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Yoo SW, Ha S, Lyoo CH, Kim Y, Yoo JY, Kim JS. Exploring the link between essential tremor and Parkinson's disease. NPJ Parkinsons Dis 2023; 9:134. [PMID: 37714868 PMCID: PMC10504235 DOI: 10.1038/s41531-023-00577-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 09/04/2023] [Indexed: 09/17/2023] Open
Abstract
Epidemiological studies have reported a link between essential tremor (ET) and Parkinson's disease (PD). Recent studies have suggested ET as a possible neurodegenerative disease whose subgroup contained Lewy bodies in the brainstem, as in PD. PD with antedated ET (PDconv) might exhibit traits different from those of the pure form of ET or PD. This study aimed to unveil the interplay between PD and premorbid ET, which might be the core pathobiology that differentiates PDconv from PD. The study included 51 ET, 32 PDconv, and 95 PD patients who underwent positron emission tomography using 18F-N-(3-fluoropropyl)-2beta-carbon ethoxy-3beta-(4-iodophenyl) nortropane and 123I-meta-iodobenzylguanidine myocardial scintigraphy to analyze central dopaminergic and peripheral noradrenergic integrity. The results show that PDconv group followed the typical striatal pathology of PD but with a delay in noradrenergic impairment as it caught up with the denervating status of PD a few years after PD diagnosis. Whereas the two PD subtypes displayed similar patterns of presynaptic dopamine transporter deficits, ET patients maintained high densities in all subregions except thalamus. Presynaptic dopaminergic availability decreased in a linear or quadratic fashion across the three groups (ET vs. PDconv vs. PD). The age at onset and duration of ET did not differ between pure ET and PDconv patients and did not influence the striatal monoamine status. The myocardium in PDconv patients was initially less denervated than in PD patients, but it degenerated more rapidly. These findings suggest that PDconv could be a distinctive subclass in which the pathobiology of PD interacts with that of ET in the early phase of the disease.
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Affiliation(s)
- Sang-Won Yoo
- Department of Neurology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Seunggyun Ha
- Division of Nuclear Medicine, Department of Radiology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Chul Hyoung Lyoo
- Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Yuna Kim
- Department of Neurology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Ji-Yeon Yoo
- Department of Neurology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Joong-Seok Kim
- Department of Neurology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
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2
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Kosmowska B, Paleczna M, Biała D, Kadłuczka J, Wardas J, Witkin JM, Cook JM, Sharmin D, Marcinkowska M, Kuter KZ. GABA-A Alpha 2/3 but Not Alpha 1 Receptor Subunit Ligand Inhibits Harmaline and Pimozide-Induced Tremor in Rats. Biomolecules 2023; 13:biom13020197. [PMID: 36830567 PMCID: PMC9953228 DOI: 10.3390/biom13020197] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/11/2023] [Accepted: 01/15/2023] [Indexed: 01/20/2023] Open
Abstract
Treatment of tremors, such as in essential tremor (ET) and Parkinson's disease (PD) is mostly ineffective. Exact tremor pathomechanisms are unknown and relevant animal models are missing. GABA-A receptor is a target for tremorolytic medications, but current non-selective drugs produce side effects and have safety liabilities. The aim of this study was a search for GABA-A subunit-specific tremorolytics using different tremor-generating mechanisms. Two selective positive allosteric modulators (PAMs) were tested. Zolpidem, targeting GABA-A α1, was not effective in models of harmaline-induced ET, pimozide- or tetrabenazine-induced tremulous jaw movements (TJMs), while the novel GABA-A α2/3 selective MP-III-024 significantly reduced both the harmaline-induced ET tremor and pimozide-induced TJMs. While zolpidem decreased the locomotor activity of the rats, MP-III-024 produced small increases. These results provide important new clues into tremor suppression mechanisms initiated by the enhancement of GABA-driven inhibition in pathways controlled by α2/3 but not α1 containing GABA-A receptors. Tremor suppression by MP-III-024 provides a compelling reason to consider selective PAMs targeting α2/3-containing GABA-A receptors as novel therapeutic drug targets for ET and PD-associated tremor. The possibility of the improved tolerability and safety of this mechanism over non-selective GABA potentiation provides an additional rationale to further pursue the selective α2/3 hypothesis.
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Affiliation(s)
- Barbara Kosmowska
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna St., 31-343 Krakow, Poland
| | - Martyna Paleczna
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna St., 31-343 Krakow, Poland
| | - Dominika Biała
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna St., 31-343 Krakow, Poland
| | - Justyna Kadłuczka
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna St., 31-343 Krakow, Poland
| | - Jadwiga Wardas
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna St., 31-343 Krakow, Poland
| | - Jeffrey M. Witkin
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
- RespireRx Pharmaceuticals Inc., Glen Rock, NJ 07452, USA
| | - James M. Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
- RespireRx Pharmaceuticals Inc., Glen Rock, NJ 07452, USA
| | - Dishary Sharmin
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
| | - Monika Marcinkowska
- Department of Pharmaceutical Chemistry, Jagiellonian University, Medical College, 9 Medyczna St., 30-688 Krakow, Poland
| | - Katarzyna Z. Kuter
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna St., 31-343 Krakow, Poland
- Correspondence: ; Tel.: +48-12-662-32-26
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3
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Tremblay C, Serrano GE, Dunckley N, Zhang N, Fiock KL, Adler CH, Driver-Dunckley E, Mehta SH, Shill HA, Beach TG. Postmortem Cerebellar Volume Is Not Reduced in Essential Tremor: A Comparison with Multiple System Atrophy and Controls. JOURNAL OF PARKINSON'S DISEASE 2023; 13:333-340. [PMID: 36938740 PMCID: PMC10200177 DOI: 10.3233/jpd-225033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/23/2023] [Indexed: 03/15/2023]
Abstract
BACKGROUND Essential tremor (ET) is a common movement disorder in which cerebellar microscopic and volume alterations have been repeatedly reported although with disagreement between studies. However, pronounced heterogeneity was found with regard to cerebellar volume alterations. OBJECTIVE This study aimed to assess postmortem cerebellar volume in subjects with or without ET, as compared with subjects with multiple system atrophy (MSA), a well-established cerebellar neurodegeneration. METHODS Cases with ET (n = 29), MSA (n = 7), and non-demented control cases without any movement disorder (n = 22) were selected from the Arizona Study of Aging and Neurodegenerative Disorders (AZSAND), a longitudinal clinicopathological study with annual research-dedicated clinical assessments by neuropsychologists, subspecialist movement disorders, and cognitive/behavioral neurologists, with comprehensive neuropathological examinations after death. Group comparisons were controlled for common age-related neurodegenerative and cerebrovascular pathologies. Cerebellar volumes were calculated using digital images of slices taken at the time of autopsy, immediately after brain removal and before fixation. RESULTS Cerebellar volume was not reduced in ET subjects compared to controls. The two groups did not differ in terms of incidental cerebrovascular and Alzheimer's disease neuropathology. In contrast, cerebellar volume was significantly reduced in subjects with MSA when compared to ET and control subjects. CONCLUSION In a well-characterized cohort, postmortem cerebellar volume measurements suggest that there are no volume alterations in ET when compared to controls, in contrast to significant cerebellar atrophy in subjects with MSA.
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Affiliation(s)
| | | | | | - Nan Zhang
- Department of Neurology, Mayo Clinic College of Medicine, Mayo Clinic Arizona, Scottsdale, AZ, USA
| | | | - Charles H. Adler
- Department of Neurology, Mayo Clinic College of Medicine, Mayo Clinic Arizona, Scottsdale, AZ, USA
| | - Erika Driver-Dunckley
- Department of Neurology, Mayo Clinic College of Medicine, Mayo Clinic Arizona, Scottsdale, AZ, USA
| | - Shyamal H. Mehta
- Department of Neurology, Mayo Clinic College of Medicine, Mayo Clinic Arizona, Scottsdale, AZ, USA
| | - Holly A. Shill
- Department of Neurology, Barrow Neurological Institute, Phoenix, AZ, USA
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4
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Cho HJ. Is essential tremor a degenerative or an electrical disorder? Electrical disorder. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 163:103-128. [PMID: 35750360 DOI: 10.1016/bs.irn.2022.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Essential tremor (ET) is one of the most common movement disorders, yet we do not have a complete understanding of its pathophysiology. From a phenomenology standpoint, ET is an isolated tremor syndrome of bilateral upper limb action tremor with or without tremor in other body locations. ET is a pathological tremor that arises from excessive oscillation in the central motor network. The tremor network comprises of multiple brain regions including the inferior olive, cerebellum, thalamus, and motor cortex, and there is evidence that a dynamic oscillatory disturbance within this network leads to tremor. ET is a chronic disorder, and the natural history shows a slow progression of tremor intensity with age. There are reported data suggesting that ET follows the disease model of a neurodegenerative disorder, however whether ET is a degenerative or electrical disorder has been a subject of debate. In this chapter, we will review cumulative evidence that ET as a syndrome is a fundamentally electric disorder. The etiology is likely heterogenous and may not be primarily neurodegenerative.
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Affiliation(s)
- Hyun Joo Cho
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States.
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5
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Ondo W. Enhancing GABA inhibition is the next generation of medications for essential tremor. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 163:317-334. [PMID: 35750368 DOI: 10.1016/bs.irn.2022.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
γ-Aminobutyric acid (GABA) is the most prevalent inhibitory CNS neurotransmitter. Activating GABA-A receptors hyperpolarizes cells via Cl- influx, which inhibits action potentials. Although the exact pathophysiologies of tremor are incompletely understood, proposed neuroanatomy extensively implicates GABA pathways. Pathological studies and imaging studies also show GABA abnormalities in patients with ET. Most importantly, medications that activate GABA-A receptors, such as primidone, often improve tremor. Ongoing clinical trials and physiology research should further refine potential future GABAergic targets and treatments, which are currently the most promising targets for pharmacological intervention.
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Affiliation(s)
- William Ondo
- Houston Methodist Hospital, Weill Cornel Medical School, Houston, TX, United States.
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6
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Buechele F, Baumann CR, Lees A, Deuschl G. Encouraging a Generation of Tremor Researchers: Macdonald Critchley's Paper on Essential Tremor. Mov Disord Clin Pract 2022; 9:38-41. [PMID: 35005063 PMCID: PMC8721832 DOI: 10.1002/mdc3.13333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/15/2021] [Accepted: 07/27/2021] [Indexed: 11/06/2022] Open
Affiliation(s)
- Fabian Buechele
- Department of Neurology University Hospital Zürich, University of Zürich Zürich
| | - Christian R Baumann
- Department of Neurology University Hospital Zürich, University of Zürich Zürich
| | - Andrew Lees
- University College London; and Reta Lila Weston Institute of Neurological Studies London United Kingdom
| | - Günther Deuschl
- Department of Neurology University Hospital Zürich, University of Zürich Zürich.,Department of Neurology Universitätsklinikum Schleswig-Holstein, Kiel Campus, Christian-Albrechts University Kiel Germany
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7
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Mavroudis I, Kazis D, Petridis F, Chatzikonstantinou S, Karantali E, Njau S, Costa V, Ciobica A, Trus C, Balmus I, Baloyannis S. Morphological and morphometric changes in the Purkinje cells of patients with essential tremor. Exp Ther Med 2021; 23:167. [PMID: 35069848 PMCID: PMC8753961 DOI: 10.3892/etm.2021.11090] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 07/30/2021] [Indexed: 11/09/2022] Open
Abstract
Essential tremor (ET) is a progressive neurological syndrome characterised by involuntary tremors of the hands or arms, head, jaw and voice. The pathophysiology of ET is not clearly understood yet. However, previous studies have reported several changes in the brain of patients with ET. One of the brain areas extensively investigated is the cerebellum. In the present study, a morphometric analysis of Purkinje cells in patients with ET and ET-plus was performed, and subsequently compared with normal controls using the Golgi silver staining method and 3D neuronal reconstruction. Substantial morphological changes were uncovered in the Purkinje cells of patients with ET compared with normal controls, including a decreased dendritic length and field density, an overall loss of terminal branches and a decreased density of dendritic spines.
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Affiliation(s)
- Ioannis Mavroudis
- Department of Neurology, Leeds Teaching Hospitals, NHS Trust, Leeds, LS1 3EX, United Kingdom
| | - Dimitrios Kazis
- Third Department of Neurology, Aristotle University of Thessaloniki, Thessaloniki 54636, Greece
| | - Foivos Petridis
- Third Department of Neurology, Aristotle University of Thessaloniki, Thessaloniki 54636, Greece
| | | | - Eleni Karantali
- Third Department of Neurology, Aristotle University of Thessaloniki, Thessaloniki 54636, Greece
| | - Samuel Njau
- Department of Forensic Medicine and Toxicology, Aristotle University of Thessaloniki, Thessaloniki 54636, Greece
| | - Vasiliki Costa
- Laboratory of Neuropathology and Electron Microscopy, Aristotle University of Thessaloniki, Thessaloniki 54636, Greece
| | - Alin Ciobica
- Department of Biology, Faculty of Biology, Alexandru Ioan Cuza University, Iasi 700506, Romania
| | - Constantin Trus
- Department of Morphological and Functional Sciences, Faculty of Medicine, Dunarea de Jos University, Galati 800008, Romania
| | - Ioana Balmus
- Department of Exact Sciences and Natural Sciences, Institute of Interdisciplinary Research, Alexandru Ioan Cuza University of Iași, Iași 700057, Romania
| | - Stavros Baloyannis
- Laboratory of Neuropathology and Electron Microscopy, Aristotle University of Thessaloniki, Thessaloniki 54636, Greece
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8
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Kosmowska B, Wardas J. The Pathophysiology and Treatment of Essential Tremor: The Role of Adenosine and Dopamine Receptors in Animal Models. Biomolecules 2021; 11:1813. [PMID: 34944457 PMCID: PMC8698799 DOI: 10.3390/biom11121813] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/25/2021] [Accepted: 11/30/2021] [Indexed: 12/13/2022] Open
Abstract
Essential tremor (ET) is one of the most common neurological disorders that often affects people in the prime of their lives, leading to a significant reduction in their quality of life, gradually making them unable to independently perform the simplest activities. Here we show that current ET pharmacotherapy often does not sufficiently alleviate disease symptoms and is completely ineffective in more than 30% of patients. At present, deep brain stimulation of the motor thalamus is the most effective ET treatment. However, like any brain surgery, it can cause many undesirable side effects; thus, it is only performed in patients with an advanced disease who are not responsive to drugs. Therefore, it seems extremely important to look for new strategies for treating ET. The purpose of this review is to summarize the current knowledge on the pathomechanism of ET based on studies in animal models of the disease, as well as to present and discuss the results of research available to date on various substances affecting dopamine (mainly D3) or adenosine A1 receptors, which, due to their ability to modulate harmaline-induced tremor, may provide the basis for the development of new potential therapies for ET in the future.
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Affiliation(s)
| | - Jadwiga Wardas
- Department of Neuropsychopharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, 31-343 Kraków, Poland;
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9
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Pasquini J, Ceravolo R. The Molecular Neuroimaging of Tremor. Curr Neurol Neurosci Rep 2021; 21:74. [PMID: 34817737 PMCID: PMC8613162 DOI: 10.1007/s11910-021-01157-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2021] [Indexed: 11/28/2022]
Abstract
Purpose of Review Tremor is a hyperkinetic movement disorder most commonly encountered in essential tremor (ET) and Parkinson’s disease (PD). The purpose of this review is to summarize molecular neuroimaging studies with major implications on pathophysiological and clinical features of tremor. Recent Findings Oscillatory brain activity responsible for tremor manifestation is thought to originate in a cerebello-thalamo-cortical network. Molecular neuroimaging has helped clarify metabolic aspects and neurotransmitter influences on the main tremor network. In ET, recent positron emission tomography (PET) studies are built on previous knowledge and highlighted the possibility of investigating metabolic brain changes after treatments, in the attempt to establish therapeutic biomarkers. In PD, molecular neuroimaging has advanced the knowledge of non-dopaminergic determinants of tremor, providing insights into serotonergic and noradrenergic contributions. Summary Recent advances have greatly extended the knowledge of tremor pathophysiology and it is now necessary to translate such knowledge in more efficacious treatments for this symptom.
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Affiliation(s)
- Jacopo Pasquini
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy. .,Clinical Ageing Research Unit, Newcastle University, Campus for Ageing & Vitality, Westgate Road, Newcastle upon Tyne, NE4 5PL, UK.
| | - Roberto Ceravolo
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.,Neurodegenerative Diseases Center, Azienda Ospedaliero Universitaria Pisana, Pisa, Italy
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10
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Ågren R, Awad A, Blomstedt P, Fytagoridis A. Voxel-Based Morphometry of Cerebellar Lobules in Essential Tremor. Front Aging Neurosci 2021; 13:667854. [PMID: 34177554 PMCID: PMC8222624 DOI: 10.3389/fnagi.2021.667854] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 05/03/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The extent of neurodegeneration underlying essential tremor (ET) remains a matter of debate. Despite various extents of cerebellar atrophy on structural magnetic resonance imaging (MRI), previous studies have shown substantial heterogeneity and included a limited number of patients. Novel automated pipelines allow detailed segmentation of cerebellar lobules based on structural MRI. OBJECTIVE To compare the volumes of cerebellar lobules in ET patients with those in healthy controls (HCs) using an automated segmentation pipeline. METHODS Structural MRI scans of ET patients eligible for deep brain stimulation (n = 55) and of age-matched and gender-matched HCs (n = 55, from the IXI database) were segmented using the automated CEREbellum Segmentation pipeline. Lobule-specific volume differences between the ET and HC groups were evaluated using a general linear model corrected for multiple tests. RESULTS Total brain tissue volumes did not differ between the ET and HC groups. ET patients demonstrated reduced volumes of lobules I-II, left Crus II, left VIIB, and an increased volume of right X when compared with the HC group. CONCLUSION A large cohort of ET patients demonstrated subtle signs of decreased cerebellar lobule volumes. These findings oppose the hypothesis of localized atrophy in cerebellar motor areas in ET, but not the possibility of cerebellar pathophysiology in ET. Prospective investigations using alternative neuroimaging modalities may further elucidate the pathophysiology of ET and provide insights into diagnostic and therapeutic approaches.
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Affiliation(s)
- Richard Ågren
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Amar Awad
- Unit of Functional and Stereotactic Neurosurgery, Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden
- Physiology Section, Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
- Umeå Center for Functional Brain Imaging (UFBI), Umeå University, Umeå, Sweden
| | - Patric Blomstedt
- Unit of Functional and Stereotactic Neurosurgery, Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden
| | - Anders Fytagoridis
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
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11
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Cerebello-thalamo-cortical network is intrinsically altered in essential tremor: evidence from a resting state functional MRI study. Sci Rep 2020; 10:16661. [PMID: 33028912 PMCID: PMC7541442 DOI: 10.1038/s41598-020-73714-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 08/03/2020] [Indexed: 12/18/2022] Open
Abstract
Cerebello-thalamo-cortical network is suggested to be involved in the pathophysiology of Essential Tremor (ET). 23 patients with ET and 23 matched HC underwent a 3T-MRI with acquisition of a resting state sequence. Connectivity was investigated using a seed-based regression analyses approach. In ET patients were observed:Reduced connectivity between left primary motor cortex (M1) seed and right premotor cortex and cerebellum and bilateral premotor, parietal areas, supplementary motor area (SMA); Increased connectivity between left somatosensory cortex (S1) seed and parietal areas, M1, premotor cortex, SMA; reduced connectivity of this seed with cerebellum. Increased connectivity of SMA seed with premotor cortex and decreased with parietal and precentral areas; Increased connectivity between left thalamus seed and cerebellum; Reduced connectivity between right cerebellum seeds and other cerebellar areas, precentral and premotor areas. ET showed altered connectivity within the cortical sensory-motor network and between cerebral cortex and cerebellum. The increased connectivity between cerebellum and thalamus is consistent with their crucial role in tremor generation. These findings support the dynamical entrainment of multiple central oscillators throughout the cerebello-thalamo-cortical network in ET. This evidence is strengthened by the finding that this network is altered also when the core symptom is absent.
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12
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Casamento-Moran A, Yacoubi B, Wilkes BJ, Hess CW, Foote KD, Okun MS, Wagle Shukla A, Vaillancourt DE, Christou EA. Quantitative Separation of Tremor and Ataxia in Essential Tremor. Ann Neurol 2020; 88:375-387. [PMID: 32418250 DOI: 10.1002/ana.25781] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 04/19/2020] [Accepted: 05/10/2020] [Indexed: 12/14/2022]
Abstract
OBJECTIVE This study addresses an important problem in neurology, distinguishing tremor and ataxia using quantitative methods. Specifically, we aimed to quantitatively separate dysmetria, a cardinal sign of ataxia, from tremor in essential tremor (ET). METHODS In Experiment 1, we compared 19 participants diagnosed with ET undergoing thalamic deep brain stimulation (DBS; ETDBS ) to 19 healthy controls (HC). We quantified tremor during postural tasks using accelerometry and dysmetria with fast, reverse-at-target goal-directed movements. To ensure that endpoint accuracy was unaffected by tremor, we quantified dysmetria in selected trials manifesting a smooth trajectory to the endpoint. Finally, we manipulated tremor amplitude by switching DBS ON and OFF to examine its effect on dysmetria. In Experiment 2, we compared 10 ET participants with 10 HC to determine whether we could identify and distinguish dysmetria from tremor in non-DBS ET. RESULTS Three findings suggest that we can quantify dysmetria independently of tremor in ET. First, ETDBS and ET exhibited greater dysmetria than HC and dysmetria did not correlate with tremor (R2 < 0.01). Second, even for trials with tremor-free trajectories to the target, ET exhibited greater dysmetria than HC (p < 0.01). Third, activating DBS reduced tremor (p < 0.01) but had no effect on dysmetria (p > 0.2). INTERPRETATION We demonstrate that dysmetria can be quantified independently of tremor using fast, reverse-at-target goal-directed movements. These results have important implications for the understanding of ET and other cerebellar and tremor disorders. Future research should examine the neurophysiological mechanisms underlying each symptom and characterize their independent contribution to disability. ANN NEUROL 2020;88:375-387.
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Affiliation(s)
- Agostina Casamento-Moran
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA
| | - Basma Yacoubi
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA
| | - Bradley J Wilkes
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA
| | - Christopher W Hess
- Department of Neurology, Fixel Institute for Neurological Diseases, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - Kelly D Foote
- Department of Neurology, Fixel Institute for Neurological Diseases, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - Michael S Okun
- Department of Neurology, Fixel Institute for Neurological Diseases, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - Aparna Wagle Shukla
- Department of Neurology, Fixel Institute for Neurological Diseases, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - David E Vaillancourt
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA.,Department of Neurology, Fixel Institute for Neurological Diseases, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - Evangelos A Christou
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA
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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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14
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Paul JL, Dashtipour K, Chen Z, Wang C. DNA methylome study of human cerebellar tissues identified genes and pathways possibly involved in essential tremor. PRECISION CLINICAL MEDICINE 2019; 2:221-234. [PMID: 31886034 PMCID: PMC6927097 DOI: 10.1093/pcmedi/pbz028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 11/30/2019] [Accepted: 12/01/2019] [Indexed: 01/13/2023] Open
Abstract
Background Essential tremor (ET) is a neurological syndrome of unknown origin with poorly understood etiology and pathogenesis. It is suggested that the cerebellum and its tracts may be involved in the pathophysiology of ET. DNA methylome interrogation of cerebellar tissue may help shine some light on the understanding of the mechanism of the development of ET. Our study used postmortem human cerebellum tissue samples collected from 12 ET patients and 11 matched non-ET controls for DNA methylome study to identify differentially methylated genes in ET. Results Using Nugen’s Ovation reduced representation bisulfite sequencing (RRBS), we identified 753 genes encompassing 938 CpG sites with significant differences in DNA methylation between the ET and the control group. Identified genes were further analyzed with Ingenuity Pathway Analysis (IPA) by which we identified certain significant pathways, upstream regulators, diseases and functions, and networks associated with ET. Conclusions Our study provides evidence that there are significant differences in DNA methylation patterns between the ET and control samples, suggesting that the methylation alteration of certain genes in the cerebellum may be associated with ET pathogenesis. The identified genes allude to the GABAergic hypothesis which supports the notation that ET is a neurodegenerative disease, particularly involving the cerebellum.
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Affiliation(s)
- Jennifer L Paul
- Center for Genomics, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA
| | - Khashayar Dashtipour
- Division of Movement Disorders, Department of Neurology, Loma Linda University Medical Center, Loma Linda, CA 92350, USA
| | - Zhong Chen
- Center for Genomics, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA
| | - Charles Wang
- Center for Genomics, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA.,Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA
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Neuropathology and pathogenesis of extrapyramidal movement disorders: a critical update. II. Hyperkinetic disorders. J Neural Transm (Vienna) 2019; 126:997-1027. [DOI: 10.1007/s00702-019-02030-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 06/14/2019] [Indexed: 12/14/2022]
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16
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Mavroudis I, Petridis F, Kazis D. Neuroimaging and neuropathological findings in essential tremor. Acta Neurol Scand 2019; 139:491-496. [PMID: 30977113 DOI: 10.1111/ane.13101] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 03/14/2019] [Accepted: 04/05/2019] [Indexed: 12/21/2022]
Abstract
Essential tremor is a chronic neurological syndrome of heterogenous clinical phenotypes and multiple etiologies. Numerous studies have been done in order to investigate the pathological, neuroimaging, physiological, and clinical features of essential tremor; however, a clear pathophysiological mechanism has not been identified. One of the brain structures has been extensively investigated at the macroscopic and the microscopic level in the cerebellum. In the present study, we aim to discuss the main neuroimaging and neuropathological changes of the cerebellum in essential tremor.
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Affiliation(s)
- Ioannis Mavroudis
- Department of Neurology Leeds Teaching Hospitals Leeds UK
- Third Department of Neurology Aristotle University of Thessaloniki Thessaloniki Greece
| | - Foivos Petridis
- Third Department of Neurology Aristotle University of Thessaloniki Thessaloniki Greece
| | - Dimitrios Kazis
- Third Department of Neurology Aristotle University of Thessaloniki Thessaloniki Greece
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Wang P, Luo X, Zhong C, Yang L, Guo F, Yu N. Resting state fMRI reveals the altered synchronization of BOLD signals in essential tremor. J Neurol Sci 2018; 392:69-76. [PMID: 30025236 DOI: 10.1016/j.jns.2018.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 06/14/2018] [Accepted: 07/08/2018] [Indexed: 10/28/2022]
Abstract
Essential tremor (ET) is one of the most common movement disorders in humans. Nevertheless, there remain several controversies surrounding ET, such as whether it is a disorder of abnormal neuronal oscillations within the tremor network. In this work, the resting-state fMRI data were collected from 17 ET patients and 17 age- and gender-matched healthy controls. First, using FOur-dimensional (spatiotemporal) Consistency of local neural Activities (FOCA) the abnormal synchronization of fMRI signals in ET patients were investigated. Then, global functional connectivity intensity (gFCI) and density (gFCD) were analyzed in the regions exhibiting significant FOCA differences. Compared with healthy controls, patients with ET showed the increased FOCA values found in the bilateral cuneus, the left lingual gyrus, the left paracentral lobule, the right middle temporal gyrus, the bilateral precentral gyrus, the right postcentral gyrus, the pallidum and putamen. Decreased FOCA values in ET patients were located in the frontal gyrus, the bilateral anterior cingulate and the medial dorsal nucleus of right thalamus. In ET patients, significant changes in gFCI and gFCD were located in the cuneus, the middle temporal gyrus and the middle frontal gyrus. Changes in gFCI were also found in the medial frontal gyrus and thalamus in addition to changes in gFCD in the precentral gyrus. Our results provided further evidence that ET might present with abnormal spontaneous activity in the tremor network, including motor-related cotex, basal ganglia and thalamus, as well as distributed non-motor areas. This work also demonstrated that FOCA and functional connectivity have the potential to provide important insight into the pathophysiological mechanism of ET.
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Affiliation(s)
- Pu Wang
- Department of Neurology, Chongzhou People's Hospital, Chongzhou, Sichuan, China
| | - Xiangdong Luo
- Department of Neurology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
| | - Chengqing Zhong
- Department of Neurology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
| | - Lili Yang
- Department of Neurology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
| | - Fuqiang Guo
- Department of Neurology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China.
| | - Nengwei Yu
- Department of Neurology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China.
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Abstract
Tremor is a phenomenon observed in a broad spectrum of diseases with different pathophysiologies. While patients with tremor may not complain in the clinic of symptoms of imbalance, gait difficulties, or falls, laboratory research studies using quantitative analysis of gait and posture and neurophysiologic techniques have demonstrated impaired gait and balance across a variety of tremor etiologies. These findings have been supported by careful epidemiologic studies assessing symptoms of imbalance. Imaging and neurophysiologic studies have identified cerebellar networks as important mediators of tremor, and therefore a likely common site of dysfunction to explain the phenomenologic overlap between impaired postural and gait control with tremor. Further understanding of these mechanisms and networks is of crucial importance in the development of new treatments, particularly surgical or minimally invasive lesional therapies.
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Affiliation(s)
- Hugo Morales-Briceño
- Movement Disorders Unit, Department of Neurology, Westmead Hospital, Sydney, NSW, Australia
| | - Alessandro F Fois
- Movement Disorders Unit, Department of Neurology, Westmead Hospital, Sydney, NSW, Australia
| | - Victor S C Fung
- Movement Disorders Unit, Department of Neurology, Westmead Hospital, Sydney, NSW, Australia; Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
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Nonmotor Symptoms in Essential Tremor and Other Tremor Disorders. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2017; 134:1373-1396. [PMID: 28805576 DOI: 10.1016/bs.irn.2017.05.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Tremor, like dystonia, is a term used at the phenomenological, syndromic, and aetiopathological level. Parkinsonian, essential, and dystonic tremor are the three most common tremor diagnoses encountered in clinical practice. Investigation of nonmotor symptoms in essential tremor and dystonic tremor syndromes is significantly hampered by the lack of clear clinical diagnostic criteria for these groups at a syndromic level, and the absence of biomarkers which allow definitive diagnosis at an aetiopathological level. Much work is needed in clarifying the motor features of these disorders in order to allow delineation of the nonmotor features of the most common tremor syndromes. With this limitation in mind, this chapter reviews what is known about nonmotor symptoms in these two tremor types. The final sections deal with nonmotor symptoms observed in patients with lesional tremor, thankfully a much more clearly defined albeit less common group of patients.
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Abstract
A fundamental question about essential tremor (ET) is whether its associated pathological changes and disease mechanisms are linkable to a specific brain region. To that end, recent tissue-based studies have made significant strides in elucidating changes in the ET brain. Emerging from these studies is increasing neuropathological evidence linking ET to the cerebellum. These studies have systematically identified a broad range of structural, degenerative changes in the ET cerebellum, spanning across all Purkinje cell compartments. These include the dendritic compartment (where there is an increase in number of Purkinje cell dendritic swellings, a pruning of the dendritic arbor, and a reduction in spine density), the cell body (where, aside from reductions in Purkinje cell linear density in some studies, there is an increase in the number of heterotopic Purkinje cell soma), and the axonal compartment (where a plethora of changes in axonal morphology have been observed, including an increase in the number of thickened axonal profiles, torpedoes, axonal recurrent collaterals, axonal branching, and terminal axonal sprouting). Additional changes, possibly due to secondary remodeling, have been observed in neighboring neuronal populations. These include a hypertrophy of basket cell axonal processes and changes in the distribution of climbing fiber-Purkinje cell synapses. These changes all distinguish ET from normal control brains. Initial studies further indicate that the profile (i.e., constellation) of these changes may separate ET from other diseases of the cerebellum, thereby serving as a disease signature. With the discovery of these changes, a new model of ET has arisen, which posits that it may be a neurodegenerative disorder centered in the cerebellar cortex. These newly emerging neuropathological studies pave the way for anatomically focused, hypothesis-driven, molecular mechanistic studies of disease pathogenesis.
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Abstract
Currently available therapies for essential tremor (ET) provide sufficient control only for less than a half of patients and many unmet needs exist. This is in part due to the empiric nature of existing treatment options and persisting uncertainties about the pathogenesis of ET. The emerging concept of ET as a possible neurodegenerative disorder, better understanding of associated biochemical changes, including alterations in the γ-aminobutyric acid (GABA)-ergic system and gap junctions, and the identification of the role of the leucine-rich repeat and immunoglobulin-like domain-containing 1 (LINGO-1) gene in ET pathogenesis suggest new avenues for more targeted therapies. Here we review the most promising new approaches to treating ET, including allosteric modulation of GABA receptors and modifications of the LINGO-1 pathway. Medically refractory tremor can be successfully treated by high-frequency deep brain stimulation (DBS) of the ventral intermediate nucleus, but surgical therapies are also fraught with limitations due to adverse effects of stimulation and the loss of therapeutic response. The selection of additional thalamic and extrathalamic targets for electrode placements and the development of a closed-loop DBS system enabling automatic adjustment of stimulation parameters in response to changes in electrophysiologic brain activity are also reviewed. Tremor cancellation methods using exoskeleton and external hand-held devices are also briefly discussed.
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Affiliation(s)
- Peter Hedera
- Department of Neurology, Vanderbilt University, 465 21st Avenue South, 6140 MRB III, Nashville, TN 37240, 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: 37] [Impact Index Per Article: 4.6] [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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Gövert F, Becktepe JS, Deuschl G. Current concepts of essential tremor. Rev Neurol (Paris) 2016; 172:416-422. [PMID: 27561441 DOI: 10.1016/j.neurol.2016.07.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 07/18/2016] [Indexed: 01/27/2023]
Abstract
Essential tremor is clinically defined but there is increasing evidence that it is not a unique entity. Its pathophysiology has been studied with many methods but may also vary between subtypes. Neurophysiologically, there is strong evidence that a specific cerebello-thalamo-cortical loop is abnormally oscillating. The cause of its uncontrolled oscillation is not yet understood. The clear proof of a degenerative cause is still lacking and abnormal receptors or other causes of altered non-progressive functional disturbance cannot be excluded. Strong evidence supports the major involvement of the cerebellum and there is ample evidence that GABA is the main neurotransmitter involved in the pathophysiology in ET. Genetics have provided so far only a few rare subtypes which are due to specific mutations but there is no doubt that it is mostly a hereditary condition. There is evidence that the large subgroup of late onset tremor is a separate condition and this tremor is an independent risk factor for earlier mortality and comes with signs of premature aging (aging-related tremor). It will be important to improve phenotyping of patients in more detail possibly to include not only features of the tremor itself but also other clinical assessments like force measurements or cognitive testing. Based on these variables, we may be able to better understand the presumably different mechanisms underlying different variants of the disease.
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Affiliation(s)
- F Gövert
- Department of Neurology, Christian-Albrecht University of Kiel, Universitätsklinikum Schleswig-Holstein, Kiel Campus, Schittenhelmstrasse 10, 24105 Kiel, Germany
| | - J S Becktepe
- Department of Neurology, Christian-Albrecht University of Kiel, Universitätsklinikum Schleswig-Holstein, Kiel Campus, Schittenhelmstrasse 10, 24105 Kiel, Germany
| | - G Deuschl
- Department of Neurology, Christian-Albrecht University of Kiel, Universitätsklinikum Schleswig-Holstein, Kiel Campus, Schittenhelmstrasse 10, 24105 Kiel, Germany.
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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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Lee S, Asaad WF, Jones SR. Computational modeling to improve treatments for essential tremor. ACTA ACUST UNITED AC 2016; 19:19-25. [PMID: 29167694 DOI: 10.1016/j.ddmod.2017.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Essential tremor (ET) is a neurological disorder of unknown etiology that is typically characterized by an involuntary periodic movement of the upper limbs. No longer considered monosymptomatic, ET patients often have additional motor and even cognitive impairments. Although there are several pharmacological treatments, no drugs have been developed specifically for ET [1], and 30-70% of patients are medication-refractory [2]. A subset of medication-refractory patients may benefit from electrical deep brain stimulation (DBS) of the ventral intermediate nucleus of the thalamus (VIM), which receives cerebellar inputs. Abnormal cerebellar input to VIM is presumed to be a major contributor to tremor symptoms, which is alleviated by DBS. Computational modeling of the effects of DBS in VIM has been a powerful tool to design DBS protocols to reduce tremor activity. However, far less is known about how these therapies affect non-tremor symptoms, and more experimental and computational modeling work is required to address these growing considerations. Models capable of addressing multiple facets of ET will lead to novel, more efficient treatment.
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Affiliation(s)
- Shane Lee
- Department of Neuroscience and Brown Institute for Brain Science, Brown University, United States
| | - Wael F Asaad
- Department of Neuroscience and Brown Institute for Brain Science, Brown University, United States
- Department of Neurosurgery, Brown University Alpert Medical School, United States
- Department of Neurosurgery, Rhode Island Hospital, United States
- Norman Prince Neurosciences Institute, Lifespan, United States
| | - Stephanie R Jones
- Department of Neuroscience and Brown Institute for Brain Science, Brown University, United States
- Providence Veteran's Affairs Medical Center, Center for Neurorestoration and Neurotechnology, United States
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Lafo JA, Jones JD, Okun MS, Bauer RM, Price CC, Bowers D. Memory Similarities Between Essential Tremor and Parkinson's Disease: A Final Common Pathway? Clin Neuropsychol 2015; 29:985-1001. [PMID: 26689342 DOI: 10.1080/13854046.2015.1118553] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
OBJECTIVE A growing body of literature supports the view that essential tremor (ET) involves alteration of cerebellar-thalamo-cortical networks which can result in working memory and executive deficits. In this study, we tested the hypothesis that individuals with ET would exhibit worse performance on memory tasks requiring more intrinsic organization and structuring (i.e., word lists) relative to those with fewer 'executive' demands (i.e., stories), similar to that previously observed in individuals with Parkinson's disease (PD). METHOD Participants included a convenience sample of 68 ET patients and 68 idiopathic PD patients, retrospectively matched based on age, education, and sex. All patients underwent routine neuropsychological evaluation assessing recent memory, auditory attention/working memory, language, and executive function. Memory measures included the Hopkins Verbal Learning Test-R and WMS-III Logical Memory. RESULTS Both ET and PD patients performed significantly worse on word list than story memory recall tasks. The magnitude of the difference between these two memory tasks was similar for ET and PD patients. In both patient groups, performance on measures of executive function and auditory attention/working memory was not distinctly correlated with word list vs. story recall. CONCLUSIONS These findings suggest that frontal-executive dysfunction in both ET and PD may negatively influence performance on memory tests that are not inherently organized. Although the pathophysiology of these two 'movement disorders' are quite distinct, both have downstream effects on thalamo-frontal circuitry which may provide a common pathway for a similar memory phenotype. Findings are discussed in terms of neuroimaging evidence, conceptual models, and best practice.
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Affiliation(s)
- Jacob A Lafo
- a Department of Clinical and Health Psychology, College of Public Health & Health Professions , University of Florida , Gainesville , FL , USA.,c Center for Movement Disorders and Neurorestoration , University of Florida College of Medicine, University of Florida , Gainesville , FL , USA
| | - Jacob D Jones
- a Department of Clinical and Health Psychology, College of Public Health & Health Professions , University of Florida , Gainesville , FL , USA.,c Center for Movement Disorders and Neurorestoration , University of Florida College of Medicine, University of Florida , Gainesville , FL , USA
| | - Michael S Okun
- b Department of Neurology , University of Florida College of Medicine, University of Florida , Gainesville , FL , USA.,c Center for Movement Disorders and Neurorestoration , University of Florida College of Medicine, University of Florida , Gainesville , FL , USA
| | - Russell M Bauer
- a Department of Clinical and Health Psychology, College of Public Health & Health Professions , University of Florida , Gainesville , FL , USA.,c Center for Movement Disorders and Neurorestoration , University of Florida College of Medicine, University of Florida , Gainesville , FL , USA
| | - Catherine C Price
- a Department of Clinical and Health Psychology, College of Public Health & Health Professions , University of Florida , Gainesville , FL , USA.,c Center for Movement Disorders and Neurorestoration , University of Florida College of Medicine, University of Florida , Gainesville , FL , USA
| | - Dawn Bowers
- b Department of Neurology , University of Florida College of Medicine, University of Florida , Gainesville , FL , USA.,c Center for Movement Disorders and Neurorestoration , University of Florida College of Medicine, University of Florida , Gainesville , FL , USA
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Abstract
Essential tremor (ET) is one of the most common neurological diseases, with an estimated 7 million affected individuals in the United States. Postmortem studies in the past few years have resulted in new knowledge as well as a new formulation of disease pathophysiology. This new formulation centers on the notion that ET might be a disease of the cerebellum and, more specifically, the Purkinje cell (PC) population. Indeed, several investigators have proposed that ET may be a "Purkinjopathy." Supporting this formulation are data from controlled postmortem studies demonstrating (1) a range of morphological changes in the PC axon, (2) abnormalities in the position and orientation of PC bodies, (3) reduction in the number of PCs in some studies, (4) morphological changes in and pruning of the PC dendritic arbor with loss of dendritic spines, and (5) alterations in both the PC-basket cell interface and the PC-climbing fiber interface in ET cases. This new formulation has engendered some controversy and raised additional questions. Whether the constellation of changes observed in ET differs from that seen in other degenerative disorders of the cerebellum remains to be determined, although initial studies suggest the likely presence of a distinct profile of changes in ET.
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Affiliation(s)
- Elan D Louis
- Division of Movement Disorders, Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, USA Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, CT, USA
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Mücke D, Becker J, Barbe MT, Meister I, Liebhart L, Roettger TB, Dembek T, Timmermann L, Grice M. The effect of deep brain stimulation on the speech motor system. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2014; 57:1206-1218. [PMID: 24686442 DOI: 10.1044/2014_jslhr-s-13-0155] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
PURPOSE Chronic deep brain stimulation of the nucleus ventralis intermedius is an effective treatment for individuals with medication-resistant essential tremor. However, these individuals report that stimulation has a deleterious effect on their speech. The present study investigates one important factor leading to these effects: the coordination of oral and glottal articulation. METHOD Sixteen native-speaking German adults with essential tremor, between 26 and 86 years old, with and without chronic deep brain stimulation of the nucleus ventralis intermedius and 12 healthy, age-matched subjects were recorded performing a fast syllable repetition task (/papapa/, /tatata/, /kakaka/). Syllable duration and voicing-to-syllable ratio as well as parameters related directly to consonant production, voicing during constriction, and frication during constriction were measured. RESULTS Voicing during constriction was greater in subjects with essential tremor than in controls, indicating a perseveration of voicing into the voiceless consonant. Stimulation led to fewer voiceless intervals (voicing-to-syllable ratio), indicating a reduced degree of glottal abduction during the entire syllable cycle. Stimulation also induced incomplete oral closures (frication during constriction), indicating imprecise oral articulation. CONCLUSION The detrimental effect of stimulation on the speech motor system can be quantified using acoustic measures at the subsyllabic level.
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Schmouth JF, Dion PA, Rouleau GA. Genetics of essential tremor: From phenotype to genes, insights from both human and mouse studies. Prog Neurobiol 2014; 119-120:1-19. [DOI: 10.1016/j.pneurobio.2014.05.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/16/2014] [Accepted: 05/02/2014] [Indexed: 11/30/2022]
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Gironell A. The GABA Hypothesis in Essential Tremor: Lights and Shadows. TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2014; 4:254. [PMID: 25120944 PMCID: PMC4108714 DOI: 10.7916/d8sf2t9c] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 06/16/2014] [Indexed: 02/07/2023]
Abstract
Background The gamma-aminobutyric acid (GABA) hypothesis in essential tremor (ET) implies a disturbance of the GABAergic system, especially involving the cerebellum. This review examines the evidence of the GABA hypothesis. Methods The review is based on published data about GABA dysfunction in ET, taking into account studies on cerebrospinal fluid, pathology, electrophysiology, genetics, neuroimaging, experimental animal models, and human drug therapies. Results Findings from several studies support the GABA hypothesis in ET. The hypothesis follows four steps: 1) cerebellar neurodegeneration with Purkinje cell loss; 2) a decrease in GABA system activity in deep cerebellar neurons; 3) disinhibition in output deep cerebellar neurons with pacemaker activity; and 4) an increase in rhythmic activity of the thalamus and thalamo-cortical circuit, contributing to the generation of tremor. Doubts have been cast on this hypothesis, however, by the fact that it is based on relatively few works, controversial post-mortem findings, and negative genetic studies on the GABA system. Furthermore, GABAergic drug efficacy is low and some GABAergic drugs do not have antitremoric efficacy. Discussion The GABA hypothesis continues to be the most robust pathophysiological hypothesis to explain ET. There is light in all GABA hypothesis steps, but a number of shadows cannot be overlooked. We need more studies to clarify the neurodegenerative nature of the disease, to confirm the decrease of GABA activity in the cerebellum, and to test more therapies that enhance the GABA transmission specifically in the cerebellum area.
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Affiliation(s)
- Alexandre Gironell
- Movement Disorders Unit, Department of Neurology, Sant Pau Hospital, Autonomous University of Barcelona, Catalonia, Spain
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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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Mismatch Negativity in essential tremor: Role of age at onset in pre-attentive auditory discrimination. Clin Neurophysiol 2014; 125:708-714. [DOI: 10.1016/j.clinph.2013.09.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 08/30/2013] [Accepted: 09/16/2013] [Indexed: 01/11/2023]
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Jellinger KA. Is there cerebellar pathology in essential tremor? Mov Disord 2014; 29:435-6. [PMID: 24585416 DOI: 10.1002/mds.25852] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 02/03/2014] [Indexed: 11/11/2022] Open
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Delay C, Tremblay C, Brochu E, Paris-Robidas S, Emond V, Rajput AH, Rajput A, Calon F. Increased LINGO1 in the cerebellum of essential tremor patients. Mov Disord 2014; 29:1637-47. [PMID: 24531928 DOI: 10.1002/mds.25819] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 11/28/2013] [Accepted: 12/30/2013] [Indexed: 12/21/2022] Open
Abstract
Essential tremor (ET) is the most prevalent adult-onset movement disorder. Despite its health burden, no clear pathognomonic sign has been identified to date because of the rarity of clinicopathological studies. Moreover, treatment options are still scarce and have not significantly changed in the last 30 years, underscoring the urgent need to develop new treatment avenues. In the recent years, leucine-rich repeat (LRR) and immunoglobulin (Ig) domain-containing Nogo receptor-interacting proteins 1 and 2 (LINGO1 and LINGO2, respectively) have been increasingly regarded as possible ET modulators due to emerging genetic association studies linking LINGO with ET. We have investigated LINGO protein and messenger RNA (mRNA) expression in the cerebellum of patients with ET, patients with Parkinson's disease (PD), and a control group using Western immunoblotting and in situ hybridization. Protein levels of LINGO1, but not LINGO2, were significantly increased in the cerebellar cortex of ET patients compared with controls, particularly in individuals with longer disease duration. Compared with controls, LINGO1 protein levels were increased in the cerebellar white matter of PD and ET patients but, for the latter, only when disease duration exceeded 20 years. However, no alteration in LINGO1 mRNA was observed between groups in either the cerebellar cortex or the white matter. We observed alterations in LINGO expression in diseased brain that seemed to progress along with the disease, being initiated in the cerebellar cortex before reaching the white matter. Because LINGO up-regulation has been identified as a potential pathological response to ongoing neurodegenerative processes, the present data suggest that LINGO1 is a potential drug target for ET.
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Affiliation(s)
- Charlotte Delay
- Faculty of Pharmacy, Université Laval, Québec City, Québec, Canada; Centre de Recherche du Centre Hospitalier Universitaire de Québec, Neurosciences Axis, Québec City, Québec, Canada
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Hedera P, Cibulčík F, Davis TL. Pharmacotherapy of essential tremor. J Cent Nerv Syst Dis 2013; 5:43-55. [PMID: 24385718 PMCID: PMC3873223 DOI: 10.4137/jcnsd.s6561] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 11/10/2013] [Accepted: 11/25/2013] [Indexed: 12/11/2022] Open
Abstract
Essential tremor (ET) is a common movement disorder but its pathogenesis remains poorly understood. This has limited the development of effective pharmacotherapy. The current therapeutic armamentaria for ET represent the product of careful clinical observation rather than targeted molecular modeling. Here we review their pharmacokinetics, metabolism, dosing, and adverse effect profiles and propose a treatment algorithm. We also discuss the concept of medically refractory tremor, as therapeutic trials should be limited unless invasive therapy is contraindicated or not desired by patients.
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Affiliation(s)
- Peter Hedera
- Department of Neurology, Vanderbilt University, Nashville, TN
| | - František Cibulčík
- Department of Neurology, Slovak Medical University and University Hospital Bratislava, Slovakia
| | - Thomas L Davis
- Department of Neurology, Vanderbilt University, Nashville, TN
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Abstract
Classic essential tremor is a clinical syndrome of action tremor in the upper limbs (at least 95 % of patients) and less commonly the head, face/jaw, voice, tongue, trunk, and lower limbs, in the absence of other neurologic signs. However, the longstanding notion that essential tremor is a monosymptomatic tremor disorder is being challenged by a growing literature describing associated disturbances of tandem walking, personality, mood, hearing, and cognition. There is also epidemiologic, pathologic, and genetic evidence that essential tremor is pathophysiologically heterogeneous. Misdiagnosis of essential tremor is common because clinicians frequently overlook other neurologic signs and because action tremor in the hands is caused by many conditions, including dystonia, Parkinson disease, and drug-induced tremor. Thus, essential tremor is nothing more than a syndrome of idiopathic tremulousness, and the challenge for researchers and clinicians is to find specific etiologies of this syndrome.
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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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Helmich RC, Toni I, Deuschl G, Bloem BR. The Pathophysiology of Essential Tremor and Parkinson’s Tremor. Curr Neurol Neurosci Rep 2013; 13:378. [DOI: 10.1007/s11910-013-0378-8] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Fang W, Lv F, Luo T, Cheng O, Liao W, Sheng K, Wang X, Wu F, Hu Y, Luo J, Yang QX, Zhang H. Abnormal regional homogeneity in patients with essential tremor revealed by resting-state functional MRI. PLoS One 2013; 8:e69199. [PMID: 23869236 PMCID: PMC3711903 DOI: 10.1371/journal.pone.0069199] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 06/06/2013] [Indexed: 01/23/2023] Open
Abstract
Essential tremor (ET) is one of the most common movement disorders in human adults. It can be characterized as a progressive neurological disorder of which the most recognizable feature is a tremor of the arms or hands that is apparent during voluntary movements such as eating and writing. The pathology of ET remains unclear. Resting-state fMRI (RS-fMRI), as a non-invasive imaging technique, was employed to investigate abnormalities of functional connectivity in ET in the brain. Regional homogeneity (ReHo) was used as a metric of RS-fMRI to assess the local functional connectivity abnormality in ET with 20 ET patients and 20 age- and gender-matched healthy controls (HC). The ET group showed decreased ReHo in the anterior and posterior bilateral cerebellar lobes, the bilateral thalamus and the insular lobe, and increased ReHo in the bilateral prefrontal and parietal cortices, the left primary motor cortex and left supplementary motor area. The abnormal ReHo value of ET patients in the bilateral anterior cerebellar lobes and the right posterior cerebellar lobe were negatively correlated with the tremor severity score, while positively correlated with that in the left primary motor cortex. These findings suggest that the abnormality in cerebello-thalamo-cortical motor pathway is involved in tremor generation and propagation, which may be related to motor-related symptoms in ET patients. Meanwhile, the abnormality in the prefrontal and parietal regions may be associated with non-motor symptoms in ET. These findings suggest that the ReHo could be utilized for investigations of functional-pathological mechanism of ET.
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Affiliation(s)
- Weidong Fang
- Department of Radiology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Fajin Lv
- Department of Radiology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Tianyou Luo
- Department of Radiology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China
- * E-mail: (TL); (HZ)
| | - Oumei Cheng
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Wei Liao
- Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China
- Zhejiang Key Laboratory for Research in Assessment of Cognitive Impairments, Hangzhou, China
| | - Ke Sheng
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xuefeng Wang
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Fei Wu
- Department of Radiology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yida Hu
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Jing Luo
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Qing X. Yang
- Center for NMR Research, Department of Radiology, Penn State College of Medicine, Hershey, Pennsylvania, United States of America
| | - Han Zhang
- Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China
- Zhejiang Key Laboratory for Research in Assessment of Cognitive Impairments, Hangzhou, China
- * E-mail: (TL); (HZ)
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Rajput AH, Robinson CA, Rajput A. Purkinje cell loss is neither pathological basis nor characteristic of essential tremor. Parkinsonism Relat Disord 2013; 19:490-1. [PMID: 23312988 DOI: 10.1016/j.parkreldis.2012.11.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 11/29/2012] [Indexed: 10/27/2022]
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