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Yang J, Lei D, Qin K, Pinaya WHL, Suo X, Li W, Li L, Kemp GJ, Gong Q. Using deep learning to classify pediatric posttraumatic stress disorder at the individual level. BMC Psychiatry 2021; 21:535. [PMID: 34711200 PMCID: PMC8555083 DOI: 10.1186/s12888-021-03503-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 09/28/2021] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Children exposed to natural disasters are vulnerable to developing posttraumatic stress disorder (PTSD). Previous studies using resting-state functional neuroimaging have revealed alterations in graph-based brain topological network metrics in pediatric PTSD patients relative to healthy controls (HC). Here we aimed to apply deep learning (DL) models to neuroimaging markers of classification which may be of assistance in diagnosis of pediatric PTSD. METHODS We studied 33 pediatric PTSD and 53 matched HC. Functional connectivity between 90 brain regions from the automated anatomical labeling atlas was established using partial correlation coefficients, and the whole-brain functional connectome was constructed by applying a threshold to the resultant 90 * 90 partial correlation matrix. Graph theory analysis was used to examine the topological properties of the functional connectome. A DL algorithm then used this measure to classify pediatric PTSD vs HC. RESULTS Graphic topological measures using DL provide a potentially clinically useful classifier for differentiating pediatric PTSD and HC (overall accuracy 71.2%). Frontoparietal areas (central executive network), cingulate cortex, and amygdala contributed the most to the DL model's performance. CONCLUSIONS Graphic topological measures based on fMRI data could contribute to imaging models of clinical utility in distinguishing pediatric PTSD from HC. DL model may be a useful tool in the identification of brain mechanisms PTSD participants.
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Affiliation(s)
- Jing Yang
- Huaxi MR Research Center (HMRRC), Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital of Sichuan University, Chengdu, 610041, China
- Department of Radiology, Chongqing University Cancer Hospital, School of Medicine, Chongqing University, Chongqing, China
| | - Du Lei
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH, 45219, USA
| | - Kun Qin
- Huaxi MR Research Center (HMRRC), Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Walter H L Pinaya
- Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, London, SE5 8AF, UK
| | - Xueling Suo
- Huaxi MR Research Center (HMRRC), Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Wenbin Li
- Huaxi MR Research Center (HMRRC), Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Lingjiang Li
- Mental Health Institute, the Second Xiangya Hospital of Central South University, Changsha, 410008, Hunan, China
| | - Graham J Kemp
- Liverpool Magnetic Resonance Imaging Centre (LiMRIC) and Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, L9 7AL, UK
| | - Qiyong Gong
- Huaxi MR Research Center (HMRRC), Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital of Sichuan University, Chengdu, 610041, China.
- Research Unit of Psychoradiology, Chinese Academy of Medical Sciences, Chengdu, Sichuan, China.
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2
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Pietracupa S, Bologna M, Tommasin S, Elifani F, Vasselli F, Paparella G, Petsas N, Berardelli A, Pantano P. No evidence of iron deposition in essential tremor: a susceptibility-weighted imaging study. Neurol Sci 2021; 42:4667-4672. [PMID: 33721138 DOI: 10.1007/s10072-021-05173-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 03/06/2021] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To evaluate the role of iron deposition in subcortical nuclei of patients with essential tremor (ET). METHODS Twenty-three patients with ET underwent a standardized 3T-MRI protocol. We specifically assessed iron deposition using susceptibility-weighted angiography (SWAN) images in seven specific regions of interest (ROIs): the thalamus, putamen, globus pallidus, caudate nucleus, substantia nigra, red nucleus, and dentate nucleus. Tremor in ET patients was clinically assessed using the Fahn-Tolosa-Marin Tremor Rating Scale (FTM-TRS). ET patient data were compared with data obtained from 23 Parkinson's disease (PD) patients and 14 healthy subjects (HS). RESULTS No differences in iron deposition in the seven ROIs were found between ET patients and HS. Conversely, PD patients showed increased iron deposition in the substantia nigra in comparison with both ET patients and HS. CONCLUSIONS Our results indicate the absence of iron deposition in subcortical nuclei of ET patients, which is generally considered a marker of neurodegeneration.
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Affiliation(s)
- Sara Pietracupa
- Department of Neurology, Neuromed Institute IRCCS, Via Atinense, 18, 86077, Pozzilli, IS, Italy.
| | - Matteo Bologna
- Department of Neurology, Neuromed Institute IRCCS, Via Atinense, 18, 86077, Pozzilli, IS, Italy.,Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Silvia Tommasin
- Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Francesca Elifani
- Department of Neurology, Neuromed Institute IRCCS, Via Atinense, 18, 86077, Pozzilli, IS, Italy
| | - Federica Vasselli
- Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Giulia Paparella
- Department of Neurology, Neuromed Institute IRCCS, Via Atinense, 18, 86077, Pozzilli, IS, Italy
| | - Nikolaos Petsas
- Department of Neurology, Neuromed Institute IRCCS, Via Atinense, 18, 86077, Pozzilli, IS, Italy
| | - Alfredo Berardelli
- Department of Neurology, Neuromed Institute IRCCS, Via Atinense, 18, 86077, Pozzilli, IS, Italy.,Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Patrizia Pantano
- Department of Neurology, Neuromed Institute IRCCS, Via Atinense, 18, 86077, Pozzilli, IS, Italy.,Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
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3
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Louis ED, Faust PL. Essential tremor: the most common form of cerebellar degeneration? CEREBELLUM & ATAXIAS 2020; 7:12. [PMID: 32922824 PMCID: PMC7427947 DOI: 10.1186/s40673-020-00121-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 08/03/2020] [Indexed: 02/07/2023]
Abstract
Background The degenerative cerebellar ataxias comprise a large and heterogeneous group of neurological diseases whose hallmark clinical feature is ataxia, and which are accompanied, to variable degrees, by other features that are attributable to cerebellar dysfunction. Essential tremor (ET) is an exceptionally common neurological disease whose primary motor feature is action tremor, although patients often manifest intention tremor, mild gait ataxia and several other features of cerebellar dysfunction. Main Body In this paper, we review the abundant evidence derived from clinical, neuroimaging and postmortem studies, linking ET to cerebellar dysfunction. Furthermore, we review the combination of clinical, natural history and postmortem features suggesting that ET is neurodegenerative. We then compare the prevalence of ET (400 – 900 cases per 100,000) to that of the other cerebellar degenerations (ranging from <0.5 – 9 cases per 100,000, and in composite likely to be on the order of 20 cases per 100,000) and conclude that ET is 20 to 45 times more prevalent than all other forms of cerebellar degeneration combined. Conclusion Given the data we present, it is logical to conclude that ET is, by far, the most common form of cerebellar degeneration.
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Affiliation(s)
- Elan D Louis
- Department of Neurology and Therapeutics, University of Texas Southwestern, Dallas, TX USA
| | - Phyllis L Faust
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center and the New York Presbyterian Hospital, New York, NY USA
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4
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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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5
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Kuo SH, Louis ED, Faust PL, Handforth A, Chang SY, Avlar B, Lang EJ, Pan MK, Miterko LN, Brown AM, Sillitoe RV, Anderson CJ, Pulst SM, Gallagher MJ, Lyman KA, Chetkovich DM, Clark LN, Tio M, Tan EK, Elble RJ. Current Opinions and Consensus for Studying Tremor in Animal Models. CEREBELLUM (LONDON, ENGLAND) 2019; 18:1036-1063. [PMID: 31124049 PMCID: PMC6872927 DOI: 10.1007/s12311-019-01037-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Tremor is the most common movement disorder; however, we are just beginning to understand the brain circuitry that generates tremor. Various neuroimaging, neuropathological, and physiological studies in human tremor disorders have been performed to further our knowledge of tremor. But, the causal relationship between these observations and tremor is usually difficult to establish and detailed mechanisms are not sufficiently studied. To overcome these obstacles, animal models can provide an important means to look into human tremor disorders. In this manuscript, we will discuss the use of different species of animals (mice, rats, fruit flies, pigs, and monkeys) to model human tremor disorders. Several ways to manipulate the brain circuitry and physiology in these animal models (pharmacology, genetics, and lesioning) will also be discussed. Finally, we will discuss how these animal models can help us to gain knowledge of the pathophysiology of human tremor disorders, which could serve as a platform towards developing novel therapies for tremor.
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Affiliation(s)
- Sheng-Han Kuo
- Department of Neurology, Columbia University, 650 West 168th Street, Room 305, New York, NY, 10032, USA.
| | - Elan D Louis
- Department of Neurology, Yale School of Medicine, Yale University, 800 Howard Avenue, Ste Lower Level, New Haven, CT, 06519, 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.
| | - Phyllis L Faust
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY, USA
| | - Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Su-Youne Chang
- Department of Neurologic Surgery and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - Billur Avlar
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Eric J Lang
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Ming-Kai Pan
- Department of Medical Research and Neurology, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Lauren N Miterko
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
| | - Amanda M Brown
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Roy V Sillitoe
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Collin J Anderson
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | | | - Kyle A Lyman
- Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | | | - Lorraine N Clark
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Murni Tio
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Eng-King Tan
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Rodger J Elble
- Department of Neurology, Southern Illinois University School of Medicine, Springfield, IL, USA
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6
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Benito-León J, Sanz-Morales E, Melero H, Louis ED, Romero JP, Rocon E, Malpica N. Graph theory analysis of resting-state functional magnetic resonance imaging in essential tremor. Hum Brain Mapp 2019; 40:4686-4702. [PMID: 31332912 DOI: 10.1002/hbm.24730] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 07/05/2019] [Accepted: 07/08/2019] [Indexed: 11/10/2022] Open
Abstract
Essential tremor (ET) is a neurological disease with both motor and nonmotor manifestations; however, little is known about its underlying brain basis. Furthermore, the overall organization of the brain network in ET remains largely unexplored. We investigated the topological properties of brain functional network, derived from resting-state functional magnetic resonance imaging (MRI) data, in 23 ET patients versus 23 healthy controls. Graph theory analysis was used to assess the functional network organization. At the global level, the functional network of ET patients was characterized by lower small-worldness values than healthy controls-less clustered functionality of the brain. At the regional level, compared with the healthy controls, ET patients showed significantly higher values of global efficiency, cost and degree, and a shorter average path length in the left inferior frontal gyrus (pars opercularis), right inferior temporal gyrus (posterior division and temporo-occipital part), right inferior lateral occipital cortex, left paracingulate, bilateral precuneus bilaterally, left lingual gyrus, right hippocampus, left amygdala, nucleus accumbens bilaterally, and left middle temporal gyrus (posterior part). In addition, ET patients showed significant higher local efficiency and clustering coefficient values in frontal medial cortex bilaterally, subcallosal cortex, posterior cingulate cortex, parahippocampal gyri bilaterally (posterior division), right lingual gyrus, right cerebellar flocculus, right postcentral gyrus, right inferior semilunar lobule of cerebellum and culmen of vermis. Finally, the right intracalcarine cortex and the left orbitofrontal cortex showed a shorter average path length in ET patients, while the left frontal operculum and the right planum polare showed a higher betweenness centrality in ET patients. In conclusion, the efficiency of the overall brain functional network in ET is disrupted. Further, our results support the concept that ET is a disorder that disrupts widespread brain regions, including those outside of the brain regions responsible for tremor.
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Affiliation(s)
- Julián Benito-León
- Department of Neurology, University Hospital 12 de Octubre, Madrid, Spain.,Center of Biomedical Network Research on Neurodegenerative Diseases (CIBERNED), Madrid, Spain.,Department of Medicine, Faculty of Medicine, Complutense University, Madrid, Spain
| | - Emilio Sanz-Morales
- Medical Image Analysis Laboratory (LAIMBIO), Rey Juan Carlos University, Madrid, Spain
| | - Helena Melero
- Medical Image Analysis Laboratory (LAIMBIO), Rey Juan Carlos University, Madrid, Spain
| | - Elan D Louis
- Department of Neurology, Yale School of Medicine, Yale University, New Haven, Connecticut.,Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, Connecticut.,Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, Connecticut
| | - Juan P Romero
- Faculty of Biosanitary Sciences, Francisco de Vitoria University, Madrid, Spain.,Brain Damage Unit, Hospital Beata Maria Ana, Madrid, Spain
| | - Eduardo Rocon
- Neural and Cognitive Engineering group, Center for Automation and Robotics (CAR) CSIC-UPM, Arganda del Rey, Spain
| | - Norberto Malpica
- Medical Image Analysis Laboratory (LAIMBIO), Rey Juan Carlos University, Madrid, Spain
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Rao AK, Louis ED. Ataxic Gait in Essential Tremor: A Disease-Associated Feature? TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2019; 9:648. [PMID: 31413894 PMCID: PMC6691745 DOI: 10.7916/d8-28jq-8t52] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 03/05/2019] [Indexed: 12/25/2022]
Abstract
Background While accumulating evidence suggests that balance and gait impairments are commonly seen in patients with essential tremor (ET), questions remain regarding their prevalence, their relationship with normal aging, whether they are similar to the impairments seen in spinocerebellar ataxias, their functional consequences, and whether some ET patients carry greater susceptibility. Methods We conducted a literature search (until December 2018) on this topic. Results We identified 23 articles on gait or balance impairments in ET. The prevalence of balance impairment (missteps on tandem walk test) was seven times higher in ET patients than controls. Gait impairments in ET included reduced speed, increased asymmetry, and impaired dynamic balance. While balance and gait problems worsened with age, ET patients were more impaired than controls, independent of age. The pattern of impairments seen in ET was qualitatively similar to that seen in spinocerebellar ataxias. Balance and gait impairments resulted in greater number of near falls in ET patients. Factors associated with balance and gait impairments in ET included age, presence of tremor in midline structures, and cognitive dysfunction. Discussion Accumulating evidence suggests that balance and gait impairments are common in ET patients and occur to a greater extent in controls. Thus, they represent a disease-associated feature. These impairments, which are qualitatively similar to those seen in spinocerebellar ataxias, are not merely subclinical but result in difficulty performing functional tasks and increase falls risk. A subset of patients is more susceptible to balance and gait impairments. The full spectrum of impairments remains to be characterized.
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Affiliation(s)
- Ashwini K Rao
- Department of Rehabilitation & Regenerative Medicine (Program in Physical Therapy), G.H. Sergievsky Center, Huntington's Disease Center of Excellence, Center of Excellence in Alzheimer's Disease, Columbia University, New York, NY, USA
| | - Elan D Louis
- Department of Neurology and Epidemiology (Chronic Diseases); Chief, Division of Movement Disorders, Co-Director- Center for Neuroepidemiology and Clinical Neurology Research, New Haven, CT, USA
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8
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Clinical correlates of abnormal subcortical volumes in Essential Tremor. J Neural Transm (Vienna) 2019; 126:569-576. [DOI: 10.1007/s00702-019-02004-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 04/09/2019] [Indexed: 10/27/2022]
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9
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Tak AZA, Şengül Y, Karadağ AS. Evaluation of thickness of retinal nerve fiber layer, ganglion cell layer, and choroidal thickness in essential tremor: can eyes be a clue for neurodegeneration? Acta Neurol Belg 2018; 118:235-241. [PMID: 29076006 DOI: 10.1007/s13760-017-0852-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 10/14/2017] [Indexed: 12/15/2022]
Abstract
The pathology of essential tremor (ET) and underlying mechanisms of the disease are still unclear, but an increasing amount of research has been conducted on the subject. Discussions are ongoing about ET's definition as a neurodegenerative disease. Optic coherence tomography (OCT) provides a window to the brain where direct visualization of central nervous system (CNS) changes may be possible, and it can help us to develop a new point of view on ET. The goal of this study was to examine OCT parameters in ET. 40 ET patients and 40 healthy controls, i.e., a total of 160 eyes were evaluated. Retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), and choroid thinning were analyzed using spectral domain OCT. The mean age was 25.77 ± 8.98 in the ET group and 27.25 ± 8.22 in the control group. We found a decreased global RNFL thickness for both eyes in ET patients. All GCL and IPL thickness parameters were lower in the patients with ET (P < 0.001, P 0.03). Choroid was significantly thicker in ET patients than the controls (P < 0.001). Our study's results suggest that the usefulness of OCT in detecting neurodegeneration in ET. RNFL, GCL, IPL measurements are highly reproduced findings of neurodegeneration. Increased choroid volume may indicate neuroinflammation. Eyes in ET may shed light on nature of the disease, and may be used as a diagnostic tool.
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Affiliation(s)
- Ali Zeynel Abidin Tak
- Department of Neurology, School of Medicine, Adiyaman University Siteler Mahallesi, Atatürk Bulvarı, No. 411, Adiyaman, Turkey
| | - Yıldızhan Şengül
- Department of Neurology, Bezmialem Vakif Universitesi Hastanesi, Adnan Menderes Bulvarı, Vatan Caddesi, Fatih, 34093, Istanbul, Turkey.
| | - Ayşe Sevgi Karadağ
- Department of Ophthalmolgy, School of Medicine, Adiyaman University Siteler Mahallesi, Atatürk Bulvarı, No. 411, Adiyaman, Turkey
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10
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Lenka A, Benito-León J, Louis ED. Is there a Premotor Phase of Essential Tremor? Tremor Other Hyperkinet Mov (N Y) 2017; 7:498. [PMID: 29051842 PMCID: PMC5633681 DOI: 10.7916/d80s01vk] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 09/02/2017] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Essential tremor (ET) is the most common tremor disorder. In addition to its hallmark feature, kinetic tremor of the upper limbs, patients may have a number of non-motor symptoms and signs (NMS). Several lines of evidence suggest that ET is a neurodegenerative disorder and certain NMS may antedate the onset of tremor. This article comprehensively reviews the evidence for the existence of a "premotor phase" of ET, and discusses plausible biological explanations and implications. METHODS A PubMed search in May 2017 identified articles for this review. RESULTS The existence of a premotor phase of ET gains support primarily from longitudinal data. In individuals who develop incident ET, baseline (i.e., premotor) evaluations reveal greater cognitive dysfunction, a faster rate of cognitive decline, and the presence of a protective effect of education against dementia. In addition, baseline evaluations also reveal more self-reported depression, antidepressant medication use, and shorter sleep duration in individuals who eventually develop incident ET. In cross-sectional studies, certain personality traits and NMS (e.g., olfactory dysfunction) also suggest the existence of a premotor phase. DISCUSSION There is preliminary evidence supporting the existence of a premotor phase of ET. The mechanisms are unclear; however, the presence of Lewy bodies in some ET brains in autopsy studies and involvement of multiple neural networks in ET as evident from the neuroimaging studies, are possible contributors. Most evidence is from a longitudinal cohort (Neurological Disorders of Central Spain: NEDICES); additional longitudinal studies are warranted to gain better insights into the premotor phase of ET.
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Affiliation(s)
- Abhishek Lenka
- Department of Clinical Neurosciences, National Institute of Mental Health and Neurosciences, Bangalore, India
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Julian Benito-León
- Department of Neurology, University Hospital “12 de Octubre”, Madrid, Spain
- Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
- Department of Medicine, Complutense University, Madrid, Spain
| | - Elan D. Louis
- Division of Movement Disorders, Department of Neurology Yale School of Medicine, Yale University, New Haven, CT, USA
- Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, CT, USA
- Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, CT, USA
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11
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Louis ED, Lenka A. The Olivary Hypothesis of Essential Tremor: Time to Lay this Model to Rest? Tremor Other Hyperkinet Mov (N Y) 2017; 7:473. [PMID: 28966877 PMCID: PMC5618117 DOI: 10.7916/d8ff40rx] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 06/09/2017] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Although essential tremor (ET) is the most common tremor disorder, its pathogenesis is not fully understood. The traditional model of ET, proposed in the early 1970s, posited that the inferior olivary nucleus (ION) was the prime generator of tremor in ET and that ET is a disorder of electrophysiological derangement, much like epilepsy. This article comprehensively reviews the origin and basis of this model, its merits and problems, and discusses whether it is time to lay this model to rest. METHODS A PubMed search was performed in March 2017 to identify articles for this review. RESULTS The olivary model gains support from the recognition of neurons with pacemaker property in the ION and the harmaline-induced tremor models (as the ION is the prime target of harmaline). However, the olivary model is problematic, as neurons with pacemaker property are not specific to the ION and the harmaline model does not completely represent the human disease ET. In addition, a large number of neuroimaging studies in ET have not detected structural or functional changes in the ION; rather, abnormalities have been reported in structures related to the cerebello-thalamo-cortical network. Moreover, a post-mortem study of microscopic changes in the ION did not detect any differences between ET cases and controls. DISCUSSION The olivary model largely remains a physiological construct. Numerous observations have cast considerable doubt as to the validity of this model in ET. Given the limitations of the model, we conclude that it is time now to lay this model to rest.
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Affiliation(s)
- Elan D. Louis
- Division of Movement Disorders, Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, USA
- Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, CT, USA
- Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - Abhishek Lenka
- Department of Clinical Neurosciences, National Institute of Mental Health and Neurosciences, Bangalore, India
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore, India
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12
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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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13
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Abstract
A fundamental question about essential tremor (ET) is whether its associated pathological changes and disease mechanisms are linkable to a specific brain region. To that end, recent tissue-based studies have made significant strides in elucidating changes in the ET brain. Emerging from these studies is increasing neuropathological evidence linking ET to the cerebellum. These studies have systematically identified a broad range of structural, degenerative changes in the ET cerebellum, spanning across all Purkinje cell compartments. These include the dendritic compartment (where there is an increase in number of Purkinje cell dendritic swellings, a pruning of the dendritic arbor, and a reduction in spine density), the cell body (where, aside from reductions in Purkinje cell linear density in some studies, there is an increase in the number of heterotopic Purkinje cell soma), and the axonal compartment (where a plethora of changes in axonal morphology have been observed, including an increase in the number of thickened axonal profiles, torpedoes, axonal recurrent collaterals, axonal branching, and terminal axonal sprouting). Additional changes, possibly due to secondary remodeling, have been observed in neighboring neuronal populations. These include a hypertrophy of basket cell axonal processes and changes in the distribution of climbing fiber-Purkinje cell synapses. These changes all distinguish ET from normal control brains. Initial studies further indicate that the profile (i.e., constellation) of these changes may separate ET from other diseases of the cerebellum, thereby serving as a disease signature. With the discovery of these changes, a new model of ET has arisen, which posits that it may be a neurodegenerative disorder centered in the cerebellar cortex. These newly emerging neuropathological studies pave the way for anatomically focused, hypothesis-driven, molecular mechanistic studies of disease pathogenesis.
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14
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Shin H, Lee DK, Lee JM, Huh YE, Youn J, Louis ED, Cho JW. Atrophy of the Cerebellar Vermis in Essential Tremor: Segmental Volumetric MRI Analysis. THE CEREBELLUM 2016; 15:174-81. [PMID: 26062905 DOI: 10.1007/s12311-015-0682-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Postmortem studies of essential tremor (ET) have demonstrated the presence of degenerative changes in the cerebellum, and imaging studies have examined related structural changes in the brain. However, their results have not been completely consistent and the number of imaging studies has been limited. We aimed to study cerebellar involvement in ET using MRI segmental volumetric analysis. In addition, a unique feature of this study was that we stratified ET patients into subtypes based on the clinical presence of cerebellar signs and compared their MRI findings. Thirty-nine ET patients and 36 normal healthy controls, matched for age and sex, were enrolled. Cerebellar signs in ET patients were assessed using the clinical tremor rating scale and International Cooperative Ataxia Rating Scale. ET patients were divided into two groups: patients with cerebellar signs (cerebellar-ET) and those without (classic-ET). MRI volumetry was performed using CIVET pipeline software. Data on whole and segmented cerebellar volumes were analyzed using SPSS. While there was a trend for whole cerebellar volume to decrease from controls to classic-ET to cerebellar-ET, this trend was not significant. The volume of several contiguous segments of the cerebellar vermis was reduced in ET patients versus controls. Furthermore, these vermis volumes were reduced in the cerebellar-ET group versus the classic-ET group. The volume of several adjacent segments of the cerebellar vermis was reduced in ET. This effect was more evident in ET patients with clinical signs of cerebellar dysfunction. The presence of tissue atrophy suggests that ET might be a neurodegenerative disease.
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Affiliation(s)
- Hyeeun Shin
- Department of Neurology, Anyang Sam Hospital, Gyeunggi-do, Republic of Korea
| | - Dong-Kyun Lee
- Department of Biomedical Engineering, Hanyang University, Seoul, Republic of Korea
| | - Jong-Min Lee
- Department of Biomedical Engineering, Hanyang University, Seoul, Republic of Korea
| | - Young-Eun Huh
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Irwon dong 50, Gangnam-gu, Seoul, 135-710, Republic of Korea
- Neuroscience Center, Samsung Medical Center, Seoul, Republic of Korea
| | - Jinyoung Youn
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Irwon dong 50, Gangnam-gu, Seoul, 135-710, Republic of Korea
- Neuroscience Center, Samsung Medical Center, Seoul, Republic of Korea
| | - Elan D Louis
- Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, 06520, USA
- Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, 10032, USA
| | - Jin Whan Cho
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Irwon dong 50, Gangnam-gu, Seoul, 135-710, Republic of Korea.
- Neuroscience Center, Samsung Medical Center, Seoul, Republic of Korea.
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15
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Waln O, Wu Y, Perlman R, Wendt J, Van AK, Jankovic J. Dopamine transporter imaging in essential tremor with and without parkinsonian features. J Neural Transm (Vienna) 2015; 122:1515-21. [PMID: 26133163 DOI: 10.1007/s00702-015-1419-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 06/22/2015] [Indexed: 12/16/2022]
Abstract
Mild parkinsonian features can be observed in patients with essential tremor (ET). Although dopamine transporter (DAT) imaging is usually normal in ET, some studies found mild dopaminergic deficit in ET patients compared to healthy controls (HC). We analyzed clinical and DAT imaging data in ET patients with and without parkinsonian features. Thirty-nine ET patients with and without parkinsonian features and 13 HC underwent detailed examination by a movement disorders neurologist and 123-I ioflupane SPECT. Two independent radiologists "blinded" to the clinical diagnosis analyzed images visually and by semi-quantitative calculation of striatal binding ratios in different volumes of interests. ET patients were divided into pure ET group (no parkinsonian features, n = 22), ET-P [one parkinsonian feature not sufficient for the clinical diagnosis of Parkinson's disease (PD), n = 9], and ET + PD (two or more parkinsonian features meeting diagnostic criteria for PD, n = 8). As expected, ET + PD patients had the lowest striatal binding ratios. We also found a trend toward slightly lower striatal binding ratios in ET patients ET compared to HC, especially in caudate nucleus. There was no significant correlation between striatal binding ratios, ET severity or duration. Patients with ET and parkinsonian features represent a heterogeneous group that includes ET + PD and ET-P. The latter group shares some clinical features with PD but has no dopaminergic deficit on DAT imaging as determined by visual image interpretation. On the other hand, minimal dopaminergic deficit (as compared to controls) is detected in some ET patients with semi-quantitative image analysis, although the pattern may be different from that of PD.
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Affiliation(s)
- Olga Waln
- Department of Neurology, Methodist Neurological Institute, Houston, TX, USA.
| | - Ying Wu
- Department of Radiology, NorthShore University Health System, Evanston, IL, USA.,Department of Radiology, Pritzker School of Medicine, Chicago, IL, USA
| | - Reid Perlman
- Department of Radiology, NorthShore University Health System, Evanston, IL, USA.,Department of Radiology, Pritzker School of Medicine, Chicago, IL, USA
| | - Juliet Wendt
- Department of Radiology, Baylor College of Medicine, Houston, TX, USA
| | - Anh K Van
- Department of Radiology, Baylor College of Medicine, Houston, TX, USA
| | - Joseph Jankovic
- Department of Neurology, Parkinson's Disease Center and Movement Disorder Clinic, Baylor College of Medicine, 7200 Cambridge, Suite 9A, MS: BCM 609, Houston, TX, 77030-4202, USA.
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16
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Abstract
Essential tremor (ET) is one of the most common neurological diseases, with an estimated 7 million affected individuals in the United States. Postmortem studies in the past few years have resulted in new knowledge as well as a new formulation of disease pathophysiology. This new formulation centers on the notion that ET might be a disease of the cerebellum and, more specifically, the Purkinje cell (PC) population. Indeed, several investigators have proposed that ET may be a "Purkinjopathy." Supporting this formulation are data from controlled postmortem studies demonstrating (1) a range of morphological changes in the PC axon, (2) abnormalities in the position and orientation of PC bodies, (3) reduction in the number of PCs in some studies, (4) morphological changes in and pruning of the PC dendritic arbor with loss of dendritic spines, and (5) alterations in both the PC-basket cell interface and the PC-climbing fiber interface in ET cases. This new formulation has engendered some controversy and raised additional questions. Whether the constellation of changes observed in ET differs from that seen in other degenerative disorders of the cerebellum remains to be determined, although initial studies suggest the likely presence of a distinct profile of changes in ET.
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Affiliation(s)
- Elan D Louis
- Division of Movement Disorders, Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, USA Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, CT, USA
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17
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Louis ED, Michalec M. Reduced body mass index in essential tremor: a study of 382 cases and 392 matched controls. Eur J Neurol 2015; 22:384-8. [PMID: 25367457 PMCID: PMC4289439 DOI: 10.1111/ene.12589] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 08/29/2014] [Indexed: 11/27/2022]
Abstract
BACKGROUND AND PURPOSE There is mounting evidence that essential tremor (ET) is a neurodegenerative disease. Reduced body mass index (BMI) is a clinical feature of many neurodegenerative diseases, yet there has been little documentation of BMI in patients with ET. METHODS Essential tremor cases and controls were enrolled in a study of the environmental epidemiology of ET at Columbia University Medical Center. Weight and height were measured using a standard protocol; BMI was weight (kg) divided by height (m(2)). Daily calorie count (kcal) was calculated using the Willett Semi-Quantitative Food Frequency Questionnaire. Tremor severity was assessed with a clinical rating scale (total tremor score, range 0-36). RESULTS The 382 ET cases and 392 controls were similar with respect to age, gender and other demographic variables. BMI was lower in ET cases than controls [26.7 ± 5.0 (median = 26.2) vs. 27.7 ± 5.6 (median = 26.7), P = 0.03] despite the fact that the daily caloric intake was marginally higher in ET cases than controls (P = 0.09). In ET cases, BMI was not associated with tremor severity (Spearman's r = -0.02, P = 0.66) but, among younger onset ET cases, longer tremor duration was associated with lower BMI (Spearman's r = -0.14, P = 0.049). CONCLUSIONS The observed lower BMI in ET is consistent with the neurodegenerative hypothesis of ET. The data also suggest that some mechanism other than decreased daily caloric intake or an involuntary movement-related increased burning of calories is likely to account for this case-control difference.
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Affiliation(s)
- E D Louis
- GH Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, New York, NY, USA
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