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Matthews LG, Puryear CB, Correia SS, Srinivasan S, Belfort GM, Pan MK, Kuo SH. T-type calcium channels as therapeutic targets in essential tremor and Parkinson's disease. Ann Clin Transl Neurol 2023; 10:462-483. [PMID: 36738196 PMCID: PMC10109288 DOI: 10.1002/acn3.51735] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 12/20/2022] [Accepted: 12/21/2022] [Indexed: 02/05/2023] Open
Abstract
Neuronal action potential firing patterns are key components of healthy brain function. Importantly, restoring dysregulated neuronal firing patterns has the potential to be a promising strategy in the development of novel therapeutics for disorders of the central nervous system. Here, we review the pathophysiology of essential tremor and Parkinson's disease, the two most common movement disorders, with a focus on mechanisms underlying the genesis of abnormal firing patterns in the implicated neural circuits. Aberrant burst firing of neurons in the cerebello-thalamo-cortical and basal ganglia-thalamo-cortical circuits contribute to the clinical symptoms of essential tremor and Parkinson's disease, respectively, and T-type calcium channels play a key role in regulating this activity in both the disorders. Accordingly, modulating T-type calcium channel activity has received attention as a potentially promising therapeutic approach to normalize abnormal burst firing in these diseases. In this review, we explore the evidence supporting the theory that T-type calcium channel blockers can ameliorate the pathophysiologic mechanisms underlying essential tremor and Parkinson's disease, furthering the case for clinical investigation of these compounds. We conclude with key considerations for future investigational efforts, providing a critical framework for the development of much needed agents capable of targeting the dysfunctional circuitry underlying movement disorders such as essential tremor, Parkinson's disease, and beyond.
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Affiliation(s)
| | - Corey B Puryear
- Praxis Precision Medicines, Boston, Massachusetts, 02110, USA
| | | | - Sharan Srinivasan
- Praxis Precision Medicines, Boston, Massachusetts, 02110, USA.,Department of Neurology, University of Michigan, Ann Arbor, Michigan, 48109, USA
| | | | - Ming-Kai Pan
- Department and Graduate Institute of Pharmacology, National Taiwan University College of Medicine, Taipei, 10051, Taiwan.,Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, 10617, Taiwan.,Department of Medical Research, National Taiwan University Hospital, Taipei, 10002, Taiwan.,Cerebellar Research Center, National Taiwan University Hospital, Yun-Lin Branch, Yun-Lin, 64041, Taiwan
| | - Sheng-Han Kuo
- Department of Neurology, Columbia University, New York, New York, 10032, USA.,Initiative for Columbia Ataxia and Tremor, Columbia University, New York, New York, 10032, USA
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2
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Pillai KS, Bhat P, Srivastava AK, Rajan R, Radhakrishnan DM, Elavarasi A, Srivastava MP, Singh MB, Vishnu VY, Prasad K, Pandit AK, Goyal V. Zonisamide add-on in tremor-dominant Parkinson's disease- A randomized controlled clinical trial. Parkinsonism Relat Disord 2022; 105:1-6. [PMID: 36323130 DOI: 10.1016/j.parkreldis.2022.10.017] [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: 07/11/2022] [Revised: 10/13/2022] [Accepted: 10/13/2022] [Indexed: 11/07/2022]
Abstract
INTRODUCTION and objective: Tremor is a disabling symptom of PD that usually responds poorly to available standard pharmacological agents. This study aimed to assess the effect of Zonisamide 25 mg on tremor in tremor-dominant PD patients as compared to placebo. METHODS This was a randomized, placebo-controlled, double-blind study. Parkinson's disease patients were allocated either to the intervention group (standard treatment along with Zonisamide 25 mg add-on) or the placebo group (standard treatment along with placebo). Baseline Unified Parkinson's Disease Rating Scale (UPDRS) and Tremor Research Group Essential Tremor Rating Scale (TETRAS) scores, as well as accelerometric tremor analysis were done and follow-up assessments of the same were done after 12 weeks of intervention. Percentage change from baseline in the UPDRS tremor score was the primary outcome whereas percentage change from baseline of total UPDRS score, UPDRS rigidity and bradykinesia scores, TETRAS score, and accelerometric tremor analysis values were the secondary outcomes. RESULTS There was no significant difference in the percentage change from baseline UPDRS tremor scores between the two groups (placebo: 8.33 [-19.89-23.86] vs drug: 26.14 [-35.58 to -16.07], p-value: 0.164, CI: 0.157-0.171). Best-case analysis for missing values showed a significant improvement in the drug group, compared to the placebo group (p-value: < 0.001, CI: <0.001 - <0.001). CONCLUSION Zonisamide at a dose of 25 mg per day did not improve tremor in tremor-dominant PD patients, however, a positive trend was seen as compared to Placebo in the UPDRS tremor score. Larger studies are required to confirm this finding.
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Affiliation(s)
| | - Priyanka Bhat
- Department of Neurology, All India Institute of Medical Sciences, Delhi, India
| | | | - Roopa Rajan
- Department of Neurology, All India Institute of Medical Sciences, Delhi, India
| | | | | | - Mv Padma Srivastava
- Department of Neurology, All India Institute of Medical Sciences, Delhi, India
| | - Mamta Bhushan Singh
- Department of Neurology, All India Institute of Medical Sciences, Delhi, India
| | - V Y Vishnu
- Department of Neurology, All India Institute of Medical Sciences, Delhi, India
| | - Kameshwar Prasad
- Department of Neurology, All India Institute of Medical Sciences, Delhi, India
| | - Awadh Kishor Pandit
- Department of Neurology, All India Institute of Medical Sciences, Delhi, India
| | - Vinay Goyal
- Department of Neurology, All India Institute of Medical Sciences, Delhi, India; Institute of Neurosciences, Medanta the Medicity, Gurugram, Haryana, India.
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Sáenz-Farret M, Tijssen MAJ, Eliashiv D, Fisher RS, Sethi K, Fasano A. Antiseizure Drugs and Movement Disorders. CNS Drugs 2022; 36:859-876. [PMID: 35861924 DOI: 10.1007/s40263-022-00937-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/30/2022] [Indexed: 11/03/2022]
Abstract
The relationship between antiseizure drugs and movement disorders is complex and not adequately reviewed so far. Antiseizure drugs as a treatment for tremor and other entities such as myoclonus and restless leg syndrome is the most common scenario, although the scientific evidence supporting their use is variable. However, antiseizure drugs also represent a potential cause of iatrogenic movement disorders, with parkinsonism and tremor the most common disorders. Many other antiseizure drug-induced movement disorders are possible and not always correctly identified. This review was conducted by searching for all the possible combinations between 15 movement disorders (excluding ataxia) and 24 antiseizure drugs. The main objective was to describe the movement disorders treated and worsened or induced by antiseizure drugs. We also summarized the proposed mechanisms and risk factors involved in the complex interaction between antiseizure drugs and movement disorders. Antiseizure drugs mainly used to treat movement disorders are clonazepam, gabapentin, lacosamide, levetiracetam, oxcarbazepine, perampanel, phenobarbital, pregabalin, primidone, topiramate, and zonisamide. Antiseizure drugs that worsen or induce movement disorders are cenobamate, ethosuximide, felbamate, lamotrigine, phenytoin, tiagabine, and vigabatrin. Antiseizure drugs with a variable effect on movement disorders are carbamazepine and valproate while no effect on movement disorders has been reported for brivaracetam, eslicarbazepine, lacosamide, and stiripentol. Although little information is available on the adverse effects or benefits on movement disorders of newer antiseizure drugs (such as brivaracetam, cenobamate, eslicarbazepine, lacosamide, and rufinamide), the evidence collected in this review should guide the choice of antiseizure drugs in patients with concomitant epilepsy and movement disorders. Finally, these notions can lead to a better understanding of the mechanisms involved in the pathophysiology and treatments of movement disorders.
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Affiliation(s)
- Michel Sáenz-Farret
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital, University Health Network, Division of Neurology, University of Toronto, 399 Bathurst St, Toronto, ON, M5T 2S8, Canada
| | - Marina A J Tijssen
- Department of Neurology, University of Groningen, Groningen, The Netherlands.,Expertise Center Movement Disorders Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Dawn Eliashiv
- UCLA Seizure Disorder Center, Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Robert S Fisher
- Departments of Neurology and Neurological Sciences and Neurosurgery, Stanford University, Stanford, CA, USA
| | - Kapil Sethi
- Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Alfonso Fasano
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital, University Health Network, Division of Neurology, University of Toronto, 399 Bathurst St, Toronto, ON, M5T 2S8, Canada. .,Krembil Brain Institute, Toronto, ON, Canada. .,Center for Advancing Neurotechnological Innovation to Application (CRANIA), Toronto, ON, Canada.
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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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5
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Bellows S, Jimenez-Shahed J. Is essential tremor a disorder of GABA dysfunction? No. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 163:285-310. [PMID: 35750366 DOI: 10.1016/bs.irn.2022.02.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Although essential tremor is common, its underlying pathophysiology remains uncertain, and several hypotheses seek to explain the tremor mechanism. The GABA hypothesis states that disinhibition of deep cerebellar neurons due to reduced GABAergic input from Purkinje cells results in increased pacemaker activity, leading to rhythmic output to the thalamo-cortical circuit and resulting in tremor. However, some neuroimaging, spectroscopy, and pathology studies have not shown a clear or consistent GABA deficiency in essential tremor, and animal models have indicated that large reductions of Purkinje cell inhibition may improve tremor. Instead, tremor is increasingly attributable to dysfunction in oscillating networks, where altered (but not necessarily reduced) inhibitory signaling can result in tremor. Hypersynchrony of Purkinje cell activity may account for excessive oscillatory cerebellar output, with potential contributions along multiple sites of the olivocerebellar loop. Although older animal tremor models, such as harmaline tremor, have explored contributions from the inferior olivary body, increasing evidence has pointed to the role of aberrant climbing fiber synaptic organization in oscillatory cerebellar activity and tremor generation. New animal models such as hotfoot17j mice, which exhibit abnormal climbing fiber organization due to mutations in Grid2, have recapitulated many features of ET. Similar abnormal climbing fiber architecture and excessive cerebellar oscillations as measured by EEG have been found in humans with essential tremor. Further understanding of hypersynchrony and excessive oscillatory activity in ET phenotypes may lead to more targeted and effective treatment options.
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6
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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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Sharma S, Pandey S. Treatment of essential tremor: current status. Postgrad Med J 2019; 96:84-93. [DOI: 10.1136/postgradmedj-2019-136647] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 08/14/2019] [Accepted: 09/13/2019] [Indexed: 12/18/2022]
Abstract
Essential tremor is the most common cause of tremor involving upper limbs, head and voice. The first line of treatment for limb tremor is pharmacotherapy with propranolol or primidone. However, these two drugs reduce the tremor severity by only half. In medication refractory and functionally disabling tremor, alternative forms of therapy need to be considered. Botulinum toxin injections are likely efficacious for limb, voice and head tremor but are associated with side effects. Surgical interventions include deep brain stimulation; magnetic resonance-guided focused ultrasound and thalamotomy for unilateral and deep brain stimulation for bilateral procedures. Recent consensus classification for essential tremor has included a new subgroup, ‘Essential tremor plus’, who have associated subtle neurological ‘soft signs’, such as dystonic posturing of limbs and may require a different treatment approach. In this review, we have addressed the current management of essential tremor with regard to different anatomical locations of tremor as well as different modalities of treatment.
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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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Papapetropoulos S, Lee MS, Boyer S, Newbold EJ. A Phase 2, Randomized, Double-Blind, Placebo-Controlled Trial of CX-8998, a Selective Modulator of the T-Type Calcium Channel in Inadequately Treated Moderate to Severe Essential Tremor: T-CALM Study Design and Methodology for Efficacy Endpoint and Digital Biomarker Selection. Front Neurol 2019; 10:597. [PMID: 31244760 PMCID: PMC6579833 DOI: 10.3389/fneur.2019.00597] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/21/2019] [Indexed: 11/13/2022] Open
Abstract
Background: Essential tremor (ET) is a common, progressive neurological syndrome with bilateral upper-limb dysfunction of at least 3-year duration, with or without tremor in other body locations. This disorder has a negative impact on daily function and quality of life. A single oral therapy has been approved by FDA for ET. Off-label pharmacotherapies have inadequate efficacy and poor tolerability with high rates of patient dissatisfaction and discontinuation. Safe and efficacious pharmacotherapies are urgently needed to decrease tremor and improve daily living. T-CALM (Tremor-CAv3 modulation) protocol is designed to assess safety and efficacy of CX-8998, a selective modulator of the T-type calcium channel, for ET therapy. Methods/Design: T-CALM is a phase 2, proof of concept, randomized, double-blind, placebo-controlled trial. Titrated doses of CX-8998 to 10 mg BID or placebo will be administered for 28 days to moderate to severe ET patients who are inadequately treated with existing therapies. The primary endpoint will be change from baseline to day 28 of The Essential Tremor Rating Assessment Performance Subscale (TETRAS-PS). Secondary efficacy endpoints for clinician and patient perception of daily function will include TETRAS Activity of Daily Living (ADL), Quality of Life in Essential Tremor Questionnaire (QUEST), Clinical Global Impression-Improvement (CGI-I), Patient Global Impression of Change (PGIC), and Goal Attainment Scale (GAS). Kinesia One, Kinesia 360, and iMotor will biometrically evaluate motor function and tremor amplitude. Safety will be assessed by adverse events, physical and neurological exams and laboratory tests. Sample size of 43 patients per group is estimated to have 90% power to detect a 5.5-point difference between CX-8998 and placebo for TETRAS-PS. Efficacy analyses will be performed with covariance (ANCOVA) and 2-sided test at 0.05 significance level. Discussion: T-CALM has a unique design with physician rating scales, patient-focused questionnaires and scales and objective motor measurements to assess clinically meaningful and congruent efficacy. Patient perception of ET debilitation and therapy with CX-8998 will be key findings. Overall goal of T-CALM is generation of safety and efficacy data to support a go, no-go decision to further develop CX-8998 for ET. Design of T-CALM may guide future clinical studies of ET pharmacotherapies. Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT03101241
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Abstract
BACKGROUND Essential tremor (ET) is one of the most common movement disorders. The treatment is primarily based on pharmacological agents. Although primidone and propranolol are well established treatments in clinical practice, they can be ineffective in 25% to 55% of patients, and can produce serious adverse events in a large percentage of them. For these reasons, it may be worthwhile evaluating the treatment alternatives for ET. Zonisamide has been suggested as a potentially useful agent for the treatment of ET but there is uncertainty about its efficacy and safety. OBJECTIVES To assess the effect on functional abilities and the safety profile of zonisamide in adults with essential tremor (ET). SEARCH METHODS We carried out a systematic search, without language restrictions to identify all relevant trials. We searched CENTRAL, MEDLINE, Embase, NICE, ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform (ICTRP) to January 2017. We searched BIOSIS Citation Index (2000 to January 2017) for conference proceedings. We handsearched grey literature and examined the reference lists of identified studies and reviews. SELECTION CRITERIA We included all randomised controlled trials (RCTs) of zonisamide versus placebo or any other treatment. We included studies in which the diagnosis of ET was made according to accepted and validated diagnostic criteria. We excluded studies conducted in patients presenting secondary forms of tremor or reporting only neurophysiological parameters to assess outcomes. DATA COLLECTION AND ANALYSIS Two review authors independently collected and extracted data using a data collection form. We assessed the risk of bias and the quality of evidence.We used inverse variance methods for continuous outcomes and measurement scales. We compared differences between treatment groups as mean differences. We combined results for dichotomous outcomes using Mantel-Haenszel methods and obtained risk differences to compare treatment groups. We used Review Manager 5 software for data management and analysis. MAIN RESULTS We only considered one study eligible for this review (20 participants). Assessments of risk of bias for most domains were unclear or low. Adverse events were only reported in participants from the zonisamide group, making it possible that they were aware of treatment group assignment. We are uncertain as to the effects of zonisamide on motor tasks (mean difference (MD) -0.00, 95% confidence interval (CI) -1.51 to 1.51, very low-quality evidence) and functional disabilities (MD -0.30, 95% CI -1.23 to 0.63, very low-quality evidence) when compared with placebo. Three participants in the zonisamide group (30%) and two participants in the placebo group (20%) discontinued the treatment and withdrew from the study for any reason (very low-quality evidence), however the increased risk of withdrawal in the zonisamide group was statistically non-significant (risk difference (RD) 0.1, 95% CI -0.28 to 0.48). Six participants in the zonisamide group (60%) and none of the participants in the placebo group (0%) developed adverse events (AEs), with a RD of 0.60 (95% CI 0.28 to 0.92; very low quality evidence). The most common AEs, experienced with zonisamide treatment, were headache, nausea, fatigue, sleepiness, and diarrhoea. Quality of life was not assessed in the study included. AUTHORS' CONCLUSIONS Based on currently available data, there is insufficient evidence to assess the efficacy and safety of zonisamide treatment for ET.
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Affiliation(s)
- Elisa Bruno
- University of CataniaDepartment GF Ingrassia, Section of NeurosciencesCataniaItaly95123
| | - Alessandra Nicoletti
- University of CataniaDepartment GF Ingrassia, Section of NeurosciencesCataniaItaly95123
| | - Graziella Filippini
- Fondazione IRCCS, Istituto Neurologico Carlo BestaScientific Directionvia Celoria, 11MilanItaly20133
| | - Graziella Quattrocchi
- University of CataniaDepartment GF Ingrassia, Section of NeurosciencesCataniaItaly95123
| | - Carlo Colosimo
- Terni University HospitalDepartment of NeurologyTerniItaly05100
| | - Mario Zappia
- University of CataniaDepartment GF Ingrassia, Section of NeurosciencesCataniaItaly95123
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Chen J. Zonisamide for the Management of Essential Tremor: An Illustrative Case Report on Long-Term Effectiveness. JOURNAL OF CONTEMPORARY PHARMACY PRACTICE 2017. [DOI: 10.37901/jcphp16-00007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Essential tremor, a common adult pathologic tremor disorder, is characterized by action tremors. Mainstays of treatment include gabapentin, primidone, and propranolol. However, many patients obtain insufficient benefit or do not tolerate these medications (especially the elderly). Short-term studies demonstrate that zonisamide may be effective for essential tremor; however, long-term data are lacking. This is a case report of an 83-year-old, right-handed man with essential tremor of the upper extremities and head who previously failed several pharmacological treatments (defined as obtaining inadequate benefit from maximum tolerated dose) with gabapentin, nadalol, propranolol, and primidone and was initiated on zonisamide monotherapy. Long-term zonisamide therapy (200 mg daily) was well tolerated in this elderly patient and associated with clinically significant improvement of upper extremity tremor and clinically modest improvement in head tremor. The beneficial effects and tolerability were sustained over nearly 28 months of follow-up treatment.
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12
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Essential tremor: Update of therapeutic strategies (medical treatment and gamma knife thalamotomy). Rev Neurol (Paris) 2016; 172:408-415. [DOI: 10.1016/j.neurol.2016.07.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 07/06/2016] [Accepted: 07/25/2016] [Indexed: 11/18/2022]
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Handforth A. Linking Essential Tremor to the Cerebellum—Animal Model Evidence. THE CEREBELLUM 2015; 15:285-98. [DOI: 10.1007/s12311-015-0750-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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15
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Pietrzak B, Zwierzyńska E, Krupa A. A Pharmaco-EEG-Based Assessment of the Interaction Between Ethanol and Zonisamide. Alcohol Alcohol 2014; 49:505-14. [DOI: 10.1093/alcalc/agu024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Abstract
Tremor is a hyperkinetic movement disorder characterized by rhythmic oscillations of one or more body parts. It can be disabling and may impair quality of life. Various etiological subtypes of tremor are recognized, with essential tremor (ET) and Parkinsonian tremor being the most common. Here we review the current literature on tremor treatment regarding ET and head and voice tremor, as well as dystonic tremor, orthostatic tremor, tremor due to multiple sclerosis (MS) or lesions in the brainstem or thalamus, neuropathic tremor, and functional (psychogenic) tremor, and summarize main findings. Most studies are available for ET and only few studies specifically focused on other tremor forms. Controlled trials outside ET are rare and hence most of the recommendations are based on a low level of evidence. For ET, propranolol and primidone are considered drugs of first choice with a mean effect size of approximately 50 % tremor reduction. The efficacy of topiramate is also supported by a large double-blind placebo-controlled trial, while other drugs have less supporting evidence. With a mean effect size of about 90 % deep brain stimulation in the nucleus ventralis intermedius or the subthalamic nucleus may be the most potent treatment; however, there are no controlled trials and it is reserved for severely affected patients. Dystonic limb tremor may respond to anticholinergics. Botulinum toxin improves head and voice tremor. Gabapentin and clonazepam are often recommended for orthostatic tremor. MS tremor responds only poorly to drug treatment. For patients with severe MS tremor, thalamic deep brain stimulation has been recommended. Patients with functional tremor may benefit from antidepressants and are best be treated in a multidisciplinary setting. Several tremor syndromes can already be treated with success. But new drugs specifically designed for tremor treatment are needed. ET is most likely covering different entities and their delineation may also improve treatment. Modern study designs and long-term studies are needed.
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Affiliation(s)
- Susanne A. Schneider
- Department of Neurology, Christian-Albrechts-University Kiel, University-Hospital Schleswig-Holstein, Campus Kiel, Schittenhelmstr. 10, 24105 Kiel, Germany
| | - Günther Deuschl
- Department of Neurology, Christian-Albrechts-University Kiel, University-Hospital Schleswig-Holstein, Campus Kiel, Schittenhelmstr. 10, 24105 Kiel, Germany
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17
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Shaw JD, Allison KG, Staffetti JS, Zesiewicz TA. Diagnosis and treatment of essential tremor. Neurodegener Dis Manag 2013. [DOI: 10.2217/nmt.13.52] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
SUMMARY Essential tremor (ET) is one of the most prevalent movement disorders in the world, affecting millions of people. Medications that are commonly used to treat ET include antiepileptic or antihypertensive medications. Primidone and propranolol are considered effective, first-line agents for treating ET, while atenolol, alprazolam and topiramate are considered second-line agents. Gabapentin appears to improve ET when used as a monotherapy, although not as an adjunct therapy. Alternatives to pharmacologic treatment for refractory ET include botulinum toxin A injections, deep-brain stimulation of the ventral intermediate nucleus of the thalamus and thalamotomy. Future developments in the treatment of ET will depend on valid animal models and a greater understanding of its pathophysiology.
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Affiliation(s)
- Jessica Davenport Shaw
- University of South Florida, Department of Neurology, Frances J Zesiewicz Center & Foundation for Parkinson’s Disease & University of South Florida Ataxia Research Center, 12901 Bruce B Downs Boulevard, MDC Box 55, Tampa, FL 33612, USA
| | - Kevin G Allison
- University of South Florida, Department of Neurology, Frances J Zesiewicz Center & Foundation for Parkinson’s Disease & University of South Florida Ataxia Research Center, 12901 Bruce B Downs Boulevard, MDC Box 55, Tampa, FL 33612, USA
| | - Joseph S Staffetti
- University of South Florida, Department of Neurology, Frances J Zesiewicz Center & Foundation for Parkinson’s Disease & University of South Florida Ataxia Research Center, 12901 Bruce B Downs Boulevard, MDC Box 55, Tampa, FL 33612, USA
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Abstract
OPINION STATEMENT Essential tremor is one of the most common movement disorders in the world. Although millions of people worldwide are affected by ET, only one medication, propranolol, is approved by the United States Food and Drug Administration to treat it. None of the medications currently used as ET therapy were developed specifically for this purpose, and select antihypertensive and antiepileptic medications remain at the forefront of ET therapy. Propranolol and primidone are considered "effective" agents that treat ET; topiramate, atenolol, and alprazolam are "probably effective", and nimodipine, nadolol, and clonazepam are "possibly effective". Medications that probably do not adequately treat ET include levetiracetam and pregabalin. Gabapentin appears to improve ET when used as monotherapy, but not when used as adjunct therapy. Sotalol has been found to be "probably effective" in treating ET in previous reviews, but it may be associated with arrhythmias and should not be routinely recommended. Botulinum toxin A may reduce limb tremor, but may cause dose dependent weakness. Deep brain stimulation (DBS) of the VIM is used as an alternative to pharmacological therapy of ET in patients who fail to adequately respond to medical therapy. The magnitude of effect from DBS is greater than from medical management, but more severe side effects are possible with surgery. Future treatment options for ET will depend on valid animal models, and a better understanding of its pathophysiology.
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Handforth A. Harmaline tremor: underlying mechanisms in a potential animal model of essential tremor. TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2012; 2. [PMID: 23440018 PMCID: PMC3572699 DOI: 10.7916/d8td9w2p] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 03/24/2012] [Indexed: 01/18/2023]
Abstract
BACKGROUND Harmaline and harmine are tremorigenic β-carbolines that, on administration to experimental animals, induce an acute postural and kinetic tremor of axial and truncal musculature. This drug-induced action tremor has been proposed as a model of essential tremor. Here we review what is known about harmaline tremor. METHODS Using the terms harmaline and harmine on PubMed, we searched for papers describing the effects of these β-carbolines on mammalian tissue, animals, or humans. RESULTS Investigations over four decades have shown that harmaline induces rhythmic burst-firing activity in the medial and dorsal accessory inferior olivary nuclei that is transmitted via climbing fibers to Purkinje cells and to the deep cerebellar nuclei, then to brainstem and spinal cord motoneurons. The critical structures required for tremor expression are the inferior olive, climbing fibers, and the deep cerebellar nuclei; Purkinje cells are not required. Enhanced synaptic norepinephrine or blockade of ionic glutamate receptors suppresses tremor, whereas enhanced synaptic serotonin exacerbates tremor. Benzodiazepines and muscimol suppress tremor. Alcohol suppresses harmaline tremor but exacerbates harmaline-associated neural damage. Recent investigations on the mechanism of harmaline tremor have focused on the T-type calcium channel. DISCUSSION Like essential tremor, harmaline tremor involves the cerebellum, and classic medications for essential tremor have been found to suppress harmaline tremor, leading to utilization of the harmaline model for preclinical testing of antitremor drugs. Limitations are that the model is acute, unlike essential tremor, and only approximately half of the drugs reported to suppress harmaline tremor are subsequently found to suppress tremor in clinical trials.
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Affiliation(s)
- Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
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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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Louis ED. Treatment of Essential Tremor: Are there Issues We are Overlooking? Front Neurol 2012; 2:91. [PMID: 22275907 PMCID: PMC3257846 DOI: 10.3389/fneur.2011.00091] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 12/28/2011] [Indexed: 12/19/2022] Open
Abstract
Background: Essential tremor (ET) is one of the most common neurological diseases. Although a large number of medications have been tested, there are only two first-line medications, primidone and propranolol, which is a situation that has not changed in approximately 30 years. Several recent reviews have summarized the current pharmacotherapeutic options for ET and the approach to the management of ET patients. Yet there remain a number of important issues, both scientific and clinical, that have not been broached in the literature and that have therapeutic implications. Objectives: To introduce several clinical and scientific issues that have not formally entered the published literature on the treatment of ET. Methods: In September 2011, materials for this article were gathered during a literature search of PubMed using the following terms: ET, clinical, clinical trial, treatment, medications, therapeutics. English-language articles were selected for further review. Results: The paper focuses on several topics that have received scant or no discussion in the published literature on ET therapeutics. These topics are as follows: the nature of the underlying disease pathophysiology, the presence of pathological heterogeneity, the complexity of cellular and neurochemical changes which may be underlying this disorder, the presence of clinical heterogeneity, the selection of treatment endpoints, the effects of diagnostic uncertainty, the presence of cognitive and psychiatric features in ET, the identification of possible modifiable risk factors, and the absence of any neuroprotective therapies. Conclusion: The author has identified several topics that have received scant or no discussion in the published literature on ET therapeutics. Further discussion of the issues raised here may lead to improvements in clinical trial methodologies as well as facilitate the development of fresh approaches to pharmacotherapy.
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Affiliation(s)
- Elan D Louis
- Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University New York, NY, USA
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Miwa H, Kondo T. T-type calcium channel as a new therapeutic target for tremor. THE CEREBELLUM 2012; 10:563-9. [PMID: 21479969 DOI: 10.1007/s12311-011-0277-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Voltage-gated calcium channels play an important role in many physiological and pathological processes. Accumulating studies suggest that the T-type calcium channel is a potential target for the treatment of various neurological disorders, such as epilepsy, insomnia, and neuropathic pain. Here, we highlight recent advances in our understanding of T-type calcium channel regulation and their implications for tremor disorders. Several T-type calcium channel blockers effectively suppressed experimental tremors that have been suggested to originate from either the cerebellum or basal ganglia. Among T-type calcium channel blockers that have been used clinically, the anti-tremor efficacy of zonisamide garnered our attention. Based on both basic and clinical studies, the possibility is emerging that T-type calcium channel blockers that transit into the central nervous system may have therapeutic potentials for tremor disorders.
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Affiliation(s)
- Hideto Miwa
- Department of Neurology, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8510, Japan.
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Zesiewicz TA, Elble RJ, Louis ED, Gronseth GS, Ondo WG, Dewey RB, Okun MS, Sullivan KL, Weiner WJ. Evidence-based guideline update: treatment of essential tremor: report of the Quality Standards subcommittee of the American Academy of Neurology. Neurology 2011; 77:1752-5. [PMID: 22013182 DOI: 10.1212/wnl.0b013e318236f0fd] [Citation(s) in RCA: 189] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND This evidence-based guideline is an update of the 2005 American Academy of Neurology practice parameter on the treatment of essential tremor (ET). METHODS A literature review using MEDLINE, EMBASE, Science Citation Index, and CINAHL was performed to identify clinical trials in patients with ET published between 2004 and April 2010. RESULTS AND RECOMMENDATIONS Conclusions and recommendations for the use of propranolol, primidone (Level A, established as effective); alprazolam, atenolol, gabapentin (monotherapy), sotalol, topiramate (Level B, probably effective); nadolol, nimodipine, clonazepam, botulinum toxin A, deep brain stimulation, thalamotomy (Level C, possibly effective); and gamma knife thalamotomy (Level U, insufficient evidence) are unchanged from the previous guideline. Changes to conclusions and recommendations from the previous guideline include the following: 1) levetiracetam and 3,4-diaminopyridine probably do not reduce limb tremor in ET and should not be considered (Level B); 2) flunarizine possibly has no effect in treating limb tremor in ET and may not be considered (Level C); and 3) there is insufficient evidence to support or refute the use of pregabalin, zonisamide, or clozapine as treatment for ET (Level U).
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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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Effects of T-type calcium channel blockers on a parkinsonian tremor model in rats. Pharmacol Biochem Behav 2011; 97:656-9. [DOI: 10.1016/j.pbb.2010.11.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 11/15/2010] [Accepted: 11/18/2010] [Indexed: 11/19/2022]
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Siniscalchi A, Gallelli L, De Sarro G. Use of antiepileptic drugs for hyperkinetic movement disorders. Curr Neuropharmacol 2010; 8:359-66. [PMID: 21629443 PMCID: PMC3080592 DOI: 10.2174/157015910793358187] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Revised: 04/23/2010] [Accepted: 04/30/2010] [Indexed: 11/23/2022] Open
Abstract
Many studies investigated the use of antiepileptic drugs (AEDs) in several neurological diseases other than epilepsy. These neurological disorders, usually, involve neuronal excitability through the modulating of ion channels, receptors and intracellular signaling pathways, and are the targets of the AEDs. This article provides a review of the clinical efficacy of both conventional and newer AEDs in hyperkinetic movement disorders. Some of these indications for AEDs have been established, while others are under investigation. The modulation of GABAergic transmission may explain the neuronal hyper-excitability that underlies some forms of hyperkinetic movement disorders. So, AEDs able to increase GABAergic neurotransmission may play a role in hyperkinetic movement disorders treatment. Therefore, AEDs could represent a useful therapeutic option in the management of hyperkinetic movement disorders where the available treatments are ineffective.
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Affiliation(s)
- A Siniscalchi
- Department of Neuroscience, Neurology Division, Annunziata Hospital, Cosenza, Italy
| | - L Gallelli
- Pharmacology, Department of Experimental and Clinical Medicine, Faculty of Medicine, University Magna Graecia of Catanzaro, Clinical Pharmacology Unit, Mater Domini University Hospital, Catanzaro, Italy
| | - G De Sarro
- Pharmacology, Department of Experimental and Clinical Medicine, Faculty of Medicine, University Magna Graecia of Catanzaro, Clinical Pharmacology Unit, Mater Domini University Hospital, Catanzaro, Italy
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Handforth A, Homanics GE, Covey DF, Krishnan K, Lee JY, Sakimura K, Martin FC, Quesada A. T-type calcium channel antagonists suppress tremor in two mouse models of essential tremor. Neuropharmacology 2010; 59:380-7. [PMID: 20547167 DOI: 10.1016/j.neuropharm.2010.05.012] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 05/14/2010] [Accepted: 05/24/2010] [Indexed: 11/17/2022]
Abstract
Essential tremor is a common disorder that lacks molecular targets for therapeutic development. T-type calcium channel activation has been postulated to underlie rhythmicity in the olivo-cerebellar system that is implicated in essential tremor. We therefore tested whether compounds that antagonize T-type calcium channel currents suppress tremor in two mouse models that possess an essential tremor-like pharmacological response profile. Tremor was measured using digitized spectral motion power analysis with harmaline-induced tremor and in the GABA(A) receptor α1 subunit-null model. Mice were given ethosuximide, zonisamide, the neuroactive steroid (3β,5α,17β)-17-hydroxyestrane-3-carbonitrile (ECN), the 3,4-dihydroquinazoline derivative KYS05064, the mibefradil derivative NNC 55-0396, or vehicle. In non-sedating doses, each compound reduced harmaline-induced tremor by at least 50% (range of maximal suppression: 53-81%), and in the GABA(A) α1-null model by at least 70% (range 70-93%). Because the T-type calcium channel Cav3.1 is the dominant subtype expressed in the inferior olive, we assessed the tremor response of Cav3.1-deficient mice to harmaline, and found that null and heterozygote mice exhibit as much tremor as wild-type mice. In addition, ECN and NNC 55-0396 suppressed harmaline tremor as well in Cav3.1-null mice as in wild-type mice. The finding that five T-type calcium antagonists suppress tremor in two animal tremor models suggests that T-type calcium channels may be an appropriate target for essential tremor therapy development. It is uncertain whether medications developed to block only the Cav3.1 subtype would exhibit efficacy.
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Affiliation(s)
- Adrian Handforth
- Neurology Service (W127), Veterans Affairs Greater Los Angeles Healthcare System, 11301 Wilshire Blvd, Los Angeles, CA 90073, USA.
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Abstract
PURPOSE OF REVIEW Tremor continuously attracts the attention of clinicians and basic researchers in search of pathophysiological, molecular and genetic mechanisms of the oscillatory activity. RECENT FINDINGS A widespread dynamic network of cortical and subcortical oscillators taking part in tremor generation intermittently has been postulated. Essential tremor is accompanied by functional deficits but may also occur along with subtle cerebellar changes. According to recent epidemiological studies there may be a link of essential tremor with Parkinson's disease. Many of the epidemiologic studies suffer from small cohorts, small effects or the lack of a definite test for essential tremor leaving the diagnosis a pure clinical one. A very recent large genome-wide association study has revealed that the LINGO1 gene is associated with an increased risk for essential tremor. Topiramate is becoming the best-established second line treatment for essential tremor. Targets for deep brain stimulation in the grey matter below the ventral intermediate nucleus of the thalamus seem to be most effective. SUMMARY New concepts of the central origin of tremors stimulate the search for new therapeutic targets for tremor suppression outside the basal ganglia and thalamus (e.g. cortex). The role of structural neurodegenerative changes in essential tremor remains an open question. Further studies on specific subgroups of patients are necessary.
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