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Cabral AM, Lora-Millán JS, Pereira AA, Rocon E, Andrade ADO. On the Effect of Vibrotactile Stimulation in Essential Tremor. Healthcare (Basel) 2024; 12:448. [PMID: 38391822 PMCID: PMC10888095 DOI: 10.3390/healthcare12040448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 01/24/2024] [Accepted: 02/05/2024] [Indexed: 02/24/2024] Open
Abstract
(1) Background: Vibrotactile stimulation has been studied for tremor, but there is little evidence for Essential Tremor (ET). (2) Methods: This research employed a dataset from a previous study, with data collected from 18 individuals subjected to four vibratory stimuli. To characterise tremor changes before, during, and after stimuli, time and frequency domain features were estimated from the signals. Correlation and regression analyses verified the relationship between features and clinical tremor scores. (3) Results: Individuals responded differently to vibrotactile stimulation. The 250 Hz stimulus was the only one that reduced tremor amplitude after stimulation. Compared to the baseline, the 250 Hz and random frequency stimulation reduced tremor peak power. The clinical scores and amplitude-based features were highly correlated, yielding accurate regression models (mean squared error of 0.09). (4) Conclusions: The stimulation frequency of 250 Hz has the greatest potential to reduce tremors in ET. The accurate regression model and high correlation between estimated features and clinical scales suggest that prediction models can automatically evaluate and control stimulus-induced tremor. A limitation of this research is the relatively reduced sample size.
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Affiliation(s)
- Ariana Moura Cabral
- Centre for Innovation and Technology Assessment in Health, Postgraduate Program in Electrical and Biomedical Engineering, Faculty of Electrical Engineering, Federal University of Uberlândia, Uberlândia 38400-902, Brazil
| | | | - Adriano Alves Pereira
- Centre for Innovation and Technology Assessment in Health, Postgraduate Program in Electrical and Biomedical Engineering, Faculty of Electrical Engineering, Federal University of Uberlândia, Uberlândia 38400-902, Brazil
| | - Eduardo Rocon
- BioRobotics Group, Centre for Automation and Robotics (CAR), CSIC-UPM, 28500 Madrid, Spain
| | - Adriano de Oliveira Andrade
- Centre for Innovation and Technology Assessment in Health, Postgraduate Program in Electrical and Biomedical Engineering, Faculty of Electrical Engineering, Federal University of Uberlândia, Uberlândia 38400-902, Brazil
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Free DB, Syndergaard I, Pigg AC, Muceli S, Hallett M, Farina D, Charles SK. Hand and distal joint tremor are most coherent with the activity of elbow flexors and wrist extensors in persons with essential tremor. J Appl Physiol (1985) 2024; 136:337-348. [PMID: 38126087 PMCID: PMC11218932 DOI: 10.1152/japplphysiol.00407.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 11/27/2023] [Accepted: 12/19/2023] [Indexed: 12/23/2023] Open
Abstract
Essential tremor (ET) affects millions of people. Although frontline treatment options (medication, deep brain stimulation, and focused ultrasound ablation) have provided significant relief, many patients are unsatisfied with the outcomes. Peripheral suppression techniques, such as injections of botulinum toxin or sensory electrical stimulation of muscles, are gaining popularity, but could be optimized if the muscles most responsible for a patient's tremor were identified. The purpose of this study was to quantify the relationship between the activity in various upper limb muscles and the resulting tremor in patients with ET. Surface electromyogram (sEMG) from the 15 major superficial muscles of the upper limb and displacement of the hand and upper limb joints were recorded from 22 persons with ET while they performed kinetic and postural tasks representative of activities of daily living. We calculated the peak coherence (frequency-dependent correlation) in the tremor band (4-8 Hz) between the sEMG of each muscle and the displacement in each major degree of freedom (DOF). Averaged across subjects with ET, the highest coherence was found between elbow flexors (particularly biceps brachii and brachioradialis) and the distal DOF (forearm, wrist, and hand motion), and between wrist extensors (extensor carpi radialis and ulnaris) and the same distal DOF. These coherence values represent the upper bound on the proportion of the tremor caused by each muscle. We conclude that, without further information, elbow flexors and wrist extensors should be among the first muscles considered for peripheral suppression techniques in persons with ET.NEW & NOTEWORTHY We characterized the relationships between activity in upper limb muscles and tremor in persons with essential tremor using coherence, which provides an upper bound on the proportion of the tremor due to each muscle. Averaged across subjects and various tasks, tremor in the hand and distal joints was most coherent with elbow flexors and wrist extensors. We conclude that, without further information, these muscle groups should be among the first considered for peripheral suppression techniques.
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Affiliation(s)
- Daniel B Free
- Department of Mechanical Engineering, Brigham Young University, Provo, Utah, United States
| | - Ian Syndergaard
- Department of Mechanical Engineering, Brigham Young University, Provo, Utah, United States
| | - Adam C Pigg
- Department of Mechanical Engineering, Brigham Young University, Provo, Utah, United States
| | - Silvia Muceli
- Department of Electrical Engineering, Chalmers University of Technology, Gothenburg, Sweden
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Mark Hallett
- Division of Intramural Research, National Institute of Neurological Disorders and Stroke, National Institute of Health, Bethesda, Maryland, United States
| | - Dario Farina
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Steven K Charles
- Department of Mechanical Engineering, Brigham Young University, Provo, Utah, United States
- Department of Neuroscience, Brigham Young University, Provo, Utah, United States
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Reference Values of the Forearm Tremor Power Spectra for Youth Athletes. J Hum Kinet 2023; 86:133-143. [PMID: 37181254 PMCID: PMC10170535 DOI: 10.5114/jhk/159644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
The aim of the study was to determine reference graphs of power spectral density functions of forearm physiological tremor and to compare their parameters in the male and female population of young athletes from various sports. One hundred fifty-nine (159) female (15.7 ± 2.1 years, 59.8 ± 8.1 kg, 169.1 ± 7.5 cm) and 276 male (16.4 ± 1.9 years 72.7 ± 10.3 kg and 180.9 ± 8.7 cm) youth athletes participated in the study. Forearm tremor was measured accelerometrically in a sitting position. Power spectrum density (PSD) function was calculated for each individual tremor waveform. Because of right skewness of power distribution, the PSD functions were subjected to logarithmic transformation. Average log-powers in low (2–4 Hz) and high (8–14 Hz) frequency ranges and mean frequencies in those ranges were analyzed. Tremor log-powers for male were greater than for female athletes (p < 0.001), while frequencies of spectrum maxima did not differ from each other. Frequencies of spectrum maxima correlated (p < 0.001) with age (r = 0.277 and 0.326 for males and females, respectively). The obtained reference functions may be utilized in order to quantify and assess tremor size and its changes evoked by stress and fatigue, which can be applied for selection and training monitoring in sports, but also in medicine for detection and diagnosis of pathologic tremor in young individuals.
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Upper Limb Function but Not Proprioception is Impaired in Essential Tremor: A Between-Groups Study and Causal Mediation Analysis. Tremor Other Hyperkinet Mov (N Y) 2023; 13:1. [PMID: 36644368 PMCID: PMC9818046 DOI: 10.5334/tohm.731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 12/19/2022] [Indexed: 01/04/2023] Open
Abstract
Background Essential tremor (ET) is characterized by abnormal oscillatory muscle activity and cerebellar involvement, factors that can lead to proprioceptive deficits, especially in active tasks. The present study aimed to quantify the severity of proprioceptive deficits in people with ET and estimate how these contribute to functional impairments. Methods Upper limb sensory, proprioceptive and motor function was assessed inindividuals with ET (n = 20) and healthy individuals (n = 22). To measure proprioceptive ability, participants discriminated the width of grasped objects and the weight of objects liftedwith the wrist extensors. Causal mediation analysis was used to estimate the extentthat impairments in upper limb function in ET was mediated by proprioceptive ability. Results Participants with ET had impaired upper limb function in all outcomes, and had greater postural and kinetic tremor. There were no differences between groups in proprioceptive discrimination of width (between-group mean difference [95% CI]: 0.32 mm [-0.23 to 0.87 mm]) or weight (-1.12 g [-7.31 to 5.07 g]). Causal mediation analysis showed the effect of ET on upper limb function was not mediated by proprioceptive ability. Conclusions Upper limb function but not proprioception was impaired in ET. The effect of ET on motor function was not mediated by proprioception. These results indicate that the central nervous system of people with ET is able to accommodate mild to moderate tremor in active proprioceptive tasks that rely primarily on afferent signals from muscle spindles.
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Santos PSA, Santos EGR, Monteiro LCP, Santos-Lobato BL, Pinto GHL, Belgamo A, Cabral AS, de Athayde Costa E Silva A, Callegari B, Souza GS. The hand tremor spectrum is modified by the inertial sensor mass during lightweight wearable and smartphone-based assessment in healthy young subjects. Sci Rep 2022; 12:16808. [PMID: 36207392 PMCID: PMC9547012 DOI: 10.1038/s41598-022-21310-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Accepted: 09/26/2022] [Indexed: 11/19/2022] Open
Abstract
Tremors are common disorders characterized by an involuntary and relatively rhythmic oscillation that can occur in any part of the body and may be physiological or associated with some pathological condition. It is known that the mass loading can change the power spectral distribution of the tremor. Nowadays, many instruments have been used in the evaluation of tremors with bult-in inertial sensors, such as smartphones and wearables, which can significantly differ in the device mass. The aim of this study was to compare the quantification of hand tremor using Fourier spectral techniques obtained from readings of accelerometers built-in a lightweight handheld device and a commercial smartphone in healthy young subjects. We recruited 28 healthy right-handed subjects with ages ranging from 18 to 40 years. We tested hand tremors at rest and postural conditions using lightweight wearable device (5.7 g) and smartphone (169 g). Comparing both devices at resting tremor, we found with smartphone the power distribution of peak ranging 5 and 12 Hz in both hands. With wearable, the result was similar but less evident. When comparing both devices in postural tremor, there were significant differences in both frequency ranges in peak frequency and peak amplitude in both hands. Our main findings show that in resting condition the hand tremor spectrum had a higher peak amplitude in the 5–12 Hz range when the tremor was recorded with smartphones, and in postural condition there was a significantly (p < 0.05) higher peak power spectrum and peak frequency in the dominant hand tremors recorded with smartphones compared to those obtained with lightweight wearable device. Devices having different masses can alter the features of the hand tremor spectrum and their mutual comparisons can be prejudiced.
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Affiliation(s)
| | | | | | | | | | - Anderson Belgamo
- Departamento de Ciência da Computação, Instituto Federal de São Paulo, Piracicaba, Brazil
| | - André Santos Cabral
- Centro de Ciências Biológicas e da Saúde, Universidade do Estado do Pará, Belém, Brazil
| | - Anselmo de Athayde Costa E Silva
- Programa de Pós-Graduação em Ciências do Movimento Humano, Instituto de Ciências da Saúde, Universidade Federal do Pará, Belém, Brazil
| | - Bianca Callegari
- Programa de Pós-Graduação em Ciências do Movimento Humano, Instituto de Ciências da Saúde, Universidade Federal do Pará, Belém, Brazil.,Laboratório de Estudos da Motricidade Humana, Instituto de Ciências da Saúde, Universidade Federal do Pará, Belém, Brazil
| | - Givago Silva Souza
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Brazil. .,Núcleo de Medicina Tropical, Universidade Federal do Pará, Av Generalíssimo Deodoro 92, Umarizal, Belém, Pará, 66055240, Brazil.
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Bhidayasiri R, Maytharakcheep S, Phumphid S, Maetzler W. Improving functional disability in patients with tremor: A clinical perspective of the efficacies, considerations, and challenges of assistive technology. J Neurol Sci 2022; 435:120197. [DOI: 10.1016/j.jns.2022.120197] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/06/2021] [Accepted: 02/17/2022] [Indexed: 11/24/2022]
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Roth N, Rosenblum S. Does Cup-Grip Type Affect Tremor among People with Essential Tremor? SENSORS 2021; 21:s21237797. [PMID: 34883799 PMCID: PMC8659972 DOI: 10.3390/s21237797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 11/21/2021] [Accepted: 11/22/2021] [Indexed: 12/02/2022]
Abstract
Essential tremor (ET) is a movement disorder that may cause functional disability in daily activities, such as drinking from a cup or drawing. This study aims to characterize effects of varied cup-grip types and measured axes on the actual performance of people with ET and find correlations between cup-grip type and measured axes, and spiral drawing measures. Participants (20 with ET and 18 controls) held a cup of water in a steady position in three grip types and drew a spiral. The cup acceleration was measured by the cup triaxial accelerometer, analyzed in X, Y and Z axes (directions); deviation of the measured acceleration from the desired steady position acceleration was computed. Significant group differences were found for outcome measures in all grip types. Among participants with ET, significantly higher measured values were found in the cup’s horizontal plane (X and Y axes) compared to the vertical direction (Z axis) and for on-the-handle versus around-the-cup grips in the X and Y axes. Significant correlations were found between this grip’s measures and spiral-drawing actual performance measures, indicating the measurement axis and grip type may affect actual performance. These findings may support the future development of assistive devices for tremor suppression and personalized supportive therapy.
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Affiliation(s)
- Navit Roth
- The Laboratory of Complex Human Activity and Participation (CHAP), Department of Occupational Therapy, University of Haifa, Haifa 3498838, Israel;
- Department of Mechanical Engineering, ORT Braude Academic College of Engineering, Karmiel 2161002, Israel
- Correspondence:
| | - Sara Rosenblum
- The Laboratory of Complex Human Activity and Participation (CHAP), Department of Occupational Therapy, University of Haifa, Haifa 3498838, Israel;
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Roth N, Braun-Benyamin O, Rosenblum S. Drawing Direction Effect on a Task's Performance Characteristics among People with Essential Tremor. SENSORS 2021; 21:s21175814. [PMID: 34502703 PMCID: PMC8433857 DOI: 10.3390/s21175814] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 12/26/2022]
Abstract
Essential tremor (ET) is a common movement disorder affecting the performance of various daily tasks, including drawing. While spiral-drawing task characteristics have been described among patients with ET, research about the significance of the drawing direction of both spiral and lines tasks on the performance process is scarce. This study mapped inter-group differences between people with ET and controls related to drawing directions and the intra-effect of the drawing directions on the tremor level among people with ET. Twenty participants with ET and eighteen without ET drew spirals and vertical and horizontal lines on a digitizer with an inking pen. Time-based outcome measures were gathered to address the effect of the drawing directions on tremor by analyzing various spiral sections and comparing vertical and horizontal lines. Significant group differences were found in deviation of the spiral radius from a filtered radius curve and in deviation of the distance curve from a filtered curve for both line types. Significant differences were found between defined horizontal and vertical spiral sections within each group and between both line types within the ET group. A significant correlation was found between spiral and vertical line deviations from filtered curve outcome measures. Achieving objective measures about the significance of drawing directions on actual performance may support the clinical evaluation of people with ET toward developing future intervention methods for improving their functional abilities.
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Affiliation(s)
- Navit Roth
- The Laboratory of Complex Human Activity and Participation (CHAP), Department of Occupational Therapy, University of Haifa, Haifa 3498838, Israel;
- Department of Mechanical Engineering, ORT Braude Academic College of Engineering, Karmiel 2161002, Israel;
- Correspondence:
| | - Orit Braun-Benyamin
- Department of Mechanical Engineering, ORT Braude Academic College of Engineering, Karmiel 2161002, Israel;
| | - Sara Rosenblum
- The Laboratory of Complex Human Activity and Participation (CHAP), Department of Occupational Therapy, University of Haifa, Haifa 3498838, Israel;
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Lora-Millan JS, Delgado-Oleas G, Benito-León J, Rocon E. A Review on Wearable Technologies for Tremor Suppression. Front Neurol 2021; 12:700600. [PMID: 34434161 PMCID: PMC8380769 DOI: 10.3389/fneur.2021.700600] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/28/2021] [Indexed: 12/29/2022] Open
Abstract
Tremor is defined as a rhythmic, involuntary oscillatory movement of a body part. Although everyone exhibits a certain degree of tremor, some pathologies lead to very disabling tremors. These pathological tremors constitute the most prevalent movement disorder, and they imply severe difficulties in performing activities of daily living. Although tremors are currently managed through pharmacotherapy or surgery, these treatments present significant associated drawbacks: drugs often induce side effects and show decreased effectiveness over years of use, while surgery is a hazardous procedure for a very low percentage of eligible patients. In this context, recent research demonstrated the feasibility of managing upper limb tremors through wearable technologies that suppress tremors by modifying limb biomechanics or applying counteracting forces. Furthermore, recent experiments with transcutaneous afferent stimulation showed significant tremor attenuation. In this regard, this article reviews the devices developed following these tremor management paradigms, such as robotic exoskeletons, soft robotic exoskeletons, and transcutaneous neurostimulators. These works are presented, and their effectiveness is discussed. The article also evaluates the different metrics used for the validation of these devices and the lack of a standard validation procedure that allows the comparison among them.
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Affiliation(s)
- Julio S. Lora-Millan
- Centro de Automática y Robótica, Consejo Superior de Investigaciones Científicas – Universidad Politécnica de Madrid, Madrid, Spain
| | - Gabriel Delgado-Oleas
- Centro de Automática y Robótica, Consejo Superior de Investigaciones Científicas – Universidad Politécnica de Madrid, Madrid, Spain
- Ingeniería Electrónica, Universidad del Azuay, Cuenca, Ecuador
| | - Julián Benito-León
- Department of Neurology, University Hospital “12 de Octubre”, Madrid, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas, Madrid, Spain
- Department of Medicine, Complutense University, Madrid, Spain
| | - Eduardo Rocon
- Centro de Automática y Robótica, Consejo Superior de Investigaciones Científicas – Universidad Politécnica de Madrid, Madrid, Spain
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Correlation of proximal and distal muscle strength with upper limb functional ability in patients with essential tremor. Acta Neurol Belg 2020; 120:601-607. [PMID: 30565036 DOI: 10.1007/s13760-018-01068-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 12/12/2018] [Indexed: 12/14/2022]
Abstract
Despite being considered as a benign, genetic and monosymptomatic disorder, ET is a poorly understood entity with etiological and pathological heterogeneity. The aim of the present study was to examine the relation between proximal and distal muscle strength and upper limb functionality and tremor severity in patients with essential tremor (ET). The study enrolled 25 tremor patients followed at the neurology clinic of a university hospital and 19 healthy controls. Demographic data, risk factors, disease duration and dominant hand of the participants were recorded. Back and leg strength was assessed using a back and leg dynamometer and hand dynamometer and pinchmeter were used to determine hand strength. Functional ability of the participants was evaluated using the Minnesota Manual Dexterity Test (MMDT), Perdue Pegboard (PPBT) and Nine Hole Peg Test (NHPT). Tremor severity was assessed using the Fahn-Tolosa-Marin Tremor Rating Scale (FTMTRS) and the Lower Extremity Clinical Tremor Assessment Scale (LECTAS). A significant difference was found in the average back and leg muscle strength between ET patients and healthy controls (p < 0.05). The mean values for right/left hand muscle strength were not significantly different between the two groups (p > 0.05). Among the upper limb functional ability tests, significant differences were found between the two groups in the mean time to complete NHPT, Minnesota placing subtest and PPBT test (p < 0.05). While gender and risk factors were not significantly different between the two groups (p > 0.05), there was a significant difference with respect to the educational level (p < 0.01). No significant difference was found between back and leg muscle strength and FTMTRS and LECTAS (p > 0.05). A negative correlation and a significant association were found between average strength measurements obtained with the left hand dynamometer and FTMTRS in the ET group (p = 0.030, r = - 0.434). A positive correlation and a significant association were found between left hand strength and mean turning time in the MMDT in the control group (p = 0.041, r = 0.473). ET patients experience loss of proximal muscle strength and functional disability. Further studies are planned to investigate the effects of physical therapy modalities targeting increased proximal muscle strength on tremor severity and functional ability in ET patients.
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11
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Cao H, Thompson-Westra J, Hallett M, Haubenberger D. The response of the central and peripheral tremor component to octanoic acid in patients with essential tremor. Clin Neurophysiol 2018; 129:1467-1471. [PMID: 29678370 DOI: 10.1016/j.clinph.2018.03.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 02/26/2018] [Accepted: 03/10/2018] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To investigate the effect of octanoic acid (OA) on the peripheral component of tremor, as well as OA's differential effects on the central and peripheral tremor component in essential tremor (ET) patients. METHODS We analyzed postural tremor accelerometry data from a double-blind placebo-controlled cross-over study evaluating the effect of 4 mg/kg OA in ET. The weighted condition was used to identify tremor power for both the central and peripheral tremor components. Exploratory non-parametric statistical analyses were used to describe the relation between the central and peripheral component of tremor power. RESULTS A peripheral tremor component was identified in 4 out of 18 subjects. Tremor power was reduced after OA administration in both the central and the peripheral tremor component. There was a positive correlation of tremor power between the central and peripheral component, both after placebo and OA. CONCLUSIONS When present, the peripheral component was closely related to the central tremor component. We hypothesize that the magnitude of the peripheral mechanical component of tremor is determined by that of the central component. SIGNIFICANCE Both central and peripheral component of tremor are reduced after OA, with the central component providing the energy driving the peripheral component.
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Affiliation(s)
- Hongmei Cao
- Department of Neurology, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, 277 Yanta Western Road, Xi'an 710061, China; National Institute of Neurological Disorders and Stroke, National Institutes of Health, 9000 Rockville Pike, Building 10, Bethesda, MD 20892, USA
| | - Johanna Thompson-Westra
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, 9000 Rockville Pike, Building 10, Bethesda, MD 20892, USA
| | - Mark Hallett
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, 9000 Rockville Pike, Building 10, Bethesda, MD 20892, USA
| | - Dietrich Haubenberger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, 9000 Rockville Pike, Building 10, Bethesda, MD 20892, USA.
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12
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Geiger DW, Eggett DL, Charles SK. A method for characterizing essential tremor from the shoulder to the wrist. Clin Biomech (Bristol, Avon) 2018; 52:117-123. [PMID: 29428341 DOI: 10.1016/j.clinbiomech.2017.12.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 10/14/2017] [Accepted: 12/08/2017] [Indexed: 02/07/2023]
Abstract
BACKGROUND Despite the pervasive and devastating effect of Essential Tremor (ET), the distribution of ET throughout the upper limb is unknown. We developed a method for characterizing the distribution of ET and performed a preliminary characterization in a small number of subjects with ET. METHODS Using orientation sensors and inverse kinematics, we measured tremor in each of the seven major degrees of freedom (DOF) from the shoulder to the wrist while ten patients with mild ET assumed 16 different postures. We described the tremor in each DOF in terms of power spectral density measures and investigated how tremor varied between DOF, postures, gravitational torques, and repetitions. FINDINGS Our method successfully resulted in tremor measures in each DOF, allowing one to compare tremor between DOF and determine the distribution of tremor throughout the upper limb, including how the distribution changes with posture. In our small number of subjects, we found that the amount of power in the frequency band associated with ET (4-12Hz) was lowest in the shoulder and greatest in the wrist. Similarly, the existence and amplitude of peaks in this band increased from proximal to distal. Although the amount of tremor differed significantly between postures, we did not find any clear patterns with changes in posture or gravitational torque. INTERPRETATION This method can be used to characterize the distribution of tremor throughout the upper limb. Our preliminary characterization suggests that the amount of tremor increases in a proximal-distal manner.
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Affiliation(s)
- Daniel W Geiger
- Department of Mechanical Engineering, Brigham Young University, 435 CTB, Provo, UT 84602, United States
| | - Dennis L Eggett
- Department of Statistics, Brigham Young University, 223 TMCB, Provo, UT 84602, United States
| | - Steven K Charles
- Department of Mechanical Engineering, Brigham Young University, 435 CTB, Provo, UT 84602, United States; Neuroscience Center, Brigham Young University, S-192 ESC, Provo, UT 84602, United States.
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13
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Abstract
Currently available therapies for essential tremor (ET) provide sufficient control only for less than a half of patients and many unmet needs exist. This is in part due to the empiric nature of existing treatment options and persisting uncertainties about the pathogenesis of ET. The emerging concept of ET as a possible neurodegenerative disorder, better understanding of associated biochemical changes, including alterations in the γ-aminobutyric acid (GABA)-ergic system and gap junctions, and the identification of the role of the leucine-rich repeat and immunoglobulin-like domain-containing 1 (LINGO-1) gene in ET pathogenesis suggest new avenues for more targeted therapies. Here we review the most promising new approaches to treating ET, including allosteric modulation of GABA receptors and modifications of the LINGO-1 pathway. Medically refractory tremor can be successfully treated by high-frequency deep brain stimulation (DBS) of the ventral intermediate nucleus, but surgical therapies are also fraught with limitations due to adverse effects of stimulation and the loss of therapeutic response. The selection of additional thalamic and extrathalamic targets for electrode placements and the development of a closed-loop DBS system enabling automatic adjustment of stimulation parameters in response to changes in electrophysiologic brain activity are also reviewed. Tremor cancellation methods using exoskeleton and external hand-held devices are also briefly discussed.
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Affiliation(s)
- Peter Hedera
- Department of Neurology, Vanderbilt University, 465 21st Avenue South, 6140 MRB III, Nashville, TN 37240, USA
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Herrnstadt G, Menon C. Voluntary-Driven Elbow Orthosis with Speed-Controlled Tremor Suppression. Front Bioeng Biotechnol 2016; 4:29. [PMID: 27066477 PMCID: PMC4814799 DOI: 10.3389/fbioe.2016.00029] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 03/17/2016] [Indexed: 12/04/2022] Open
Abstract
Robotic technology is gradually becoming commonplace in the medical sector and in the service of patients. Medical conditions that have benefited from significant technological development include stroke, for which rehabilitation with robotic devices is administered, and surgery assisted by robots. Robotic devices have also been proposed for assistance of movement disorders. Pathological tremor, among the most common movement disorders, is one such example. In practice, the dissemination and availability of tremor suppression robotic systems has been limited. Devices in the marketplace tend to either be non-ambulatory or to target specific functions, such as eating and drinking. We have developed a one degree-of-freedom (DOF) elbow orthosis that could be worn by an individual with tremor. A speed-controlled, voluntary-driven suppression approach is implemented with the orthosis. Typically tremor suppression methods estimate the tremor component of the signal and produce a canceling counterpart signal. The suggested approach instead estimates the voluntary component of the motion. A controller then actuates the orthosis based on the voluntary signal, while simultaneously rejecting the tremorous motion. In this work, we tested the suppressive orthosis using a one DOF robotic system that simulates the human arm. The suggested suppression approach does not require a model of the human arm. Moreover, the human input along with the orthosis forearm gravitational forces, of non-linear nature, are considered as part of the disturbance to the suppression system. Therefore, the suppression system can be modeled linearly. Nevertheless, the orthosis forearm gravitational forces can be compensated by the suppression system. The electromechanical design of the orthosis is presented, and data from an essential tremor patient is used as the human input. Velocity tracking results demonstrate an RMS error of 0.31 rad/s, and a power spectral density shows a reduction of the tremor signal by 99.8%, while the intentional component power was reduced by <1%.
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Affiliation(s)
- Gil Herrnstadt
- MENRVA Lab, Engineering Science Department, Simon Fraser University , Burnaby, BC , Canada
| | - Carlo Menon
- MENRVA Lab, Engineering Science Department, Simon Fraser University , Burnaby, BC , Canada
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Correlates Between Force and Postural Tremor in Older Individuals with Essential Tremor. THE CEREBELLUM 2015; 15:688-695. [DOI: 10.1007/s12311-015-0732-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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16
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Dideriksen JL, Gallego JA, Holobar A, Rocon E, Pons JL, Farina D. One central oscillatory drive is compatible with experimental motor unit behaviour in essential and Parkinsonian tremor. J Neural Eng 2015; 12:046019. [DOI: 10.1088/1741-2560/12/4/046019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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17
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Kavanagh JJ, Wedderburn-Bisshop J, Keogh JWL. Resistance Training Reduces Force Tremor and Improves Manual Dexterity in Older Individuals With Essential Tremor. J Mot Behav 2015; 48:20-30. [PMID: 25923582 DOI: 10.1080/00222895.2015.1028583] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Although symptoms of Essential Tremor (ET) are typically controlled with medication, it is of interest to explore additional therapies to assist with functionality. The purpose of this study was to determine if a generalized upper limb resistance training (RT) program improves manual dexterity and reduces force tremor in older individuals with ET. Ten Essential Tremor and 9 controls were recruited into a dual group, pretest-posttest intervention study. Participants performed 6 weeks of upper-limb RT, and battery of manual dexterity and isometric force tremor assessments were performed before and after the RT to determine the benefits of the program. The six-week, high-load, RT program produced strength increases in each limb for the ET and healthy older group. These changes in strength aligned with improvements in manual dexterity and tremor-most notably for the ET group. The least affected limb and the most affected limb exhibited similar improvements in functional assessments of manual dexterity, whereas reductions in force tremor amplitude following the RT program were restricted to the most affected limb of the ET group. These findings suggest that generalized upper limb RT program has the potential to improve aspects of manual dexterity and reduce force tremor in older ET patients.
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Affiliation(s)
- Justin J Kavanagh
- a Centre for Musculoskeletal Research , Griffith University , Gold Coast , Australia
| | | | - Justin W L Keogh
- b Faculty of Health Sciences and Medicine , Bond University , Gold Coast , Australia
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Rahimi F, Bee C, Wang D, Janabi-Sharifi F, Almeida QJ. Subgroup analysis of PD tremor with loading: action tremor as a combination of classical rest and physiological tremor. Clin Biomech (Bristol, Avon) 2015; 30:114-20. [PMID: 25576018 DOI: 10.1016/j.clinbiomech.2014.12.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 12/18/2014] [Accepted: 12/18/2014] [Indexed: 02/07/2023]
Abstract
BACKGROUND In Parkinson disease, tremor is a challenging symptom to manage, partly due to inadequate characterization. The current (classic) model of tremor is characterized by a resting tremor with a single strong peak in 3.5-6.5Hz range. The presence of action tremor, including postural, isometric, and kinetic tremors, has been disputed in the literature but not comprehensively evaluated. Analysis of hand tremor in action compared to rest, and possible subgrouping of tremor trends, may improve characterization. METHODS Twenty Parkinson patients and 14 controls were recruited. Tremor amplitude was measured across 9 sequentially loaded tasks, in off and on medication states. Tremor energy was separated into 2 frequency bands (B1, 3.5-6.5Hz; B2=physiological tremor, 7.5-16.5Hz) across all activity levels. Automatic classification was used for subgroup analysis. FINDINGS Automatic classification yielded 3 predominant tremor trends (G1, G2, and G3). These were significantly different from each other and from controls. G1 demonstrated closest resemblance to classical Parkinsonian tremor, with highest tremor energy at rest and with overall dominance in B1 for lower loads. G2-G3 did not show tremor energy dominance in either band. Medication reduced tremor energy only for G1 in both B1 and B2. INTERPRETATION Subgrouping the loading effect on tremor is a novel and viable method of rationalizing (non-classic) action tremor in Parkinson disease. Rest and action tremors appear not to be limited to 3.5-6.5Hz and may have considerable share of physiological tremor. Finding the contribution of each frequency band to total tremor energy and their trends with load may optimize therapy options.
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Affiliation(s)
- Fariborz Rahimi
- Electrical Engineering Department, University of Bonab, Velayat Highway, Bonab, East Azerbaijan 5551761167, Iran; Electrical and Computer Engineering department, University of Waterloo, Waterloo, Ontario, Canada.
| | - Carina Bee
- Royal College of Surgeons in Ireland, Dublin, Ireland.
| | - David Wang
- Electrical and Computer Engineering department, University of Waterloo, Waterloo, Ontario, Canada.
| | - Farrokh Janabi-Sharifi
- Mechanical and Industrial Engineering Department, Ryerson University, Toronto, Ontario, Canada.
| | - Quincy J Almeida
- Sun Life Financial Movement Disorders Research & Rehabilitation Centre, Wilfrid Laurier University, Waterloo, Ontario, Canada.
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Gallego JA, Dideriksen JL, Holobar A, Ibáñez J, Pons JL, Louis ED, Rocon E, Farina D. Influence of common synaptic input to motor neurons on the neural drive to muscle in essential tremor. J Neurophysiol 2014; 113:182-91. [PMID: 25274343 DOI: 10.1152/jn.00531.2014] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Tremor in essential tremor (ET) is generated by pathological oscillations at 4-12 Hz, likely originating at cerebello-thalamo-cortical pathways. However, the way in which tremor is represented in the output of the spinal cord circuitries is largely unknown because of the difficulties in identifying the behavior of individual motor units from tremulous muscles. By using novel methods for the decomposition of multichannel surface EMG, we provide a systematic analysis of the discharge properties of motor units in nine ET patients, with concurrent recordings of EEG activity. This analysis allowed us to infer the contribution of common synaptic inputs to motor neurons in ET. Motor unit short-term synchronization was significantly greater in ET patients than in healthy subjects. Furthermore, the strong association between the degree of synchronization and the peak in coherence between motor unit spike trains at the tremor frequency indicated that the high synchronization levels were generated mainly by common synaptic inputs specifically at the tremor frequency. The coherence between EEG and motor unit spike trains demonstrated the presence of common cortical input to the motor neurons at the tremor frequency. Nonetheless, the strength of this input was uncorrelated to the net common synaptic input at the tremor frequency, suggesting a contribution of spinal afferents or secondary supraspinal pathways in projecting common input at the tremor frequency. These results provide the first systematic analysis of the neural drive to the muscle in ET and elucidate some of its characteristics that determine pathological tremulous muscle activity.
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Affiliation(s)
- Juan A Gallego
- Neuroengineering and Cognitive Science Group, Centre for Automation and Robotics, Consejo Superior de Investigaciones Científicas, Arganda del Rey, Spain
| | - Jakob L Dideriksen
- Department of Neurorehabilitation Engineering, Bernstein Focus Neurotechnology Göttingen, Bernstein Center for Computational Neuroscience, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Ales Holobar
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Jaime Ibáñez
- Neural Rehabilitation Group, Cajal Institute, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - José L Pons
- Neural Rehabilitation Group, Cajal Institute, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Elan D Louis
- Department of Neurology, College of Physicians and Surgeons, and Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York; and
| | - Eduardo Rocon
- Neuroengineering and Cognitive Science Group, Centre for Automation and Robotics, Consejo Superior de Investigaciones Científicas, Arganda del Rey, Spain; Postgraduate Program, Universidade Federal do Espírito Santo, Vitória, Brazil
| | - Dario Farina
- Department of Neurorehabilitation Engineering, Bernstein Focus Neurotechnology Göttingen, Bernstein Center for Computational Neuroscience, University Medical Center Göttingen, Georg-August University, Göttingen, Germany;
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Gallego JÁ, Rocon E, Belda-Lois JM, Pons JL. A neuroprosthesis for tremor management through the control of muscle co-contraction. J Neuroeng Rehabil 2013; 10:36. [PMID: 23587119 PMCID: PMC3661364 DOI: 10.1186/1743-0003-10-36] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 03/25/2013] [Indexed: 11/16/2022] Open
Abstract
Background Pathological tremor is the most prevalent movement disorder. Current treatments do not attain a significant tremor reduction in a large proportion of patients, which makes tremor a major cause of loss of quality of life. For instance, according to some estimates, 65% of those suffering from upper limb tremor report serious difficulties during daily living. Therefore, novel forms for tremor management are required. Since muscles intrinsically behave as a low pass filter, and tremor frequency is above that of volitional movements, the authors envisioned the exploitation of these properties as a means of developing a novel treatment alternative. This treatment would rely on muscle co-contraction for tremor management, similarly to the strategy employed by the intact central nervous system to stabilize a limb during certain tasks. Methods We implemented a neuroprosthesis that regulated the level of muscle co-contraction by injecting current at a pair of antagonists through transcutaneous neurostimulation. Co-contraction was adapted to the instantaneous parameters of tremor, which were estimated from the raw recordings of a pair of solid state gyroscopes with a purposely designed adaptive algorithm. For the experimental validation, we enrolled six patients suffering from parkinsonian or essential tremor of different severity, and evaluated the effect of the neuroprosthesis during standard tasks employed for neurological examination. Results The neuroprosthesis attained significant attenuation of tremor (p<0.001), and reduced its amplitude up to a 52.33±25.48%. Furthermore, it alleviated both essential and parkinsonian tremor in spite of their different etiology and symptomatology. Tremor severity was not a limiting factor on the performance of the neuroprosthesis, although there was a subtle trend towards larger attenuation of more severe tremors. Tremor frequency was not altered during neurostimulation, as expected from the central origin of Parkinson’s disease and essential tremor. All patients showed a good tolerance to neurostimulation in terms of comfort and absence of pain, and some spontaneously reported that they felt that tremor was reduced when the neuroprosthesis was activated. Conclusions The results presented herein demonstrate that the neuroprosthesis provides systematic attenuation of the two major types of tremor, irrespectively from their severity. This study sets the basis for the validation of the neuroprosthesis as an alternative, non-invasive means for tremor management.
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Affiliation(s)
- Juan Álvaro Gallego
- Bioengineering Group, Consejo Superior de Investigaciones Científicas (CSIC), Ctra Campo Real km 0.2-La Poveda, 28500 Arganda del Rey, Spain.
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Durbaba R, Cassidy A, Budini F, Macaluso A. The effects of isometric resistance training on stretch reflex induced tremor in the knee extensor muscles. J Appl Physiol (1985) 2013; 114:1647-56. [PMID: 23580599 DOI: 10.1152/japplphysiol.00917.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study examines the effect of 4 wk of high-intensity isometric resistance training on induced tremor in knee extensor muscles. Fourteen healthy volunteers were assigned to either the training group (n = 7) or the nontraining control group (n = 7). Induced tremor was assessed by measuring force fluctuations during anisometric contractions against spring loading, whose compliance was varied to allow for preferential activation of the short or long latency stretch reflex components. Effects of high-intensity isometric resistance training on induced tremor was assessed under two contraction conditions: relative force matching, where the relative level of activity was equal for both pre- and post-training sessions, set at 30% maximum voluntary contraction (MVC), and absolute force matching, where the level of activity was set to 30% pretrained MVC. The training group experienced a 26.5% increase in MVC in contrast to the 0.8% for the control group. For relative force-matching contractions, induced tremor amplitude and frequency did not change in either the training or control group. During absolute force-matching contractions, induced tremor amplitude was decreased by 37.5% and 31.6% for the short and long components, respectively, with no accompanying change in frequency, for the training group. No change in either measure was observed in the control group for absolute force-matching contractions. The results are consistent with high-intensity isometric resistance training induced neural changes leading to increased strength, coupled with realignment of stretch reflex automatic gain compensation to the new maximal force output. Also, previous reported reductions in anisometric tremor following strength training may partly be due to changed stretch reflex behavior.
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Affiliation(s)
- Rade Durbaba
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle, United Kingdom.
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WIDJAJA FERDINAN, SHEE CHENGYAP, ANG WEITECH, AU WINGLOK, POIGNET PHILIPPE. SENSING OF PATHOLOGICAL TREMOR USING SURFACE ELECTROMYOGRAPHY AND ACCELEROMETER FOR REAL-TIME ATTENUATION. J MECH MED BIOL 2012. [DOI: 10.1142/s0219519411004344] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Tremor is the most common movement disorder and it is affecting more and more people as the world is aging. The cost involved is big considering the financial and social impact. This paper explores an assistive technology solution for upper limb pathological tremor compensation. Using both surface electromyography (SEMG) and accelerometer (ACC), a real-time pathological tremor compensation with functional electrical stimulation (FES) is proposed. One advantage of using SEMG is the electromechanical delay (SEMG data precedes the ACC data by 20–100 ms). Hence by detecting the tremor in advance, there is enough time window to do the necessary computation and to actuate the antagonist muscle by FES. This is also possible because the time taken for FES to actuate the muscle is significantly less than that of the neural signal, as detected by SEMG. For estimation of tremor parameters and separation between voluntary motion and tremor, an algorithm based on extended Kalman filter (EKF) is proposed. Experimental result from one essential tremor patient has shown 57% reduction in tremor power as measured by the ACC.
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Affiliation(s)
- FERDINAN WIDJAJA
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - CHENG YAP SHEE
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - WEI TECH ANG
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - WING LOK AU
- Department of Neurology, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore
| | - PHILIPPE POIGNET
- Robotics Department, Montpellier Laboratory of Computer Science, Robotics and Microelectronics (LIRMM), 161 rue Ada, Montpellier, 34392, France
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Matsumoto Y, Seki M, Ando T, Kobayashi Y, Iijima H, Nagaoka M, Fujie MG. Analysis of EMG signals of patients with essential tremor focusing on the change of tremor frequency. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2012:2244-2250. [PMID: 23366370 DOI: 10.1109/embc.2012.6346409] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Essential tremor is a disorder that causes involuntary oscillations in patients while engaging in actions or while maintaining a posture. ET patients have serious difficulties in performing activities of daily living such as eating food, drinking water, and writing. We have thus been developing an EMG-controlled exoskeletal robot to suppress tremors. The EMG signal of ET patients involves a mix of voluntary movement and tremor signals. To control the exoskeletal robot accurately, tremor signals must be removed from the patient's EMG signal. To date, we have been developing a filter to remove tremor signals from the patient's EMG. The design of this filter was based on the hypothesis that the rectified tremor signals are able to be approximated by a powered sine wave. This filter was found to have a large effect on removing tremor signals. However, tremor signals are generated both while performing voluntary movement and while maintaining a posture, and the filter was attenuating both signals. To control this robot accurately, the signal generated while performing voluntary movement is expected not to be attenuated. To accomplish this, we try to use a parameter that reflects a state of the patient's movement, performing a voluntary movement or maintaining a posture, as a switch to activate the powered sine filter. This paper provides an analysis of the favorable parameters. We focus on two parameters: the peak-to-peak interval of the rectified EMG signal, and the interval of the flat and low amplitude area of the rectified EMG signal. Through evaluation, it is affirmed that both parameters change with the state of the patient's movement. However, the latter parameter is superior to the former in terms of variability, which indicates that the interval of the flat and low amplitude area of the rectified EMG signal is a more favorable parameter to promote control of the exoskeletal robot. As a future work, we will mount the parameter to the algorithm and evaluate the robotic system.
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Affiliation(s)
- Yuya Matsumoto
- Graduate School of Creative Science and Engineering, Waseda University, Tokyo, Japan.
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Dideriksen JL, Gianfelici F, Maneski LZP, Farina D. EMG-Based Characterization of Pathological Tremor Using the Iterated Hilbert Transform. IEEE Trans Biomed Eng 2011; 58:2911-21. [DOI: 10.1109/tbme.2011.2163069] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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25
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The effect of inertial loading on wrist kinetic tremor and rhythmic muscle activity in individuals with essential tremor. Clin Neurophysiol 2011; 122:1794-801. [DOI: 10.1016/j.clinph.2010.10.050] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 10/03/2010] [Accepted: 10/28/2010] [Indexed: 02/08/2023]
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Norman KE, D'Amboise SN, Pari G, Héroux ME. Tremor during movement correlates well with disability in people with essential tremor. Mov Disord 2011; 26:2088-94. [PMID: 21656852 DOI: 10.1002/mds.23811] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Revised: 04/17/2011] [Accepted: 05/02/2011] [Indexed: 11/12/2022] Open
Abstract
Essential tremor is the most common movement disorder, typically characterized by the presence of both postural and kinetic tremor of the hand. In recent studies, we described the effects of altering force and load conditions on tremor amplitude and power in people with essential tremor. In the same participants, we also measured tremor-related functional disability. In this article we report on the current study on correlations of measures of tremor severity with those of tremor-related functional disability. Twenty-one participants with essential tremor had tremor measured in their more tremorous hand. Power spectral and amplitude measures of tremor were calculated for each of 16 conditions: force tremor at 4 submaximal force levels, postural tremor in unloaded and 3 submaximal load conditions, and kinetic tremor in unloaded and 3 submaximal load conditions for each of concentric and eccentric contractions of the wrist extensors. Participants were rated on the hand items of the Fahn-Tolosa-Marin rating scale and timed on the unilateral hand tasks of the Test Évaluant la Performance des Membres supérieurs des Personnes Âgées. The most consistently high and significant correlations were found between kinetic tremor measures and the hand task scores and tremor-B scores (r = 0.548-0.780, P < .01). Postural tremor measures correlated with disability measures only in loaded conditions, most consistently with the hand task measures (r = 0.640-0.725, P < .01). Thus, measures of kinetic tremor and loaded postural tremor, but not unloaded postural tremor or force tremor, relate well to disability captured with dynamic tasks.
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Affiliation(s)
- Kathleen E Norman
- School of Rehabilitation Therapy, Queen's University, Kingston, Ontario, Canada.
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Dideriksen JL, Enoka RM, Farina D. A model of the surface electromyogram in pathological tremor. IEEE Trans Biomed Eng 2011; 58. [PMID: 21342835 DOI: 10.1109/tbme.2011.2118756] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The study developed a novel multi-scale model for simulating the surface electromyogram (EMG) of an antagonistic pair of muscles during pathological tremor. By combining and expanding mathematical descriptions from motor units to limb kinematics, the model constitutes the first attempt to simulate the surface EMG and the individual motor unit activity under the influence of descending voluntary command, oscillatory noise in the descending signal, and afferent feedback when controlling a freely moving limb to achieve a predefined angular trajectory. The oscillatory noise was adjusted to simulate various types of pathological tremor. The simulations replicated previously reported experimental results for the power spectral density of the surface EMG, the angular velocity of the limb, and single motor unit activity. The model provides a powerful tool for extracting information about how the surface EMG can be used to describe tremor in various conditions, including different tremor frequencies and intensities, that cannot be achieved solely with experimental approaches.
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Dideriksen JL, Farina D. An integrative model of the surface EMG in pathological tremor. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2010:6083-6. [PMID: 21097129 DOI: 10.1109/iembs.2010.5627630] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A novel integrative model for simulating the surface EMG signal during pathological tremor is presented. The model combines neuromuscular elements, biomechanical descriptions, and surface EMG generation. First single motor unit spike trains are generated based on the sum of the simulated descending drive, afferent input and an oscillatory noise causing tremor. Based on this activity pattern, the muscle force is estimated, from which the limb movement is derived. The surface EMG is simulated as the sum of the surface action potentials generated by the active motor units. The model was able to simulate several features of tremor that have been previously observed experimentally, including the spectral characteristics of the surface EMG during tremor and the pattern of activity of single motor units.
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Affiliation(s)
- Jakob L Dideriksen
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, 9000, Denmark.
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Héroux ME, Pari G, Norman KE. The effect of contraction intensity on force fluctuations and motor unit entrainment in individuals with essential tremor. Clin Neurophysiol 2009; 121:233-9. [PMID: 20045376 DOI: 10.1016/j.clinph.2009.10.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2009] [Revised: 10/28/2009] [Accepted: 10/28/2009] [Indexed: 10/20/2022]
Abstract
OBJECTIVES Quantify the effect of increasing contraction intensity on the amplitude of force fluctuations and neuromuscular and force tremor spectral power. METHODS Twenty-one subjects with essential tremor (ET) and 22 healthy controls applied isometric wrist extension contractions. Various sub-maximal contraction intensities were evaluated (5%-, 10%-, 20%- and 30%-MVC). Force fluctuations and wrist extensor neuromuscular activity were recorded using a load cell and electromyography (EMG). RESULTS Higher contraction intensities were associated with larger amplitude force fluctuations and greater neuromuscular activation. However, spectral power associated with tremor peaks remained relatively constant (EMG) or decreased (force) with increasing contraction intensity. CONCLUSIONS Motor unit entrainment associated with centrally generated oscillatory inputs does not increase with greater levels of muscle activation. SIGNIFICANCE Rather than influencing a constant proportion of active motor units, abnormal oscillatory drive influences a relative constant number of total motor units. When combined with the findings from our previous study on postural tremor, the present results provide preliminary evidence that abnormal stretch reflex activity may contribute to this motor unit entrainment.
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Affiliation(s)
- M E Héroux
- School of Human Kinetic, University of British Columbia, 210 - 6081 University Boulevard, BC, Canada.
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