactivity of cerebellothalamic output pathways is the most conspicuous finding, as indicated by animal and human studies. It has been argued that this overactivity may be due to impaired central inhibition, and converging evidence points toward a potential role of gamma-aminobutyric acid (GABA) dysfunction in tremor generation. METHODS Using (11)C-flumazenil and PET, we calculated the distribution volume, an index of availability of benzodiazepine receptor sites of the GABA(A) complex, in a group of 8 patients with bilateral essential tremor, as compared with 11 healthy controls. RESULTS Significant increases in binding of (11)C-flumazenil at the benzodiazepine receptor site of the GABA(A) receptor in the cerebellum, the ventrolateral thalamus, and the lateral premotor cortex were identified in the essential tremor group. CONCLUSION Essential tremor is associated with reduced GABAergic function and increased availability of benzodiazepine receptor sites in brain regions implicated specifically in tremor genesis. This finding is thought to reflect overactivity of cerebellothalamic circuits and, hence, lends support to the "GABA hypothesis" of essential tremor.
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Affiliation(s)
- Henning Boecker
- Nuklearmedizinische Klinik, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
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Kinugawa K, Vidailhet M, Clot F, Apartis E, Grabli D, Roze E. Myoclonus-dystonia: an update. Mov Disord 2009; 24:479-89. [PMID: 19117361 DOI: 10.1002/mds.22425] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Our knowledge of the clinical, neurophysiological, and genetic aspects of myoclonus-dystonia (M-D) has improved markedly in the recent years. Basic research has provided new insights into the complex dysfunctions involved in the pathogenesis of M-D. On the basis of a comprehensive literature search, this review summarizes current knowledge on M-D, with a focus on recent findings. We also propose modified diagnostic criteria and recommendations for clinical management.
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Martínez C, García-Martín E, Alonso-Navarro H, Benito-León J, Puertas I, Rubio L, López-Alburquerque T, Agúndez JAG, Jiménez-Jiménez FJ. Alcohol dehydrogenase 2 genotype and allelic variants are not associated with the risk for essential tremor. Clin Neuropharmacol 2007; 30:196-200. [PMID: 17762315 DOI: 10.1097/wnf.0b013e3180413d94] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To investigate the possible association between alcohol dehydrogenase 1B, beta-polypeptide (ADH2) genotype and allelic variants and the risk for developing essential tremor (ET). METHODS Leukocytary DNA from 204 ET patients and 200 healthy controls was studied for the genotype ADH2 and the occurrence of ADH2 allelic variants using allele-specific polymerase chain reaction amplification and MslI-restriction fragment length polymorphism's analyses. RESULTS The frequencies of the ADH2*1/ADH2*2 genotype and of the allelic variant ADH2*2 did not differ significantly in ET patients when compared with those of the controls. The mean age at onset of ET did not differ significantly between patients with genotypes ADH2*1/ADH2*2 and ADH2*1/ADH2*1. The frequencies of the genotype ADH2*1/ADH2*2 and of the allelic variant ADH2*2 in patients with voice, tongue, and chin tremors did not differ from those of the controls, whereas patients with voice tremor showed lower frequencies of mutated genotypes and ADH2*2 alleles. The frequencies of ADH2 genotypes and ADH2 alleles did not differ significantly between patients who did not drink ethanol and those who reported improvement, no improvement, or unknown response of tremor to ethanol. CONCLUSIONS These results suggest that ADH2 genotype and allelic variants are not associated with the risk for ET in white Spanish people.
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Affiliation(s)
- Carmen Martínez
- Department of Pharmacology and Psychiatry, Medical School, University of Extremadura, Badajoz, Spain
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Abstract
Many movement disorders, including tics, chorea, tremor, myoclonus and parkinsonism, may result from substance abuse. However, alcohol in particular is associated in a more complex manner with two specific movement disorders, essential tremor (ET) and myoclonus-dystonia (M-D). In this review we discuss the comorbidity of alcohol abuse in both ET and M-D, the ameliorative effects of alcohol in both diseases, and review the data evaluating alcohol abuse secondary to self-medication. We also discuss shared pathophysiologic mechanisms in the understanding of both of these disorders, as the elucidation of the mechanisms by which alcohol exerts its effects may lead to novel therapeutic approaches.
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Abstract
Tremor is often a disabling primary condition or secondary to another disorder. No universally effective pharmacological agent exists for the treatment of essential tremor, and patients differ greatly in their response to therapies, thus requiring individualised regimens. Deep brain stimulation is the best option for patients with disabling, drug-resistant essential tremor. Resting tremor in Parkinson's disease is usually not the primary disabling feature, and in most cases, levodopa/carbidopa is satisfactory for many years. Young Parkinson's patients with dominant, disabling tremor benefit from anticholinergics in addition to dopaminergic therapies. However, older Parkinson's patients with more disabling tremor may suffer from dose-dependent side effects, and deep brain stimulation should be considered. This article outlines the available pharmacological agents and treatment considerations for various disabling tremors, including essential tremor and Parkinson's disease.
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Kralic JE, Criswell HE, Osterman JL, O'Buckley TK, Wilkie ME, Matthews DB, Hamre K, Breese GR, Homanics GE, Morrow AL. Genetic essential tremor in gamma-aminobutyric acidA receptor alpha1 subunit knockout mice. J Clin Invest 2005; 115:774-9. [PMID: 15765150 PMCID: PMC1052003 DOI: 10.1172/jci23625] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Accepted: 12/21/2004] [Indexed: 12/16/2022] Open
Abstract
Essential tremor is the most common movement disorder and has an unknown etiology. Here we report that gamma-aminobutyric acidA (GABA(A)) receptor alpha1-/- mice exhibit postural and kinetic tremor and motor incoordination that is characteristic of essential tremor disease. We tested mice with essential-like tremor using current drug therapies that alleviate symptoms in essential tremor patients (primidone, propranolol, and gabapentin) and several candidates hypothesized to reduce tremor, including ethanol; the noncompetitive N-methyl-D-aspartate receptor antagonist MK-801; the adenosine A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA); the GABA(A) receptor modulators diazepam, allopregnanolone, and Ro15-4513; and the L-type Ca2+ channel antagonist nitrendipine. Primidone, propranolol, and gabapentin reduced the amplitude (power) of the pathologic tremor. Nonsedative doses of ethanol eliminated tremor in mice. Diazepam, allopregnanolone, Ro15-4513, and nitrendipine had no effect or enhanced tremor, whereas MK-801 and CCPA reduced tremor. To understand the etiology of tremor in these mice, we studied the electrophysiological properties of cerebellar Purkinje cells. Cerebellar Purkinje cells in GABA(A) receptor alpha1-/- mice exhibited a profound loss of all responses to synaptic or exogenous GABA, but no differences in abundance, gross morphology, or spontaneous synaptic activity were observed. This genetic animal model elucidates a mechanism of GABAergic dysfunction in the major motor pathway and potential targets for pharmacotherapy of essential tremor.
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Affiliation(s)
- Jason E Kralic
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7178, USA
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Kralic JE, Criswell HE, Osterman JL, O’Buckley TK, Wilkie ME, Matthews DB, Hamre K, Breese GR, Homanics GE, Morrow AL. Genetic essential tremor in γ-aminobutyric acidA receptor α1 subunit knockout mice. J Clin Invest 2005. [DOI: 10.1172/jci200523625] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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