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Prasad S, Rajan A, Ingalhalikar M, Bharath RD, Saini J, Pal PK. Probabilistic Tractography-Based Tremor Network Connectivity in Tremor Dominant Parkinson's Disease and Essential Tremor plus. Brain Connect 2024; 14:340-350. [PMID: 38874981 DOI: 10.1089/brain.2023.0066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024] Open
Abstract
Background: The basal ganglia-thalamocortical (BGTC) and cerebello-thalamocortical (CTC) networks are implicated in tremor genesis; however, exact contributions across disorders have not been studied. Objective: Evaluate the structural connectivity of BGTC and CTC in tremor-dominant Parkinson's disease (TDPD) and essential tremor plus (ETP) with the aid of probabilistic tractography and graph theory analysis. Methods: Structural connectomes of the BGTC and CTC were generated by probabilistic tractography for TDPD (n = 25), ETP (ET with rest tremor, n = 25), and healthy control (HC, n = 22). The Brain Connectivity Toolbox was used for computing standard topological graph measures of segregation, integration, and centrality. Tremor severity was ascertained using the Fahn-Tolosa-Marin tremor rating scale (FTMRS). Results: There was no difference in total FTMRS scores. Compared with HC, TDPD had a lower global efficiency and characteristic path length. Abnormality in segregation, integration, and centrality of bilateral putamen, globus pallidus externa (GPe), and GP interna (GPi), with reduction of centrality of right caudate and cerebellar lobule 8, was observed. ETP showed reduction in segregation and integration of right GPe and GPi, ventrolateral posterior nucleus, and centrality of right putamen, compared with HC. Differences between TDPD and ETP were a reduction of strength of the right putamen, and lower clustering coefficient, local efficiency, and strength of the left GPi in TDPD. Conclusions: Contrary to expectations, TDPD and ETP may not be significantly different with regard to tremor pathogenesis, with definite overlaps. There may be fundamental similarities in network disruption across different tremor disorders with the same tremor activation patterns, along with disease-specific changes.
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Affiliation(s)
- Shweta Prasad
- Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India
| | - Archith Rajan
- Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India
| | - Madhura Ingalhalikar
- Symbiosis Center for Medical Image Analysis and Symbiosis Institute of Technology, Symbiosis International (Deemed) University, Pune, India
| | - Rose Dawn Bharath
- Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India
| | - Jitender Saini
- Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India
| | - Pramod Kumar Pal
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India
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Sadeghi F, Pötter-Nerger M, Grimm K, Gerloff C, Schulz R, Zittel S. Smaller Cerebellar Lobule VIIb is Associated with Tremor Severity in Parkinson's Disease. CEREBELLUM (LONDON, ENGLAND) 2024; 23:355-362. [PMID: 36802020 PMCID: PMC10950956 DOI: 10.1007/s12311-023-01532-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/09/2023] [Indexed: 02/23/2023]
Abstract
Alterations in the cerebellum's morphology in Parkinson's disease (PD) point to its pathophysiological involvement in this movement disorder. Such abnormalities have previously been attributed to different PD motor subtypes. The aim of the study was to relate volumes of specific cerebellar lobules to motor symptom severity, in particular tremor (TR), bradykinesia/rigidity (BR), and postural instability and gait disorders (PIGD) in PD. We performed a volumetric analysis based on T1-weighted MRI images of 55 participants with PD (22 females, median age 65 years, Hoehn and Yahr stage 2). Multiple regression models were fitted to investigate associations between volumes of cerebellar lobules with clinical symptom severity based on MDS-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III score and sub-scores for TR, BR, and PIGD; adjusted for age, sex, disease duration, and intercranial volume as cofactors. Smaller volume of lobule VIIb was associated with higher tremor severity (P = 0.004). No structure-function relationships were detected for other lobules or other motor symptoms. This distinct structural association denotes the involvement of the cerebellum in PD tremor. Characterizing morphological features of the cerebellum leads to a better understanding of its role in the spectrum of motor symptoms in PD and contributes further to identifying potential biological markers.
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Affiliation(s)
- Fatemeh Sadeghi
- Klinik und Poliklinik für Neurologie, Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Monika Pötter-Nerger
- Klinik und Poliklinik für Neurologie, Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Kai Grimm
- Klinik und Poliklinik für Neurologie, Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Christian Gerloff
- Klinik und Poliklinik für Neurologie, Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Robert Schulz
- Klinik und Poliklinik für Neurologie, Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Simone Zittel
- Klinik und Poliklinik für Neurologie, Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany.
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van der Stouwe AMM. Lack of effect of deep brain stimulation on resting-state functional connectivity in essential tremor provides valuable insights. Brain Commun 2024; 6:fcae060. [PMID: 38482374 PMCID: PMC10935647 DOI: 10.1093/braincomms/fcae060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 02/19/2024] [Accepted: 02/27/2024] [Indexed: 05/02/2024] Open
Abstract
This scientific commentary refers to 'Deep brain stimulation does not modulate resting-state functional connectivity in essential tremor', by Awad et al. (https://doi.org/10.1093/braincomms/fcae012).
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Affiliation(s)
- A M Madelein van der Stouwe
- Department of Neurology, University Medical Center Groningen, 9700 RB Groningen, the Netherlands
- Expertise Center Movement Disorders Groningen, University Medical Center Groningen, 9700 RB Groningen, the Netherlands
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4
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Fanning A, Kuo SH. Clinical Heterogeneity of Essential Tremor: Understanding Neural Substrates of Action Tremor Subtypes. CEREBELLUM (LONDON, ENGLAND) 2023:10.1007/s12311-023-01551-3. [PMID: 37022657 PMCID: PMC10556200 DOI: 10.1007/s12311-023-01551-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/21/2023] [Indexed: 04/07/2023]
Abstract
Essential tremor (ET) is a common movement disorder affecting millions of people. Studies of ET patients and perturbations in animal models have provided a foundation for the neural networks involved in its pathophysiology. However, ET encompasses a wide variability of phenotypic expression, and this may be the consequence of dysfunction in distinct subcircuits in the brain. The cerebello-thalamo-cortical circuit is a common substrate for the multiple subtypes of action tremor. Within the cerebellum, three sets of cerebellar cortex-deep cerebellar nuclei connections are important for tremor. The lateral hemispheres and dentate nuclei may be involved in intention, postural and isometric tremor. The intermediate zone and interposed nuclei could be involved in intention tremor. The vermis and fastigial nuclei could be involved in head and proximal upper extremity tremor. Studying distinct cerebellar circuitry will provide important framework for understanding the clinical heterogeneity of ET.
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Affiliation(s)
- Alexander Fanning
- Department of Neurology, Columbia University, New York, NY, 10032, USA
- Initiative for Columbia Ataxia and Tremor, Columbia University, New York, NY, 10032, USA
| | - Sheng-Han Kuo
- Department of Neurology, Columbia University, New York, NY, 10032, USA.
- Initiative for Columbia Ataxia and Tremor, Columbia University, New York, NY, 10032, USA.
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5
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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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6
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Nieuwhof F, Toni I, Buijink AW, van Rootselaar AF, van de Warrenburg BP, Helmich RC. Phase-locked transcranial electrical brain stimulation for tremor suppression in dystonic tremor syndromes. Clin Neurophysiol 2022; 140:239-250. [DOI: 10.1016/j.clinph.2022.03.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 12/19/2022]
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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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8
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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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9
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Pan MK, Kuo SH. Essential tremor: Clinical perspectives and pathophysiology. J Neurol Sci 2022; 435:120198. [PMID: 35299120 PMCID: PMC10363990 DOI: 10.1016/j.jns.2022.120198] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/01/2021] [Accepted: 02/17/2022] [Indexed: 12/12/2022]
Abstract
Essential tremor (ET) is one of the most common neurological disorders and can be highly disabling. In recent years, studies on the clinical perspectives and pathophysiology have advanced our understanding of ET. Specifically, clinical heterogeneity of ET, with co-existence of tremor and other neurological features such as dystonia, ataxia, and cognitive dysfunction, has been identified. The cerebellum has been found to be the key brain region for tremor generation, and structural alterations of the cerebellum have been extensively studied in ET. Finally, four main ET pathophysiologies have been proposed: 1) environmental exposures to β-carboline alkaloids and the consequent olivocerebellar hyper-excitation, 2) cerebellar GABA deficiency, 3) climbing fiber synaptic pathology with related cerebellar oscillatory activity, 4) extra-cerebellar oscillatory activity. While these four theories are not mutually exclusive, they can represent distinctive ET subtypes, indicating multiple types of abnormal brain circuitry can lead to action tremor. This article is part of the Special Issue "Tremor" edited by Daniel D. Truong, Mark Hallett, and Aasef Shaikh.
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10
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Nieuwhof F, Toni I, Dirkx MF, Gallea C, Vidailhet M, Buijink AWG, van Rootselaar AF, van de Warrenburg BPC, Helmich RC. Cerebello-thalamic activity drives an abnormal motor network into dystonic tremor. Neuroimage Clin 2021; 33:102919. [PMID: 34929584 PMCID: PMC8688717 DOI: 10.1016/j.nicl.2021.102919] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/10/2021] [Accepted: 12/15/2021] [Indexed: 01/18/2023]
Abstract
Dystonic tremor syndromes are highly burdensome and treatment is often inadequate. This is partly due to poor understanding of the underlying pathophysiology. Several lines of research suggest involvement of the cerebello-thalamo-cortical circuit and the basal ganglia in dystonic tremor syndromes, but their role is unclear. Here we aimed to investigate the contribution of the cerebello-thalamo-cortical circuit and the basal ganglia to the pathophysiology of dystonic tremor syndrome, by directly linking tremor fluctuations to cerebral activity during scanning. In 27 patients with dystonic tremor syndrome (dystonic tremor: n = 23; tremor associated with dystonia: n = 4), we used concurrent accelerometery and functional MRI during a posture holding task that evoked tremor, alternated with rest. Using multiple regression analyses, we separated tremor-related activity from brain activity related to (voluntary) posture holding. Using dynamic causal modelling, we tested for altered effective connectivity between tremor-related brain regions as a function of tremor amplitude fluctuations. Finally, we compared grey matter volume between patients (n = 27) and matched controls (n = 27). We found tremor-related activity in sensorimotor regions of the bilateral cerebellum, contralateral posterior and anterior ventral lateral nuclei of the thalamus (VLp and VLa), contralateral primary motor cortex (hand area), contralateral pallidum, and the bilateral frontal cortex (laterality with respect to the tremor). Grey matter volume was increased in patients compared to controls in the portion of contralateral thalamus also showing tremor-related activity, as well as in bilateral medial and left lateral primary motor cortex, where no tremor-related activity was present. Effective connectivity analyses showed that inter-regional coupling in the cerebello-thalamic pathway, as well as the thalamic self-connection, were strengthened as a function of increasing tremor power. These findings indicate that the pathophysiology of dystonic tremor syndromes involves functional and structural changes in the cerebello-thalamo-cortical circuit and pallidum. Deficient input from the cerebellum towards the thalamo-cortical circuit, together with hypertrophy of the thalamus, may play a key role in the generation of dystonic tremor syndrome.
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Affiliation(s)
- Freek Nieuwhof
- Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University, 6500 HB Nijmegen, the Netherlands
| | - Ivan Toni
- Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University, 6500 HB Nijmegen, the Netherlands
| | - Michiel F Dirkx
- Department of Neurology, Centre of Expertise for Parkinson & Movement Disorders, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, 6500 HB Nijmegen, the Netherlands
| | - Cecile Gallea
- MOV'IT Section (Movement Investigations and Therapeutics), Paris Brain Institute (CNRS/INSERM UMR 7225/1127), Sorbonne Université, 75013 Paris, France
| | - Marie Vidailhet
- Institut du Cerveau et de la Moelle épinière (ICM) UMR 1127, Hôpital de la Pitié-Salpétrière, Department of Neurology, AP-HP, Sorbonne Université, 75013 Paris, France
| | - Arthur W G Buijink
- Department of Neurology, Amsterdam University Medical Centers, 1105 AZ Amsterdam Neuroscience, University of Amsterdam, Amsterdam, the Netherlands
| | - Anne-Fleur van Rootselaar
- Department of Neurology, Amsterdam University Medical Centers, 1105 AZ Amsterdam Neuroscience, University of Amsterdam, Amsterdam, the Netherlands
| | - Bart P C van de Warrenburg
- Department of Neurology, Centre of Expertise for Parkinson & Movement Disorders, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, 6500 HB Nijmegen, the Netherlands
| | - Rick C Helmich
- Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University, 6500 HB Nijmegen, the Netherlands; Department of Neurology, Centre of Expertise for Parkinson & Movement Disorders, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, 6500 HB Nijmegen, the Netherlands.
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van den Berg KRE, Helmich RC. The Role of the Cerebellum in Tremor - Evidence from Neuroimaging. Tremor Other Hyperkinet Mov (N Y) 2021; 11:49. [PMID: 34820148 PMCID: PMC8603856 DOI: 10.5334/tohm.660] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 10/28/2021] [Indexed: 01/04/2023] Open
Abstract
Background Neuroimaging research has played a key role in identifying which cerebral changes are associated with tremor. Here we will focus on the cerebellum, which may drive tremor oscillations, process tremor-related afferents, modulate activity in remote brain regions, or a combination. Methods On the 6th of October 2021, we conducted a PubMed search to select articles providing neuroimaging evidence for cerebellar involvement in essential tremor (ET), Parkinson's disease (PD) tremor, and dystonic tremor (DT). Results In ET, tremor-related activity is found in motor areas of the bilateral cerebellum, and altered functional connectivity within and outside the cerebellum correlates with tremor severity. Furthermore, ET is associated with cerebellar atrophy, but also with compensatory structural changes outside the cerebellum (e.g. supplementary motor area). In PD, tremor-related cerebellar activity and increased cerebello-thalamic coupling has been found. Emerging evidence suggests that the cerebellum plays a key role in dopamine-resistant rest tremor and in postural tremor. Cerebellar structural alterations have been identified in PD, but only some relate to tremor. DT is associated with more widespread cerebral networks than other tremor types. Discussion In ET, the cerebellum likely acts as an oscillator, potentially due to loss of inhibitory mechanisms. In contrast, in PD the cerebellum may be a modulator, which contributes to tremor oscillations by influencing the thalamo-cortical system. The precise role of the cerebellum in DT remains unclear. We recommend that future research measures tremor-related activity directly by combining electrophysiology with neuroimaging, while brain stimulation techniques may be used to establish causality. Highlights This review of neuroimaging studies has provided convincing evidence that the cerebellum plays a key role in the pathophysiology of ET, PD tremor, and dystonic tremor syndromes. This contribution may consist of driving tremor oscillations, processing tremor-related afferents, modulating activity in remote brain regions, or all the above.
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Affiliation(s)
- Kevin R. E. van den Berg
- Centre of Expertise for Parkinson and Movement Disorders, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Rick C. Helmich
- Centre of Expertise for Parkinson and Movement Disorders, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands
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12
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Pietracupa S, Bologna M, Tommasin S, Berardelli A, Pantano P. The Contribution of Neuroimaging to the Understanding of Essential Tremor Pathophysiology: a Systematic Review. THE CEREBELLUM 2021; 21:1029-1051. [PMID: 34657271 DOI: 10.1007/s12311-021-01335-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/10/2021] [Indexed: 12/14/2022]
Abstract
Essential tremor (ET) is one of the most common movement disorders. Over the last 10 years, magnetic resonance imaging (MRI) has shed light on the structural and functional abnormalities possibly involved in ET pathophysiology. In this systematic review, we aimed to identify the cortical and subcortical structures involved and the role that different brain areas play in the pathophysiology of motor and non-motor ET features. We found that structural (grey and white matter) cerebellar damage and connectivity alterations between the cerebellum and various cortical areas play a role in both motor and non-motor symptoms of ET. In particular, many studies found an association between MRI findings and non-motor symptoms.
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Affiliation(s)
| | - Matteo Bologna
- IRCCS Neuromed, Via Atinense 18, Pozzilli, IS, Italy.,Department of Human Neuroscience, Sapienza University of Rome, Rome, Italy
| | - Silvia Tommasin
- Department of Human Neuroscience, Sapienza University of Rome, Rome, Italy
| | - Alfredo Berardelli
- IRCCS Neuromed, Via Atinense 18, Pozzilli, IS, Italy.,Department of Human Neuroscience, Sapienza University of Rome, Rome, Italy
| | - Patrizia Pantano
- IRCCS Neuromed, Via Atinense 18, Pozzilli, IS, Italy.,Department of Human Neuroscience, Sapienza University of Rome, Rome, Italy
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13
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Holtbernd F, Shah NJ. Imaging the Pathophysiology of Essential Tremor-A Systematic Review. Front Neurol 2021; 12:680254. [PMID: 34220687 PMCID: PMC8244929 DOI: 10.3389/fneur.2021.680254] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 05/04/2021] [Indexed: 11/28/2022] Open
Abstract
Background: The pathophysiology underlying essential tremor (ET) still is poorly understood. Recent research suggests a pivotal role of the cerebellum in tremor genesis, and an ongoing controversy remains as to whether ET constitutes a neurodegenerative disorder. In addition, mounting evidence indicates that alterations in the gamma-aminobutyric acid neurotransmitter system are involved in ET pathophysiology. Here, we systematically review structural, functional, and metabolic neuroimaging studies and discuss current concepts of ET pathophysiology from an imaging perspective. Methods: We conducted a PubMed and Scopus search from 1966 up to December 2020, entering essential tremor in combination with any of the following search terms and their corresponding abbreviations: positron emission tomography (PET), single-photon emission computed tomography (SPECT), magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), and gamma-aminobutyric acid (GABA). Results: Altered functional connectivity in the cerebellum and cerebello-thalamico-cortical circuitry is a prevalent finding in functional imaging studies. Reports from structural imaging studies are less consistent, and there is no clear evidence for cerebellar neurodegeneration. However, diffusion tensor imaging robustly points toward microstructural cerebellar changes. Radiotracer imaging suggests that the dopaminergic axis is largely preserved in ET. Similarly, measurements of nigral iron content and neuromelanin are unremarkable in most studies; this is in contrast to Parkinson's disease (PD). PET and MRS studies provide limited evidence for cerebellar and thalamic GABAergic dysfunction. Conclusions: There is robust evidence indicating that the cerebellum plays a key role within a multiple oscillator tremor network which underlies tremor genesis. However, whether cerebellar dysfunction relies on a neurodegenerative process remains unclear. Dopaminergic and iron imaging do not suggest a substantial overlap of ET with PD pathophysiology. There is limited evidence for alterations of the GABAergic neurotransmitter system in ET. The clinical, demographical, and genetic heterogeneity of ET translates into neuroimaging and likely explains the various inconsistencies reported.
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Affiliation(s)
- Florian Holtbernd
- Institute of Neuroscience and Medicine (INM-4/INM-11), Forschungszentrum Juelich GmbH, Juelich, Germany
- JARA-BRAIN Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Juelich GmbH, Rheinisch-Westfaelische Technische Hochschule Aachen University, Aachen, Germany
- Department of Neurology, Rheinisch-Westfaelische Technische Hochschule Aachen University, Aachen, Germany
| | - N. Jon Shah
- Institute of Neuroscience and Medicine (INM-4/INM-11), Forschungszentrum Juelich GmbH, Juelich, Germany
- JARA-BRAIN Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Juelich GmbH, Rheinisch-Westfaelische Technische Hochschule Aachen University, Aachen, Germany
- Department of Neurology, Rheinisch-Westfaelische Technische Hochschule Aachen University, Aachen, Germany
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Abstract
Patients with essential tremor, vocal tremor, torticollis, myoclonus-dystonia and posthypoxic myoclonus often benefit in a surprisingly rapid and robust manner from ingestion of a modest amount of alcohol (ethanol). Despite considerable investigation, the mechanism of ethanol’s ability to produce this effect remains a mystery. In this paper, we review the pharmacology of ethanol and its analogue GHB (or sodium oxybate), summarize the published literature of alcohol-responsive hyperkinetic movement disorders, and demonstrate videos of patients we have treated over the last fifteen years with either an ethanol challenge or with chronic sodium oxybate therapy. We then propose a novel explanation for this phenomenon—namely, that ingestion of modest doses of ethanol (or sodium oxybate) normalizes the aberrant motor networks underling these disorders. We propose that alcohol and its analogues improve clinical symptoms and their physiologic correlate by restoring the normal firing pattern of the major outflow pathways of the cerebellum (the Purkinje cells and deep cerebellar nuclei), We present evidence to support this hypothesis in animal models and in affected patients, and suggest future investigations to test this model.
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Boscolo Galazzo I, Magrinelli F, Pizzini FB, Storti SF, Agosta F, Filippi M, Marotta A, Mansueto G, Menegaz G, Tinazzi M. Voxel-based morphometry and task functional magnetic resonance imaging in essential tremor: evidence for a disrupted brain network. Sci Rep 2020; 10:15061. [PMID: 32934259 PMCID: PMC7493988 DOI: 10.1038/s41598-020-69514-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 07/13/2020] [Indexed: 11/09/2022] Open
Abstract
The pathophysiology of essential tremor (ET) is controversial and might be further elucidated by advanced neuroimaging. Focusing on homogenous ET patients diagnosed according to the 2018 consensus criteria, this study aimed to: (1) investigate whether task functional MRI (fMRI) can identify networks of activated and deactivated brain areas, (2) characterize morphometric and functional modulations, relative to healthy controls (HC). Ten ET patients and ten HC underwent fMRI while performing two motor tasks with their upper limb: (1) maintaining a posture (both groups); (2) simulating tremor (HC only). Activations/deactivations were obtained from General Linear Model and compared across groups/tasks. Voxel-based morphometry and linear regressions between clinical and fMRI data were also performed. Few cerebellar clusters of gray matter loss were found in ET. Conversely, widespread fMRI alterations were shown. Tremor in ET (task 1) was associated with extensive deactivations mainly involving the cerebellum, sensory-motor cortex, and basal ganglia compared to both tasks in HC, and was negatively correlated with clinical tremor scales. Homogeneous ET patients demonstrated deactivation patterns during tasks triggering tremor, encompassing a network of cortical and subcortical regions. Our results point towards a marked cerebellar involvement in ET pathophysiology and the presence of an impaired cerebello-thalamo-cortical tremor network.
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Affiliation(s)
- Ilaria Boscolo Galazzo
- Department of Computer Science, University of Verona, Strada Le Grazie 15, Ca' Vignal 2, 37134, Verona, Italy.
| | - Francesca Magrinelli
- Department of Neurosciences, Biomedicine and Movement Sciences, Neurology Section, University of Verona, Piazzale L.A. Scuro 10, 37134, Verona, Italy.
| | | | - Silvia Francesca Storti
- Department of Computer Science, University of Verona, Strada Le Grazie 15, Ca' Vignal 2, 37134, Verona, Italy
| | - Federica Agosta
- Neuroimaging Research Unit, Division of Neuroscience, Institute of Experimental Neurology, San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy
| | - Massimo Filippi
- Neuroimaging Research Unit, Division of Neuroscience, Institute of Experimental Neurology, San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy
| | - Angela Marotta
- Department of Neurosciences, Biomedicine and Movement Sciences, Neurology Section, University of Verona, Piazzale L.A. Scuro 10, 37134, Verona, Italy
| | - Giancarlo Mansueto
- Department of Diagnostics and Pathology, University of Verona, Verona, Italy
| | - Gloria Menegaz
- Department of Computer Science, University of Verona, Strada Le Grazie 15, Ca' Vignal 2, 37134, Verona, Italy
| | - Michele Tinazzi
- Department of Neurosciences, Biomedicine and Movement Sciences, Neurology Section, University of Verona, Piazzale L.A. Scuro 10, 37134, Verona, Italy
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16
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Nieuwhof F, de Bie RMA, Praamstra P, van den Munckhof P, Helmich RC. The cerebral tremor circuit in a patient with Holmes tremor. Ann Clin Transl Neurol 2020; 7:1453-1458. [PMID: 32725752 PMCID: PMC7448163 DOI: 10.1002/acn3.51143] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 07/02/2020] [Accepted: 07/06/2020] [Indexed: 12/12/2022] Open
Abstract
The cerebral network associated with Holmes tremor has never been determined directly. A previous study reported a brain network that is functionally connected, in healthy individuals, to different lesions that cause Holmes tremor (lesion connectome). We report a 71-year-old man with severe left-sided tremor caused by a microbleed near the right red nucleus. Using accelerometry-fMRI, we show tremor-related activity in contralateral sensorimotor cortex and cerebellar vermis. This network was distinct from, but functionally coupled to, the Holmes lesion connectome. We propose that Holmes tremor involves three distinct cerebral mechanisms: a structural lesion, an intermediate lesion connectome, and symptom-related activity.
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Affiliation(s)
- Freek Nieuwhof
- Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Rob M A de Bie
- Department of Neurology, Amsterdam UMC - Locatie AMC, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Peter Praamstra
- Department of Neurology, Center of Expertise for Parkinson & Movement Disorders, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Pepijn van den Munckhof
- Department of Neurosurgery, Amsterdam UMC - Locatie AMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Rick C Helmich
- Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands.,Department of Neurology, Center of Expertise for Parkinson & Movement Disorders, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands
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17
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18
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Tuleasca C, Bolton TAW, Régis J, Najdenovska E, Witjas T, Girard N, Delaire F, Vincent M, Faouzi M, Thiran JP, Bach Cuadra M, Levivier M, Van De Ville D. Normalization of aberrant pretherapeutic dynamic functional connectivity of extrastriate visual system in patients who underwent thalamotomy with stereotactic radiosurgery for essential tremor: a resting-state functional MRI study. J Neurosurg 2020; 132:1792-1801. [PMID: 31075777 DOI: 10.3171/2019.2.jns183454] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 02/12/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The tremor circuitry has commonly been hypothesized to be driven by one or multiple pacemakers within the cerebello-thalamo-cortical pathway, including the cerebellum, contralateral motor thalamus, and primary motor cortex. However, previous studies, using multiple methodologies, have advocated that tremor could be influenced by changes within the right extrastriate cortex, at both the structural and functional level. The purpose of this work was to evaluate the role of the extrastriate cortex in tremor generation and further arrest after left unilateral stereotactic radiosurgery thalamotomy (SRS-T). METHODS The authors considered 12 healthy controls (HCs, group 1); 15 patients with essential tremor (ET, right-sided, drug-resistant; group 2) before left unilateral SRS-T; and the same 15 patients (group 3) 1 year after the intervention, to account for delayed effects. Blood oxygenation level-dependent functional MRI during resting state was used to characterize the dynamic interactions of the right extrastriate cortex, comparing HC subjects against patients with ET before and 1 year after SRS-T. In particular, the authors applied coactivation pattern analysis to extract recurring whole-brain spatial patterns of brain activity over time. RESULTS The authors found 3 different sets of coactivating regions within the right extrastriate cortex in HCs and patients with pretherapeutic ET, reminiscent of the "cerebello-visuo-motor," "thalamo-visuo-motor" (including the targeted thalamus), and "basal ganglia and extrastriate" networks. The occurrence of the first pattern was decreased in pretherapeutic ET compared to HCs, whereas the other two patterns showed increased occurrences. This suggests a misbalance between the more prominent cerebellar circuitry and the thalamo-visuo-motor and basal ganglia networks. Multiple regression analysis showed that pretherapeutic standard tremor scores negatively correlated with the increased occurrence of the thalamo-visuo-motor network, suggesting a compensatory pathophysiological trait. Clinical improvement after SRS-T was related to changes in occurrences of the basal ganglia and extrastriate cortex circuitry, which returned to HC values after the intervention, suggesting that the dynamics of the extrastriate cortex had a role in tremor generation and further arrest after the intervention. CONCLUSIONS The data in this study point to a broader implication of the visual system in tremor generation, and not only through visual feedback, given its connections to the dorsal visual stream pathway and the cerebello-thalamo-cortical circuitry, with which its dynamic balance seems to be a crucial feature for reduced tremor. Furthermore, SRS-T seems to bring abnormal pretherapeutic connectivity of the extrastriate cortex to levels comparable to those of HC subjects.
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Affiliation(s)
- Constantin Tuleasca
- 1Service de Neurochirurgie, Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Sud, Centre Hospitalier Universitaire de Bicêtre, Paris
- 2Faculté de Médecine, Sorbonne Université, Paris, France
- 3Neurosurgery Service and Gamma Knife Center, Centre Hospitalier Universitaire Vaudois, Lausanne
- 4Medical Image Analysis Laboratory and Department of Radiology-Center of Biomedical Imaging, Centre Hospitalier Universitaire Vaudois, Lausanne
- 5Signal Processing Laboratory (LTS 5), École Polytechnique Fédérale de Lausanne
- 6Faculty of Biology and Medicine University of Lausanne
| | - Thomas A W Bolton
- 7Medical Image Processing Laboratory, École Polytechnique Fédérale de Lausanne, Switzerland
- 8Department of Radiology and Medical Informatics, University of Geneva, Switzerland
| | - Jean Régis
- 9Stereotactic and Functional Neurosurgery Service and Gamma Knife Unit, CHU Timone, Marseille
| | - Elena Najdenovska
- 4Medical Image Analysis Laboratory and Department of Radiology-Center of Biomedical Imaging, Centre Hospitalier Universitaire Vaudois, Lausanne
| | | | - Nadine Girard
- 11Department of Diagnostic and Interventional Neuroradiology, Centre de Résonance Magnétique Biologique et Médicale, Unité Mixte de Recherche, Centre National de la Recherche Scientifique, Faculté de Médecine et Assistance Publique-Hôpitaux de Marseille, Hôpital Timone, Marseille, France
| | - Francois Delaire
- 9Stereotactic and Functional Neurosurgery Service and Gamma Knife Unit, CHU Timone, Marseille
| | - Marion Vincent
- 9Stereotactic and Functional Neurosurgery Service and Gamma Knife Unit, CHU Timone, Marseille
| | - Mohamed Faouzi
- 12Institute of Social and Preventive Medicine, Lausanne; and
| | - Jean-Philippe Thiran
- 5Signal Processing Laboratory (LTS 5), École Polytechnique Fédérale de Lausanne
- 13Department of Radiology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Meritxell Bach Cuadra
- 4Medical Image Analysis Laboratory and Department of Radiology-Center of Biomedical Imaging, Centre Hospitalier Universitaire Vaudois, Lausanne
- 5Signal Processing Laboratory (LTS 5), École Polytechnique Fédérale de Lausanne
| | - Marc Levivier
- 3Neurosurgery Service and Gamma Knife Center, Centre Hospitalier Universitaire Vaudois, Lausanne
- 6Faculty of Biology and Medicine University of Lausanne
| | - Dimitri Van De Ville
- 7Medical Image Processing Laboratory, École Polytechnique Fédérale de Lausanne, Switzerland
- 8Department of Radiology and Medical Informatics, University of Geneva, Switzerland
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Lopez AM, Trujillo P, Hernandez AB, Lin YC, Kang H, Landman BA, Englot DJ, Dawant BM, Konrad PE, Claassen DO. Structural Correlates of the Sensorimotor Cerebellum in Parkinson's Disease and Essential Tremor. Mov Disord 2020; 35:1181-1188. [PMID: 32343870 DOI: 10.1002/mds.28044] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 12/15/2019] [Accepted: 02/28/2020] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Parkinson's disease (PD) and essential tremor (ET) are commonly encountered movement disorders. Pathophysiologic processes that localize to the cerebellum are described in both. There are limited studies investigating cerebellar structural changes in these conditions, largely because of inherent challenges in the efficiency of segmentation. METHODS We applied a novel multiatlas cerebellar segmentation method to T1-weighted images in 282 PD and 111 essential tremor patients to define 26 cerebellar lobule volumes. The severity of postural and resting tremor in both populations and gait and postural instability in PD patients were defined using subscores of the UPDRS and Washington Heights-Inwood Genetic Study motor scales. These clinical measurements were related to lobule volume size. Multiple comparisons were controlled using a false discovery rate method. RESULTS Group differences were identified between ET and PD patients, with reductions in deep cerebellar nucleus volume in ET versus reduced lobule VI volume in PD. In ET patients, lobule VIII was negatively correlated with the severity of postural tremor. In PD patients, lobule IV was positively correlated with resting tremor and total tremor severity. We observed differences in cerebellar structure that localized to sensorimotor lobules of the cerebellum. Lobule volumes appeared to differentially relate to clinical symptoms, suggesting important clinicopathologic distinctions between these conditions. These results emphasize the role of the cerebellum in tremor symptoms and should foster future clinical and pathologic investigations of the sensorimotor lobules of the cerebellum. © 2020 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Alexander M Lopez
- Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Paula Trujillo
- Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Adreanna B Hernandez
- Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Ya-Chen Lin
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Hakmook Kang
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Bennett A Landman
- Department of Radiology/Biomedical Engineering, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Dario J Englot
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Benoit M Dawant
- Department of Radiology/Biomedical Engineering, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Peter E Konrad
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Daniel O Claassen
- Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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20
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Brown AM, White JJ, van der Heijden ME, Zhou J, Lin T, Sillitoe RV. Purkinje cell misfiring generates high-amplitude action tremors that are corrected by cerebellar deep brain stimulation. eLife 2020; 9:e51928. [PMID: 32180549 PMCID: PMC7077982 DOI: 10.7554/elife.51928] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 02/26/2020] [Indexed: 02/06/2023] Open
Abstract
Tremor is currently ranked as the most common movement disorder. The brain regions and neural signals that initiate the debilitating shakiness of different body parts remain unclear. Here, we found that genetically silencing cerebellar Purkinje cell output blocked tremor in mice that were given the tremorgenic drug harmaline. We show in awake behaving mice that the onset of tremor is coincident with rhythmic Purkinje cell firing, which alters the activity of their target cerebellar nuclei cells. We mimic the tremorgenic action of the drug with optogenetics and present evidence that highly patterned Purkinje cell activity drives a powerful tremor in otherwise normal mice. Modulating the altered activity with deep brain stimulation directed to the Purkinje cell output in the cerebellar nuclei reduced tremor in freely moving mice. Together, the data implicate Purkinje cell connectivity as a neural substrate for tremor and a gateway for signals that mediate the disease.
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Affiliation(s)
- Amanda M Brown
- Department of Pathology and Immunology, Baylor College of MedicineHoustonUnited States
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute of Texas Children's HospitalHoustonUnited States
| | - Joshua J White
- Department of Pathology and Immunology, Baylor College of MedicineHoustonUnited States
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute of Texas Children's HospitalHoustonUnited States
| | - Meike E van der Heijden
- Department of Pathology and Immunology, Baylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute of Texas Children's HospitalHoustonUnited States
| | - Joy Zhou
- Department of Pathology and Immunology, Baylor College of MedicineHoustonUnited States
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute of Texas Children's HospitalHoustonUnited States
| | - Tao Lin
- Department of Pathology and Immunology, Baylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute of Texas Children's HospitalHoustonUnited States
| | - Roy V Sillitoe
- Department of Pathology and Immunology, Baylor College of MedicineHoustonUnited States
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute of Texas Children's HospitalHoustonUnited States
- Development, Disease Models & Therapeutics Graduate Program, Baylor College of MedicineHoustonUnited States
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21
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DeSimone JC, Archer DB, Vaillancourt DE, Wagle Shukla A. Network-level connectivity is a critical feature distinguishing dystonic tremor and essential tremor. Brain 2020; 142:1644-1659. [PMID: 30957839 DOI: 10.1093/brain/awz085] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 02/04/2019] [Accepted: 02/06/2019] [Indexed: 11/12/2022] Open
Abstract
Dystonia is a movement disorder characterized by involuntary muscle co-contractions that give rise to disabling movements and postures. A recent expert consensus labelled the incidence of tremor as a core feature of dystonia that can affect body regions both symptomatic and asymptomatic to dystonic features. We are only beginning to understand the neural network-level signatures that relate to clinical features of dystonic tremor. At the same time, clinical features of dystonic tremor can resemble that of essential tremor and present a diagnostic confound for clinicians. Here, we examined network-level functional activation and connectivity in patients with dystonic tremor and essential tremor. The dystonic tremor group included primarily cervical dystonia patients with dystonic head tremor and the majority had additional upper-limb tremor. The experimental paradigm included a precision grip-force task wherein online visual feedback related to force was manipulated across high and low spatial feedback levels. Prior work using this paradigm in essential tremor patients produced exacerbation of grip-force tremor and associated changes in functional activation. As such, we directly compared the effect of visual feedback on grip-force tremor and associated functional network-level activation and connectivity between dystonic tremor and essential tremor patient cohorts to better understand disease-specific mechanisms. Increased visual feedback similarly exacerbated force tremor during the grip-force task in dystonic tremor and essential tremor cohorts. Patients with dystonic tremor and essential tremor were characterized by distinct functional activation abnormalities in cortical regions but not in the cerebellum. We examined seed-based functional connectivity from the sensorimotor cortex, globus pallidus internus, ventral intermediate thalamic nucleus, and dentate nucleus, and observed abnormal functional connectivity networks in dystonic tremor and essential tremor groups relative to controls. However, the effects were far more widespread in the dystonic tremor group as changes in functional connectivity were revealed across cortical, subcortical, and cerebellar regions independent of the seed location. A unique pattern for dystonic tremor included widespread reductions in functional connectivity compared to essential tremor within higher-level cortical, basal ganglia, and cerebellar regions. Importantly, a receiver operating characteristic determined that functional connectivity z-scores were able to classify dystonic tremor and essential tremor with 89% area under the curve, whereas combining functional connectivity with force tremor yielded 94%. These findings point to network-level connectivity as an important feature that differs substantially between dystonic tremor and essential tremor and should be further explored in implementing appropriate diagnostic and therapeutic strategies.
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Affiliation(s)
- Jesse C DeSimone
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA
| | - Derek B Archer
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA
| | - David E Vaillancourt
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.,Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA.,Department of Neurology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Aparna Wagle Shukla
- Department of Neurology, College of Medicine, University of Florida, Gainesville, FL, USA.,Fixel Center for Neurological Disease, College of Medicine, University of Florida, Gainesville, FL, USA
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22
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Zhang M, Li W, Hu L, Chen L, Yang L, Zhang T, Shen H, Peng Y, Gao S, Chen Z, Wang T, Zhao Z. Oral propranolol for treatment of the subgroups of essential tremor: a systematic review and meta-analysis protocol. BMJ Open 2020; 10:e032096. [PMID: 31948986 PMCID: PMC7044890 DOI: 10.1136/bmjopen-2019-032096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 11/21/2019] [Accepted: 12/04/2019] [Indexed: 11/23/2022] Open
Abstract
INTRODUCTION Essential tremor (ET), a tremor disorder, is one of the most common movement disorders. Only oral drugs (propranolol, primidone, topiramate, etc)are still the first-line treatment recommended by the Food and Drug Administration. Propranolol is thought to potentially reduce upper limb action tremor. However, it has a poor effect on axial tremor symptoms, such as essential head tremor and voice tremor. Studies have shown that tremor severity develops over time, possibly producing other clinical tremors and neurological soft signs (such as memory loss, gait abnormalities, balance disorders, etc), which further increases the difficulty of treating tremors. However, some recent studies provide emerging evidence for oral propranolol on subgroups of ET, which is based on the anatomical distribution of ET (lower extremities, head, sound, tongue, etc). This systematic review aims to synthesise these new data to improve the efficacy of propranolol in ET subgroups. METHODS AND ANALYSIS We will search for randomised controlled trials from the PubMed, MEDLINE, EMBASE, Cochrane Library, UptoDate and PEDro databases from inception to June 2019. All data will be extracted independently by two reviewers and compared at the end of the review. The two reviewers will screen the study quality, and the Cochrane Collaboration's tool in Review Manager (RevMan) V.5.3.3 will be used to evaluate risk of bias. Our primary outcome will be the functional disability component related to tremors, as measured by the Fahn-Tolosa-Marin Tremor Rating Scale subscales B and C. Secondary outcomes will include severity of tremors and quality of life. Narrative and meta-analytical syntheses are planned. ETHICS AND DISSEMINATION Published aggregated data will be used in this review analysis and therefore no ethical approval is required. The results will be published in peer-reviewed journals, and proliferation activities will include diverse social stakeholders, non-academic groups and patients. PROSPERO REGISTRATION NUMBER CRD42018112580.
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Affiliation(s)
- Manyu Zhang
- Department of Neurology, First Affiliated Hospital, Hainan Medical University, Haikou, Hainan, China
| | - Wei Li
- Department of Neurology, First Affiliated Hospital, Hainan Medical University, Haikou, Hainan, China
| | - Lan Hu
- Department of Neurology, First Affiliated Hospital, Hainan Medical University, Haikou, Hainan, China
| | - Li Chen
- Department of Neurology, First Affiliated Hospital, Hainan Medical University, Haikou, Hainan, China
| | - Liu Yang
- Department of Neurology, First Affiliated Hospital, Hainan Medical University, Haikou, Hainan, China
| | - Tian Zhang
- Department of Neurology, First Affiliated Hospital, Hainan Medical University, Haikou, Hainan, China
| | - Hui Shen
- Department of Neurology, First Affiliated Hospital, Hainan Medical University, Haikou, Hainan, China
| | - Yanan Peng
- Department of Neurology, First Affiliated Hospital, Hainan Medical University, Haikou, Hainan, China
| | - Shijun Gao
- Department of Neurology, First Affiliated Hospital, Hainan Medical University, Haikou, Hainan, China
| | - Zhibin Chen
- Department of Neurology, First Affiliated Hospital, Hainan Medical University, Haikou, Hainan, China
| | - Tan Wang
- Department of Neurology, First Affiliated Hospital, Hainan Medical University, Haikou, Hainan, China
| | - Zhenqiang Zhao
- Department of Neurology, First Affiliated Hospital, Hainan Medical University, Haikou, Hainan, China
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Abstract
Tremor and myoclonus are two common hyperkinetic movement disorders. Tremor is characterized by rhythmic oscillatory movements while myoclonic jerks are usually arrhythmic. Tremor can be classified into subtypes including the most common types: essential, enhanced physiological, and parkinsonian tremor. Myoclonus classification is based on its anatomic origin: cortical, subcortical, spinal, and peripheral myoclonus. The clinical presentations are unfortunately not always classic and electrophysiologic investigations can be helpful in making a phenotypic diagnosis. Video-polymyography is the main technique to (sub)classify the involuntary movements. In myoclonus, advanced electrophysiologic testing, such as back-averaging, coherence analysis, somatosensory-evoked potentials, and the C-reflex can be of additional value. Recent developments in tremor point toward a role for intermuscular coherence analysis to differentiate between tremor subtypes. Classification of the movement disorder based on clinical and electrophysiologic features is important, as it enables the search for an etiological diagnosis and guides tailored treatment.
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Affiliation(s)
- R Zutt
- Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands
| | - J W Elting
- Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands
| | - M A J Tijssen
- Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands.
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Awad A, Blomstedt P, Westling G, Eriksson J. Deep brain stimulation in the caudal zona incerta modulates the sensorimotor cerebello-cerebral circuit in essential tremor. Neuroimage 2019; 209:116511. [PMID: 31901420 DOI: 10.1016/j.neuroimage.2019.116511] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/09/2019] [Accepted: 12/30/2019] [Indexed: 01/25/2023] Open
Abstract
Essential tremor is effectively treated with deep brain stimulation (DBS), but the neural mechanisms underlying the treatment effect are poorly understood. Essential tremor is driven by a dysfunctional cerebello-thalamo-cerebral circuit resulting in pathological tremor oscillations. DBS is hypothesised to interfere with these oscillations at the stimulated target level, but it is unknown whether the stimulation modulates the activity of the cerebello-thalamo-cerebral circuit during different task states (with and without tremor) in awake essential tremor patients. To address this issue, we used functional MRI in 16 essential tremor patients chronically implanted with DBS in the caudal zona incerta. During scanning, the patients performed unilateral tremor-inducing postural holding and pointing tasks as well as rest, with contralateral stimulation turned On and Off. We show that DBS exerts both task-dependent as well as task-independent modulation of the sensorimotor cerebello-cerebral regions (p ≤ 0.05, FWE cluster-corrected for multiple comparisons). Task-dependent modulation (DBS × task interaction) resulted in two patterns of stimulation effects. Firstly, activity decreases (blood oxygen level-dependent signal) during tremor-inducing postural holding in the primary sensorimotor cortex and cerebellar lobule VIII, and activity increases in the supplementary motor area and cerebellar lobule V during rest (p ≤ 0.05, post hoc two-tailed t-test). These effects represent differences at the effector level and may reflect DBS-induced tremor reduction since the primary sensorimotor cortex, cerebellum and supplementary motor area exhibit less motor task-activity as compared to the resting condition during On stimulation. Secondly, task-independent modulation (main effect of DBS) was observed as activity increase in the lateral premotor cortex during all motor tasks, and also during rest (p ≤ 0.05, post hoc two-tailed t-test). This task-independent effect may mediate the therapeutic effects of DBS through the facilitation of the premotor control over the sensorimotor circuit, making it less susceptible to tremor entrainment. Our findings support the notion that DBS in essential tremor is modulating the sensorimotor cerebello-cerebral circuit, distant to the stimulated target, and illustrate the complexity of stimulation mechanisms by demonstrating task-dependent as well as task-independent actions in cerebello-cerebral regions.
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Affiliation(s)
- Amar Awad
- Umeå Center for Functional Brain Imaging (UFBI), Umeå University, Sweden; Department of Integrative Medical Biology, Physiology Section, Umeå University, Sweden.
| | - Patric Blomstedt
- Department of Pharmacology and Clinical Neuroscience, Umeå University, Sweden
| | - Göran Westling
- Department of Integrative Medical Biology, Physiology Section, Umeå University, Sweden
| | - Johan Eriksson
- Umeå Center for Functional Brain Imaging (UFBI), Umeå University, Sweden; Department of Integrative Medical Biology, Physiology Section, Umeå University, Sweden
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Maas RPPWM, Helmich RCG, van de Warrenburg BPC. The role of the cerebellum in degenerative ataxias and essential tremor: Insights from noninvasive modulation of cerebellar activity. Mov Disord 2019; 35:215-227. [PMID: 31820832 PMCID: PMC7027854 DOI: 10.1002/mds.27919] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 10/19/2019] [Accepted: 10/23/2019] [Indexed: 12/20/2022] Open
Abstract
Over the last three decades, measuring and modulating cerebellar activity and its connectivity with other brain regions has become an emerging research topic in clinical neuroscience. The most important connection is the cerebellothalamocortical pathway, which can be functionally interrogated using a paired‐pulse transcranial magnetic stimulation paradigm. Cerebellar brain inhibition reflects the magnitude of suppression of motor cortex excitability after stimulating the contralateral cerebellar hemisphere and therefore represents a neurophysiological marker of the integrity of the efferent cerebellar tract. Observations that cerebellar noninvasive stimulation techniques enhanced performance of certain motor and cognitive tasks in healthy individuals have inspired attempts to modulate cerebellar activity and connectivity in patients with cerebellar diseases in order to achieve clinical benefit. We here comprehensively explore the therapeutic potential of these techniques in two movement disorders characterized by prominent cerebellar involvement, namely the degenerative ataxias and essential tremor. The article aims to illustrate the (patho)physiological insights obtained from these studies and how these translate into clinical practice, where possible by addressing the association with cerebellar brain inhibition. Finally, possible explanations for some discordant interstudy findings, shortcomings in our current understanding, and recommendations for future research will be provided. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Roderick P P W M Maas
- Department of Neurology & Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Rick C G Helmich
- Department of Neurology & Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Bart P C van de Warrenburg
- Department of Neurology & Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
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Thangavelu K, Talk AC, Clark GI, Dissanayaka NNW. Psychosocial factors and perceived tremor disability in essential tremor. Neurosci Biobehav Rev 2019; 108:246-253. [PMID: 31682885 DOI: 10.1016/j.neubiorev.2019.10.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 10/19/2019] [Accepted: 10/26/2019] [Indexed: 11/15/2022]
Abstract
Growing evidence suggests that patients with essential tremor (ET) show impairment in psychosocial functions and subsequently increasing vulnerability to anxiety. Here we review evidence supporting a positive relationship between self-reported motor disability and psychological symptoms in ET and critically analyze evidence suggesting how psychosocial factors enhance tremor disability in ET. Theories related to motor competency, behavioral conditioning, and social anxiety have been proposed to relate self-concepts to self-reported tremor disability. We review these theories and then propose a new model in an effort to focus on the self-concepts among ET patients as a factor in tremor disability. Patients with ET exhibited cognitive abnormalities, depression, anxiety, and a higher prevalence of avoidant personality types. Although anxiety, depression and personality types may influence tremor disability in ET, self-concepts may better explain perceived tremor disability in social situations. We conclude by discussing a proposed biopsychosocial model and suggesting future research on ET specific assessment tools and intervention methods.
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Affiliation(s)
- Karthick Thangavelu
- School of Psychology, University of New England, Armidale, NSW 2351, Australia; UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Royal Brisbane & Women's Hospital, Herston QLD 4029, Brisbane, Australia
| | - Andrew C Talk
- School of Psychology, University of New England, Armidale, NSW 2351, Australia
| | - Gavin I Clark
- School of Psychology, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Nadeeka N W Dissanayaka
- UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Royal Brisbane & Women's Hospital, Herston QLD 4029, Brisbane, Australia; Department of Neurology, Royal Brisbane & Women's Hospital, Herston QLD 4029, Brisbane, Australia; School of Psychology, The University of Queensland, St Lucia, QLD 4067, Brisbane, Australia.
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Fasano A, Helmich RC. Tremor habituation to deep brain stimulation: Underlying mechanisms and solutions. Mov Disord 2019; 34:1761-1773. [PMID: 31433906 DOI: 10.1002/mds.27821] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 07/01/2019] [Accepted: 07/18/2019] [Indexed: 12/14/2022] Open
Abstract
DBS of the ventral intermediate nucleus is an extremely effective treatment for essential tremor, although a waning benefit is observed after a variable time in a variable proportion of patients (ranging from 0% to 73%), a concept historically defined as "tolerance." Tolerance is currently an established concept in the medical community, although there is debate on its real existence. In fact, very few publications have actually addressed the problem, thus making tolerance a typical example of science based on "eminence rather than evidence." The underpinnings of the phenomena associated with the progressive loss of DBS benefit are not fully elucidated, although the interplay of different-not mutually exclusive-factors has been advocated. In this viewpoint, we gathered the evidence explaining the progressive loss of benefit observed after DBS. We grouped these factors in three categories: disease-related factors (tremor etiology and progression); surgery-related factors (electrode location, microlesional effect and placebo); and stimulation-related factors (not optimized stimulation, stimulation-induced side effects, habituation, and tremor rebound). We also propose possible pathophysiological explanations for the phenomenon and define a nomenclature of the associated features: early versus late DBS failure; tremor rebound versus habituation (to be preferred over tolerance). Finally, we provide a practical approach for preventing and treating this loss of DBS benefit, and we draft a possible roadmap for the research to come. © 2019 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Alfonso Fasano
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital, UHN, Toronto, Ontario, Canada; Division of Neurology, University of Toronto, Toronto, Ontario, Canada.,Krembil Brain Institute, Toronto, Ontario, Canada.,CenteR for Advancing Neurotechnological Innovation to Application (CRANIA), Toronto, Ontario, Canada
| | - Rick C Helmich
- Radboud University Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Department of Neurology, Nijmegen, The Netherlands
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Abstract
It is a clinical experience that acute lesions of the cerebellum induce pathological tremor, which tends to improve. However, quantitative characteristics, imaging correlates, and recovery of cerebellar tremor have not been systematically investigated. We studied the prevalence, quantitative parameters measured with biaxial accelerometry, and recovery of pathological tremor in 68 patients with lesions affecting the cerebellum. We also investigated the correlation between the occurrence and characteristics of tremor and lesion localization using 3D T1-weighted MRI images which were normalized and segmented according to a spatially unbiased atlas template for the cerebellum. Visual assessment detected pathological tremor in 19% while accelerometry in 47% of the patients. Tremor was present both in postural and intentional positions, but never at rest. Two types of pathological tremor were distinguished: (1) low-frequency tremor in 36.76% of patients (center frequency 2.66 ± 1.17 Hz) and (2) normal frequency-high-intensity tremor in 10.29% (center frequency 8.79 ± 1.43 Hz). The size of the lesion did not correlate with the presence or severity of tremor. Involvement of the anterior lobe and lobule VI was related to high tremor intensity. In all followed up patients with acute cerebellar ischemia, the tremor completely recovered within 8 weeks. Our results indicate that cerebellar lesions might induce pathological postural and intentional tremor of 2-3 Hz frequency. Due to its low frequency and low amplitude, quantitative tremorometry is neccessary to properly identify it. There is no tight correlation between lesion localization and quantitative characteristics of cerebellar tremor.
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Boonstra FM, Noffs G, Perera T, Jokubaitis VG, Vogel AP, Moffat BA, Butzkueven H, Evans A, van der Walt A, Kolbe SC. Functional neuroplasticity in response to cerebello-thalamic injury underpins the clinical presentation of tremor in multiple sclerosis. Mult Scler 2019; 26:696-705. [PMID: 30907236 DOI: 10.1177/1352458519837706] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Tremor is present in almost half of multiple sclerosis (MS) patients. The lack of understanding of its pathophysiology is hampering progress in development of treatments. OBJECTIVES To clarify the structural and functional brain changes associated with the clinical phenotype of upper limb tremor in people with MS. METHODS Fifteen healthy controls (46.1 ± 15.4 years), 27 MS participants without tremor (46.7 ± 11.6 years) and 42 with tremor (46.6 ± 11.5 years) were included. Tremor was quantified using the Bain score (0-10) for overall severity, handwriting and Archimedes spiral drawing. Functional magnetic resonance imaging activations were compared between participants groups during performance of a joystick task designed to isolate tremulous movement. Inflammation and atrophy of cerebello-thalamo-cortical brain structures were quantified. RESULTS Tremor participants were found to have atrophy of the cerebellum and thalamus, and higher ipsilateral cerebellar lesion load compared to participants without tremor (p < 0.020). We found higher ipsilateral activation in the inferior parietal lobule, the premotor cortex and supplementary motor area in MS tremor participants compared to MS participants without tremor during the joystick task. Finally, stronger activation in those areas was associated with lower tremor severity. CONCLUSION Subcortical neurodegeneration and inflammation along the cerebello-thalamo-cortical and cortical functional neuroplasticity contribute to the severity of tremor in MS.
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Affiliation(s)
- Frederique Mc Boonstra
- Department of Medicine and Radiology, University of Melbourne, Parkville, VIC, Australia
| | - Gustavo Noffs
- Department of Neurology, Royal Melbourne Hospital, Parkville, VIC, Australia/Centre for Neuroscience of Speech, University of Melbourne, Parkville, VIC, Australia
| | - Thushara Perera
- The Bionics Institute, East Melbourne, VIC, Australia/Department of Medical Bionics, University of Melbourne, Parkville, VIC, Australia
| | - Vilija G Jokubaitis
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Adam P Vogel
- Centre for Neuroscience of Speech, University of Melbourne, Parkville, VIC, Australia/The Bionics Institute, East Melbourne, VIC, Australia/Department of Neurodegeneration, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany/Redenlab, Melbourne, VIC, Australia
| | - Bradford A Moffat
- Department of Medicine and Radiology, University of Melbourne, Parkville, VIC, Australia
| | - Helmut Butzkueven
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Andrew Evans
- Department of Neurology, Royal Melbourne Hospital, Parkville, VIC, Australia/The Bionics Institute, East Melbourne, VIC, Australia
| | - Anneke van der Walt
- Department of Neurology, Royal Melbourne Hospital, Parkville, VIC, Australia/The Bionics Institute, East Melbourne, VIC, Australia/Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Scott C Kolbe
- Department of Medicine and Radiology, University of Melbourne, Parkville, VIC, Australia/Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
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Muthuraman M, Raethjen J, Koirala N, Anwar AR, Mideksa KG, Elble R, Groppa S, Deuschl G. Cerebello-cortical network fingerprints differ between essential, Parkinson’s and mimicked tremors. Brain 2018; 141:1770-1781. [DOI: 10.1093/brain/awy098] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 02/13/2018] [Indexed: 11/13/2022] Open
Affiliation(s)
- Muthuraman Muthuraman
- Section of Movement Disorders and Neurostimulation, Biomedical Statistics and Multimodal Signal processing unit, Department of Neurology, Focus Program Translational Neuroscience (FTN), University Medical Center of the Johannes Gutenberg-University Mainz, Mainz-55131, Germany
| | - Jan Raethjen
- Department of Neurology, Christian-Albrechts-University, Kiel-24105, Germany
| | - Nabin Koirala
- Section of Movement Disorders and Neurostimulation, Biomedical Statistics and Multimodal Signal processing unit, Department of Neurology, Focus Program Translational Neuroscience (FTN), University Medical Center of the Johannes Gutenberg-University Mainz, Mainz-55131, Germany
| | - Abdul Rauf Anwar
- Department of Neurology, Christian-Albrechts-University, Kiel-24105, Germany
- Biomedical Engineering Centre, University of Engineering & Technology, Lahore (KSK Campus)-54890, Pakistan
| | - Kidist G Mideksa
- Department of Neurology, Christian-Albrechts-University, Kiel-24105, Germany
- Institute for Circuit and System Theory, Christian-Albrechts-University, Kiel-24143, Germany
| | - Rodger Elble
- Department of Neurology, Southern Illinois University School of Medicine, Springfield, 62794-9643, USA
| | - Sergiu Groppa
- Section of Movement Disorders and Neurostimulation, Biomedical Statistics and Multimodal Signal processing unit, Department of Neurology, Focus Program Translational Neuroscience (FTN), University Medical Center of the Johannes Gutenberg-University Mainz, Mainz-55131, Germany
| | - Günter Deuschl
- Department of Neurology, Christian-Albrechts-University, Kiel-24105, Germany
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32
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Lawrenson C, Bares M, Kamondi A, Kovács A, Lumb B, Apps R, Filip P, Manto M. The mystery of the cerebellum: clues from experimental and clinical observations. CEREBELLUM & ATAXIAS 2018; 5:8. [PMID: 29610671 PMCID: PMC5877388 DOI: 10.1186/s40673-018-0087-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 03/15/2018] [Indexed: 11/22/2022]
Abstract
The cerebellum has a striking homogeneous cytoarchitecture and participates in both motor and non-motor domains. Indeed, a wealth of evidence from neuroanatomical, electrophysiological, neuroimaging and clinical studies has substantially modified our traditional view on the cerebellum as a sole calibrator of sensorimotor functions. Despite the major advances of the last four decades of cerebellar research, outstanding questions remain regarding the mechanisms and functions of the cerebellar circuitry. We discuss major clues from both experimental and clinical studies, with a focus on rodent models in fear behaviour, on the role of the cerebellum in motor control, on cerebellar contributions to timing and our appraisal of the pathogenesis of cerebellar tremor. The cerebellum occupies a central position to optimize behaviour, motor control, timing procedures and to prevent body oscillations. More than ever, the cerebellum is now considered as a major actor on the scene of disorders affecting the CNS, extending from motor disorders to cognitive and affective disorders. However, the respective roles of the mossy fibres, the climbing fibres, cerebellar cortex and cerebellar nuclei remains unknown or partially known at best in most cases. Research is now moving towards a better definition of the roles of cerebellar modules and microzones. This will impact on the management of cerebellar disorders.
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Affiliation(s)
- Charlotte Lawrenson
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Tankard’s Close, University Walk, Bristol, BS8 1TD UK
| | - Martin Bares
- First Department of Neurology, Faculty of Medicine, Masaryk University and St. Anne’s Teaching Hospital, Brno, Czech Republic
- Department of Neurology, School of Medicine, University of Minnesota, Minneapolis, USA
| | - Anita Kamondi
- Department of Neurology, National Institute of Clinical Neurosciences, Amerikai út 57, Budapest, 1145 Hungary
- Department of Neurology, Semmelweis University, Üllői út 26, Budapest, 1083 Hungary
| | - Andrea Kovács
- Department of Neurology, National Institute of Clinical Neurosciences, Amerikai út 57, Budapest, 1145 Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Üllői út 26, Budapest, 1083 Hungary
| | - Bridget Lumb
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Tankard’s Close, University Walk, Bristol, BS8 1TD UK
| | - Richard Apps
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Tankard’s Close, University Walk, Bristol, BS8 1TD UK
| | - Pavel Filip
- First Department of Neurology, Faculty of Medicine, Masaryk University and St. Anne’s Teaching Hospital, Brno, Czech Republic
| | - Mario Manto
- FNRS ULB-Erasme, 808 Route de Lennik, 1070 Bruxelles, Belgium
- Service des Neurosciences, UMons, 7000 Mons, Belgium
- Department of Neurology, Centre Hospitalier Universitaire (CHU) de Charleroi, 6000 Charleroi, Belgium
- Laboratoire de Médecine Expérimentale, Site Vésale, ULB Unité 222, 6110 Montigny-le-Tilleul, Belgium
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Gaura V, Lavisse S, Payoux P, Goldman S, Verny C, Krystkowiak P, Damier P, Supiot F, Bachoud-Levi AC, Remy P. Association Between Motor Symptoms and Brain Metabolism in Early Huntington Disease. JAMA Neurol 2017; 74:1088-1096. [PMID: 28672395 DOI: 10.1001/jamaneurol.2017.1200] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Importance Brain hypometabolism is associated with the clinical consequences of the degenerative process, but little is known about regional hypermetabolism, sometimes observed in the brain of patients with clinically manifest Huntington disease (HD). Studying the role of regional hypermetabolism is needed to better understand its interaction with the motor symptoms of the disease. Objective To investigate the association between brain hypometabolism and hypermetabolism with motor scores of patients with early HD. Design, Setting, and Participants This study started in 2001, and analysis was completed in 2016. Sixty symptomatic patients with HD and 15 healthy age-matched control individuals underwent positron emission tomography to measure cerebral metabolism in this cross-sectional study. They also underwent the Unified Huntington's Disease Rating Scale motor test, and 2 subscores were extracted: (1) a hyperkinetic score, combining dystonia and chorea, and (2) a hypokinetic score, combining bradykinesia and rigidity. Main Outcomes and Measures Statistical parametric mapping software (SPM5) was used to identify all hypo- and hypermetabolic regions in patients with HD relative to control individuals. Correlation analyses (P < .001, uncorrected) between motor subscores and brain metabolic values were performed for regions with significant hypometabolism and hypermetabolism. Results Among 60 patients with HD, 22 were women (36.7%), and the mean (SD) age was 44.6 (7.6) years. Of the 15 control individuals, 7 were women (46.7%), and the mean (SD) age was 42.2 (7.3) years. In statistical parametric mapping, striatal hypometabolism was significantly correlated with the severity of all motor scores. Hypermetabolism was negatively correlated only with hypokinetic scores in the cuneus (z score = 3.95, P < .001), the lingual gyrus (z score = 4.31, P < .001), and the crus I/II of the cerebellum (z score = 3.77, P < .001), a region connected to associative cortical areas. More severe motor scores were associated with higher metabolic values in the inferior parietal lobule, anterior cingulate, inferior temporal lobule, the dentate nucleus, and the cerebellar lobules IV/V, VI, and VIII bilaterally corresponding to the motor regions of the cerebellum (z score = 3.96 and 3.42 in right and left sides, respectively; P < .001). Conclusions and Relevance Striatal hypometabolism is associated with clinical disease severity. Conversely, hypermetabolism is likely compensatory in regions where it is associated with decreasing motor scores. Hypermetabolism might be detrimental in other structures in which it is associated with more severe motor symptoms. In the cerebellum, both compensatory and detrimental contributions seem to occur. This study helps to better understand the motor clinical relevance of hypermetabolic brain regions in HD.
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Affiliation(s)
- Véronique Gaura
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Département des Sciences du Vivant, Institut d'Imagerie Biomédicale, MIRCen, Fontenay-aux-Roses, France.,Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, Fontenay-aux-Roses, France.,Department of Nuclear Medicine, CHU Tenon Hospital, Paris, France
| | - Sonia Lavisse
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Département des Sciences du Vivant, Institut d'Imagerie Biomédicale, MIRCen, Fontenay-aux-Roses, France.,Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, Fontenay-aux-Roses, France
| | - Pierre Payoux
- ToNIC, Toulouse NeuroImaging Centre, Université de Toulouse, INSERM, UPS, Toulouse, France.,Department of Nuclear Medicine, CHU Toulouse, Purpan University Hospital, Toulouse, France
| | - Serge Goldman
- Department of Nuclear Medicine, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Christophe Verny
- Centre National de Référence des Maladies Neurodégénératives Service de Neurologie and UMR CNRS 6214 INSERM U1083, CHU d'Angers, Angers, France
| | | | - Philippe Damier
- Neurology Department, CHRU de Nantes, Nantes, France.,Université Pierre et Marie Curie, Paris, France
| | - Frédéric Supiot
- Department of Nuclear Medicine, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Anne-Catherine Bachoud-Levi
- INSERM U955, Equipe 01, Neuropsychologie Interventionnelle, Créteil, France.,NeurATRIS, Fontenay-aux-Roses, France.,AP-HP, Hôpital Henri Mondor, Centre de Référence-Maladie de Huntington, Service de Neurologie, Créteil, France.,Faculté de Médecine, Université Paris Est-Créteil, Créteil, France.,Equipe Neuropsychologie Interventionnelle, Département d'Études Cognitives, École Normale Supérieure, PSL Research University, INSERM, Paris, France
| | - Philippe Remy
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Département des Sciences du Vivant, Institut d'Imagerie Biomédicale, MIRCen, Fontenay-aux-Roses, France.,Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, Fontenay-aux-Roses, France.,NeurATRIS, Fontenay-aux-Roses, France.,Faculté de Médecine, Université Paris Est-Créteil, Créteil, France.,Centre Expert Parkinson, CHU Henri Mondor, Créteil, France
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Pedrosa DJ, Nelles C, Brown P, Volz LJ, Pelzer EA, Tittgemeyer M, Brittain JS, Timmermann L. The differentiated networks related to essential tremor onset and its amplitude modulation after alcohol intake. Exp Neurol 2017; 297:50-61. [PMID: 28754506 DOI: 10.1016/j.expneurol.2017.07.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 06/29/2017] [Accepted: 07/24/2017] [Indexed: 01/26/2023]
Abstract
The dysregulation of endogenous rhythms within brain networks have been implicated in a broad range of motor and non-motor pathologies. Essential tremor (ET), classically the purview of a single aberrant pacemaker, has recently become associated with network-level dysfunction across multiple brain regions. Specifically, it has been suggested that motor cortex constitutes an important node in a tremor-generating network involving the cerebellum. Yet the mechanisms by which these regions relate to tremor remain a matter of considerable debate. We sought to discriminate the contributions of cerebral and cerebellar dysregulation by combining high-density electroencephalography with subject-specific structural MRI. For that, we contrasted ET with voluntary (mimicked) tremor before and after ingestion of alcohol to regulate the tremorgenic networks. Our results demonstrate distinct loci of cortical tremor coherence, most pronounced over the sensorimotor cortices in healthy controls, but more frontal motor areas in ET-patients consistent with a heightened involvement of the supplementary motor area. We further demonstrate that the reduction in tremor amplitude associated with alcohol intake is reflected in altered cerebellar - but not cerebral - coupling with movement. Taken together, these findings implicate tremor emergence as principally associated with increases in activity within frontal motor regions, whereas modulation of the amplitude of established tremor relates to changes in cerebellar activity. These findings progress a mechanistic understanding of ET and implicate network-level vulnerabilities in the rhythmic nature of communication throughout the brain.
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Affiliation(s)
- David J Pedrosa
- Nuffield Department of Clinical Neurosciences, MRC Brain Network Dynamics Unit, University of Oxford, Oxford, United Kingdom; Department of Neurology, University Hospital Cologne, Cologne, Germany.
| | - Christian Nelles
- Department of Neurology, University Hospital Cologne, Cologne, Germany
| | - Peter Brown
- Nuffield Department of Clinical Neurosciences, MRC Brain Network Dynamics Unit, University of Oxford, Oxford, United Kingdom
| | - Lukas J Volz
- Department of Neurology, University Hospital Cologne, Cologne, Germany; SAGE Center for the Study of the Mind, University of California, Santa Barbara, USA
| | - Esther A Pelzer
- Max-Planck Institute for Neurological Research Cologne, Cologne, Germany
| | - Marc Tittgemeyer
- Max-Planck Institute for Neurological Research Cologne, Cologne, Germany
| | - John-Stuart Brittain
- Nuffield Department of Clinical Neurosciences, MRC Brain Network Dynamics Unit, University of Oxford, Oxford, United Kingdom
| | - Lars Timmermann
- Department of Neurology, University Hospital Cologne, Cologne, Germany; Department of Neurology, University Hospital Marburg, Marburg, Germany
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Dyke JP, Cameron E, Hernandez N, Dydak U, Louis ED. Gray matter density loss in essential tremor: a lobule by lobule analysis of the cerebellum. CEREBELLUM & ATAXIAS 2017; 4:10. [PMID: 28680651 PMCID: PMC5494891 DOI: 10.1186/s40673-017-0069-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 06/29/2017] [Indexed: 11/23/2022]
Abstract
Background The pathophysiological basis for essential tremor (ET) remains unclear, although evidence increasingly links it to a disordered and perhaps degenerative cerebellum. Prior imaging studies have treated the cerebellum en bloc. Our hypothesis was that regional differences in cerebellar gray matter (GM) density may better distinguish ET cases from controls. Forty-seven ET cases and 36 control subjects were imaged using magnetic resonance imaging (MRI). The cerebellum was segmented into 34 lobes using a Spatially Unbiased Infra-Tentorial Template (SUIT) atlas within the Statistical Parametric Mapping (SPM) analysis package. Age, gender and Montreal Cognitive Assessment (MoCA) scores were regressed out from the statistical models to isolate group effects. ET cases were further stratified into phenotypically-defined subgroups. The Benjamini-Hochberg False Discovery Rate procedure (BH FDR) (α = 0.1) was used to correct for multiple comparisons. Results When all ET cases and controls were compared, none of the regions met the BH FDR criteria for significance. When compared with controls, ET cases with head or jaw tremor (n = 27) had significant changes in GM density in nine cerebellar lobules, with a majority in the left cerebellar region, and each meeting the BH FDR criteria. Likewise, ET cases with voice tremor (n = 22) exhibited significant changes in 11 lobules in both left and right regions and the vermis. These analyses, in sum, indicated decreases in GM density in lobules I-IV, V, VI, VII and VIII as well as the vermis. ET cases with severe tremor (n = 20) did not show regions of change that survived the BH FDR procedure when compared to controls. Conclusions We showed that ET cases with various forms of cranial tremor differed from controls with respect to cerebellar GM density, with evidence of GM reduction across multiple cerebellar regions. Additional work, using a lobule-by-lobule approach, is needed to confirm these results and precisely map the regional differences in ET cases, subgroups of ET cases, and controls.
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Affiliation(s)
- Jonathan P Dyke
- Department of Radiology, Citigroup Biomedical Imaging Center, Weill Cornell Medicine, New York, NY USA
| | - Eric Cameron
- School of Health Sciences, Purdue University, West Lafayette, IN USA.,Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN USA
| | - Nora Hernandez
- Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT USA
| | - Ulrike Dydak
- School of Health Sciences, Purdue University, West Lafayette, IN USA.,Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN USA
| | - Elan D Louis
- 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.,Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, CT USA.,Departments of Neurology and Chronic Disease Epidemiology Yale School of Medicine, Yale School of Public Health Yale University, New Haven, CT USA
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Gallea C, Popa T, García-Lorenzo D, Valabregue R, Legrand AP, Apartis E, Marais L, Degos B, Hubsch C, Fernández-Vidal S, Bardinet E, Roze E, Lehéricy S, Meunier S, Vidailhet M. Orthostatic tremor: a cerebellar pathology? Brain 2016; 139:2182-97. [PMID: 27329770 PMCID: PMC4958903 DOI: 10.1093/brain/aww140] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 04/22/2016] [Indexed: 12/24/2022] Open
Abstract
SEE MUTHURAMAN ET AL DOI101093/AWW164 FOR A SCIENTIFIC COMMENTARY ON THIS ARTICLE: Primary orthostatic tremor is characterized by high frequency tremor affecting the legs and trunk during the standing position. Cerebellar defects were suggested in orthostatic tremor without direct evidence. We aimed to characterize the anatomo-functional defects of the cerebellar motor pathways in orthostatic tremor. We used multimodal neuroimaging to compare 17 patients with orthostatic tremor and 17 age- and gender-matched healthy volunteers. Nine of the patients with orthostatic tremor underwent repetitive transcranial stimulation applied over the cerebellum during five consecutive days. We quantified the duration of standing position and tremor severity through electromyographic recordings. Compared to healthy volunteers, grey matter volume in patients with orthostatic tremor was (i) increased in the cerebellar vermis and correlated positively with the duration of the standing position; and (ii) increased in the supplementary motor area and decreased in the lateral cerebellum, which both correlated with the disease duration. Functional connectivity between the lateral cerebellum and the supplementary motor area was abnormally increased in patients with orthostatic tremor, and correlated positively with tremor severity. After repetitive transcranial stimulation, tremor severity and functional connectivity between the lateral cerebellum and the supplementary motor area were reduced. We provide an explanation for orthostatic tremor pathophysiology, and demonstrate the functional relevance of cerebello-thalamo-cortical connections in tremor related to cerebellar defects.
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Affiliation(s)
- Cécile Gallea
- 1 Centre de NeuroImagerie de Recherche - Institut du Cerveau et de la Moelle épinière, ICM, Paris, France 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France 5 AP-HP, Hôpital de la Pitié Salpêtrière, Département de Neuroradiologie, Paris, France
| | - Traian Popa
- 1 Centre de NeuroImagerie de Recherche - Institut du Cerveau et de la Moelle épinière, ICM, Paris, France 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France
| | - Daniel García-Lorenzo
- 1 Centre de NeuroImagerie de Recherche - Institut du Cerveau et de la Moelle épinière, ICM, Paris, France 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France 5 AP-HP, Hôpital de la Pitié Salpêtrière, Département de Neuroradiologie, Paris, France
| | - Romain Valabregue
- 1 Centre de NeuroImagerie de Recherche - Institut du Cerveau et de la Moelle épinière, ICM, Paris, France 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France 5 AP-HP, Hôpital de la Pitié Salpêtrière, Département de Neuroradiologie, Paris, France
| | | | - Emmanuelle Apartis
- 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France 7 AP-HP, Hôpital de Saint-Antoine, Département de Neurologie, Paris, France
| | - Lea Marais
- 1 Centre de NeuroImagerie de Recherche - Institut du Cerveau et de la Moelle épinière, ICM, Paris, France 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France 5 AP-HP, Hôpital de la Pitié Salpêtrière, Département de Neuroradiologie, Paris, France
| | - Bertrand Degos
- 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France 8 AP-HP, Hôpital de la Pitié Salpêtrière, Département de Neurologie, Paris, France
| | - Cecile Hubsch
- 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France 8 AP-HP, Hôpital de la Pitié Salpêtrière, Département de Neurologie, Paris, France
| | - Sara Fernández-Vidal
- 1 Centre de NeuroImagerie de Recherche - Institut du Cerveau et de la Moelle épinière, ICM, Paris, France 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France
| | - Eric Bardinet
- 1 Centre de NeuroImagerie de Recherche - Institut du Cerveau et de la Moelle épinière, ICM, Paris, France 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France
| | - Emmanuel Roze
- 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France 8 AP-HP, Hôpital de la Pitié Salpêtrière, Département de Neurologie, Paris, France
| | - Stéphane Lehéricy
- 1 Centre de NeuroImagerie de Recherche - Institut du Cerveau et de la Moelle épinière, ICM, Paris, France 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France 5 AP-HP, Hôpital de la Pitié Salpêtrière, Département de Neuroradiologie, Paris, France
| | - Sabine Meunier
- 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France
| | - Marie Vidailhet
- 2 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Paris, France 3 CNRS, UMR 7225, Paris, France 4 Inserm, U 1127, Paris, France 8 AP-HP, Hôpital de la Pitié Salpêtrière, Département de Neurologie, Paris, France
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