Improvements in spatiotemporal outcomes, but not in recruitment of automatic postural responses, are correlated with improved step quality following perturbation-based balance training in chronic stroke.

Introduction: People with stroke often exhibit balance impairments, even in the chronic phase. Perturbation-based balance training (PBT) is a therapy that has yielded promising results in healthy elderly and several patient populations. Here, we present a threefold approach showing changes in people with chronic stroke after PBT on the level of recruitment of automatic postural responses (APR), step parameters and step quality. In addition, we provide insight into possible correlations across these outcomes and their changes after PBT. Methods: We performed a complementary analysis of a recent PBT study. Participants received a 5-week PBT on the Radboud Fall simulator. During pre- and post-intervention assessments participants were exposed to platform translations in forward and backward directions. We performed electromyography of lower leg muscles to identify changes in APR recruitment. In addition, 3D kinematic data of stepping behavior was collected. We determined pre-post changes in muscle onset, magnitude and modulation of recruitment, step characteristics, and step quality. Subsequently, we determined whether improvements in step or muscle characteristics were correlated with improved step quality. Results: We observed a faster gastrocnemius muscle onset in the stance and stepping leg during backward stepping. During forward stepping we found a trend toward a faster tibialis anterior muscle onset in the stepping leg. We observed no changes in modulation or magnitude of muscle recruitment. Leg angles improved by 2.3° in forward stepping and 2.5° in backward stepping. The improvement in leg angle during forward stepping was accompanied by a -4.1°change in trunk angle, indicating a more upright position. Step length, duration and velocity improved in both directions. Changes in spatiotemporal characteristics were strongly correlated with improvements in leg angle, but no significant correlations were observed of muscle onset or recruitment with leg or trunk angle. Conclusion: PBT leads to a multi-factorial improvement in onset of APR, spatiotemporal characteristics of stepping, and reactive step quality in people with chronic stroke. However, current changes in APR onset were not correlated with improvement in step quality. Therefore, we suggest that, in addition to spatiotemporal outcomes, other characteristics of muscle recruitment or behavioral substitution may induce step quality improvement after PBT.

[Heterotopic ossifications after COVID-19 pneumonia]. / Heterotope ossificatie na een covid-19-pneumonie.

COVID-19 patients admitted to the Intensive Care Unit may develop painful range of motion restrictions of the large joints due to heterotopic ossifications. Here we describe two patients who developed restricted and painful passive and active mobility of the hips, shoulders and elbows after mechanical ventilation because of respiratory failure due to COVID-19 pneumonia. Conventional radiography showed extensive heterotopic ossifications. Retrospectively, alkaline phosphatase levels were elevated. It is likely that local and systemic factors contribute to the development of heterotopic ossifications. Early diagnosis is important to provide complementary non-pharmacological interventions (gentle passive mobilization) and medication (non-steroidal anti-inflammatory drugs, such as indomethacin). If pain and limited joint mobility remain present, surgical removal of ectopic bone could be considered. Future trials are needed to systematically map the prevalence of heterotopic ossifications in COVID-19 patients who were admitted to the Intensive Care Unit, andto evaluate whether prophylactic treatment with non-steroidal anti-inflammatory drug is of relevance.

Tarsal fusion for pes equinovarus deformity improves gait capacity in chronic stroke patients.

BACKGROUND: Gait impairments are common and disabling in chronic stroke patients. Pes equinovarus deformity is one of the primary motor deficits underlying reduced gait capacity after stroke. It predisposes to stance-phase instability and subsequent ankle sprain or falls. This instability is most pronounced when walking barefoot. Tarsal fusion is a recommended treatment option for varus deformity, but scientific evidence is sparse. We therefore evaluated whether a tarsal fusion improved barefoot walking capacity in chronic stroke patients with pes equinovarus deformity. METHODS: Ten patients with a pes equinovarus deformity secondary to supratentorial stroke underwent surgical correction involving a tarsal fusion of one or more joints. Instrumented gait analysis was performed pre- and postoperatively using a repeated-measures design. Primary outcome measure was gait speed. RESULTS: Walking speed significantly improved by 32% after surgery (0.38 m/s ± 0.20 to 0.50 m/s ± 0.17, p = 0.007). Significant improvement was also observed when looking at cadence (p = 0.028), stride length (p = 0.016), and paretic step length (p = 0.005). Step length on the nonparetic side did not change. Peak ankle moment increased significantly on the nonparetic side (p = 0.021), but not on the paretic side (p = 0.580). In addition, functional ambulation scores increased significantly (p = 0.008), as did satisfaction with gait performance (p = 0.017). CONCLUSIONS: Tarsal fusion for equinovarus deformity in chronic stroke patients improves gait capacity, and the degree of improvement is of clinical relevance. Our results suggest that the improved gait capacity may be related to better prepositioning and loading of the paretic foot, leading to larger paretic step length and nonparetic ankle kinetics.

Perturbation-Based Balance Training to Improve Step Quality in the Chronic Phase After Stroke: A Proof-of-Concept Study.

Introduction: People with stroke often have impaired stepping responses following balance perturbations, which increases their risk of falling. Computer-controlled movable platforms are promising tools for delivering perturbation-based balance training under safe and standardized circumstances. Purpose: This proof-of-concept study aimed to identify whether a 5-week perturbation-based balance training program on a movable platform improves reactive step quality in people with chronic stroke. Materials and Methods: Twenty people with chronic stroke received a 5-week perturbation-based balance training (10 sessions, 45 min) on a movable platform. As the primary outcome, backward, and forward reactive step quality (i.e., leg angle at stepping-foot contact) was assessed with a lean-and-release (i.e., non-trained) task at pre-intervention, immediately post-intervention, and 6 weeks after intervention (follow-up). Additionally, reactive step quality was assessed on the movable platform in multiple directions, as well as, the percentage side steps upon sideward perturbations. To ensure that changes in the primary outcome could not solely be attributed to learning effects on the task due to repeated testing, 10 randomly selected participants received an additional pre-intervention assessment, 6 weeks prior to training. Clinical assesments included the 6-item Activity-specific Balance Confidence (6-ABC) scale, Berg Balance Scale (BBS), Trunk Impairment Scale (TIS), 10-Meter Walking Test (10-MWT), and Timed Up and Go-test (TUG). Results: After lean-and-release, we observed 4.3° and 2.8° greater leg angles at post compared to pre-intervention in the backward and forward direction, respectively. Leg angles also significantly improved in all perturbation directions on the movable platform. In addition, participants took 39% more paretic and 46% more non-paretic side steps. These effects were retained at follow-up. Post-intervention, BBS and TIS scores had improved. At follow-up, TIS and 6-ABC scores had significantly improved compared to pre-intervention. No significant changes were observed between the two pre-intervention assessments (n=10). Conclusion: A 5-week perturbation-based balance training on a movable platform appears to improve reactive step quality in people with chronic stroke. Importantly, improvements were retained after 6 weeks. Further controlled studies in larger patient samples are needed to verify these results and to establish whether this translates to fewer falls in daily life. Trial registration: The Netherlands National Trial Register (NTR3804). http://www.trialregister.nl/trialreg/admin/rctview.aspTC=3804.

Management of Gait Impairments in Chronic Unilateral Upper Motor Neuron Lesions: A Review.

Importance: Gait impairments are common in patients with chronic supratentorial upper motor neuron lesions and are a source of disability. Clinical management aimed at improving the gait pattern in these patients is generally perceived as a challenging task because many possible abnormalities may interact. Moreover, a multitude of treatment options exist, ranging from assistive devices and muscle stretching to pharmacologic and surgical interventions, but evidence is inconclusive for most approaches and clear treatment guidelines are lacking. Observations: Gait deviations in adults with a chronic supratentorial upper motor neuron lesion can approximately be reduced to the following 3 groups of primary deficits: (1) imbalance of muscle strength, length, and activity around the ankle and tarsal joints leading to pes equinovarus or pes equinus; (2) calf muscle weakness; and (3) overactivity of proximal leg muscles. Conclusions and Relevance: A stepwise treatment algorithm emphasizes medical-technical interventions, which are based on evidence when available and otherwise reflect practice-based experience.

Effects of Exercise Therapy on Balance Capacity in Chronic Stroke: Systematic Review and Meta-Analysis.

BACKGROUND AND PURPOSE: The purpose of this systematic review and meta-analysis was to investigate the effects of exercise training on balance capacity in people in the chronic phase after stroke. Furthermore, we aimed to identify which training regimen was most effective. METHODS: Electronic databases were searched for randomized controlled trials evaluating the effects of exercise therapy on balance capacity in the chronic phase after stroke. Studies were included if they were of moderate or high methodological quality (PEDro score ≥4). Data were pooled if a specific outcome measure was reported in at least 3 randomized controlled trials. A sensitivity analysis and consequent subgroup analyses were performed for the different types of experimental training (balance and/or weight-shifting training, gait training, multisensory training, high-intensity aerobic exercise training, and other training programs). RESULTS: Forty-three randomized controlled trials out of 369 unique hits were included. A meta-analysis could be conducted for the Berg Balance Scale (28 studies, n=985), Functional Reach Test (5 studies, n=153), Sensory Organization Test (4 studies, n=173), and mean postural sway velocity (3 studies, n=89). A significant overall difference in favor of the intervention group was found for the Berg Balance Scale (mean difference 2.22 points (+3.9%); 95% confidence interval [CI], 1.26-3.17; P<0.01; I(2)=52%), Functional Reach Test (mean difference=3.12 cm; 95% CI, 0.90-5.35; P<0.01; I(2)=74%), and Sensory Organization Test (mean difference=6.77 (+7%) points; 95% CI, 0.83-12.7; P=0.03; I(2)=0%). Subgroup analyses of the studies that included Berg Balance Scale outcomes demonstrated a significant improvement after balance and/or weight-shifting training of 3.75 points (+6.7%; 95% CI, 1.71-5.78; P<0.01; I(2)=52%) and after gait training of 2.26 points (+4.0%; 95% CI, 0.94-3.58; P<0.01; I(2)=21, whereas no significant effects were found for other training regimens. CONCLUSIONS: This systematic review and meta-analysis showed that balance capacities can be improved by well-targeted exercise therapy programs in the chronic phase after stroke. Specifically, balance and/or weight-shifting and gait training were identified as successful training regimens.

Deficits in motor response to avoid sudden obstacles during gait in functional walkers poststroke.

BACKGROUND: Safe community ambulation requires the capacity to adapt gait to environmental changes on short notice. Reduced adaptability may contribute to an increased risk for falls. OBJECTIVE: This study investigated gait adaptability in community-dwelling persons poststroke and sought to understand some of the mechanisms of reduced adaptability. METHODS: Participants were 25 poststroke persons (Functional Ambulation Categories score 5) and 25 healthy controls of similar age. During treadmill walking, 30 obstacles were suddenly dropped in front of the affected leg or left leg of controls. The participants had to avoid the obstacle by either lengthening or shortening the ongoing stride. The obstacle avoidance success rates were determined. Electromyography activity of bilateral biceps femoris, rectus femoris, tibialis anterior, and gastrocnemius medialis muscles was recorded as well as concomitant knee and hip angle courses and spatial characteristics of the avoiding stride. RESULTS: Poststroke persons demonstrated markedly decreased obstacle avoidance success rates, most prominently under time pressure. They showed normal avoidance strategies but had delayed and reduced electromyography responses, smaller joint angle deviations from unperturbed walking, and smaller horizontal margins from the foot to the obstacle. CONCLUSIONS: Even in persons who were only mildly affected by stroke, gait adaptability may be reduced, which may place them at risk of falling. Delayed and decreased muscle responses were identified as one possible mechanism with diminished ability to adapt the length of the avoiding stride. Rehabilitation interventions could focus on these impairments.

Effect of peroneal electrical stimulation versus an ankle-foot orthosis on obstacle avoidance ability in people with stroke-related foot drop.

BACKGROUND: Walking ability of people with foot drop in the chronic phase after stroke is better with functional electrical stimulation (FES) of the peroneal nerve than without an orthotic device. However, the literature is not conclusive on whether peroneal FES also is better than an ankle-foot orthosis (AFO) in this regard. OBJECTIVE: This study aimed to identify potential benefits of peroneal FES over an AFO with respect to the ability to negotiate a sudden obstacle. DESIGN: The study design was a within-subject comparison between FES and AFO using repeated measures. METHODS: Twenty-four community-dwelling people with stroke (mean age=52.6 years, SD=12.7) who regularly used a polypropylene AFO were fitted with a transcutaneous FES device. The participants' obstacle avoidance ability was tested after 2 and 8 weeks. They had to avoid 30 obstacles that were suddenly dropped on a treadmill in front of the affected leg while walking with either FES or an AFO. The obstacle avoidance success rates were determined. RESULTS: Success rates were higher with FES than with an AFO, especially after adjustment for individual leg muscle strength. Participants with relatively low muscle strength (Motricity Index score <64) were most likely to benefit from FES regarding obstacle avoidance ability. LIMITATION: Further work is needed to determine whether the results may be generalized to other groups of people with stroke. CONCLUSIONS: Peroneal FES seems to be superior to an AFO with regard to obstacle avoidance ability in community-dwelling people with stroke. The observed gains in obstacle avoidance ability appear to be clinically most relevant in the people with relatively low leg muscle strength.

Kinematic analysis of head, trunk, and pelvis movement when people early after stroke reach sideways.

BACKGROUND: Sideways reaching with the unaffected arm while seated is a component of everyday activities and can be a challenging task early after stroke. Kinematic analysis of a lateral reach task may provide potential rehabilitation strategies. OBJECTIVE: The authors examined the difference between people with stroke and healthy controls in the movement sequence of head, trunk, and pelvis, as well as the difference in angle at maximum reach and peak velocity for each body segment during reach and return. METHODS: Twenty-four people within 12 weeks of a stroke and 20 healthy subjects performed a standardized lateral reach. Using CODAmotion, movement sequence was determined and angles and peak velocities were calculated. RESULTS: When reaching, people with stroke moved their pelvis first, followed by the trunk and head, whereas healthy controls started with their head and then moved their trunk and pelvis. Patients achieved significantly smaller angles at maximum reach compared with healthy subjects for all body segments and lower peak velocities during the reach (for head, trunk, and pelvis) and the return (for head and trunk). CONCLUSIONS: Lateral reaching to the unaffected side early after stroke revealed a different pattern than normal and patients reached less far and moved at a slower speed. Specific training strategies to improve reaching are needed.

Near-normal gait pattern with peroneal electrical stimulation as a neuroprosthesis in the chronic phase of stroke: a case report.

In recent years, the use of functional electrical stimulation (FES) of the peroneal nerve has increased as an alternative for an ankle-foot orthosis (AFO) to treat stroke-related drop foot. We present a chronic stroke patient demonstrating an almost normal gait pattern with peroneal FES as a neuroprosthesis. A 60-year-old survivor of a right hemisphere infarction 21 months ago, who regularly used a polypropylene AFO, was provided with a surface-based peroneal FES device for severe drop foot. In a second instance, he received an implanted FES system because of skin problems with the surface stimulator. With both FES devices, the patient achieved an adequate foot elevation. Moreover, his hip and knee flexion angles during walking increased to normal values and his ankle push-off power increased. His gait pattern became almost symmetrical and less variable than with the AFO. Furthermore, his ability to avoid a sudden obstacle improved to normal values with FES. Our patient showed benefits from peroneal FES beyond what can be attributed to improved foot lift alone. With regard to the potential working mechanisms underlying this response to FES, biomechanical benefits related to improved ankle push-off are suggested as the main mechanism.

The effects of an auditory startle on obstacle avoidance during walking.

Movement execution is speeded up when a startle auditory stimulus is applied with an imperative signal in a simple reaction time task experiment, a phenomenon described as StartReact. The effect has been recently observed in a step adjustment task requiring fast selection of specific movements in a choice reaction time task. Therefore, we hypothesized that inducing a StartReact effect may be beneficial in obstacle avoidance under time pressure, when subjects have to perform fast gait adjustments. Twelve healthy young adults walked on a treadmill and obstacles were released in specific moments of the step cycle. On average the EMG onset latency in the biceps femoris shortened by 20% while amplitude increased by 50%, in trials in which an auditory startle accompanied obstacle avoidance. The presentation of a startle increased the probability of using a long step strategy, enlarged stride length modifications and resulted in higher success rates, to avoid the obstacle. We also examined the effects of the startle in a condition in which the obstacle was not present in comparison to a condition in which the obstacle was visibly present but it did not fall. In the latter condition, the obstacle avoidance reaction occurred with a similar latency but smaller amplitude as in trials in which the obstacle was actually released. Our results suggest that the motor programmes used for obstacle avoidance are probably stored at subcortical structures. The release of these motor programmes by a startling auditory stimulus may combine intersensory facilitation and the StartReact effect.

Falls in individuals with stroke.

Stroke survivors are at high risk for falls in all poststroke stages. Falls may have severe consequences, both physically and psychosocially. Individuals with stroke have an increased risk for hip fractures, and after such a fracture, they less often regain independent mobility. In addition, fear of falling is a common consequence of falls, which may lead to decreased physical activity, social deprivation and, eventually, loss of independence. Important risk factors for falls are balance and gait deficits. Stroke-related balance deficits comprise reduced postural stability during quiet standing and delayed and less coordinated responses to both self-induced and external balance perturbations. Gait deficits include reduced propulsion at push-off, decreased hip and knee flexion during the swing phase, and reduced stability during the stance phase. Interventions addressing these deficits can be expected to prevent falls more successfully. Preliminary evidence shows that task-specific exercise programs targeting balance and gait deficits can indeed reduce the number of falls in individuals with stroke. Technological advances in assistive devices are another promising area. More research is needed, however, to provide conclusive evidence of the efficacy of these interventions regarding the prevention of falls in individuals with stroke.