The effects of transcranial direct current stimulation on upper-limb function post-stroke: A meta-analysis of multiple-session studies.

OBJECTIVE: To systematically review how patient characteristics and/or transcranial direct current stimulation (tDCS) parameters influence tDCS effectiveness in respect to upper limb function post-stroke. METHODS: Three electronic databases were searched for sham-controlled randomised trials using the Fugl-Meyer Assessment for upper extremity as outcome measure. A meta-analysis and nine subgroup-analyses were performed to identify which tDCS parameters yielded the greatest impact on upper limb function recovery in stroke patients. RESULTS: Eighteen high-quality studies (507 patients) were included. tDCS applied in a chronic stage yields greater results than tDCS applied in a (sub)acute stage. Additionally, patients with low baseline upper limb impairments seem to benefit more from tDCS than those with high baseline impairments. Regarding tDCS configuration, all stimulation types led to a significant improvement, but only tDCS applied during therapy, and not before therapy, yielded significant results. A positive dose-response relationship was identified for current/charge density and stimulation duration, but not for number of sessions. CONCLUSION: Our results demonstrate that tDCS improves upper limb function post-stroke. However, its effectiveness depends on numerous factors. Especially chronic stroke patients improved, which is promising as they are typically least amenable to recovery. SIGNIFICANCE: The current work highlights the importance of several patient-related and protocol-related factors regarding tDCS effectiveness.

The New Freezing of Gait Questionnaire: Unsuitable as an Outcome in Clinical Trials?

BACKGROUND: Freezing of gait (FOG) is a common gait deficit in Parkinson's disease. The New Freezing of Gait Questionnaire (NFOG-Q) is a widely used and valid tool to quantify freezing of gait severity. However, its test-retest reliability and minimal detectable change remain unknown. OBJECTIVE: To determine the test-retest reliability and responsiveness of the NFOG-Q. METHODS: Two groups of freezers, involved in 2 previous rehabilitation trials, completed the NFOG-Q at 2 time points (T1 and T2), separated by a 6-week control period without active intervention. Sample 1 (N = 57) was measured in ON and sample 2 (N = 14) in OFF. We calculated various reliability statistics for the NFOG-Q scores between T1 and T2 as well as correlation coefficients with clinical descriptors to explain the variability between time points. RESULTS: In sample 1 the NFOG-Q showed modest reliability (intraclass correlation coefficient = 0.68 [0.52-0.80]) without differences between T1 and T2. However, a minimal detectable change of 9.95 (7.90-12.27) points emerged for the total score (range 28 points, relative minimal detectable change of 35.5%). Sample 2 showed largely similar results. We found no associations between cognitive-related or disease severity-related outcomes and variability in NFOG-Q scores. CONCLUSIONS: We conclude that the NFOG-Q is insufficiently reliable or responsive to detect small effect sizes, as changes need to go beyond 35% to surpass measurement error. Therefore, we warrant caution in using the NFOG-Q as a primary outcome in clinical trials. These results emphasize the need for robust and objective freezing of gait outcome measures.

Determinants of Dual-Task Training Effect Size in Parkinson Disease: Who Will Benefit Most?

BACKGROUND AND PURPOSE: Dual-task interventions show positive effects in people with Parkinson disease (PD), but it remains unclear which factors determine the size of these benefits. As a secondary analysis of the DUALITY trial, the aim of this study was to assess the determinants of the effect size after 2 types of dual-task practice. METHODS: We randomly allocated 121 participants with PD to receive either integrated or consecutive dual-task training. Dual-task walking performance was assessed during (i) a backward digit span task (digit), (ii) an auditory Stroop task (Stroop), and (iii) a functional mobile phone task. Baseline descriptive, motor, and cognitive variables were correlated with the change in dual-task gait velocity after the intervention. Factors correlated with the change in dual-task gait velocity postintervention (P < 0.20) were entered into a stepwise forward multiple linear regression model. RESULTS: Lower dual-task gait velocity and higher cognitive capacity (Scales for Outcomes in Parkinson's Disease-Cognition [ScopaCog]) at baseline were related to larger improvements in dual-task gait velocity after both integrated and consecutive dual-task training for all 3 tasks (ß[gait] = -0.45, ß[ScopaCog] = 0.34, R = 0.23, P < 0.001, for digit; ß[gait] = -0.52, ß[ScopaCog] = 0.29, R = 0.26, P < 0.001, for Stroop; and ß[gait] = -0.40, ß[ScopaCog] = 0.30, R = 0.18, P < 0.001, for mobile phone task). DISCUSSION AND CONCLUSIONS: Participants with PD who showed a slow dual-task gait velocity and good cognitive functioning at baseline benefited most from the dual-task training, irrespective of the type of training and type of dual-task outcome.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A242).

Does dual-task training improve spatiotemporal gait parameters in Parkinson's disease?

INTRODUCTION: The DUALITY trial recently showed that both integrated and consecutive dual-task training improve dual-task gait velocity, without increasing fall risks in patients with Parkinson's disease (PD). Gait velocity was the primary outcome; not reported, however, were important gait measures related to the risk of falling such as gait variability. In this secondary analysis, we compared the efficacy of the two training programs with respect to spatiotemporal outcome parameters. METHODS: 121 PD patients (Hoehn and Yahr stage II-III while ON medication) were randomly assigned to either a consecutive group (n = 65) in which cognitive and gait tasks were trained separately, or an integrated group (n = 56) in which cognitive and gait tasks were trained simultaneously. Both groups received 24 in-home physiotherapy sessions for six consecutive weeks. Two baseline measurements were performed during a six-week control period prior to the interventions. Gait was evaluated under three different (and untrained) dual-task conditions immediately after the treatment period and at 12-week follow-up. RESULTS: Both training modalities had a comparable effect on spatiotemporal gait parameters. A significant post-training increase in stride length (P < .001) and cadence (P < .001) was found under both the single and the dual-task conditions. These improvements were maintained at follow-up, although the effect was slightly reduced. No significant changes were found for gait variability under single and dual-task conditions. CONCLUSION: We found both integrated and consecutive dual-task training to be safe and effective in improving several spatiotemporal gait parameters under trained and untrained dual-task conditions.

Training dual tasks together or apart in Parkinson's disease: Results from the DUALITY trial.

BACKGROUND AND OBJECTIVES: Many controversies surround the usefulness of dual-task training in Parkinson's disease (PD). This study (1) compared the efficacy of two different dual-task training programs for improving dual-task gait and (2) assessed the possible fall risk of such training. METHODS: Patients (N = 121) with a diagnosis of PD (aged 65.93 [±9.22] years, Hoehn and Yahr stage II-III on-medication) were randomized to (1) a consecutive group in which gait and cognitive tasks were trained separately or (2) an integrated group in which gait and cognitive tasks were trained simultaneously. Both interventions involved 6 weeks of at-home physiotherapist-led training. Two baseline tests were performed as a 6-week control period before training. Posttests were performed immediately after training and at 12-week follow-up. Dual-task gait was assessed during trained and untrained secondary tasks to assess consolidation of learning. Fall risk was determined by a weekly telephone call for 24 weeks. RESULTS: No significant time by group interactions were found, suggesting that both training modes had a similar effect on dual-task gait. Immediately after training, and not after the control period, significant improvements (P < .001) in dual-task gait velocity were found in all trained and untrained dual tasks. Improvements ranged between 7.75% and 13.44% when compared with baseline values and were retained at 12-week follow-up. No significant change in fall risk occurred in both study arms (P = .84). CONCLUSIONS: Consecutive and integrated dual-task training led to similar and sustained improvements in dual-task gait velocity without increasing fall risk. These novel findings support adoption of dual-task training in clinical practice. © 2017 International Parkinson and Movement Disorder Society.

Progression of postural control and gait deficits in Parkinson's disease and freezing of gait: A longitudinal study.

BACKGROUND AND AIMS: The relationship between impaired postural control and freezing of gait (FOG) in Parkinson's disease (PD) is still unclear. Our aim was to identify if postural control deficits and gait dysfunction progress differently in freezers compared to non-freezers and whether this relates to FOG development. METHODS: 76 PD patients, classified as freezer (n = 17) or non-freezer (n = 59), and 24 controls underwent a gait and postural control assessments at baseline and after 12 months follow-up. Non-freezers who developed FOG during the study period were categorized as FOG converters (n = 5). Gait was analyzed during walking at self-preferred pace. Postural control was assessed using the Mini-BESTest and its sub-categories: sensory orientation, anticipatory, reactive and dynamic postural control. RESULTS: Mini-BESTest scores were lower in PD compared to controls (p < 0.001), and in freezers compared to non-freezers (p = 0.02). PD has worse anticipatory (p = 0.01), reactive (p = 0.02) and dynamic postural control (p = 0.003) compared to controls. Freezers scored lower on dynamic postural control compared to non-freezers (p = 0.02). There were no baseline differences between converters and non-converters. Decline in postural control was worse in PD compared to controls (p = 0.02) as shown by a greater decrease in the total Mini-BESTest score. Similar patterns were found in freezers (p = 0.006), who also showed more decline in anticipatory (p < 0.001) and dynamic postural control (p = 0.02) compared to non-freezers. FOG converters had a greater decline in the total Mini-BESTest (p = 0.005) and dynamic postural control scores (p = 0.04) compared to non-converters. Gait outcomes showed no significant differences in any of the analyses. CONCLUSION: FOG is associated with more severe decline in postural control, which can be detected by the clinical Mini-BESTest.

Test-Retest Reliability of Dual-Task Outcome Measures in People With Parkinson Disease.

BACKGROUND: Dual-task (DT) training is gaining ground as a physical therapy intervention in people with Parkinson disease (PD). Future studies evaluating the effect of such interventions need reliable outcome measures. To date, the test-retest reliability of DT measures in patients with PD remains largely unknown. OBJECTIVE: The purpose of this study was to assess the reliability of DT outcome measures in patients with PD. DESIGN: A repeated-measures design was used. METHODS: Patients with PD ("on" medication, Mini-Mental State Examination score ≥24) performed 2 cognitive tasks (ie, backward digit span task and auditory Stroop task) and 1 functional task (ie, mobile phone task) in combination with walking. Tasks were assessed at 2 time points (same hour) with an interval of 6 weeks. Test-retest reliability was assessed for gait while performing each secondary task (DT gait) for both cognitive tasks while walking (DT cognitive) and for the functional task while walking (DT functional). RESULTS: Sixty-two patients with PD (age=39-89 years, Hoehn and Yahr stages II-III) were included in the study. Intraclass correlation coefficients (ICCs) showed excellent reliability for DT gait measures, ranging between .86 and .95 when combined with the digit span task, between .86 and .95 when combined with the auditory Stroop task, and between .72 and .90 when combined with the mobile phone task. The standard error of measurements for DT gait speed varied between 0.06 and 0.08 m/s, leading to minimal detectable changes between 0.16 and 0.22 m/s. With regard to DT cognitive measures, reaction times showed good-to-excellent reliability (digit span task: ICC=.75; auditory Stroop task: ICC=.82). LIMITATIONS: The results cannot be generalized to patients with advanced disease or to other DT measures. CONCLUSIONS: In people with PD, DT measures proved to be reliable for use in clinical studies and look promising for use in clinical practice to assess improvements after DT training. Large effects, however, are needed to obtain meaningful effect sizes.

Are factors related to dual-task performance in people with Parkinson's disease dependent on the type of dual task?

BACKGROUND: Impaired dual-task performance significantly impacts upon functional mobility in people with Parkinson's disease (PD). The aim of this study was to identify determinants of dual-task performance in people with PD in three different dual tasks to assess their possible task-dependency. METHODS: We recruited 121 home-dwelling patients with PD (mean age 65.93 years; mean disease duration 8.67 years) whom we subjected to regular walking (control condition) and to three dual-task conditions: walking combined with a backwards Digit Span task, an auditory Stroop task and a Mobile Phone task. We measured dual-task gait velocity using the GAITRite mat and dual-task reaction times and errors on the concurrent tasks as outcomes. Motor, cognitive and descriptive variables which correlated to dual-task performance (p < 0.20) were entered into a stepwise forward multiple linear regression model. RESULTS: Single-task gait velocity and executive function, tested by the alternating intake test, was significantly associated with gait velocity during the Digit Span (R(2) = 0.65; p < 0.001), the Stroop (R(2) = 0.73; p < 0.001) and the Mobile Phone task (R(2) = 0.62; p < 0.001). In addition, disease severity proved correlated to gait velocity during the Stroop task. Age was a surplus determinant of gait velocity while using a mobile phone. CONCLUSION: Single-task gait velocity and executive function as measured by a verbal fluency switching task were independent determinants of dual-task gait performance in people with PD. In contrast to expectation, these factors were the same across different tasks, supporting the robustness of the findings. Future study needs to determine whether these factors predict dual-task abnormalities prospectively.

Amplitude Manipulation Evokes Upper Limb Freezing during Handwriting in Patients with Parkinson's Disease with Freezing of Gait.

BACKGROUND: Recent studies show that besides freezing of gait (FOG), many people with Parkinson's disease (PD) also suffer from freezing in the upper limbs (FOUL). Up to now, it is unclear which task constraints provoke and explain upper limb freezing. OBJECTIVE: To investigate whether upper limb freezing and other kinematic abnormalities during writing are provoked by (i) gradual changes in amplitude or by (ii) sustained amplitude generation in patients with and without freezing of gait. METHODS: Thirty-four patients with PD, including 17 with and 17 without FOG, performed a writing task on a touch-sensitive writing tablet requiring writing at constant small and large size as well as writing at gradually increasing and decreasing size. Patients of both groups were matched for disease severity, tested while 'on' medication and compared to healthy age-matched controls. RESULTS: Fifty upper limb freezing episodes were detected in 10 patients, including 8 with and 2 without FOG. The majority of the episodes occurred when participants had to write at small or gradually decreasing size. The occurrence of FOUL and the number of FOUL episodes per patient significantly correlated with the occurrence and severity of FOG. Patients with FOUL also showed a significantly smaller amplitude in the writing parts outside the freezing episodes. CONCLUSIONS: Corroborating findings of gait research, the current study supports a core problem in amplitude control underlying FOUL, both in maintaining as well as in flexibly adapting the cycle size.

Dual tasking in Parkinson's disease: should we train hazardous behavior?

Dual-task (DT) circumstances aggravate gait disorders in Parkinson's disease (PD) and are associated with an increased risk of falling and reduced functional mobility. Clinical rehabilitation guidelines for PD consider DT interventions as potentially hazardous and recommend avoiding them in daily life. The current article challenges this notion and addresses the necessity of implementing DT training in PD. First, underlying reasons for DT interference in PD and current theoretical models are discussed. Subsequently, different training approaches to tackle DT difficulties are put forward. Finally, the effectiveness and limitations of DT training in PD are reviewed. We conclude that there is a need for DT interventions in PD and recommend randomized, power-based studies to further test their efficacy.

Protocol for a randomized comparison of integrated versus consecutive dual task practice in Parkinson's disease: the DUALITY trial.

BACKGROUND: Multiple tasking is an integral part of daily mobility. Patients with Parkinson's disease have dual tasking difficulties due to their combined motor and cognitive deficits. Two contrasting physiotherapy interventions have been proposed to alleviate dual tasking difficulties: either to discourage simultaneous execution of dual tasks (consecutive training); or to practice their concurrent use (integrated training). It is currently unclear which of these training methods should be adopted to achieve safe and consolidated dual task performance in daily life. Therefore, the proposed randomized controlled trial will compare the effects of integrated versus consecutive training of dual tasking (tested by combining walking with cognitive exercises). METHODS AND DESIGN: Hundred and twenty patients with Parkinson's disease will be recruited to participate in this multi-centered, single blind, randomized controlled trial. Patients in Hoehn & Yahr stage II-III, with or without freezing of gait, and who report dual task difficulties will be included. All patients will undergo a six-week control period without intervention after which they will be randomized to integrated or consecutive task practice. Training will consist of standardized walking and cognitive exercises delivered at home four times a week during six weeks. Treatment is guided by a physiotherapist twice a week and consists of two sessions of self-practice using an MP3 player. Blinded testers will assess patients before and after the control period, after the intervention period and after a 12-week follow-up period. The primary outcome measure is dual task gait velocity, i.e. walking combined with a novel untrained cognitive task to evaluate the consolidation of learning. Secondary outcomes include several single and dual task gait and cognitive measures, functional outcomes and a quality of life scale. Falling will be recorded as a possible adverse event using a weekly phone call for the entire study period. DISCUSSION: This randomized study will evaluate the effectiveness and safety of integrated versus consecutive task training in patients with Parkinson's disease. The study will also highlight whether dual task gait training leads to robust motor learning effects, and whether these can be retained and carried-over to untrained dual tasks and functional mobility. TRIAL REGISTRATION: Clinicaltrials.gov NCT01375413.