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Monaghan AS, Peterson DS. Torque responses to in-place-perturbations in people with multiple sclerosis. Gait Posture 2021; 84:346-351. [PMID: 33454502 DOI: 10.1016/j.gaitpost.2021.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/26/2020] [Accepted: 01/05/2021] [Indexed: 02/02/2023]
Abstract
BACKGROUND Automatic postural responses are critical to prevent falls after a loss of balance. Although responses have been shown to be delayed in people with multiple sclerosis (PwMS), the degree to which other aspects of these movements are impacted by MS remains unknown. RESEARCH QUESTION Do responses to in-place support-surface perturbations differ in PwMS compared to neurotypical adults? Are these responses related to a functional measure of postural response performance- center of mass (COM) displacement?. METHOD 52 PwMS and 20 neurotypical, age-matched adults (NA) experienced backward support surface perturbations resulting in forward loss of balance and requiring an in-place response. Center of pressure (COP) and torque were calculated from force plates while center of mass (COM) approximations were collected via motion capture. Primary outcomes were maximal torque production at the foot and its timing, rate, and onset. RESULTS PwMS and NA demonstrated no differences in maximal torque production (p = 0.79), timing of maximal torque (p = 0.29), rate of torque development (p = 0.76), or the onset of AP COP movement (p = 0.44). There was a significant negative association between the rate of torque development and forward COM displacement in both groups (Control: r=-0.64, p = 0.002; MS: r=-0.35, p = 0.01). Larger maximal torque production was also associated with smaller COM displacement in PwMS (r=-0.33, p = 0.02). CONCLUSION Torque profiles in response to backward support surface translations resulting in feet in-place responses were similar in people with mild MS and neurotypical adults. The rate of development and maximal torque were however correlated to functional postural response outcomes. These findings suggest that while not worse in PwMS during in-place perturbations, force-responses seem to be important predictors of the effectiveness of reactive postural control responses.
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Richmond SB, Whittier TT, Peterson DS, Fling BW. Advanced characterization of static postural control dysfunction in persons with multiple sclerosis and associated neural mechanisms. Gait Posture 2021; 83:114-120. [PMID: 33129171 DOI: 10.1016/j.gaitpost.2020.10.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 09/03/2020] [Accepted: 10/13/2020] [Indexed: 02/02/2023]
Abstract
BACKGROUND Multiple sclerosis (MS) is an autoimmune-based chronic inflammatory disease characterized by the neurodegeneration of the central nervous system and produces postural dysfunction. Quiet or static standing is a complex task carried out through afferent sensory inputs and efferent postural corrective outputs. Currently the mechanisms underlying these outputs remain largely unknown. RESEARCH QUESTION Assess the relationship between multi-dimensional measures of postural control and microstructural integrity of the cortical sensorimotor pathway (CSP) in persons with MS (PwMS) and neurotypical adults. METHODS Postural control performance was assessed by both overall and directional time-to-boundary measures across four manipulated sensory stance conditions (eyes open/closed; stance firm/foam) in twenty-nine neurotypical and twenty-seven PwMS. These postural outcomes were evaluated with mixed-model repeated measures analysis of variance across group (MS and control) and stance condition. Postural performance was also correlated with magnetic resonance imaging diffusion tensor-derived measures of microstructural integrity of the CSP. RESULTS PwMS displayed significantly (p = 0.026) worse anterior-posterior postural control compared to their neurotypical counterparts across sensory testing conditions and poorer CSP microstructural integrity in comparison to neurotypical adults (p = 0.008). Additionally, PwMS displayed a significant association (2D (rho = -0.384, p = 0.048), AP (rho = -0.355, p = 0.035), and ML (rho = -0.365, p = 0.030) between integrity of the CSP and postural control performance during proprioceptive-based balance, such that those with worse cortical structure had poorer balance control. SIGNIFICANCE This is the first study to establish connections between the microstructural integrity of the CSP and multi-dimensional postural control performance. Results indicate that a reduction in the CSP microstructural integrity is associated with poorer postural control in PwMS. These outcomes identify neural underpinnings of postural control dysfunction in PwMS and provide new avenues for evaluating the efficacy of postural rehabilitation strategies in PwMS that express proprioceptive-based postural deficits.
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VanGilder JL, Hooyman A, Peterson DS, Schaefer SY. Post-stroke cognitive impairments and responsiveness to motor rehabilitation: A review. CURRENT PHYSICAL MEDICINE AND REHABILITATION REPORTS 2020; 8:461-468. [PMID: 33767922 PMCID: PMC7987128 DOI: 10.1007/s40141-020-00283-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2020] [Indexed: 01/08/2023]
Abstract
PURPOSE OF REVIEW a)This review discusses the prevalence of cognitive deficits following stroke and their impact on responsiveness to therapeutic intervention within a motor learning context. RECENT FINDINGS b)Clinical and experimental studies have established that post-stroke cognitive and motor deficits may impede ambulation, augment fall risk, and influence the efficacy of interventions. Recent research suggests the presence of cognitive deficits may play a larger role in motor recovery than previously understood. SUMMARY c)Considering that cognitive impairments affect motor relearning, post-stroke motor rehabilitation therapies may benefit from formal neuropsychological testing. For example, early work suggests that in neurotypical adults, cognitive function may be predictive of responsiveness to motor rehabilitation and cognitive training may improve mobility. This sets the stage for investigations probing these topics in people post-stroke. Moreover, the neural basis for and extent to which these cognitive impairments influence functional outcome remains largely unexplored and require additional investigation.
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Jung SH, Hasegawa N, Mancini M, King LA, Carlson-Kuhta P, Smulders K, Peterson DS, Barlow N, Harker G, Morris R, Lapidus J, Nutt JG, Horak FB. Effects of the agility boot camp with cognitive challenge (ABC-C) exercise program for Parkinson’s disease. NPJ PARKINSONS DISEASE 2020; 6:31. [PMID: 33298934 PMCID: PMC7608677 DOI: 10.1038/s41531-020-00132-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 09/10/2020] [Indexed: 01/03/2023]
Abstract
Few exercise interventions practice both gait and balance tasks with cognitive tasks to improve functional mobility in people with PD. We aimed to investigate whether the Agility Boot Camp with Cognitive Challenge (ABC-C), that simultaneously targets both mobility and cognitive function, improves dynamic balance and dual-task gait in individuals with Parkinson’s disease (PD). We used a cross-over, single-blind, randomized controlled trial to determine efficacy of the exercise intervention. Eighty-six people with idiopathic PD were randomized into either an exercise (ABC-C)-first or an active, placebo, education-first intervention and then crossed over to the other intervention. Both interventions were carried out in small groups led by a certified exercise trainer (90-min sessions, 3 times a week, for 6 weeks). Outcome measures were assessed Off levodopa at baseline and after the first and second interventions. A linear mixed-effects model tested the treatment effects on the Mini-BESTest for balance, dual-task cost on gait speed, SCOPA-COG, the UPDRS Parts II and III and the PDQ-39. Although no significant treatment effects were observed for the Mini-BESTest, SCOPA-COG or MDS-UPDRS Part III, the ABC-C intervention significantly improved the following outcomes: anticipatory postural adjustment sub-score of the Mini-BESTest (p = 0.004), dual-task cost on gait speed (p = 0.001), MDS-UPDRS Part II score (p = 0.01), PIGD sub-score of MDS-UPDRS Part III (p = 0.02), and the activities of daily living domain of the PDQ-39 (p = 0.003). Participants with more severe motor impairment or more severe cognitive dysfunction improved their total Mini-BESTest scores after exercise. The ABC-C exercise intervention can improve specific balance deficits, cognitive-gait interference, and perceived functional independence and quality of life, especially in participants with more severe PD, but a longer period of intervention may be required to improve global cognitive and motor function.
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Peterson DS, Van Liew C, Stuart S, Carlson-Kuhta P, Horak FB, Mancini M. Relating Parkinson freezing and balance domains: A structural equation modeling approach. Parkinsonism Relat Disord 2020; 79:73-78. [PMID: 32889503 DOI: 10.1016/j.parkreldis.2020.08.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND People with PD who exhibit freezing of gait (FOG) also exhibit poor balance compared to those who do not freeze. However, balance is a broad construct that can be subdivided into subdomains that include dynamic balance (gait), anticipatory postural adjustments (APAs) & gait initiation, postural sway in stance, and automatic postural responses (e.g., reactive stepping). Few studies have provided a robust investigation on how each of these domains is impacted by FOG, and no studies have compared balance across groups while rigorously controlling for disease severity. METHODS Structural equation modeling was used to evaluate the relationships between FOG and balance domains constructed as latent variables and controlling for disease severity. Domains included: dynamic balance (gait), APAs, postural sway, and reactive stepping. Models were run relating domains to both the presence and severity of FOG. RESULTS Latent variables reflecting domains of Gait and APAs, but not postural sway or reactive stepping, were significantly related to the severity of FOG. Models for presence of FOG showed the same results, as Gait and APAs, but not postural sway or reactive stepping, were related to presence of FOG. CONCLUSION These results are consistent with hypotheses that balance deficits in people with PD who freeze are most pronounced in gait and anticipatory postural adjustments. Reactive stepping and postural sway domains are less effected in PD patients who freeze compared to those who do not. These findings suggest that rehabilitative strategies focused on gait and APAs may be most effective for people with PD who freeze.
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Roman G, Peterson DS, Ofori E, Vidt ME. The Modified Strain Index: A Composite Measure of Injury Risk for Signers. J Mot Behav 2020; 53:499-508. [PMID: 32799767 DOI: 10.1080/00222895.2020.1806778] [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] [Indexed: 10/23/2022]
Abstract
Up to 81% of individuals who are fluent in sign language (signers) report pain. Non-native signers (with non-signing, non-deaf parents) report greater pain than natives (≥1 signing, deaf parent). The goal of this study was to develop a composite measure of injury risk (the modified Strain Index for signers) based on previously identified biomechanics unique to signers and examine scores across sub-groups of natives and non-natives. Non-natives were hypothesized to have greater pain and higher composite scores than natives. Ten natives and 15 non-natives used a numeric scale to rate pain while signing. Measures included 'micro' rests, muscle activation, ballistic signing, non-neutral joint angle, and work envelope. Descriptive statistics were used to create categorical ratings and backward elimination multiple linear regression to establish rank order of the biomechanical tasks. Participant performance was rated, and the product of the multipliers across tasks created a score. Pain intensity was associated with the composite score (r = 0.46; p = 0.02), however there was no difference between natives (score = 13.39 ± 3.1) and non-natives (score = 19.55 ± 4.7; p = 0.34). This work presents an approach to incorporate multiple biomechanical factors into a single, composite measure unique to signers, however further evidence-based adjustments are needed to enhance its robustness.
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Peterson DS, Barajas JS, Denney L, Mehta SH. Backward Protective Stepping During Dual-Task Scenarios in People With Parkinson's Disease: A Pilot Study. Neurorehabil Neural Repair 2020; 34:702-710. [PMID: 32633614 DOI: 10.1177/1545968320935814] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Introduction. Reactive movements in response to a loss of balance are altered in people with Parkinson's disease (PD) and are critical for fall prevention. Further, falls are more common while attention is divided. Although divided attention has been shown to impact postural responses in healthy older adults, the impact of dividing attention on reactive balance, and the natural prioritization across postural and cognitive tasks in people with PD is largely unknown. Objectives. To characterize (1) the impact of a secondary cognitive task on reactive postural control and (2) the prioritization across stepping and cognitive tasks in people with PD. Methods. Sixteen people with PD and 14 age-matched controls underwent step-inducing, support-surface perturbations from stance, with and without an auditory Stroop secondary cognitive task. Cognitive, neuromuscular, and protective stepping performance were calculated for single and dual task scenarios. Results. In PD and control participants, cognitive reaction times (P = .001) and muscle onset latency (P = .007), but not protective step outcomes (P > .12 for all) were worse during dual tasking compared with single-task scenarios. Both PD and control groups prioritized the protective stepping task over the cognitive task. Overall, people with PD exhibited worse first-step margin of stability (a measure of protective step performance) than controls (P = .044). Conclusion. This study provides preliminary evidence that people with PD, like age-matched controls, exhibit cognitive and neuromuscular, but not protective step, dual-task interference. The lack of dual-task interference on step performance indicates a postural prioritization for PD and healthy older adults during dual-task protective stepping.
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Schlenstedt C, Peterson DS, Mancini M. The effect of tactile feedback on gait initiation in people with Parkinson's disease: A pilot study. Gait Posture 2020; 80:240-245. [PMID: 32559642 DOI: 10.1016/j.gaitpost.2020.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 05/29/2020] [Accepted: 06/01/2020] [Indexed: 02/02/2023]
Abstract
BACKGROUND Gait initiation and turning are common triggers for Freezing of Gait (FOG) in people with Parkinson's disease (PD). Recently, it has been shown that closed-loop tactile feedback (CLTF) can be effective to improve turning performance in people with FOG. RESEARCH QUESTION Does CLTF change the preparation and execution of the first step during gait initiation? METHODS People (n = 36) with PD with FOG (PD + FOG) (n = 18) and without FOG (PD-FOG) (n = 18) were included in the study and performed self-initiated gait with or without CLTF under single and dual task conditions. Anticipatory postural adjustments (APAs) and step kinematics were quantified with inertial measurement units (IMUs). Muscle activity of the right and left tensor fasciae latae (TFL) was measured via EMG recordings. RESULTS PD + FOG and PD-FOG did not differ in age, gender and disease duration and severity (p > 0.05). PD + FOG performed smaller APAs (F = 4.559, p = 0.04) with a higher amount of TFL co-contraction (F = 6.034, p = 0.02) compared to PD-FOG. CLTF had no effect on APAs but led to an increase in first step duration (F = 7.921, p = 0.008). CONCLUSIONS PD + FOG had smaller APAs and higher left and right TFL co-contraction during gait initiation. CLTF did not impact preparation of the first step but led to a slower execution of the first step. We speculate that, similarly to findings from turning, CLTF might result in the participant attending more closely to the first step compared to without CLTF. Whether increased attention on gait initiation is beneficial in diminishing FOG should be investigated in more detail.
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Ehgoetz Martens KA, Peterson DS, Almeida QJ, Lewis SJG, Hausdorff JM, Nieuwboer A. Behavioural manifestations and associated non-motor features of freezing of gait: A narrative review and theoretical framework. Neurosci Biobehav Rev 2020; 116:350-364. [PMID: 32603716 DOI: 10.1016/j.neubiorev.2020.06.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 06/19/2020] [Accepted: 06/22/2020] [Indexed: 12/30/2022]
Abstract
Over the past decade, non-motor related symptoms and provocative contexts have offered unique opportunities to gain insight into the potential mechanisms that may underpin freezing of gait (FOG) in Parkinson's disease (PD). While this large body of work has informed several theoretical models, to date, few are capable of explaining behavioural findings across multiple domains (i.e. cognitive, sensory-perceptual and affective) and in different behavorial contexts. As such, the exact nature of these interrelationships and their neural basis remain quite enigmatic. Here, the non-motor, behavioural evidence for cognitive, sensory-perceptual and affective contributors to FOG are reviewed and synthesized by systematically examining (i) studies that manipulated contextual environments that provoke freezing of gait, (ii) studies that uncovered factors that have been proposed to contribute to freezing, and (iii) studies that longitudinally tracked factors that predict the future development of freezing of gait. After consolidating the evidence, we offer a novel perspective for integrating these multi-faceted behavioural patterns and identify key challenges that warrant consideration in future work.
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Morris R, Smulders K, Peterson DS, Mancini M, Carlson-Kuhta P, Nutt JG, Horak FB. Cognitive function in people with and without freezing of gait in Parkinson's disease. NPJ PARKINSONS DISEASE 2020; 6:9. [PMID: 32435690 PMCID: PMC7228938 DOI: 10.1038/s41531-020-0111-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 03/13/2020] [Indexed: 11/24/2022]
Abstract
Freezing of gait (FOG) is common in people with Parkinson’s disease (PD) which is extremely debilitating. One hypothesis for the cause of FOG episodes is impaired cognitive control, however, this is still in debate in the literature. We aimed to assess a comprehensive range of cognitive tests in older adults and people with Parkinson’s with and without FOG and associate FOG severity with cognitive performance. A total of 227 participants took part in the study which included 80 healthy older adults, 81 people with PD who did not have FOG and 66 people with PD and FOG. A comprehensive battery of neuropsychological assessments tested cognitive domains of global cognition, executive function/attention, working memory, and visuospatial function. The severity of FOG was assessed using the new FOG questionnaire and an objective FOG severity score. Cognitive performance was compared between groups using an ANCOVA adjusting for age, gender, years of education and disease severity. Correlations between cognitive performance and FOG severity were analyzed using partial correlations. Cognitive differences were observed between older adults and PD for domains of global cognition, executive function/attention, and working memory. Between those with and without FOG, there were differences for global cognition and executive function/attention, but these differences disappeared when adjusting for covariates. There were no associations between FOG severity and cognitive performance. This study identified no significant difference in cognition between those with and without FOG when adjusting for covariates, particularly disease severity. This may demonstrate that complex rehabilitation programs may be undertaken in those with FOG.
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King LA, Mancini M, Smulders K, Harker G, Lapidus JA, Ramsey K, Carlson-Kuhta P, Fling BW, Nutt JG, Peterson DS, Horak FB. Cognitively Challenging Agility Boot Camp Program for Freezing of Gait in Parkinson Disease. Neurorehabil Neural Repair 2020; 34:417-427. [PMID: 32249668 PMCID: PMC7217755 DOI: 10.1177/1545968320909331] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Introduction. It is well documented that freezing of gait (FoG) episodes occur in situations that are mentally challenging, such as dual tasks, consistent with less automatic control of gait in people with Parkinson disease (PD) and FoG. However, most physical rehabilitation does not include such challenges. The purpose was to determine (1) feasibility of a cognitively challenging Agility Boot Camp-Cognitive (ABC-C) program and (2) effects of this intervention on FoG, dual-task cost, balance, executive function, and functional connectivity. Methods. A total of 46 people with PD and FoG enrolled in this randomized crossover trial. Each participant had 6 weeks of ABC-C and Education interventions. Outcome measures were the following: FoG, perceived and objective measures; dual-task cost on gait; balance; executive function; and right supplementary motor area (SMA)-pedunculopontine nucleus (PPN) functional connectivity. Effect sizes were calculated. Results. ABC-C had high compliance (90%), with a 24% dropout rate. Improvements after exercise, revealed by moderate and large effect sizes, were observed for subject perception of FoG after exercise, dual-task cost on gait speed, balance, cognition (Scales for Outcomes in Parkinson's disease-Cognition), and SMA-PPN connectivity. Conclusions. The ABC-C for people with PD and FoG is a feasible exercise program that has potential to improve FoG, balance, dual-task cost, executive function, and brain connectivity. The study provided effect sizes to help design future studies with more participants and longer duration to fully determine the potential to improve FoG.
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Schaefer SY, Sullivan JM, Peterson DS, Fauth EB. Cognitive function at admission predicts amount of gait speed change in geriatric physical rehabilitation. Ann Phys Rehabil Med 2019; 63:359-361. [PMID: 31520785 DOI: 10.1016/j.rehab.2019.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 08/18/2019] [Accepted: 08/19/2019] [Indexed: 12/30/2022]
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Loyd BJ, Fangman A, Peterson DS, Gappmaier E, Schubert MC, Thackery A, Dibble L. Rehabilitation to improve gaze and postural stability in people with multiple sclerosis: study protocol for a prospective randomized clinical trial. BMC Neurol 2019; 19:119. [PMID: 31179920 PMCID: PMC6556952 DOI: 10.1186/s12883-019-1353-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 05/31/2019] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND The use of vestibular rehabilitation principles in the management of gaze and postural stability impairments in people with multiple sclerosis (PwMS) has shown promise in pilot work completed in our lab and in a recently published randomized clinical trial (RCT). However, further work is needed to fully quantify the gaze and postural impairments present in people with multiple sclerosis and how they respond to rehabilitation. METHODS/DESIGN The study is a single blind RCT designed to examine the benefit of a gaze and postural stability (GPS) intervention program compared to a standard of care (SOC) rehabilitation program in dizzy and balance impaired PwMS. Outcomes will be collected across the domains of body structure and function, activity, and participation as classified by the World Health Organization International Classification of Functioning, Disability, and Health (ICF). Our primary outcomes are the Dizziness Handicap Inventory (DHI) and the Functional Gait Assessment (FGA). Secondary outcomes include other measures of gaze and postural stability, fatigue, and functional mobility. Participants who are interested and eligible for enrollment will be consented prior to completing a baseline assessment. Following the baseline assessment each participant will be randomized to either the GPS or SOC intervention group and will complete a 6 week treatment period. During the treatment period, both groups will participate in guided exercise 3x/week. Following the treatment period participants will be asked to return for a post-treatment evaluation and again for a follow-up assessment 1 month later. We anticipate enrolling 50 participants. DISCUSSION This study will be an innovative RCT that will utilize gaze and postural stability metrics to assess the efficacy of vestibular rehabilitation in PwMS. It will build on previous work by examining measures across the ICF and improve the current evidence base for treating PwMS. TRIAL REGISTRATION ClinicalTrials.gov, May 29th 2018, NCT03521557 .
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Van Liew C, Dibble LE, Hunt GR, Foreman KB, Peterson DS. Protective stepping in multiple sclerosis: Impacts of a single session of in-place perturbation practice. Mult Scler Relat Disord 2019; 30:17-24. [DOI: 10.1016/j.msard.2019.01.054] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 12/28/2018] [Accepted: 01/29/2019] [Indexed: 10/27/2022]
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Peterson DS, Lohse KR, Mancini M. Relating Anticipatory Postural Adjustments to Step Outcomes During Loss of Balance in People With Parkinson's Disease. Neurorehabil Neural Repair 2018; 32:887-898. [PMID: 30198384 DOI: 10.1177/1545968318798937] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Effective protective steps are critical for fall prevention, and anticipatory postural adjustments (APAs) after a perturbation but prior to protective steps affect step performance. Although APAs prior to protective steps are altered in people with Parkinson's disease (PD), whether these changes affect subsequent step performance is poorly understood. OBJECTIVE Characterize the relationship between mediolateral APA size and protective step outcomes in response to anteroposterior balance perturbations in people with PD. METHODS Twenty-eight individuals with PD completed 25 forward and 25 backward protective steps in response to support surface translations. Multilevel linear models related mediolateral APA size to protective step outcomes. RESULTS During forward protective stepping, larger mediolateral APAs were associated with delayed ( P < .001) and larger ( P = .004) steps. Larger APAs were also associated with smaller mediolateral ( P < .001) but larger anterior-posterior center of mass movement at foot off ( P < .001). During backward stepping, larger APAs were associated with later steps ( P < .001) and smaller anterior-posterior margin of stability at first foot contact ( P < .001). During backward stepping, larger APAs were also associated with worse clinical (ie, UPDRS [Unified Parkinson's Disease Rating Scale]; P = .005) and balance (ie, MiniBEST [Mini-Balance Evaluation Systems Test]; P = .021) outcomes. CONCLUSIONS During forward protective stepping, larger APAs were associated with larger and later steps, suggesting APA size may have mixed effects on the subsequent step. During backward stepping, larger APAs were associated with worse stepping outcomes (ie, later steps, smaller anterior-posterior margin of stability, worse clinical outcomes). Interventions aimed at improving APAs in PD should monitor spatial and temporal protective step outcomes to ensure treatment does not negatively affect protective steps, particularly for forward stepping.
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Peterson DS, Lohse KR, Mancini M. Anticipatory postural responses prior to protective steps are not different in people with PD who do and do not freeze. Gait Posture 2018; 64:126-129. [PMID: 29902715 PMCID: PMC8447840 DOI: 10.1016/j.gaitpost.2018.06.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 05/24/2018] [Accepted: 06/04/2018] [Indexed: 02/02/2023]
Abstract
BACKGROUND Protective stepping after a loss of balance is related to falls. Anticipatory postural responses (APAs) prior to protective stepping can impact step performance, may be larger in people with PD, and have been suggested to be related to freezing of gait (FOG). However, whether people with PD and FOG (PD + FOG) exhibit larger APAs than people with PD and no FOG (PD-FOG) is unknown. RESEARCH QUESTION Determine the impact of freezing status on APAs prior to protective steps, thus providing a better understanding of the link between FOG and APAs. METHODS Twenty-eight people with PD (13 PD + FOG) were exposed to 50 support surface translations (25 forward, 25 backward, random order) resulting in protective steps. The size of medio-lateral weight shifts prior to the protective step (i.e. APAs), and the percentage of trials with an APA were calculated via force-plates. FOG status was assessed at the time of testing as well as 3.25(+/-0.43) years later. Participants without FOG at testing, but with FOG at follow-up were identified as "converters". RESULTS AND SIGNIFICANCE For both forward and backward protective stepping, size and percentage trials with an APA were not statistically different between PD + FOG and PD-FOG, even after excluding converters from the PD-FOG group (p > 0.27 for all). No group by direction interactions were observed. These data suggest that, in mild to moderate PD, an inability to couple APAs with stepping, rather than an inappropriately sized APA, may be most related to freezing of gait.
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Barajas JS, Peterson DS. First-trial protective step performance before and after short-term perturbation practice in people with Parkinson's disease. J Neurol 2018. [PMID: 29520471 DOI: 10.1007/s00415-018-8821-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Protective steps are critical for fall prevention and are altered in people with Parkinson's disease (PD). Previous work suggests that perturbation training, in which patients are exposed to repeated slips, may improve protective postural responses. However, these studies typically take the average performance of several postural responses before and after training. To reduce falls in the community, training must improve protective stepping after the first perturbation exposure. To date, no investigations have examined whether first-trial protective stepping is improved after training in people with PD. METHODS First-trial protective stepping was measured in 14 people with PD and 9 healthy adults before and 24 h after 1 day of perturbation training. The primary outcome was margin of stability after a perturbation, a measure of protective stepping effectiveness. RESULTS Margin of stability for the first perturbation was significantly (p = 0.001) improved on day 2 compared to before perturbation practice (day 1) in both groups. Furthermore, improvement in margin of stability was correlated with age and baseline stepping performance, such that older individuals and people with worse baseline performance showed the most pronounced improvement. CONCLUSIONS Improving the first loss of balance after training is critical if such training is to reduce falls in people with PD. The observed improvement in first-trial protective stepping provides further support for perturbation training as a potential tool to improve protective steps and reduce falls in people with PD.
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Peterson DS, Fling BW. How changes in brain activity and connectivity are associated with motor performance in people with MS. Neuroimage Clin 2017; 17:153-162. [PMID: 29071209 PMCID: PMC5651557 DOI: 10.1016/j.nicl.2017.09.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 09/22/2017] [Accepted: 09/25/2017] [Indexed: 01/18/2023]
Abstract
People with multiple sclerosis (MS) exhibit pronounced changes in brain structure, activity, and connectivity. While considerable work has begun to elucidate how these neural changes contribute to behavior, the heterogeneity of symptoms and diagnoses makes interpretation of findings and application to clinical practice challenging. In particular, whether MS related changes in brain activity or brain connectivity protect against or contribute to worsening motor symptoms is unclear. With the recent emergence of neuromodulatory techniques that can alter neural activity in specific brain regions, it is critical to establish whether localized brain activation patterns are contributing to (i.e. maladaptive) or protecting against (i.e. adaptive) progression of motor symptoms. In this manuscript, we consolidate recent findings regarding changes in supraspinal structure and activity in people with MS and how these changes may contribute to motor performance. Furthermore, we discuss a hypothesis suggesting that increased neural activity during movement may be either adaptive or maladaptive depending on where in the brain this increase is observed. Specifically, we outline preliminary evidence suggesting sensorimotor cortex activity in the ipsilateral cortices may be maladaptive in people with MS. We also discuss future work that could supply data to support or refute this hypothesis, thus improving our understanding of this important topic.
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Peterson DS, Gera G, Horak FB, Fling BW. Corpus Callosum Structural Integrity Is Associated With Postural Control Improvement in Persons With Multiple Sclerosis Who Have Minimal Disability. Neurorehabil Neural Repair 2016; 31:343-353. [PMID: 27932696 DOI: 10.1177/1545968316680487] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Improvement of postural control in persons with multiple sclerosis (PwMS) is an important target for neurorehabilitation. Although PwMS are able to improve postural performance with training, the neural underpinnings of these improvements are poorly understood. OBJECTIVE To understand the neural underpinnings of postural motor learning in PwMS. METHODS Supraspinal white matter structural connectivity in PwMS was correlated with improvements in postural performance (balancing on an oscillating surface over 25 trials) and retention of improvements (24 hours later). RESULTS Improvement in postural performance was directly correlated to microstructural integrity of white matter tracts, measured as radial diffusivity, in the corpus callosum, posterior parieto-sensorimotor fibers and the brainstem in PwMS. Within the corpus callosum, the genu and midbody (fibers connecting the prefrontal and primary motor cortices, respectively) were most strongly correlated to improvements in postural control. Twenty-four-hour retention was not correlated to radial diffusivity. CONCLUSION PwMS who exhibited poorer white matter tract integrity connecting the cortical hemispheres via the corpus callosum showed the most difficulty learning to control balance on an unstable surface. Prediction of improvements in postural control through training (ie, motor learning) via structural imaging of the brain may allow for identification of individuals who are particularly well suited for postural rehabilitation interventions.
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Peterson DS, Horak FB. Effects of freezing of gait on postural motor learning in people with Parkinson's disease. Neuroscience 2016; 334:283-289. [PMID: 27530701 DOI: 10.1016/j.neuroscience.2016.08.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 08/07/2016] [Accepted: 08/08/2016] [Indexed: 11/27/2022]
Abstract
Protective postural responses, including stepping, to recover equilibrium are critical for fall prevention and are impaired in people with Parkinson's disease (PD) with freezing of gait (FoG). Improving protective postural responses through training may reduce falls in this population. However, motor learning, the basis of neurorehabilitation, is also impaired in people with PD and, in particular, people with PD who experience freezing. It is unknown whether people with PD who freeze can improve protective postural responses, and whether these improvements are similar to nonfreezers. Our goal was to assess whether people with freezing can improve protective postural responses and retain these improvements similarly to nonfreezers. Twenty-eight people with PD (13 freezers, 15 nonfreezers) were enrolled. Improvement in protective postural responses was assessed over the course of 25 forward and 25 backward support surface translations (delivered in pseudo-random order). Postural responses were re-assessed 24h later to determine whether improvements were retained. People who freeze did not improve or retain improvement in protective postural responses as well as nonfreezers in our primary outcome variable, center of mass (COM) displacement after perturbations (post hoc across group assessments: freezers- p=0.14 and nonfreezers- p=0.001, respectively). However, other protective stepping outcomes, including margin of stability, step length, and step time, improved similarly across groups. Significant improvements were retained in both groups. In conclusion, people with PD who freeze exhibited reduced ability to improve protective postural responses in some, but not all, outcome variables. Additional training may be necessary to improve protective postural responses in people with PD who freeze.
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Peterson DS, Gera G, Horak FB, Fling BW. Supraspinal control of automatic postural responses in people with multiple sclerosis. Gait Posture 2016; 47:92-5. [PMID: 27264410 PMCID: PMC4899838 DOI: 10.1016/j.gaitpost.2016.02.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 01/27/2016] [Accepted: 02/07/2016] [Indexed: 02/02/2023]
Abstract
The neural underpinnings of delayed automatic postural responses in people with multiple sclerosis (PwMS) are unclear. We assessed whether white matter pathways of two supraspinal regions (the cortical proprioceptive Broadman's Area-3; and the balance/locomotor-related pedunculopontine nucleus) were related to delayed postural muscle response latencies in response to external perturbations. 19 PwMS (48.8±11.4years; EDSS=3.5 (range: 2-4)) and 12 healthy adults (51.7±12.2years) underwent 20 discrete, backward translations of a support surface. Onset latency of agonist (medial-gastrocnemius) and antagonist (tibialis anterior) muscles were assessed. Diffusion tensor imaging assessed white-matter integrity (i.e. radial diffusivity) of cortical proprioceptive and balance/locomotor-related tracts. Latency of the tibialis anterior, but not medial gastrocnemius was larger in PwMS than control subjects (p=0.012 and 0.071, respectively). Radial diffusivity of balance/locomotor tracts was higher (worse) in PwMS than control subjects (p=0.004), and was significantly correlated with tibialis (p=0.002), but not gastrocnemius (p=0.06) onset latency. Diffusivity of cortical proprioceptive tracts was not correlated with muscle onset. Lesions in supraspinal structures including the pedunculopontine nucleus balance/locomotor network may contribute to delayed onset of postural muscle activity in PwMS, contributing to balance deficits in PwMS.
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Peterson DS, Dijkstra BW, Horak FB. Postural motor learning in people with Parkinson's disease. J Neurol 2016; 263:1518-29. [PMID: 27193311 DOI: 10.1007/s00415-016-8158-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 04/19/2016] [Accepted: 05/02/2016] [Indexed: 11/26/2022]
Abstract
Protective postural responses to external perturbations are hypokinetic in people with Parkinson's disease (PD), and improving these responses may reduce falls. However, the ability of people with PD to improve postural responses with practice is poorly understood. Our objective was to determine whether people with PD can improve protective postural responses similarly to healthy adults through repeated perturbations, and whether improvements are retained or generalize to untrained perturbations. Twelve healthy adults and 15 people with PD underwent 25 forward and 25 backward translations of the support surface, eliciting backward, and forward protective steps, respectively. We assessed whether: (1) performance improved over one day of practice, (2) changes were retained 24 h later, and (3) improvements generalized to untrained (lateral) postural responses. People with PD and healthy adults improved postural response characteristics, including center of mass displacement after perturbations (p < 0.001), margin of stability at first footfall (p = 0.001), step latency (p = 0.044), and number of steps (p = 0.001). However, unlike controls, improvements in people with PD occurred primarily in the first block of trials. Improvements were more pronounced during backward protective stepping than forward, and with the exception of step latency, were retained 24 h later. Improvements in forward-backward stepping did not generalize to lateral protective stepping. People with PD can improve protective stepping over the course of 1 day of perturbation practice. Improvements were generally similar to healthy adults, and were retained in both groups. Perturbation practice may represent a promising approach to improving protective postural responses in people with PD; however, additional research is needed to understand how to enhance generalization.
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Peterson DS, Horak FB. The Effect of Levodopa on Improvements in Protective Stepping in People With Parkinson's Disease. Neurorehabil Neural Repair 2016; 30:931-940. [PMID: 27162165 DOI: 10.1177/1545968316648669] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background The effect of levodopa on postural motor learning in people with Parkinson's disease is poorly understood. In particular, it is unknown whether levodopa affects improvement in protective postural responses after external perturbations such as a slip or trip, a critical aspect of fall prevention. Objective Determine the effect of levodopa on postural motor learning in people with Parkinson's disease. Methods We assessed improvement in protective postural responses in people with Parkinson's disease over short-term (1 day) perturbation training on and off levodopa. We also assessed retention and generalization of improvement. Participants were 22 individuals with Parkinson's disease. The primary outcome was total center of mass (COM) displacement after perturbation. Secondary outcomes assessed first step performance and included margin of stability at first foot contact. Results People with Parkinson's disease improved COM displacement (P = .011) and margin of stability (P = .016) over training. Improvements in these outcomes were more pronounced after training while on levodopa than off levodopa. Levodopa State × Training interactions were not observed for other step performance variables (eg, step latency, length, total number of steps). Improvements were retained for 24 hours, and for margin of stability, retention was more pronounced while on levodopa than off (P = .018). Conclusions Individuals with Parkinson's disease are able to improve protective postural responses through short-term perturbation training, and improvements were more pronounced when on levodopa for some variables. Perturbation training may be more effective if completed while optimally medicated with levodopa.
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Abstract
People with Parkinson's disease exhibit debilitating gait impairments, including gait slowness, increased step variability, and poor postural control. A widespread supraspinal locomotor network including the cortex, cerebellum, basal ganglia, and brain stem contributes to the control of human locomotion, and altered activity of these structures underlies gait dysfunction due to Parkinson's disease.
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Peterson DS, Smulders K. Cues and Attention in Parkinsonian Gait: Potential Mechanisms and Future Directions. Front Neurol 2015; 6:255. [PMID: 26696955 PMCID: PMC4672041 DOI: 10.3389/fneur.2015.00255] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/23/2015] [Indexed: 11/13/2022] Open
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