Robotic-Assisted Gait Training (RAGT) in Stroke Rehabilitation: A Pilot Study.

Objective: To compare the effects of 2 types of robotic-assisted gait training (RAGT) devices that have been used in stroke rehabilitation. Design: Retrospective cohort. Setting: Rehabilitation hospital. Participants: 24 community dwelling people with stroke (N=24). Interventions: RAGT with either an exoskeleton (Lokomat) (mean age=53.8 years; 30% men; mean duration of stroke =17.8 months) or an end-effector (G-EO) (mean age=50.5 years; 77.8% men; mean duration of stroke =13.11) delivered 3 times per week (36 sessions total). Main Outcome Measures: The following tests/scales were employed before and after RAGT: Functional Ambulation Categories (FACs), timed Up and Go (TUG), 10-Meter Walk Test (10MWT), 6-Minute Walk Test (6MWT), Trunk Impairment Scale, Dynamic Gait Index (DGI), Berg Balance Scale (BBS), and ability to climb stairs (time to climb 6 steps of 15 cm each; ability to climb stairs). Results: There were 5 dropouts, all from the G-EO group. At the end, 10 participants in the Lokomat and 9 in the G-EO group completed the intervention. From pre- to post-RAGT, G-EO patients improved on all functional tests/scales, whereas Lokomat patients improved only on the TUG, DGI, and BBS. Most patients showed improvements above the relative smallest real difference in the TUG, 10MWT, and 6MWT. Conclusions: Both end-effectors and exoskeletons may improve clinically relevant aspects of walking function. However, this study had a small sample, was retrospective, non-randomized, and had a significant number of drop-outs, therefore its findings should be interpreted carefully. Future studies are needed for investigating potential differences in clinical results, side effects, contraindications, and cost effectiveness between these 2 different types of RAGT.

The Applicability of Standard Error of Measurement and Minimal Detectable Change to Motor Learning Research-A Behavioral Study.

Motor learning studies face the challenge of differentiating between real changes in performance and random measurement error. While the traditional p-value-based analyses of difference (e.g., t-tests, ANOVAs) provide information on the statistical significance of a reported change in performance scores, they do not inform as to the likely cause or origin of that change, that is, the contribution of both real modifications in performance and random measurement error to the reported change. One way of differentiating between real change and random measurement error is through the utilization of the statistics of standard error of measurement (SEM) and minimal detectable change (MDC). SEM is estimated from the standard deviation of a sample of scores at baseline and a test-retest reliability index of the measurement instrument or test employed. MDC, in turn, is estimated from SEM and a degree of confidence, usually 95%. The MDC value might be regarded as the minimum amount of change that needs to be observed for it to be considered a real change, or a change to which the contribution of real modifications in performance is likely to be greater than that of random measurement error. A computer-based motor task was designed to illustrate the applicability of SEM and MDC to motor learning research. Two studies were conducted with healthy participants. Study 1 assessed the test-retest reliability of the task and Study 2 consisted in a typical motor learning study, where participants practiced the task for five consecutive days. In Study 2, the data were analyzed with a traditional p-value-based analysis of difference (ANOVA) and also with SEM and MDC. The findings showed good test-retest reliability for the task and that the p-value-based analysis alone identified statistically significant improvements in performance over time even when the observed changes could in fact have been smaller than the MDC and thereby caused mostly by random measurement error, as opposed to by learning. We suggest therefore that motor learning studies could complement their p-value-based analyses of difference with statistics such as SEM and MDC in order to inform as to the likely cause or origin of any reported changes in performance.

Application of Transcranial Direct Current Stimulation in Neurorehabilitation: The Modulatory Effect of Sleep.

The relationship between sleep disorders and neurological disorders is often reciprocal, such that sleep disorders are worsened by neurological symptoms and that neurological disorders are aggravated by poor sleep. Animal and human studies further suggest that sleep disruption not only worsens single neurological symptoms but may also lead to long-term negative outcomes. This suggests that sleep may play a fundamental role in neurorehabilitation and recovery. We further propose that sleep may not only alter the efficacy of behavioral treatments but also plasticity-enhancing adjunctive neurostimulation methods, such as transcranial direct current stimulation (tDCS). At present, sleep receives little attention in the fields of neurorehabilitation and neurostimulation. In this review, we draw together the strands of evidence from both fields of research to highlight the proposition that sleep is an important parameter to consider in the application of tDCS as a primary or adjunct rehabilitation intervention.

Upper Limb Immobilisation: A Neural Plasticity Model with Relevance to Poststroke Motor Rehabilitation.

Advances in our understanding of the neural plasticity that occurs after hemiparetic stroke have contributed to the formulation of theories of poststroke motor recovery. These theories, in turn, have underpinned contemporary motor rehabilitation strategies for treating motor deficits after stroke, such as upper limb hemiparesis. However, a relative drawback has been that, in general, these strategies are most compatible with the recovery profiles of relatively high-functioning stroke survivors and therefore do not easily translate into benefit to those individuals sustaining low-functioning upper limb hemiparesis, who otherwise have poorer residual function. For these individuals, alternative motor rehabilitation strategies are currently needed. In this paper, we will review upper limb immobilisation studies that have been conducted with healthy adult humans and animals. Then, we will discuss how the findings from these studies could inspire the creation of a neural plasticity model that is likely to be of particular relevance to the context of motor rehabilitation after stroke. For instance, as will be elaborated, such model could contribute to the development of alternative motor rehabilitation strategies for treating poststroke upper limb hemiparesis. The implications of the findings from those immobilisation studies for contemporary motor rehabilitation strategies will also be discussed and perspectives for future research in this arena will be provided as well.

Cardiac Hypertrophy Is Inhibited by a Local Pool of cAMP Regulated by Phosphodiesterase 2.

RATIONALE: Chronic elevation of 3'-5'-cyclic adenosine monophosphate (cAMP) levels has been associated with cardiac remodeling and cardiac hypertrophy. However, enhancement of particular aspects of cAMP/protein kinase A signaling seems to be beneficial for the failing heart. cAMP is a pleiotropic second messenger with the ability to generate multiple functional outcomes in response to different extracellular stimuli with strict fidelity, a feature that relies on the spatial segregation of the cAMP pathway components in signaling microdomains. OBJECTIVE: How individual cAMP microdomains affect cardiac pathophysiology remains largely to be established. The cAMP-degrading enzymes phosphodiesterases (PDEs) play a key role in shaping local changes in cAMP. Here we investigated the effect of specific inhibition of selected PDEs on cardiac myocyte hypertrophic growth. METHODS AND RESULTS: Using pharmacological and genetic manipulation of PDE activity, we found that the rise in cAMP resulting from inhibition of PDE3 and PDE4 induces hypertrophy, whereas increasing cAMP levels via PDE2 inhibition is antihypertrophic. By real-time imaging of cAMP levels in intact myocytes and selective displacement of protein kinase A isoforms, we demonstrate that the antihypertrophic effect of PDE2 inhibition involves the generation of a local pool of cAMP and activation of a protein kinase A type II subset, leading to phosphorylation of the nuclear factor of activated T cells. CONCLUSIONS: Different cAMP pools have opposing effects on cardiac myocyte cell size. PDE2 emerges as a novel key regulator of cardiac hypertrophy in vitro and in vivo, and its inhibition may have therapeutic applications.

Influence of the hip flexion angle on isokinetic hip rotator torque and acceleration time of the hip rotator muscles.

The purpose of this study was to verify the influence of the hip flexion angle on isokinetic rotator torque and acceleration times of the hip medial and lateral rotator muscles. Twenty-one healthy women were included in this study. The hip rotator function was evaluated at 3 different hip flexion angles (10°, 40°, and 90°). The results showed that both eccentric and concentric hip lateral rotator torques were greater at 40° of hip flexion when compared with 90°. Moreover, both the eccentric and concentric hip medial rotator torques were greater at 90° of hip flexion than at 40° and 10°, and greater at 40° than at 10°. In addition, both the eccentric and concentric hip medial to lateral rotator torque ratios were greater at 90° of hip flexion than at 40° and 10°, and greater at 40° than at 10°. Finally, the acceleration times of the hip medial rotator muscles were smaller at 90° of hip flexion than at 10° and smaller at 40° than at 10°. The current results highlight the importance of evaluating the hip rotator muscles at different hip flexion angles to comprehensively assess their functions.

Gender differences in lower limb kinematics during stair descent.

The purpose of this study was to compare lower limb kinematics between genders during stair descent. Fifteen females and fifteen males who were healthy and active were included in this study. The lower limb kinematics (pelvis, femur and knee) in the coronal and transversal planes were assessed during stair descent at 30°, 40°, 50° and 60° of knee flexion. The study found that females showed greater knee medial rotation for all the knee flexion angles (P = .02-.001), greater femoral adduction (P = .01 for all variables), with exception for 30° (P = .13), and greater femoral lateral rotation at 60° (P = .04). Females also showed a trend to have greater knee valgus at all the knee flexion angles (P = .06-.11) as well as less contralateral pelvis elevation at 50° and 60° (P = .10 and .12, respectively). This study showed that females carry out the stair descent with a lower limb alignment that might predispose them to develop overuse knee injuries, such as the iliotibial band syndrome and patellofemoral pain syndrome. Further prospective investigations should be carried out to verify whether these variables are factors that could predict these knee injuries.