The association of interlimb coordination and temporal symmetry with walking function and motor impairment after stroke

OBJECTIVE

Interlimb coordination during walking is impaired after stroke, with unknown effects on walking function. This cross-sectional study determined associations of interlimb coordination and temporal symmetry with walking function and motor impairment.

DESIGN

During walking, participants wore wireless sensors to detect heel strikes. We calculated interlimb coordination as the phase coordination index and temporal symmetry as the ratio of contralesional (i.e., paretic) to ipsilesional (i.e., non-paretic) stance times. Associations with walking speed (10-meter walk test), walking endurance (6-minute walk test), dynamic balance (Mini Balance Evaluation Systems Test), and motor impairment (Fugl Meyer Lower Extremity assessment) were assessed.

RESULTS

56 individuals with chronic stroke were tested. Worse interlimb coordination was correlated with slower comfortable (R = -0.38, p = 0.004) and maximal (R = -0.36, p = 0.006) walking speed and worse motor function (R = -0.45, p = 0.001). Worse temporal symmetry was correlated with worse motor function (R = 0.39, p = 0.004). Interlimb coordination had stronger associations than temporal symmetry with comfortable (R: -0.38 vs. 0.08) and maximal walking speeds (R: -0.36 vs. 0.12).

CONCLUSION

Poor interlimb coordination was associated with slow walking and motor impairment and had stronger associations with walking speeds than temporal symmetry did. Interlimb coordination may provide unique insights into walking function and a target for walking rehabilitation after stroke.

Video parameters for action observation training in stroke rehabilitation: a scoping review

PURPOSE

Action observation training (AOT) is a therapeutic approach used in stroke rehabilitation. Videos form the core of AOT, and knowledge of constituent parameters is essential to make the intervention robust and generalizable. Currently, there is a dearth of available information on video parameters to be used for AOT. Our purpose was to identify and describe the parameters that constitute AOT videos for stroke rehabilitation.

METHOD

Electronic databases like PubMed, CINAHL, Scopus, Web of Science, ProQuest, and Ovid SP from inception to date according to PRISMA-ScR guidelines. Title, abstract, and full-text screening were done independently by two authors, with a third author for conflict resolution. Data on video parameters like length, quality, perspective, speed, screen size and distance, sound, and control videos were extracted.

RESULTS

Seventy studies were included in this review. The most-reported parameters were video length (85.71%) and perspective of view (62.85%). Movement speed (7.14%) and sound (8.57%) were the least reported. Static landscapes or geometrical patterns were found suitable as control videos.

CONCLUSION

Most video parameters except for length and perspective of view remain underreported in AOT protocols. Future studies with better descriptions of video parameters are required for comprehensive AOT interventions and result generalisation.

MEASURING UNION FORMALIZATION FOR A NEW GENERATION OF FAMILY DEMOGRAPHY: A CASE STUDY FROM URBAN KENYA

Despite repeated calls for improved measures of marriage as a process in sub‐Saharan Africa, large‐scale surveys continue to rely on static marital status. As a result, there is an incomplete understanding of the effects of marriage on outcomes of interest. We use qualitative and survey data from a longitudinal study of 1,203 young mothers residing in informal settlements of Nairobi, Kenya, to (1) describe the development of an innovative measure of union formalization (UF) defined as the steps through which a union attains social legitimacy; (2) compare UF with a conventional current marital status measure; (3) examine the distribution of UF steps across union history; and (4) examine the sequence and timing of pregnancy and childbearing within the UF process. We find UF steps indicative of both increasing individualization of marriage and the ongoing importance of kin involvement hold meaning. We demonstrate extensive heterogeneity in the sequence and extent of UF steps completed and interrogate the classification of premarital childbearing using sequence analysis. We argue that measuring UF is feasible and necessary for the next generation of family demography in Africa; UF measures facilitate understanding the linkages among family dynamics, health, and social stratification within the context of ongoing socioeconomic change.

Barriers to Enrollment in a Post-Stroke Neuromodulation and Walking Study: Implications for Recruiting Women

BACKGROUND

Women have a higher risk of stroke and related disability than men but are underrepresented in stroke clinical trials. Identifying modifiable recruitment and enrollment barriers for women can improve study generalizability, statistical power, and resource utilization.

OBJECTIVE

In a post-stroke neuromodulation study, we determined the impact of sex on the occurrence of exclusion criteria and compared the sex distribution of screened and enrolled individuals with a broader stroke-affected population.

METHODS

A total of 335 individuals with chronic stroke were screened for a study examining how neuromodulation and high-intensity treadmill training affect walking speed and corticomotor excitability. Demographics and exclusions were retrospectively gathered as a secondary dataset. Exclusion criteria consisted of 6 categories (not target population, unable to do treadmill protocol, unable to do non-invasive brain stimulation, insufficient ankle motion and disinterest, and cognitive impairment). Incidence of each exclusion criterion was compared between women and men. The sex distribution was compared to a dataset from Chicago primary stroke centers.

RESULTS

A total of 81 individuals were enrolled and 254 were not. The percentage of women excluded was significantly greater than that of men (P = .04). No individual exclusion criterion or categories excluded women more frequently than men. Screened and enrolled individuals had a lower proportion of women and younger age than a representative stroke population (P < .001).

CONCLUSIONS

We identified exclusion criteria (ie, headaches, cognitive scores, and age) that are modifiable barriers to enrollment of women in this post-stroke neuromodulation study. Addressing underrepresentation of women in stroke research is pivotal for enhancing generalizability, achieving statistical power, and optimizing resources.

Concurrent validity of walking speed measured by a wearable sensor and a stopwatch during the 10-meter walk test in individuals with stroke

BACKGROUND

Walking speed is often measured with a stopwatch throughout stroke recovery. Wearable sensors also have been used recently to measure walking speed and provide information about spatiotemporal characteristics of walking.

RESEARCH QUESTION

Do walking speeds measured with stopwatch and APDM wearable sensors have concurrent validity?

METHODS

Individuals with chronic stroke (n = 62) performed the 10-meter walk test at comfortable and maximal speeds. Walking speeds were measured with a stopwatch and APDM Opal wireless wearable sensors (3-unit). Tests of concurrent validity between stopwatch and APDM (Bland-Altman plots, systematic and proportional bias, and intraclass correlations) and test-retest reliability between trials (intraclass correlations, standard error of measurement, and minimal detectable change) were performed.

RESULTS

Walking speeds measured with APDM were ∼0.07 m/s slower than those measured with stopwatch (systematic bias; t ≥ 13.1, p < 0.001). Intraclass correlations ranged from poor to excellent. There were greater differences in walking speeds between APDM and stopwatch for individuals with faster walking speeds (proportional bias). Test-retest reliability was excellent for both APDM and stopwatch (intraclass correlation≥0.94). Standard error of measurement ranged from 0.04 to 0.07 m/s and minimal detectable change ranged from 0.10 to 0.19 m/s.

SIGNIFICANCE

It may be inappropriate to use walking speed measurements from APDM sensors and stopwatch interchangeably in individuals with chronic stroke. Differences in walking speeds may reflect stopwatch error or the derivation of walking speed from wearable sensors. Test-retest reliability was excellent for both stopwatch and APDM, but minimal detectable change values were large. Large changes in walking speed may be required to be confident that the change is a true and clinically meaningful change and not measurement error. The validity and reliability of measuring walking speed with wearable sensors in individuals with chronic stroke has important implications for determining community ambulation, assessing improvements after rehabilitation, and developing exercise prescriptions.

Parenting in place: Young children's living arrangement and migrants' sleep health in South Africa

Migration research tends to treat childrearing as a secondary role for migrants. By prioritising the economic objectives of migration, most models present migrants as either delaying childbearing or, if they have young children, not living with them. However, migration has become increasingly feminised, the types of mobility more varied, while the returns to migration remain uncertain at best. At the same time, norms around childrearing are shifting, and the capacity of kin to take care of children may be weakening. In such contexts, migrants may not want to or be able to be separated from their children. Confronting such difficult decisions and their consequences may be reflected in poor sleep health for the migrant parent. We draw on data from the Migration and Health Follow-Up Study (MHFUS) in South Africa to examine the following questions: (i) To what extent is children's coresidence associated with sleep health for migrant parents? (ii) Do effects vary by sex of migrant? and (iii) Do effects vary by location of migrant? Results from propensity score matching confirm that migrants who coreside with all their young children are more likely to experience healthy sleep compared to those who have nonresident or no young children. However, stratified analysis shows that these effects are only significant for women and those not living in Gauteng province. The value of these findings is underscored by the need for research on the well-being of migrant parents who are negotiating multiple agendas in economically precarious and physically insecure destinations.

Understanding the Interaction of Transcranial Direct Current Stimulation and Visual Feedback During an Ankle Movement Task

BACKGROUND

Transcranial direct current stimulation (tDCS) has been demonstrated to facilitate motor performance in healthy individuals; however, results are variable. The neuromodulatory effects of tDCS during visuomotor tasks may be influenced by extrinsic visual feedback. However, this interaction between tDCS and visual feedback has not been explored for the lower limb. Hence, our objective was to explore if tDCS over the primary lower limb motor cortex differentially facilitates motor performance based on the availability of visual feedback.

METHODS

Twenty-two neurotypical adults performed ankle plantarflexion and dorsiflexion movements while tracking a sinusoidal target. Spatiotemporal, spatial, and temporal error were calculated between the ankle position and target. Participants attended two sessions, a week apart, with (Stim) and without (No-Stim) anodal tDCS. Sessions were divided into two blocks containing randomized visual feedback conditions: full, no, and blindfold. During Stim sessions, the first block included the application of tDCS to the lower limb M1.

RESULTS

Spatiotemporal and spatial error increased as feedback faded (p < .001). A two-way repeated-measures analysis of variance showed a significant interaction between tDCS and visual feedback (p < .05) on spatiotemporal error. Post hoc analyses revealed a significant improvement in spatiotemporal error when visual feedback was absent (p < .01). Spatial and temporal errors were not significantly affected by stimulation or visual feedback.

DISCUSSION

Our results suggest that tDCS enhances spatiotemporal ankle motor performance only when visual feedback is not available. These findings indicate that visual feedback may play an important role in demonstrating the effectiveness of tDCS.

Understanding corticomotor mechanisms for activation of non-target muscles during unilateral isometric contractions of leg muscles after stroke

PURPOSE

Muscle activation often occurs in muscles ipsilateral to a voluntarily activated muscle and to a greater extent after stroke. In this study, we measured muscle activation in non-target, ipsilateral leg muscles and used transcranial magnetic stimulation (TMS) to provide insight into whether corticomotor pathways contribute to involuntary activation.

MATERIALS AND METHODS

Individuals with stroke performed unilateral isometric ankle dorsiflexion, ankle plantarflexion, knee extension, and knee flexion. To quantify involuntary muscle activation in non-target muscles, muscle activation was measured during contractions from the ipsilateral tibialis anterior (TA), medial gastrocnemius (MG), rectus femoris (RF), and biceps femoris (BF) and normalized to resting muscle activity. To provide insight into mechanisms of involuntary non-target muscle activation, TMS was applied to the contralateral hemisphere, and motor evoked potentials (MEPs) were recorded.

RESULTS

We found significant muscle activation in nearly every non-target muscle during isometric unilateral contractions. MEPs were frequently observed in non-target muscles, but greater non-target MEP amplitude was not associated with greater non-target muscle activation.

CONCLUSIONS

Our results suggest that non-target muscle activation occurs frequently in individuals with chronic stroke. The lack of association between non-target TMS responses and non-target muscle activation suggests that non-target muscle activation may have a subcortical or spinal origin. Non-target muscle activation has important clinical implications because it may impair torque production, out-of-synergy movement, and muscle activation timing.

Non-paretic leg movements can facilitate cortical drive to the paretic leg in individuals post stroke with severe motor impairment: Implications for motor priming

Cross-education, a phenomenon where unilateral strength (or skill) training enhances strength (or skill) in the contralateral untrained limb, has been well studied in able-bodied individuals. Cross-education effect accompanies bilateral changes of corticomotor activity in the motor cortex (M1). Recent reports demonstrated greater cross-education effect in stroke survivors compared to healthy individuals, however, corticomotor responses to cross-education in stroke remains unclear. This study aimed to determine the effects of non-paretic leg movements on corticomotor excitability (CME) and reaction time of the paretic leg in severely impaired stroke survivors. Seventeen post stroke individuals with severe leg motor impairment (Fugl-Meyer lower extremity score less than 21 and absence of motor evoked potential in the paretic leg) performed three 20-min motor trainings using their non-paretic ankle: skill (targeted dynamic movements), strength (isometric resistance) and sham (sub-threshold electrical nerve stimulation). During training, verbal instructions were given to the participants to limit their movement to the non-paretic leg and this was confirmed with visual observation of the paretic leg. Transcranial magnetic stimulation measured CME of the contralateral pathways from the non-lesioned M1 to the non-paretic tibialis anterior (TA) muscle, ipsilateral pathways to the paretic TA and transcallosal inhibition (TCI) from the non-lesioned to lesioned M1. Paretic ankle reaction time was measured using a reaction time paradigm. All outcomes were measured before, immediately post, 30-min post and 60-min post priming. CME of the non-paretic TA increased after skill (.08 ± .10 mV) and strength (.06 ± .05 mV) training (p < .01). Ipsilateral CME of the paretic TA (.02 ± .01 mV) and TCI (.01 ± .01 s, ipsilateral silent period; more inhibition to the lesioned M1) increased after skill (p < .05) but not strength training. Reaction time of the paretic ankle improved after skill and strength training (-.11 ± .2 and -.13 ± .20 s, respectively; p < .05) and was sustained at 60 min. No changes were observed during the sham condition. Our findings may inform future studies for using non-paretic leg movements as a priming modality, especially for those who are contraindicated to other priming paradigms (e.g., brain stimulation) or unable to perform paretic leg movements. Conclusion: Non-paretic leg movements can be used as a priming modality, especially for those who are contraindicated to other priming paradigms (e.g., brain stimulation) or unable to perform paretic leg movements.

Can post stroke walking improve via telerehabilitation? A systematic review in adults with stroke

Objectives

The purpose of this systematic review is to analyze primary studies investigating the effects of telerehabilitation on walking outcomes for the treatment of adult stroke survivors.

Methods

Data sources included PubMed, Embase and CINAHL searched until August 2022, using combinations of several keywords such as "telerehabilitation", "stroke", and "gait". Studies were required to have bidirectional form of videoconferencing with assessor presence, and include assessment of walking function (speed, endurance and/or balance). Data extraction was performed from each full text by one author, and quality and bias were assessed using the Physiotherapy Evidence Database (PEDro).

Results

Eight studies involving 248 participants met the inclusion criteria. Seven reported significant improvements in outcomes of balance and two showed improvements in endurance after telerehabilitation. Two studies observed greater balance improvements in the telerehabilitation group compared to control and/or in-person therapy. Differences in frequency, training duration, intervention type, and absence of an in-person therapy control group were identified as causes of variation between studies.

Conclusions

The effectiveness of telerehabilitation as a mode of therapy for walking could not be definitively determined due to the limited number of studies that directly measured walking speed or endurance. However, strong evidence was found for the use of telerehabilitation for balance improvements, which has implications for walking recovery.

Impact statement

Telerehabilitation appears to be safe, feasible and demonstrated high adherence. Our results highlighted limited studies using real-time supervision to administer telerehabilitation and lack of studies focusing on outcomes of walking speed and endurance, needed to fully determine the role of telerehabilitation for gait recovery.

Systematic review registration number

PROSPERO number CRD42021238197.

A map of evidence using transcranial direct current stimulation (tDCS) to improve cognition in adults with traumatic brain injury (TBI)

Introduction

Cognition impairments often occur after a traumatic brain injury and occur at higher rates in military members. Cognitive symptoms impair daily function, including balance and life quality, years after the TBI. Current treatments to regain cognitive function after TBI, including medications and cognitive rehabilitation, have shown limited effectiveness. Transcranial direct current stimulation (tDCS) is a low-cost, non-invasive brain stimulation intervention that improves cognitive function in healthy adults and people with neuropsychologic diagnoses beyond current interventions. Despite the available evidence of the effectiveness of tDCS in improving cognition generally, only two small TBI trials have been conducted based on the most recent systematic review of tDCS effectiveness for cognition following neurological impairment. We found no tDCS studies that addressed TBI-related balance impairments.

Methods

A scoping review using a peer-reviewed search of eight databases was completed in July 2022. Two assessors completed a multi-step review and completed data extraction on included studies using a priori items recommended in tDCS and TBI research guidelines.

Results

A total of 399 results were reviewed for inclusion and 12 met the criteria and had data extracted from them by two assessors using Google Forms. Consensus on combined data results included a third assessor when needed. No studies using tDCS for cognition-related balance were found.

Discussion

Guidelines and technology measures increase the identification of brain differences that alter tDCS effects on cognition. People with mild-severe and acute-chronic TBI tolerated and benefited from tDCS. TBI-related cognition is understudied, and systematic research that incorporates recommended data elements is needed to advance tDCS interventions to improve cognition after TBI weeks to years after injury.

Functional connectivity of proximal and distal lower limb muscles and impact on gait variability in stroke

BACKGROUND

Higher gait variability after stroke increases risk of falls and compromises safe community ambulation. Corticomotor connectivity plays an important role in walking after stroke, however, its relation to gait variability remains unknown.

RESEARCH QUESTION

Do corticomotor characteristics of the proximal and distal lower limb muscles predict gait variability in individuals with chronic stroke?

METHODS

Retrospective analysis of data from 30 individuals with chronic stroke was conducted. Corticomotor characteristics were measured in the paretic and non-paretic tibialis anterior (TA, distal muscle) and rectus femoris (RF, proximal muscle) using transcranial magnetic stimulation. We calculated corticomotor excitability ratio of paretic TA and RF (CME_TA/RF), corticomotor excitability symmetry (CME_sym) between hemispheres for the TA and RF, and ipsilateral corticomotor excitability (ICE) of the paretic TA. Gait variability was quantified as the coefficient of variation of the paretic step length (spatial) and step time (temporal) during comfortable walking. Relations between corticomotor characteristics and gait variability were tested with multiple linear regression.

RESULTS

CME_TA/RF and CME_sym of RF were significant predictors of spatial gait variability. Greater corticomotor input to the paretic RF compared to the paretic TA and greater symmetry of RF were related to higher spatial gait variability. There were no significant predictors of temporal gait variability.

SIGNIFICANCE

Corticomotor inputs to the proximal RF may be important for spatial gait variability, reflecting a compensatory role of RF in walking after stroke. Stroke survivors with relatively greater corticomotor input to the paretic RF may adopt compensatory strategy to enhance propulsion and achieve foot clearance, but it may also increase spatial gait variability, particularly when combined with impaired motor control of the paretic TA. These findings may provide novel rehabilitative targets to decrease gait variability and promote safe ambulation in individuals with stroke.

Post-migration emotional well-being among Black South Africans

Internal migration has been an institutionalized part of life for Black South Africans from the 1800s, when men left their rural homes to work in mines, through apartheid and into the present. Like other settings in the Global South, we know surprisingly little about the emotional well-being of migrants, especially in sub-Saharan African contexts. We investigate changes in the emotional well-being of 2281 working-age Black South Africans after migration, drawing on four waves of data, from 2008 to 2015, from the nationally representative National Income Dynamics Study. Fixed-effects regressions show that migrants exhibit changes in life satisfaction as well as proclivity towards depression but that these outcomes vary by distance of move and type of move-moving within or between provinces. As South Africa's health policies expand beyond addressing infectious diseases, it is important to consider mental health particularly of those who face the necessity of migration to sustain a livelihood.

Occurrence of Banana bract mosaic virus on Musa ornata Roxb based hybrids in India

Musa ornata, wild species of banana is being used as a cut flower, potted plants and for landscape gardening etc., They are also being utilized in banana hybridization programmes for introgressing pest and disease tolerant traits into banana cultivars in addition to the development of inter specific ornamental banana hybrids. Symptoms of banana bract mosaic virus (BBrMV) was observed in the bracts of interspecific M. ornata based hybrid developed using another wild species i.e., Musa rubra Kurz at ICAR-National Research Centre for Banana (NRCB), Tiruchirapalli. Presence of the virus in the bracts, leaves and roots of symptomatic plants was confirmed through triple antibody sandwich enzyme linked immunosorbent assay with BBrMV monoclonal and polyclonal antibodies. BBrMV HC-Pro (1370 bp), CP (900 bp) and VPg (570 bp) genes were amplified from the infected bracts using reverse transcriptase polymerase chain reaction with BBrMV respective gene primers. The amplicons of these three genes were cloned and sequenced. Blastn analysis revealed that HC-Pro, VPg and CP gene sequences has 97.67%, 97.72% and 99.67% similarity with the respective gene sequences of BBrMV infecting banana. Phylogenetic analysis clustered the test isolate with other BBrMV isolates of banana and other hosts based on CP and HC-Pro and VPg gene sequences. The virus is transmitted through Pentalonia nigronervosa and the transmitted plants expressed symptoms under glass house conditions. To the best of our knowledge, this is the first report of BBrMV on ornamental M. ornata hybrid in India and its transmission occurs through Pentalonia nigronervosa.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13337-022-00788-6.

"Magic" Number of Treadmill Sessions Needed to Achieve Meaningful Change in Gait Speed After Stroke: A Systematic Review

ABSTRACT

The purpose of this systematic review was to determine the number of treadmill training sessions needed to make a meaningful change in gait speed for chronic stroke survivors. Relevant databases were searched up through February 2020. Articles were included if they fit the following criteria: stroke onset more than 5 mos, intention to treat with traditional treadmill training, and gait speed included as an outcome. Change in gait speed after intervention was used to classify treadmill groups as responders (at least 0.1 m/sec change) or nonresponders (less than 0.1 m/sec change). Seventeen articles met our criteria, resulting in a total of 19 intervention groups. Ten groups were classified as responders and completed a mean of 30.5 sessions within 6 wks, whereas nonresponders completed 20.4 sessions within 10 wks, indicating that at least 30 treadmill sessions (preferably in a period of 10 wks and at least 40 mins per session) is necessary to reach a meaningful change in gait speed. Although these trends were noted between the responder and nonresponder groups, no firm conclusions can be drawn regarding the "magic" number of sessions chronic stroke survivors should perform given the low correlation between number of sessions and change in gait speed.

Effects of Cross-Education on Neural Adaptations Following Non-Paretic Limb Training in Stroke: A Scoping Review with Implications for Neurorehabilitation

Current stroke rehabilitation interventions focus on intensive task specific training of the paretic limb, which may not be feasible for individuals with higher levels of impairment or in the early phase of stroke. Cross-education, a mechanism that improves strength or skill of the untrained limb following unilateral motor training, has high clinical relevance for stroke rehabilitation. Despite its potential benefits, our knowledge on the application and efficacy of cross-education in stroke is limited. We performed a scoping review to synthesize the current evidence regarding neurophysiological and motor effects of cross-education training in stroke. Low to strong evidence from five studies demonstrated strength gains ranging from 31-200% in the untrained paretic limb following non-paretic muscle training. Neurophysiological mechanisms underlying cross-education were unclear as the three studies that used transcranial magnetic stimulation to probe functional connectivity demonstrated mixed results in low sample size. Our review suggests that cross-education is a promising clinical approach in stroke, however high quality studies focusing on neurophysiological mechanisms are required to establish the efficacy and underlying mechanisms of cross-education in stroke. Recommendations regarding future directions and clinical utility are provided.

Understanding factors contributing to participant satisfaction in stroke walking recovery clinical trials

Background

Individuals with stroke face a distinct set of challenges, barriers and facilitators that need to be understood to streamline efficacy of stroke clinical trials and improve participant retention. Few long-term stroke rehabilitation trials have evaluated participant perception of their laboratory experience.

Methods

We collected data regarding trial satisfaction from 33 individuals with stroke who participated in 12 sessions of treadmill training which included pre, post and follow-up non-invasive brain stimulation and clinical assessments. We evaluated factors such as overall trial satisfaction, burden of testing, perceived benefits, perceived barriers, and perceived support using a participant satisfaction questionnaire (PSQ) that assessed participants' overall trial experience.

Results

97% of our participants found participating in the study to be rewarding and would recommend it to other persons with stroke. Transcranial magnetic stimulation (TMS) testing was found to be the major perceived burden of participation while travelling to the lab was found to be the major perceived barrier to participation. Significant correlations were found between various items of the PSQ and clinical assessments.

Conclusions

This study helped us get a preliminary perspective into the benefits and barriers faced by persons with stroke enrolled in a 4-week long clinical trial. We observed that participant satisfaction was driven by various factors including functional status, personal relevance to the research, perceptive physical and mental health improvements, interaction with research personnel, and ease of testing protocols.

Motor overflow in the lower limb after stroke: insights into mechanisms

Motor overflow (involuntary muscle activation) is common after stroke, particularly in the non-paretic upper limb. Two potential cortical mechanisms are: 1) the contralesional hemisphere controls both limbs, and 2) inhibition from the ipsilesional to the contralesional hemisphere is diminished. Few studies have differentiated between these hypotheses or investigated motor overflow in the lower limb after stroke. To investigate these potential mechanisms, individuals with chronic stroke performed unilateral isometric and dynamic dorsiflexion. Motor overflow was quantified in the contralateral, resting (non-target) ankle. Transcranial magnetic stimulation was applied, and responses were measured in both legs. Relations between motor overflow, excitability of ipsilateral motor pathways, and interhemispheric inhibition were assessed. Non-target muscle activity (motor overflow) was greater during isometric and dynamic conditions than rest in both legs (p≤0.001) and was higher in the non-paretic than the paretic leg (p=0.03). Some participants (25%) had motor overflow >4SD above the group mean in the non-paretic leg. Greater motor overflow in the non-paretic leg was associated with lesser inhibition from the ipsilesional to the contralesional hemisphere (p=0.04). In both legs, non-target TMS responses were greater during the isometric and dynamic than the rest condition (p≤0.01), but not when normalized to background muscle activity. Overall, motor overflow occurred in both legs after stroke, suggesting a common bilateral mechanism. Our correlational results suggest that alterations in interhemispheric inhibition may contribute to motor overflow. Furthermore, the lack of differences in non-target MEPs between rest, isometric, and dynamic conditions, suggests that subcortical and/or spinal pathways may contribute to motor overflow.

Feasibility and Acceptability of Game-Based Cortical Priming and Functional Lower Limb Training in a Remotely Supervised Home Setting for Chronic Stroke: A Case Series

Background

Movement-based priming has been increasingly investigated to accelerate the effects of subsequent motor training. The feasibility and acceptability of this approach at home has not been studied. We developed a game-based priming system (DIG-I-PRIME^TM) that engages the user in repeated ankle movements using serious games. We aimed to determine the feasibility, acceptability, and preliminary motor benefits of an 8-week remotely supervised telerehabilitation program utilizing game-based movement priming combined with functional lower limb motor training in chronic stroke survivors.

Methods

Three individuals with stroke participated in a telerehabilitation program consisting of 20-min movement-based priming using the DIG-I-PRIME^TM system followed by 30-min of lower limb motor training focusing on strength and balance. We evaluated feasibility using reported adverse events and compliance, and acceptability by assessing participant perception of the game-based training. Motor gains were assessed using the 10-m walk test and Functional Gait Assessment.

Results

All participants completed 24 remotely supervised training sessions without any adverse events. Participants reported high acceptability of the DIG-I-PRIME^TM system, reflected by high scores on satisfaction, enjoyment, user-friendliness, and challenge aspects of the system. Participants reported overall satisfaction with our program. Post-training changes in the 10-m walk test (0.10–0.31 m/s) and Functional Gait Assessment (4–7 points) exceeded the minimal clinically important difference.

Conclusion

Our results indicate that a remotely supervised game-based priming and functional lower limb exercise program is feasible and acceptable for stroke survivors to perform at home. Also, improved walking provides preliminary evidence of game-based priming to be beneficial as a telerehabilitation strategy for stroke motor recovery.

Commentary: Remote assessments of gait and balance - Implications for research during and beyond Covid-19

The COVID-19 pandemic has disrupted non-essential in-person research activities that require contact with human subjects. While guidelines are being developed for ramping up human subjects research, one component of research that can be performed remotely is participant screening for lower limb function and gait impairments. In this commentary, we summarize evidence-supported clinical assessments that have potential to be conducted remotely in a safe manner, to make an initial determination of the functional mobility status of persons with neurological disorders. We present assessments that do not require complex or costly equipment, specialized software, or trained personnel to administer. We provide recommendations to implement remote functional assessments for participant recruitment and continuation of lower limb neurorehabilitation research as a rapid response to the COVID-19 pandemic and for utilization beyond the current pandemic. We also highlight critical research gaps related to feasibility and measurement characteristics of remote lower limb assessments, providing opportunities for future research to advance tele-assessment and tele-rehabilitation.

Economic Inequality and Divergence in Family Formation in sub-Saharan Africa

Economic inequality has been rising in many sub-Saharan African countries alongside rapid changes to union and family formation. In high-income countries marked by rising inequality, union and family formation practices have diverged across socioeconomic statuses, with intergenerational social and health consequences for the disadvantaged. In this study, we address whether there is also evidence of demographic divergence in low-income settings. Specifically, we model the age at first marriage and first birth by socioeconomic status groups for women born between 1960-1989 using Demographic and Health Survey data from twelve sub-Saharan African countries where economic inequality levels are relatively high or rising. We argue that economic and socio-cultural factors may both serve to increasingly delay marriage and childbearing for the elite as compared to others in the context of rising inequality. We find emerging social stratification in marriage and childbearing, and demonstrate that this demographic divergence is driven by the elites who are increasingly marrying and having children at later ages, with near stagnation in the age at first marriage and birth among the remaining majority. We urge further research at the intersection of socioeconomic and demographic inequality to inform necessary policy levers and curtail negative social and health consequences.

Sensory-Based Priming for Upper Extremity Hemiparesis After Stroke: A Scoping Review

Sensory priming is a technique to facilitate neuroplasticity and improve motor skills after injury. Common sensory priming modalities include peripheral nerve stimulation/somatosensory electrical stimulation (PNS/SES), transient functional deafferentation (TFD), and vibration. The aim of this study was to determine whether sensory priming with a motor intervention results in improved upper limb motor impairment or function after stroke. PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Web of Science, and EMBASE were the databases used to search the literature in July 2020. This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and recommendations for the Cochrane collaboration. In total, 30 studies were included in the analysis: three studies examined TFD, 16 examined PNS/SES, 10 studied vibration, and one combined the three stimulation techniques. Most studies reported significant improvements for participants receiving sensory priming. Given the low risk, it may be advantageous to use sensory-based priming prior to or concurrent with upper limb training after stroke.

Motor evoked potential latency and duration from tibialis anterior in individuals with chronic stroke

Ipsilateral motor pathways from the contralesional hemisphere to the paretic limbs may be upregulated to compensate for impaired function after stroke. Onset latency and duration of motor evoked potentials (MEPs) evoked by transcranial magnetic stimulation (TMS) provide insight into compensatory pathways but have been understudied in the lower limb. This study assessed MEP onset latency and duration in the lower limb after stroke, and compared ipsilateral and contralateral MEPs in the paretic and non-paretic limb. We hypothesized that: (1) onset latency would be longer for ipsilateral than contralateral MEPs and longer for the paretic than the non-paretic limb, and (2) duration would be shorter for ipsilateral than contralateral MEPs and longer for the paretic than the non-paretic limb. Data were collected as a part of a pre-test of a randomized controlled trial. TMS was applied to the ipsilateral and contralateral hemisphere of the paretic and non-paretic limb. MEP onset latency and duration were calculated from the tibialis anterior. Thirty-five participants with chronic stroke were included in the final analysis. Onset latency was longer in the paretic than the non-paretic limb (~ 6.0 ms) and longer after ipsilateral than contralateral stimulation (~ 1.8 ms). Duration was longer in the paretic than the non-paretic limb (~ 9.2 ms) and longer after contralateral than ipsilateral stimulation (~ 5.2 ms). Ipsilateral MEPs may be elicited through ipsilateral pathways with fewer fibers with a higher activation threshold and/or greater spinal branching. MEPs from the paretic limb may reflect slower central motor conduction, peripheral changes, or changes in motor pathway.

Changes in Walking Speed After High-Intensity Treadmill Training Are Independent of Changes in Spatiotemporal Symmetry After Stroke

Objectives: Decreased walking speeds and spatiotemporal asymmetry both occur after stroke, but it is unclear whether and how they are related. It is also unclear whether rehabilitation-induced improvements in walking speed are associated with improvements in symmetry or greater asymmetry. High-intensity speed-based treadmill training (HISTT) is a recent rehabilitative strategy whose effects on symmetry are unclear. The purpose of this study was to: (1) assess whether walking speed is cross-sectionally associated with spatiotemporal symmetry in chronic stroke, (2) determine whether HISTT leads to changes in the spatiotemporal symmetry of walking, and (3) evaluate whether HISTT-induced changes in walking speed are associated with changes in spatiotemporal symmetry.

Methods: Eighty-one participants with chronic stroke performed 4 weeks of HISTT. At pre, post, and 3-month follow-up assessments, comfortable and maximal walking speed were measured with the 10-meter walk test, and spatiotemporal characteristics of walking were measured with the GAITRite mat. Step length and swing time were expressed as symmetry ratios (paretic/non-paretic). Changes in walking speed and symmetry were calculated and the association was determined.

Results: At pre-assessment, step length and swing time asymmetries were present (p < 0.001). Greater temporal symmetry was associated with faster walking speeds (p ≤ 0.001). After HISTT, walking speeds increased from pre-assessment to post-assessment and follow-up (p ≤ 0.002). There were no changes in spatiotemporal symmetry (p ≥ 0.10). Change in walking speed was not associated with change in spatial or temporal symmetry from pre- to post-assessment or from post-assessment to follow-up (R² ≤ 0.01, p ≥ 0.37).

Conclusions: HISTT improves walking speed but does not systematically improve or worsen spatiotemporal symmetry. Clinicians may need to pair walking interventions like HISTT with another intervention designed to improve walking symmetry simultaneously. The cross-sectional relation between temporal symmetry and walking speed may be mediated by other factors, and not be causative.

Ipsilateral Motor Pathways and Transcallosal Inhibition During Lower Limb Movement After Stroke

BACKGROUND

Stroke rehabilitation may be improved with a better understanding of the contribution of ipsilateral motor pathways to the paretic limb and alterations in transcallosal inhibition. Few studies have evaluated these factors during dynamic, bilateral lower limb movements, and it is unclear whether they relate to functional outcomes.

OBJECTIVE

Determine if lower limb ipsilateral excitability and transcallosal inhibition after stroke depend on target limb, task, or number of limbs involved, and whether these factors are related to clinical measures.

METHODS

In 29 individuals with stroke, ipsilateral and contralateral responses to transcranial magnetic stimulation were measured in the paretic and nonparetic tibialis anterior during dynamic (unilateral or bilateral ankle dorsiflexion/plantarflexion) and isometric (unilateral dorsiflexion) conditions. Relative ipsilateral excitability and transcallosal inhibition were assessed. Fugl-Meyer, ankle movement accuracy, and walking characteristics were assessed.

RESULTS

Relative ipsilateral excitability was greater during dynamic than isometric conditions in the paretic limb (P ≤ .02) and greater in the paretic than the nonparetic limb during dynamic conditions (P ≤ .004). Transcallosal inhibition was greater in the ipsilesional than contralesional hemisphere (P = .002) and during dynamic than isometric conditions (P = .03). Greater ipsilesional transcallosal inhibition was correlated with better ankle movement accuracy (R² = 0.18, P = .04). Greater contralateral excitability to the nonparetic limb was correlated with improved walking symmetry (R² = 0.19, P = .03).

CONCLUSIONS

Ipsilateral pathways have increased excitability to the paretic limb, particularly during dynamic tasks. Transcallosal inhibition is greater in the ipsilesional than contralesional hemisphere and during dynamic than isometric tasks. Ipsilateral pathways and transcallosal inhibition may influence walking asymmetry and ankle movement accuracy.

Ipsilateral motor pathways to the lower limb after stroke: Insights and opportunities

Stroke-related damage to the crossed lateral corticospinal tract causes motor deficits in the contralateral (paretic) limb. To restore functional movement in the paretic limb, the nervous system may increase its reliance on ipsilaterally descending motor pathways, including the uncrossed lateral corticospinal tract, the reticulospinal tract, the rubrospinal tract, and the vestibulospinal tract. Our knowledge about the role of these pathways for upper limb motor recovery is incomplete, and even less is known about the role of these pathways for lower limb motor recovery. Understanding the role of ipsilateral motor pathways to paretic lower limb movement and recovery after stroke may help improve our rehabilitative efforts and provide alternate solutions to address stroke-related impairments. These advances are important because walking and mobility impairments are major contributors to long-term disability after stroke, and improving walking is a high priority for individuals with stroke. This perspective highlights evidence regarding the contributions of ipsilateral motor pathways from the contralesional hemisphere and spinal interneuronal pathways for paretic lower limb movement and recovery. This perspective also identifies opportunities for future research to expand our knowledge about ipsilateral motor pathways and provides insights into how this information may be used to guide rehabilitation.

Modernizing Marriage: Balancing the Benefits and Liabilities of Bridewealth in Rural South Africa

The payment of bridewealth or lobola is a longstanding cultural practice that has persisted in South Africa despite significant societal shifts over the past two decades. Lobola has always been a complex and contested practice that both reinforces gender inequalities and, at the same time, provides status to women and legitimacy to marriages. In this paper, we describe rural South African women's perceptions of lobola, their experiences related to marriage and lobola, and how they reconfigure lobola to fit within modern life course aspirations and trajectories. We draw on interviews with 43 women aged 18-55 to examine desires related to lobola and the meanings of lobola given current social, economic, and health (HIV) conditions in rural areas. Our findings indicate that lobola offers women a complex set of benefits and liabilities. Although women value the support, social status, and respectability lobola offers, they also lament how lobola curtails their freedom to pursue education and limits their autonomy from husbands as well as in-laws. Women also view lobola as offering a sense of security amidst the uncertainty of the local political economy and the HIV/AIDS epidemic. We conclude that the way women incorporate lobola into their desires and plans reflects tension between the expectations and aspirations of "modern" women in a post-apartheid context in which rights feature prominently but economic security is not guaranteed, and cultural scripts reinforce longstanding gender norms but also ensure social support.

Reliability of transcallosal inhibition measurements for the lower limb motor cortex in stroke

Transcallosal inhibition (TCI) is a measure of between-hemisphere inhibitory control that can be evaluated with the ipsilateral silent period (iSP) transcranial magnetic stimulation (TMS) paradigm. The study of iSP for the lower extremity has been limited possibly due to the close orientation of the lower extremity motor representations. Change in TCI can provide insights into pathophysiological mechanisms underlying the asymmetry in corticomotor excitability in stroke. Here, we describe a method for iSP quantification and report reliability of iSP parameters for the tibialis anterior (TA) muscle in stroke. 26 individuals with stroke attended three sessions where single pulse TMS was used to measure TCI from the lesioned to non-lesioned hemisphere. A double cone coil was used for stimulating the ipsilateral motor cortex while the participant maintained an isometric contraction of the non-paretic TA. Absolute and relative reliability were computed for iSP latency, duration and area. iSP latency showed the lowest measurement error (absolute reliability) and iSP latency, duration and area showed good relative reliability (intraclass correlation coefficients > 0.6). This study suggests that iSP parameters for the tibialis anterior are reliable and attempts to provide a guideline for evaluating TCI for the lower extremity in stroke and other clinical populations.

Game-based movement facilitates acute priming effect in stroke

OBJECTIVE

Cortical priming is an emerging strategy to enhance motor recovery after stroke, however, limited information exists on the neuromodulatory effects of lower limb movement-based priming to facilitate corticomotor excitability after stroke. In this study, we investigated the feasibility and effectiveness of game-based ankle movement priming using the DIG-I-PRIME™ on corticomotor excitability and motor performance in chronic stroke survivors.

METHODS

Nineteen stroke survivors participated in a 20-min session of game-based priming. A period of rest served as a control for the priming condition. Transcranial magnetic stimulation (TMS) was used to measure corticomotor excitability of the paretic and non-paretic tibialis anterior (TA) muscle representations. Motor performance was quantified by assessing the accuracy to track a sinusoidal target wave with paretic dorsiflexion and plantarflexion.

RESULTS

Ipsilesional corticomotor excitability increased by 25% after game-based movement priming (p = 0.02) while changes were not observed after the control condition. No change in motor performance was noted.

CONCLUSION

Game-based ankle movement priming demonstrated a significant acute priming effect on the ipsilesional lower limb M1. These data provide preliminary evidence for the potential benefits of game-based priming to promote functional recovery after stroke.

Combining transcranial direct current stimulation with aerobic exercise to optimize cortical priming in stroke

Aerobic exercise (AE) and transcranial direct current stimulation (tDCS) are priming techniques that have been studied for their potential neuromodulatory effects on corticomotor excitability (CME); however, the synergistic effects of AE and tDCS are not explored in stroke. Here we investigated the synergistic effects of AE and tDCS on CME, intracortical and transcallosal inhibition, and motor control for the lower limb in stroke. Twenty-six stroke survivors participated in 3 sessions: tDCS, AE, and AE+tDCS. AE included moderate-intensity exercise and tDCS included 1 mA of anodal tDCS to the lower limb motor cortex with or without AE. Outcomes included measures of CME, short-interval intracortical inhibition (SICI), ipsilateral silent period (iSP) (an index of transcallosal inhibition) for the tibialis anterior, and ankle reaction time. Ipsilesional CME significantly decreased for AE compared with AE+tDCS and tDCS. No differences were noted in SICI, iSP measures, or reaction time between all 3 sessions. Our findings suggest that a combination of exercise and tDCS, and tDCS demonstrate greater excitability of the ipsilesional hemisphere compared with exercise only; however, these effects were specific to the descending corticomotor pathways. No additive priming effects of exercise and tDCS over tDCS was observed. Novelty: An exercise and tDCS paradigm upregulated the descending motor pathways from the ipsilesional lower limb primary motor cortex compared with exercise. Exercise or tDCS administered alone or in combination did not affect intracortical or transcallosal inhibition or reaction time.

Cortical priming strategies for gait training after stroke: a controlled, stratified trial

Background

Stroke survivors experience chronic gait impairments, so rehabilitation has focused on restoring ambulatory capacity. High-intensity speed-based treadmill training (HISTT) is one form of walking rehabilitation that can improve walking, but its effectiveness has not been thoroughly investigated. Additionally, cortical priming with transcranial direct current stimulation (tDCS) and movement may enhance HISTT-induced improvements in walking, but there have been no systematic investigations. The objective of this study was to determine if motor priming can augment the effects of HISTT on walking in chronic stroke survivors.

Methods

Eighty-one chronic stroke survivors participated in a controlled trial with stratification into four groups: 1) control–15 min of rest (n = 20), 2) tDCS–15 min of stimulation-based priming with transcranial direct current stimulation (n = 21), 3) ankle motor tracking (AMT)–15 min of movement-based priming with targeted movements of the ankle and sham tDCS (n = 20), and 4) tDCS+AMT–15 min of concurrent tDCS and AMT (n = 20). Participants performed 12 sessions of HISTT (40 min/day, 3 days/week, 4 weeks). Primary outcome measure was walking speed. Secondary outcome measures included corticomotor excitability (CME). Outcomes were measured at pre, post, and 3-month follow-up assessments.

Results

HISTT improved walking speed for all groups, which was partially maintained 3 months after training. No significant difference in walking speed was seen between groups. The tDCS+AMT group demonstrated greater changes in CME than other groups. Individuals who demonstrated up-regulation of CME after tDCS increased walking speed more than down-regulators.

Conclusions

Our results support the effectiveness of HISTT to improve walking; however, motor priming did not lead to additional improvements. Upregulation of CME in the tDCS+AMT group supports a potential role for priming in enhancing neural plasticity. Greater changes in walking were seen in tDCS up-regulators, suggesting that responsiveness to tDCS might play an important role in determining the capacity to respond to priming and HISTT.

Trial registration

ClinicalTrials.gov, NCT03492229. Registered 10 April 2018 – retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03492229.

Differential corticomotor mechanisms of ankle motor control in post stroke individuals with and without motor evoked potentials

OBJECTIVE

Deficits in ankle motor control has been identified as a significant contributor to impaired walking after stroke. Corticomotor excitability has been related to impaired upper limb motor control and poor recovery in stroke, however contributions to lower limb function are still unclear. This study used transcranial magnetic stimulation (TMS) to determine the influence of corticomotor characteristics on lower limb motor control in chronic stroke survivors.

METHODS

This retrospective study assessed 28 individuals with post stroke hemiparesis. Motor evoked potentials (MEP) measured from the paretic and non-paretic tibialis anterior (TA) muscles were used to calculate corticomotor excitability symmetry (CME_sym) and relative ipsilateral corticomotor excitability (ICE). Participants were assigned to MEP+ and MEP- groups depending on the presence (+) or absence (-) of MEPs. Ankle motor control was quantified by the ability of participants to track a sinusoidal target using dorsiflexion-plantarflexion movements of the paretic ankle and tracking error was calculated using root mean square error (RMSE).

RESULTS

Multiple linear regression model for all participants revealed only CME_sym and FMLE (p < 0.01) to significantly predict RMSE. In the MEP+ group, CME_sym significantly predicted RMSE (p = 0.03) while FMLE (p = 0.02) was a significant predictor for the MEP-.

CONCLUSION

Our results indicate that CME_sym between the ipsilesional and contralesional hemispheres does not necessarily translate to better paretic ankle motor control in chronic stroke. Presence or absence of a MEP in the TA muscle did not affect the ankle tracking performance, however, it was noted that different strategies maybe used by those with and without a MEP.

Relationship between Nintendo's Wii balance board derived variables and clinical balance scores in individuals with stroke

BACKGROUND

The Wii Balance Board (WBB) is widely studied as a balance testing platform and is reliable in detecting changes in the body's center of pressure (COP). However, the relationship between WBB derived measures and clinical tests of balance is currently unknown.

RESEARCH QUESTION

To investigate the association between static and dynamic COP measures from the WBB with balance tests commonly used in chronic stroke.

METHODS

This retrospective study included sixty-nine individuals with stroke who performed the Berg Balance Score (BBS), the Mini-BESTest and WBB assessments as a part of their baseline measurements. The WBB assessments included body weight symmetry and a dynamic target matching task that measured Reaction Time (RT) and Completion Time (CT).

RESULTS

Body weight symmetry performed with eyes open was significantly different between participants who were classified as high and moderate balance using the Mini-BESTest (p = 0.03). A significant negative linear correlation was observed between the BBS and CT (rho = -0.29, p = 0.021) and between the Mini-BESTest and RT (rho=-0.246, p = 0.05).

SIGNIFICANCE

We provide preliminary but weak evidence supporting the relationship between WBB derived variables in relevance to the BBS and Mini-BESTest. Further research is needed to fully understand the clinical utility of the WBB especially in a larger sample and to generalize these results to stroke survivors at all levels of ability.

Stimulus Intensity Affects Variability of Motor Evoked Responses of the Non-Paretic, but Not Paretic Tibialis Anterior Muscle in Stroke

Background: Transcranial magnetic stimulus induced motor evoked potentials (MEPs) are quantified either with a single suprathreshold stimulus or using a stimulus response curve. Here, we explored variability in MEPs influenced by different stimulus intensities for the tibialis anterior muscle in stroke. Methods: MEPs for the paretic and non-paretic tibialis anterior (TA) muscle representations were collected from 26 participants with stroke at seven intensities. Variability of MEP parameters was examined with coefficients of variation (CV). Results: CV for the non-paretic TA MEP amplitude and area was significantly lower at 130% and 140% active motor threshold (AMT). CV for the paretic TA MEP amplitude and area did not vary with intensity. CV of MEP latency decreased with higher intensities for both muscles. CV of the silent period decreased with higher intensity for the non-paretic TA, but was in reverse for the paretic TA. Conclusion: We recommend a stimulus intensity of greater than 130% AMT to reduce variability for the non-paretic TA. The stimulus intensity did not affect the MEP variability of the paretic TA. Variability of MEPs is affected by intensity and side tested (paretic and non-paretic), suggesting careful selection of experimental parameters for testing.

Genetic polymorphisms for BDNF, COMT, and APOE do not affect gait or ankle motor control in chronic stroke: A preliminary cross-sectional study

Background: Motor deficits after stroke are a primary cause of long-term disability. The extent of functional recovery may be influenced by genetic polymorphisms. Objectives: Determine the effect of genetic polymorphisms for brain-derived neurotrophic factor (BDNF), catechol-O-methyltransferase (COMT), and apolipoprotein E (APOE) on walking speed, walking symmetry, and ankle motor control in individuals with chronic stroke. Methods: 38 participants with chronic stroke were compared based upon genetic polymorphisms for BDNF (presence [MET group] or absence [VAL group] of a Met allele), COMT (presence [MET group] or absence [VAL group] of a Met allele), and APOE (presence [ε4+ group] of absence [ε4- group] of ε4 allele). Comfortable and maximal walking speed were measured with the 10-m walk test. Gait spatiotemporal symmetry was measured with the GAITRite electronic mat; symmetry ratios were calculated for step length, step time, swing time, and stance time. Ankle motor control was measured as the accuracy of performing an ankle tracking task. Results: No significant differences were detected (p ≥ 0.11) between the BDNF, COMT, or APOE groups for any variables. Conclusions: In these preliminary findings, genetic polymorphisms for BDNF, COMT, and APOE do not appear to affect walking speed, walking symmetry, or ankle motor performance in chronic stroke.

Remotely supervised transcranial direct current stimulation: A feasibility study for amyotrophic lateral sclerosis

BACKGROUND

Transcranial direct current stimulation (tDCS) has been investigated as a therapeutic neuromodulation tool in several neurological disorders. However, evidence supporting its efficacy in disorders such as amyotrophic lateral sclerosis (ALS) is limited possibly due to limited patient accessibility for research, particularly for individuals with advanced disease progression. Telerehabilitation using home-based protocols allows for remote supervision of tDCS over longer durations, thereby increasing participation, compliance and adherence. In this study, we explored the safety, feasibility and preliminary effects of a remotely supervised tDCS (RS-tDCS) protocol in ALS.

MATERIAL AND METHODS

In this pre-post case series study, two individuals with ALS completed 24 remotely supervised anodal tDCS sessions (20 minutes, 2 mA). Outcomes included adherence, compliance, disease progression, walking speed, risk of fall, endurance, fatigue and depression.

RESULTS

Both participants successfully completed the study without any major adverse effects. Minor side effects included mild sensations of itching and throbbing under the electrodes during stimulation. Clinical outcomes showed minimal to no change for any of the measures.

CONCLUSIONS

Preliminary findings suggest that the RS-tDCS protocol is safe and feasible in individuals with ALS. Our protocol serves as a model for future long-term studies to evaluate the clinical and neurophysiological effects of tDCS using a telerehabilitation protocol in ALS.

Characterization of stimulus response curves obtained with transcranial magnetic stimulation from bilateral tibialis anterior muscles post stroke

BACKGROUND

Stimulus response curves (SR curves), measured using transcranial magnetic stimulation (TMS) induced motor evoked potentials (MEP), yield important information regarding corticomotor connectivity. Limited understanding of SR curve analyses techniques for leg muscles after stroke may limit the utility of TMS data for walking recovery.

OBJECTIVE

To compare linear and non-linear curve fitting for MEP responses from the non-paretic and paretic tibialis anterior (TA) muscles.

METHODS

Accuracy of fit was measured using coefficient of determination (R2). Similarities of the fit were compared using slopes and area under the curve (AUC).

RESULTS

The non-linear function demonstrated higher R2 and slopes. The AUC was not significantly different between the two analyses approaches. The non-linear non-paretic SR slopes and paretic AUC had significant associations with walking speed.

CONCLUSION

Our results highlight the differences between non-linear and linear approaches to best fit the SR curves from bilateral TA muscles in stroke survivors. Although the linear function can appropriately fit the SR curve of the paretic and non-paretic TA, the non-linear function estimated a higher slope. We found the AUC to be a more robust measure that was not affected by the type of curve-fitting approach and only the AUC of the paretic TA showed significant association with walking speeds. A better understanding of SR curve fitting approaches for the TA muscles in individuals with chronic stroke allows for their optimal use in interpretation of TMS data and literature.

WITHDRAWN: Immediate Adaptations to Poststroke Walking Performance Using a Wearable Robotic Exoskeleton

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Influence of neurovascular mechanisms on response to tDCS: an exploratory study

The beneficial effects of transcranial direct current stimulation (tDCS) for stroke rehabilitation are limited by the variability in changes in corticomotor excitability (CME) after tDCS. Neuronal activity is closely related to cerebral blood flow; however, the cerebral hemodynamics of neuromodulation in relation to neural effects have been less explored. In this study, we examined the effects of tDCS on cerebral blood velocity (CBv) in chronic stroke survivors using transcranial Doppler (TCD) ultrasound in relation to changes in CME and described the neurovascular characteristics of tDCS responders. Middle cerebral artery (MCA) CBv, cerebrovascular resistance (CVRi) and other cerebral hemodynamics-related variables were continuously measured before and after 15 min of 1 mA anodal tDCS to the lesioned lower limb M1. tDCS did not modulate CBv in the whole group and upon TMS-based stratification of responders and non-responders. However, at baseline, responders demonstrated lower CME levels, lower CBv and higher CVRi as compared to non-responders. These results indicate a possible difference in baseline CME and CBv in tDCS responders that may influence their response to neuromodulation. Future trials with a large sample size and repeated baseline measurements may help validate these findings and establish a relationship between neuromodulation and neurovascular mechanisms in stroke.

Absence of a Transcranial Magnetic Stimulation-Induced Lower Limb Corticomotor Response Does Not Affect Walking Speed in Chronic Stroke Survivors

Background and Purpose- Transcranial magnetic stimulation is used to measure the functional integrity of the corticomotor system via motor evoked potentials (MEPs) in stroke. The association between corticomotor mechanisms and walking recovery is still not completely understood. This study determined the association between transcranial magnetic stimulation-induced MEPs and walking outcomes and examined the contribution of the contralesional hemisphere to walking recovery. Methods- Contralateral and ipsilateral transcranial magnetic stimulation responses from the contralesional and ipsilesional hemispheres were collected from 61 chronic stroke survivors. Clinical assessments included gait speeds, 6-minute walk distance, Timed Up and Go test, Fugl Meyer lower extremity scale, and strength measurements. Results- Stroke participants were classified based on the presence (MEP+ [n=28]) or absence (MEP- [n=33]) of MEPs in the paretic tibialis anterior and rectus femoris muscles. A between-group analyses showed no significant differences for any gait variable. MEP+ group showed significantly higher Fugl Meyer lower extremity and ankle dorsiflexor strength. Ipsilateral conductivity was not significantly different between groups. Finally, in the MEP+ group, MEP parameters did not predict gait recovery. Conclusions- Our study investigated the association between walking outcomes and neurophysiological parameters of lower limb function in a large cohort of stroke survivors. We did not find an associations between transcranial magnetic stimulation-induced tibialis anterior and rectus femoris MEPs and walking speeds. Further work is required to develop more comprehensive models in stroke for predicting walking recovery.

Comparison of Transcranial Direct Current Stimulation Electrode Montages for the Lower Limb Motor Cortex

Transcranial direct current stimulation (tDCS) has been widely explored as a neuromodulatory adjunct to modulate corticomotor excitability and improve motor behavior. However, issues with the effectiveness of tDCS have led to the exploration of empirical and experimental alternate electrode placements to enhance neuromodulatory effects. Here, we conducted a preliminary study to compare a novel electrode montage (which involved placing 13 cm² electrodes anterior and posterior to the target location) to the traditionally used electrode montage (13 cm² stimulating electrode over the target area and the 35 cm² reference electrode over the contralateral orbit). We examined the effects of tDCS of the lower limb motor area (M1) by measuring the corticomotor excitability (CME) of the tibialis anterior muscle using transcranial magnetic stimulation in twenty healthy participants. We examined behavioral effects using a skilled motor control task performed with the ankle. We did not find one electrode montage to be superior to the other for changes in the CME or motor control. When the group was dichotomized into responders and non-responders (based on upregulation in CME), we found that the responders showed significant upregulation from baseline after tDCS for both montages. However, only the responders in the traditional montage group showed significant changes in motor control after tDCS. These results do not support the superiority of the new anterior–posterior montage over the traditional montage. Further work with a larger cohort and multiple cumulative sessions may be necessary to confirm our results.

Internal migration and child health in Malawi

A strong and consistent association between migration and health has been found in many settings, but the overwhelming focus of this research has been on adults. In addition, identifying the effect of migration on health largely remains an unresolved challenge, due in part to the inability to distinguish between the effect of migration on health and the selection of children of differing health status into migration streams. In this research we examine the relationship between internal migration and child health in Malawi. We use longitudinal panel data with pre- and post-migration health measures for children and their mothers, which permits us to measure both migration health selection and the effect of migration on health. We also examine if child health changes over time in post-migration destinations. We do not find evidence of migration health selection: children who move have similar pre-migration health status to non-migrant children. We find that the impact of migration on child health is mediated by mothers' characteristics. Before controlling for mothers' health status, we find a strong negative impact of migration on health, particularly for children moving to rural areas or cities, and children moving due to changes in mothers' marital status. After controlling for mothers' health status, however, the negative impact of migration on child health disappears. We also find that child health is worse with longer durations spent in post-migration residence, compared to children who don't move.

Recumbent stepping aerobic exercise in amyotrophic lateral sclerosis: a pilot study

OBJECTIVES

Aerobic exercise can promote neuroplastic responses in the healthy and injured brain. Although the role of exercise in amyotrophic lateral sclerosis (ALS) is debated, new evidence suggests that exercise may reduce disease progression. While common exercise modalities such as the treadmill and cycle ergometer have been explored in ALS, the safety and feasibility of a total body recumbent stepper have not been investigated. Additionally, the functional and neurophysiological effects of recumbent stepping in ALS are still unknown. Here, we investigated the safety and feasibility of a 4-week recumbent stepping program to slow disease progression in ALS and possibly facilitate neuroplasticity.

METHOD

Nine individuals with ALS performed moderate intensity recumbent stepping for four weeks. Outcomes included participation satisfaction questionnaire, ALS Functional Rating Scale Revised (ALSFRS-R), clinical tests of walking and endurance, fatigue severity scale, Beck depression inventory, SF-12, and transcranial magnetic stimulation-induced motor evoked potentials (MEPs). All measurements were collected at baseline, post-intervention, and at the 1-month follow-up.

RESULTS

Eight participants completed the study without any adverse events. The ALSFRS-R scores were similar at the end of the study and at follow-up. No significant differences were noted for any of the clinical outcomes. MEPs were present only in two participants and changes in corticomotor excitability after exercise were minimal.

CONCLUSIONS

Results from this preliminary study support the safety and feasibility of 12 sessions of total body recumbent stepping in individuals with ALS.

Concurrent validity of the GAITRite electronic walkway and the 10-m walk test for measurement of walking speed after stroke

BACKGROUND

Walking speed is used to assess functional status, predict recovery, prescribe exercise, and track functional progress after stroke. Determining concurrent validity ensures that results from different tests of walking speed can be compared or used interchangeably. The GAITRite electronic walkway and the 10-m walk test (10MWT) are popular measurement tools of walking speed in the laboratory and in clinical settings, respectively.

RESEARCH QUESTION

Do walking speeds in chronic stroke survivors measured with the 10-m walk test and GAITRite electronic walkway demonstrate concurrent validity?

METHODS

77 participants with chronic stroke performed four trials of 10MWT and four trials of GAITRite-two trials at comfortable walking speed and two trials at maximal walking speed. Intraclass correlations [ICC (3,1), absolute agreement] and Bland-Altman plots were used to assess the relationship between gait speed from these two measures.

RESULTS

Walking speed showed poor to good absolute agreement between 10MWT and GAITRite for comfortable walking speed [ICC: 0.77 (95% CI: 0.46, 0.89; P < 0.001)] and excellent absolute agreement for maximal walking speed [ICC: 0.94 (95% CI: 0.91, 0.96; P < 0.001)]. Mean difference value (systematic bias) was different from 0 for comfortable walking [10MWT was faster; P < 0.001 (95% CI: 0.05, 0.10)] but not for maximal walking [P = 0.16 (95% CI: -0.01, 0.04)]. Limits of agreement were broad (comfortable walking speed, 0.43; maximal walking speed, 0.37), and there was proportional bias at both speeds whereby participants who walked faster tended to have a faster walking speed during 10MWT vs. GAITRite (comfortable walking speed, R² = 0.22, P < 0.001; maximal walking speed, R² = 0.08, P = 0.01).

SIGNIFICANCE

Systematic bias, proportional bias, and broad limits of agreement suggest that caution should be used when comparing walking speeds from 10MWT and GAITRite. It may not be appropriate to use them interchangeably. Conducting 10MWT and GAITRite tests at maximal walking speeds may allow more accurate comparisons between measures.

Stride management assist exoskeleton vs functional gait training in stroke: A randomized trial

OBJECTIVE

To test the hypothesis that gait training with a hip-assistive robotic exoskeleton improves clinical outcomes and strengthens the descending corticospinal drive to the lower limb muscles in persons with chronic stroke.

METHODS

Fifty participants completed the randomized, single-blind, parallel study. Participants received over-ground gait training with the Honda Stride Management Assist (SMA) exoskeleton or intensity-matched functional gait training, delivered in 18 sessions over 6-8 weeks. Performance-based and self-reported clinical outcomes were measured at baseline, midpoint, and completion, and at a 3-month follow-up. Corticomotor excitability (CME) of 3 bilateral leg muscles was measured using transcranial magnetic stimulation.

RESULTS

The primary outcome, walking speed, improved for the SMA group by completion of the program (0.24 ± 0.14 m/s difference, p < 0.001). Compared to the functional group, SMA users had greater improvement in walking endurance (46.0% ± 27.4% vs 35.7% ± 20.8%, p = 0.033), took more steps during therapy days (4,366 ± 2,426 vs 3,028 ± 1,510; p = 0.013), and demonstrated larger changes in CME of the paretic rectus femoris (178% ± 75% vs 33% ± 32%, p = 0.010). Participants with hemorrhagic stroke demonstrated greater improvement in balance when using the SMA (24.7% ± 20% vs 6.8% ± 6.7%, p = 0.029).

CONCLUSIONS

Gait training with the SMA improved walking speed in persons with chronic stroke, and may promote greater walking endurance, balance, and CME than functional gait training.

CLINICALTRIALSGOV IDENTIFIER

NCT01994395.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that gait training with a hip-assistive exoskeleton increases clinical outcomes and CME in persons with chronic stroke, but does not significantly improve walking speeds compared to intensity-matched functional gait training.

Gendered Emotional Support and Women's Well-Being in a Low-Income Urban African Setting

Emotional support is crucial to the well-being of low-income, single women and their children in most contexts. Support from women may be especially important for single mothers because of precarious ties to their children's fathers, the prevalence of extended matrifocal living arrangements, and gendered norms that place men as providers of financial rather than emotional support. However, in contexts marked by economic insecurity, spatial dispersion of families, and changing gender norms and kinship obligations, such an expectation may be problematic. Applying theories of emotional capital and family bargaining processes, we address three questions: 1) what is the gender composition of emotional support that single mothers receive? 2) how does gender composition change over time? and 3) does the gender composition of emotional support affect self-reported stress of single mothers? Drawing on data from a unique dataset on 462 low-income single mothers and their kin from Nairobi, Kenya, we uncover three key findings. One, whereas the bulk of strong emotional support comes from female kin, about 20% of respondents report having male dominant support networks. Two, nearly 30% of respondents report change in the composition of their emotional support over six months favoring men. Three, having a male dominant emotional support network is associated with lower stress. These results challenge what is commonly taken for granted about gender norms and kinship obligations in non-Western contexts.