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Asci F, Falletti M, Zampogna A, Patera M, Hallett M, Rothwell J, Suppa A. Rigidity in Parkinson's disease: evidence from biomechanical and neurophysiological measures. Brain 2023; 146:3705-3718. [PMID: 37018058 PMCID: PMC10681667 DOI: 10.1093/brain/awad114] [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: 10/14/2022] [Revised: 03/14/2023] [Accepted: 03/23/2023] [Indexed: 04/06/2023] Open
Abstract
Although rigidity is a cardinal motor sign in patients with Parkinson's disease (PD), the instrumental measurement of this clinical phenomenon is largely lacking, and its pathophysiological underpinning remains still unclear. Further advances in the field would require innovative methodological approaches able to measure parkinsonian rigidity objectively, discriminate the different biomechanical sources of muscle tone (neural or visco-elastic components), and finally clarify the contribution to 'objective rigidity' exerted by neurophysiological responses, which have previously been associated with this clinical sign (i.e. the long-latency stretch-induced reflex). Twenty patients with PD (67.3 ± 6.9 years) and 25 age- and sex-matched controls (66.9 ± 7.4 years) were recruited. Rigidity was measured clinically and through a robotic device. Participants underwent robot-assisted wrist extensions at seven different angular velocities randomly applied, when ON therapy. For each value of angular velocity, several biomechanical (i.e. elastic, viscous and neural components) and neurophysiological measures (i.e. short and long-latency reflex and shortening reaction) were synchronously assessed and correlated with the clinical score of rigidity (i.e. Unified Parkinson's Disease Rating Scale-part III, subitems for the upper limb). The biomechanical investigation allowed us to measure 'objective rigidity' in PD and estimate the neuronal source of this phenomenon. In patients, 'objective rigidity' progressively increased along with the rise of angular velocities during robot-assisted wrist extensions. The neurophysiological examination disclosed increased long-latency reflexes, but not short-latency reflexes nor shortening reaction, in PD compared with control subjects. Long-latency reflexes progressively increased according to angular velocities only in patients with PD. Lastly, specific biomechanical and neurophysiological abnormalities correlated with the clinical score of rigidity. 'Objective rigidity' in PD correlates with velocity-dependent abnormal neuronal activity. The observations overall (i.e. the velocity-dependent feature of biomechanical and neurophysiological measures of objective rigidity) would point to a putative subcortical network responsible for 'objective rigidity' in PD, which requires further investigation.
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Affiliation(s)
- Francesco Asci
- Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
- IRCCS Neuromed Institute, 86077 Pozzilli (IS), Italy
| | - Marco Falletti
- Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
| | - Alessandro Zampogna
- Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
| | - Martina Patera
- Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
| | - Mark Hallett
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20814, USA
| | - John Rothwell
- UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Antonio Suppa
- Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
- IRCCS Neuromed Institute, 86077 Pozzilli (IS), Italy
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2
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Chen R, Berardelli A, Bhattacharya A, Bologna M, Chen KHS, Fasano A, Helmich RC, Hutchison WD, Kamble N, Kühn AA, Macerollo A, Neumann WJ, Pal PK, Paparella G, Suppa A, Udupa K. Clinical neurophysiology of Parkinson's disease and parkinsonism. Clin Neurophysiol Pract 2022; 7:201-227. [PMID: 35899019 PMCID: PMC9309229 DOI: 10.1016/j.cnp.2022.06.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 06/11/2022] [Accepted: 06/22/2022] [Indexed: 01/01/2023] Open
Abstract
This review is part of the series on the clinical neurophysiology of movement disorders and focuses on Parkinson’s disease and parkinsonism. The pathophysiology of cardinal parkinsonian motor symptoms and myoclonus are reviewed. The recordings from microelectrode and deep brain stimulation electrodes are reported in detail.
This review is part of the series on the clinical neurophysiology of movement disorders. It focuses on Parkinson’s disease and parkinsonism. The topics covered include the pathophysiology of tremor, rigidity and bradykinesia, balance and gait disturbance and myoclonus in Parkinson’s disease. The use of electroencephalography, electromyography, long latency reflexes, cutaneous silent period, studies of cortical excitability with single and paired transcranial magnetic stimulation, studies of plasticity, intraoperative microelectrode recordings and recording of local field potentials from deep brain stimulation, and electrocorticography are also reviewed. In addition to advancing knowledge of pathophysiology, neurophysiological studies can be useful in refining the diagnosis, localization of surgical targets, and help to develop novel therapies for Parkinson’s disease.
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Affiliation(s)
- Robert Chen
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,Division of Neurology, Department of Medicine, University of Toronto, Ontario, Canada.,Edmond J. Safra Program in Parkinson's Disease, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Alfredo Berardelli
- Department of Human Neurosciences, Sapienza University of Rome, Italy.,IRCCS Neuromed Pozzilli (IS), Italy
| | - Amitabh Bhattacharya
- Department of Neurology, National Institute of Mental Health & Neurosciences (NIMHANS), Bangalore, India
| | - Matteo Bologna
- Department of Human Neurosciences, Sapienza University of Rome, Italy.,IRCCS Neuromed Pozzilli (IS), Italy
| | - Kai-Hsiang Stanley Chen
- Department of Neurology, National Taiwan University Hospital Hsinchu Branch, Hsinchu, Taiwan
| | - Alfonso Fasano
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,Division of Neurology, Department of Medicine, University of Toronto, Ontario, Canada.,Edmond J. Safra Program in Parkinson's Disease, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Rick C Helmich
- Radboud University Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Department of Neurology and Centre of Expertise for Parkinson & Movement Disorders, Nijmegen, the Netherlands
| | - William D Hutchison
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,Departments of Surgery and Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Nitish Kamble
- Department of Neurology, National Institute of Mental Health & Neurosciences (NIMHANS), Bangalore, India
| | - Andrea A Kühn
- Department of Neurology, Movement Disorder and Neuromodulation Unit, Charité - Universitätsmedizin Berlin, Germany
| | - Antonella Macerollo
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, United Kingdom.,The Walton Centre NHS Foundation Trust for Neurology and Neurosurgery, Liverpool, United Kingdom
| | - Wolf-Julian Neumann
- Department of Neurology, Movement Disorder and Neuromodulation Unit, Charité - Universitätsmedizin Berlin, Germany
| | - Pramod Kumar Pal
- Department of Neurology, National Institute of Mental Health & Neurosciences (NIMHANS), Bangalore, India
| | | | - Antonio Suppa
- Department of Human Neurosciences, Sapienza University of Rome, Italy.,IRCCS Neuromed Pozzilli (IS), Italy
| | - Kaviraja Udupa
- Department of Neurophysiology National Institute of Mental Health & Neurosciences (NIMHANS), Bangalore, India
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van 't Veld RC, Schouten AC, van der Kooij H, van Asseldonk EHF. Neurophysiological validation of simultaneous intrinsic and reflexive joint impedance estimates. J Neuroeng Rehabil 2021; 18:36. [PMID: 33596944 PMCID: PMC7888166 DOI: 10.1186/s12984-021-00809-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 01/11/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND People with brain or neural injuries, such as cerebral palsy or spinal cord injury, commonly have joint hyper-resistance. Diagnosis and treatment of joint hyper-resistance is challenging due to a mix of tonic and phasic contributions. The parallel-cascade (PC) system identification technique offers a potential solution to disentangle the intrinsic (tonic) and reflexive (phasic) contributions to joint impedance, i.e. resistance. However, a simultaneous neurophysiological validation of both intrinsic and reflexive joint impedances is lacking. This simultaneous validation is important given the mix of tonic and phasic contributions to joint hyper-resistance. Therefore, the main goal of this paper is to perform a group-level neurophysiological validation of the PC system identification technique using electromyography (EMG) measurements. METHODS Ten healthy people participated in the study. Perturbations were applied to the ankle joint to elicit reflexes and allow for system identification. Participants completed 20 hold periods of 60 seconds, assumed to have constant joint impedance, with varying magnitudes of intrinsic and reflexive joint impedances across periods. Each hold period provided a paired data point between the PC-based estimates and neurophysiological measures, i.e. between intrinsic stiffness and background EMG, and between reflexive gain and reflex EMG. RESULTS The intrinsic paired data points, with all subjects combined, were strongly correlated, with a range of [Formula: see text] in both ankle plantarflexors and dorsiflexors. The reflexive paired data points were moderately correlated, with [Formula: see text] in the ankle plantarflexors only. CONCLUSION An agreement with the neurophysiological basis on which PC algorithms are built is necessary to support its clinical application in people with joint hyper-resistance. Our results show this agreement for the PC system identification technique on group-level. Consequently, these results show the validity of the use of the technique for the integrated assessment and training of people with joint hyper-resistance in clinical practice.
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Affiliation(s)
- Ronald C van 't Veld
- Department of Biomechanical Engineering, University of Twente, Enschede, The Netherlands.
| | - Alfred C Schouten
- Department of Biomechanical Engineering, University of Twente, Enschede, The Netherlands.,Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands
| | - Herman van der Kooij
- Department of Biomechanical Engineering, University of Twente, Enschede, The Netherlands.,Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands
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Martino G, McKay JL, Factor SA, Ting LH. Neuromechanical Assessment of Activated vs. Resting Leg Rigidity Using the Pendulum Test Is Associated With a Fall History in People With Parkinson's Disease. Front Hum Neurosci 2020; 14:602595. [PMID: 33362496 PMCID: PMC7756105 DOI: 10.3389/fnhum.2020.602595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 11/16/2020] [Indexed: 11/13/2022] Open
Abstract
Leg rigidity is associated with frequent falls in people with Parkinson’s disease (PD), suggesting a potential role in functional balance and gait impairments. Changes in the neural state due to secondary tasks, e.g., activation maneuvers, can exacerbate (or “activate”) rigidity, possibly increasing the risk of falls. However, the subjective interpretation and coarse classification of the standard clinical rigidity scale has prohibited the systematic, objective assessment of resting and activated leg rigidity. The pendulum test is an objective diagnostic method that we hypothesized would be sensitive enough to characterize resting and activated leg rigidity. We recorded kinematic data and electromyographic signals from rectus femoris and biceps femoris during the pendulum test in 15 individuals with PD, spanning a range of leg rigidity severity. From the recorded data of leg swing kinematics, we measured biomechanical outcomes including first swing excursion, first extension peak, number and duration of the oscillations, resting angle, relaxation index, maximum and minimum angular velocity. We examined associations between biomechanical outcomes and clinical leg rigidity score. We evaluated the effect of increasing rigidity through activation maneuvers on biomechanical outcomes. Finally, we assessed whether either biomechanical outcomes or changes in outcomes with activation were associated with a fall history. Our results suggest that the biomechanical assessment of the pendulum test can objectively quantify parkinsonian leg rigidity. We found that the presence of high rigidity during clinical exam significantly impacted biomechanical outcomes, i.e., first extension peak, number of oscillations, relaxation index, and maximum angular velocity. No differences in the effect of activation maneuvers between groups with clinically assessed low rigidity were observed, suggesting that activated rigidity may be independent of resting rigidity and should be scored as independent variables. Moreover, we found that fall history was more common among people whose rigidity was increased with a secondary task, as measured by biomechanical outcomes. We conclude that different mechanisms contributing to resting and activated rigidity may play an important yet unexplored functional role in balance impairments. The pendulum test may contribute to a better understanding of fundamental mechanisms underlying motor symptoms in PD, evaluating the efficacy of treatments, and predicting the risk of falls.
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Affiliation(s)
- Giovanni Martino
- W.H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA, United States
| | - J Lucas McKay
- W.H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA, United States.,Department of Biomedical Informatics, Emory University, Atlanta, GA, United States.,Jean and Paul Amos PD and Movement Disorders Program, Department of Neurology, Emory University, Atlanta, GA, United States
| | - Stewart A Factor
- Jean and Paul Amos PD and Movement Disorders Program, Department of Neurology, Emory University, Atlanta, GA, United States
| | - Lena H Ting
- W.H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA, United States.,Department of Rehabilitation Medicine, Division of Physical Therapy, Emory University, Atlanta, GA, United States
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Cano-de-la-Cuerda R, Vela-Desojo L, Moreno-Verdú M, Ferreira-Sánchez MDR, Macías-Macías Y, Miangolarra-Page JC. Trunk Range of Motion Is Related to Axial Rigidity, Functional Mobility and Quality of Life in Parkinson's Disease: An Exploratory Study. SENSORS (BASEL, SWITZERLAND) 2020; 20:E2482. [PMID: 32349394 PMCID: PMC7248848 DOI: 10.3390/s20092482] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/15/2020] [Accepted: 04/25/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND People with Parkinson's disease (PD) present deficits of the active range of motion (ROM), prominently in their trunk. However, if these deficits are associated with axial rigidity, the functional mobility or health related quality of life (HRQoL), remains unknown. The aim of this paper is to study the relationship between axial ROM and axial rigidity, the functional mobility and HRQoL in patients with mild to moderate PD. METHODS An exploratory study was conducted. Non-probabilistic sampling of consecutive cases was used. Active trunk ROM was assessed by a universal goniometer. A Biodex System isokinetic dynamometer was used to measure the rigidity of the trunk. Functional mobility was determined by the Get Up and Go (GUG) test, and HRQoL was assessed with the PDQ-39 and EuroQol-5D questionnaires. RESULTS Thirty-six mild to moderate patients with PD were evaluated. Significant correlations were observed between trunk extensors rigidity and trunk flexion and extension ROM. Significant correlations were observed between trunk flexion, extension and rotation ROM and GUG. Moreover, significant correlations were observed between trunk ROM for flexion, extension and rotations (both sides) and PDQ-39 total score. However, these correlations were considered poor. CONCLUSIONS Trunk ROM for flexion and extension movements, measured by a universal goniometer, were correlated with axial extensors rigidity, evaluated by a technological device at 30°/s and 45°/s, and functional mobility. Moreover, trunk ROM for trunk flexion, extension and rotations were correlated with HRQoL in patients with mild to moderate PD.
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Affiliation(s)
- Roberto Cano-de-la-Cuerda
- Department of Physiotherapy, Occupational Therapy, Rehabilitation and Physical Medicine, Health Sciences Faculty, Rey Juan Carlos University, Alcorcón, 28922 Madrid, Spain; (R.C.-d.-l.-C.); (J.C.M.-P.)
| | - Lydia Vela-Desojo
- Neurology Service. Division of Movements Disorders, Hospital Universitario Fundación Alcorcón (HUFA), Alcorcón, 28922 Madrid, Spain; (L.V.-D.); (Y.M.-M.)
| | - Marcos Moreno-Verdú
- Asociación Parkinson Madrid, 28014 Madrid, Spain
- Department of Radiology, Rehabilitation and Physiotherapy, Complutense University of Madrid, 28040 Madrid, Spain;
| | | | - Yolanda Macías-Macías
- Neurology Service. Division of Movements Disorders, Hospital Universitario Fundación Alcorcón (HUFA), Alcorcón, 28922 Madrid, Spain; (L.V.-D.); (Y.M.-M.)
| | - Juan Carlos Miangolarra-Page
- Department of Physiotherapy, Occupational Therapy, Rehabilitation and Physical Medicine, Health Sciences Faculty, Rey Juan Carlos University, Alcorcón, 28922 Madrid, Spain; (R.C.-d.-l.-C.); (J.C.M.-P.)
- Rehabilitation Unit, Hospital Universitario de Fuenlabrada, Fuenlabrada, 28942 Madrid, Spain
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Ferreira-Sánchez MDR, Moreno-Verdú M, Cano-de-la-Cuerda R. Quantitative Measurement of Rigidity in Parkinson´s Disease: A Systematic Review. SENSORS (BASEL, SWITZERLAND) 2020; 20:E880. [PMID: 32041374 PMCID: PMC7038663 DOI: 10.3390/s20030880] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 01/27/2020] [Accepted: 02/04/2020] [Indexed: 12/16/2022]
Abstract
Rigidity is one of the cardinal symptoms of Parkinson´s disease (PD). Present in up 89% of cases, it is typically assessed with clinical scales. However, these instruments show limitations due to their subjectivity and poor intra- and inter-rater reliability. To compile all of the objective quantitative methods used to assess rigidity in PD and to study their validity and reliability, a systematic review was conducted using the Web of Science, PubMed, and Scopus databases. Studies from January 1975 to June 2019 were included, all of which were written in English. The Strengthening the Reporting of observational studies in Epidemiology Statement (STROBE) checklist for observational studies was used to assess the methodological rigor of the included studies. Thirty-six studies were included. Rigidity was quantitatively assessed in three ways, using servomotors, inertial sensors, and biomechanical and neurophysiological study of muscles. All methods showed good validity and reliability, good correlation with clinical scales, and were useful for detecting rigidity and studying its evolution. People with PD exhibit higher values in terms of objective muscle stiffness than healthy controls. Rigidity depends on the angular velocity and articular amplitude of the mobilization applied. There are objective, valid, and reliable methods that can be used to quantitatively assess rigidity in people with PD.
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Affiliation(s)
| | - Marcos Moreno-Verdú
- Department of Radiology, Rehabilitation and Physiotherapy, Universidad Complutense de Madrid (UCM), 28040 Madrid, Spain;
- Asociación Parkinson Madrid, 28014 Madrid, Spain
| | - Roberto Cano-de-la-Cuerda
- Department of Physical Therapy, Occupational Therapy, Physical Medicine and Rehabilitation, Universidad Rey Juan Carlos (URJC), Alcorcón, 28922 Madrid, Spain;
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Perera T, Lee WL, Jones M, Tan JL, Proud EL, Begg A, Sinclair NC, Peppard R, McDermott HJ. A palm-worn device to quantify rigidity in Parkinson's disease. J Neurosci Methods 2019; 317:113-120. [PMID: 30776378 DOI: 10.1016/j.jneumeth.2019.02.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 02/12/2019] [Accepted: 02/12/2019] [Indexed: 11/16/2022]
Abstract
BACKGROUND Parkinsonian rigidity is identified on clinical examination as resistance to passive movement. Measurement of rigidity commonly relies on ordinal rating scales (MDS-UPDRS), however instrumented objective measures may provide greater mechanistic insight. NEW METHOD We present a palm-worn instrument to objectively quantify rigidity on a continuous scale. The device employs a miniature motor to flex the third digit of the hand about the metacarpophalangeal joint whilst transducers record flexion/extension forces. We aim to determine congruence with the MDS-UPDRS, investigate sensitivity to the impact of deep brain stimulation (DBS) and contralateral movement, and make comparisons with healthy individuals. Eight participants with Parkinson's disease underwent evaluation during conditions: on and off DBS, and with and without contralateral limb movement to activate rigidity. During each DBS condition, wash-in/out effects were tracked using both our instrument and two blinded clinical raters. Sixteen healthy volunteers (age-matched/young) served as controls. RESULTS Rigidity measured using our instrument had moderate agreement with the MDS-UPDRS and showed differences between therapeutic state, activation conditions, and disease/healthy cohorts. Rigidity gradually worsened over a one-hour period after DBS cessation, but improved more rapidly with DBS resumption. COMPARISON WITH EXISTING METHODS Previous attempts to quantify rigidity include manual approaches where a clinician is required to manipulate limbs while sensors passively gather information, or large automated instruments to move the wrist or elbow. CONCLUSION Given its ability to track changes in rigidity due to therapeutic intervention, our technique could have applications where continuous measurement is required or where a suitably qualified rater is absent.
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Affiliation(s)
- Thushara Perera
- Bionics Institute, East Melbourne, Victoria, Australia; Department of Medical Bionics, University of Melbourne, East Melbourne, Victoria, Australia.
| | - Wee-Lih Lee
- Bionics Institute, East Melbourne, Victoria, Australia
| | - Mary Jones
- Bionics Institute, East Melbourne, Victoria, Australia; Department of Neurology, St. Vincent's Hospital, Fitzroy, Victoria, Australia
| | - Joy L Tan
- Bionics Institute, East Melbourne, Victoria, Australia; Department of Medical Bionics, University of Melbourne, East Melbourne, Victoria, Australia
| | - Elizabeth L Proud
- Department of Physiotherapy, University of Melbourne, Parkville, Victoria, Australia
| | - Angus Begg
- Bionics Institute, East Melbourne, Victoria, Australia
| | - Nicholas C Sinclair
- Bionics Institute, East Melbourne, Victoria, Australia; Department of Medical Bionics, University of Melbourne, East Melbourne, Victoria, Australia
| | - Richard Peppard
- Bionics Institute, East Melbourne, Victoria, Australia; Department of Neurology, St. Vincent's Hospital, Fitzroy, Victoria, Australia
| | - Hugh J McDermott
- Bionics Institute, East Melbourne, Victoria, Australia; Department of Medical Bionics, University of Melbourne, East Melbourne, Victoria, Australia
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Abstract
The motor symptoms of Parkinson's disease are not limited to the cardinal symptoms of bradykinesia, rigidity, and resting tremor, but also include a variety of interrelated motor phenomena such as deficits in spatiotemporal planning and movement sequencing, scaling and timing of movements, and intermuscular coordination that can be clinically observed. Although many of these phenomena overlap, a review of the full breadth of the motor phenomenon can aid in the diagnosis and monitoring of disease progression.
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Affiliation(s)
- Christopher W. Hess
- University of Florida Center for Movement Disorders & Neurorestoration, Gainesville, FL, 32607, USA
| | - Mark Hallett
- Human Motor Control Section, Medical Neurology Branch, NINDS, NIH, Bethesda, Maryland, 20892, USA
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Jalaleddini K, Golkar MA, Kearney RE. Measurement of Dynamic Joint Stiffness from Multiple Short Data Segments. IEEE Trans Neural Syst Rehabil Eng 2017; 25:925-934. [PMID: 28278472 DOI: 10.1109/tnsre.2017.2659749] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This paper presents our new method, Short Segment-Structural Decomposition SubSpace (SS-SDSS), for the estimation of dynamic joint stiffness from short data segments. The main application is for data sets that are only piecewise stationary. Our approach is to: 1) derive a data-driven, mathematical model for dynamic stiffness for short data segments; 2) bin the non-stationary data into a number of short, stationary data segments; and 3) estimate the model parameters from subsets of segments with the same properties. This method extends our previous state-spacework by recognizing that initial conditions have important effects for short data segments; consequently, initial conditions are incorporated into the stiffness model and estimated for each segment. A simulation study that faithfully replicated experimental conditions delineated the range of experimental conditions for which the method can successfully identify stiffness. An experimental study on the ankle of a healthy subject during a torque matching tasks demonstrated the successful estimation of dynamic stiffness in a slow, time-varying experiment. Together, the simulation and experimental studies demonstrate that the SS-SDSS method is a valuable tool to measure stiffness in functionally important tasks.
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Jalaleddini K, Tehrani ES, Kearney RE. A Subspace Approach to the Structural Decomposition and Identification of Ankle Joint Dynamic Stiffness. IEEE Trans Biomed Eng 2016; 64:1357-1368. [PMID: 28113221 DOI: 10.1109/tbme.2016.2604293] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE The purpose of this paper is to present a structural decomposition subspace (SDSS) method for decomposition of the joint torque to intrinsic, reflexive, and voluntary torques and identification of joint dynamic stiffness. METHODS First, it formulates a novel state-space representation for the joint dynamic stiffness modeled by a parallel-cascade structure with a concise parameter set that provides a direct link between the state-space representation matrices and the parallel-cascade parameters. Second, it presents a subspace method for the identification of the new state-space model that involves two steps: 1) the decomposition of the intrinsic and reflex pathways and 2) the identification of an impulse response model of the intrinsic pathway and a Hammerstein model of the reflex pathway. RESULTS Extensive simulation studies demonstrate that SDSS has significant performance advantages over some other methods. Thus, SDSS was more robust under high noise conditions, converging where others failed; it was more accurate, giving estimates with lower bias and random errors. The method also worked well in practice and yielded high-quality estimates of intrinsic and reflex stiffnesses when applied to experimental data at three muscle activation levels. CONCLUSION The simulation and experimental results demonstrate that SDSS accurately decomposes the intrinsic and reflex torques and provides accurate estimates of physiologically meaningful parameters. SIGNIFICANCE SDSS will be a valuable tool for studying joint stiffness under functionally important conditions. It has important clinical implications for the diagnosis, assessment, objective quantification, and monitoring of neuromuscular diseases that change the muscle tone.
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