Shaping corticospinal pathways in virtual reality: effects of task complexity and sensory feedback during mirror therapy in neurologically intact individuals.

BACKGROUND: Restoration of limb function for individuals with unilateral weakness typically requires volitional muscle control, which is often not present for individuals with severe impairment. Mirror therapy-interventions using a mirror box to reflect the less-impaired limb onto the more-impaired limb-can facilitate corticospinal excitability, leading to enhanced recovery in severely impaired clinical populations. However, the mirror box applies limitations on mirror therapy, namely that all movements appear bilateral and are confined to a small area, impeding integration of complex activities and multisensory feedback (e.g., visuo-tactile stimulation). These limitations can be addressed with virtual reality, but the resulting effect on corticospinal excitability is unclear. OBJECTIVE: Examine how virtual reality-based unilateral mirroring, complex activities during mirroring, and visuo-tactile stimulation prior to mirroring affect corticospinal excitability. MATERIALS AND METHODS: Participants with no known neurological conditions (n = 17) donned a virtual reality system (NeuRRoVR) that displayed a first-person perspective of a virtual avatar that matched their motions. Transcranial magnetic stimulation-induced motor evoked potentials in the nondominant hand muscles were used to evaluate corticospinal excitability in four conditions: resting, mirroring, mirroring with prior visuo-tactile stimulation (mirroring + TACT), and control. During mirroring, the movements of each participant's dominant limb were reflected onto the nondominant limb of the virtual avatar, and the avatar's dominant limb was kept immobile (i.e., unilateral mirroring). The mirroring + TACT condition was the same as the mirroring condition, except that mirroring was preceded by visuo-tactile stimulation of the nondominant limb. During the control condition, unilateral mirroring was disabled. During all conditions, participants performed simple (flex/extend fingers) and complex (stack virtual blocks) activities. RESULTS: We found that unilateral mirroring increased corticospinal excitability compared to no mirroring (p < 0.001), complex activities increased excitability compared to simple activities during mirroring (p < 0.001), and visuo-tactile stimulation prior to mirroring decreased excitability (p = 0.032). We also found that these features did not interact with each other. DISCUSSIONS: The findings of this study shed light onto the neurological mechanisms of mirror therapy and demonstrate the unique ways in which virtual reality can augment mirror therapy. The findings have important implications for rehabilitation for design of virtual reality systems for clinical populations.

Rest the brain to learn new gait patterns after stroke.

BACKGROUND: The ability to relearn a lost skill is critical to motor recovery after a stroke. Previous studies indicate that stroke typically affects the processes underlying motor control and execution but not the learning of those skills. However, these studies could be confounded by the presence of significant motor impairments. Furthermore, prior research involving the upper extremity indicates that stroke survivors have an advantage in offline motor learning when compared with controls. However, this has not been examined using motor acuity tasks (i.e., tasks focusing on the quality of executed actions) that have direct functional relevance to rehabilitation. OBJECTIVE: Investigate how stroke affects leg motor skill learning during walking in stroke survivors. METHODS: Twenty-five participants (10 stroke; 15 controls) were recruited for this prospective, case-control study. Participants learned a novel foot-trajectory tracking task on two consecutive days while walking on a treadmill. The task necessitated greater hip and knee flexion during the swing phase of the gait. Online learning was measured by comparing tracking error at the beginning and end of each practice session, offline (rest-driven) learning was measured by comparing the end of the first practice session to the beginning of the second, and retention was measured by comparing the beginning of the first practice session to the beginning of the second. Online learning, offline learning, and retention were compared between the stroke survivors and uninjured controls. RESULTS: Stroke survivors improved their tracking performance on the first day (p = 0.033); however, the amount of learning in stroke survivors was lower in comparison with the control group on both days (p ≤ 0.05). Interestingly, stroke survivors showed higher offline learning gains when compared with uninjured controls (p = 0.011). CONCLUSIONS: Even stroke survivors with no perceivable motor impairments have difficulty acquiring new motor skills related to walking, which may be related to the underlying neural damage caused at the time of stroke. Furthermore, stroke survivors may require longer training with adequate rest to acquire new motor skills.

Multiple Chronic Conditions Explain Ethnic Differences in Functional Outcome Among Patients With Ischemic Stroke.

BACKGROUND AND PURPOSE: Mexican Americans (MAs) have worse stroke outcomes and a different profile of multiple chronic conditions (MCC) compared with non-Hispanic White people. MCC has implications for stroke treatment, complications, and poststroke care, which impact poststroke functional outcome (FO). We sought to assess the contribution of MCC to the ethnic difference in FO at 90 days between MAs and non-Hispanic White people. METHODS: In a prospective cohort of ischemic stroke patients (2008-2016) from Nueces County, Texas, data were collected from patient interviews, medical records, and hospital discharge data. MCC was assessed using a stroke-specific and function-relevant index (range, 0-35; higher scores greater MCC burden). Poststroke FO was measured by an average score of 22 activities of daily living (ADLs) and instrumental ADLs at 90 days (range, 1-4; higher scores worse FO). The contribution of MCC to the ethnic difference in FO was assessed using Tobit regression. Effect modification by ethnicity was examined. RESULTS: Among the 896 patients, 70% were MA and 51% were women. Mean age was 68±12.2 years; 33% of patients were dependent in ADL/instrumental ADLs (FO score >3, representing a lot of difficulty with ADL/instrumental ADLs) at 90 days. MAs had significantly higher age-adjusted MCC burden compared with non-Hispanic White people. Patients with high MCC score (at the 75th percentile) on average scored 0.70 points higher in the FO score (indicating worse FO) compared with those with low MCC score (at the 25th percentile) after adjusting for age, initial National Institutes of Health Stroke Scale, and sociodemographic factors. MCC explained 19% of the ethnic difference in FO, while effect modification by ethnicity was not statistically significant. CONCLUSIONS: MAs had a higher age-adjusted MCC burden, which partially explained the ethnic difference in FO. The prevention and treatment of MCC could potentially mitigate poststroke functional impairment and lessen ethnic disparities in stroke outcomes.

Multiple Chronic Conditions and Functional Outcome after Ischemic Stroke: A Systematic Review and Meta-Analysis.

BACKGROUND: Multiple chronic conditions (MCC) contribute to functional disability in the general population although its role in predicting functional outcome (FO) among patients with stroke is not well understood. There is no universal agreement on the approach to measuring MCC in stroke, and findings have been mixed regarding MCC being an independent predictor for poststroke FO. OBJECTIVES: This review aims to summarize the findings of studies that have investigated the relationship between MCC and FO after ischemic stroke using a MCC index. METHOD: PubMed and Embase were systematically searched for studies conducted among ischemic stroke patients that have examined the adjusted association between prestroke MCC and FO. The quality of the included studies was appraised using a risk of bias (RoB) assessment checklist. A meta-analysis was performed for the association between MCC and FO using a random effects model to estimate the overall pooled ORs. RESULTS: Twelve of the 18 studies included were hospital-based cohort studies, with a median RoB score of 4.75 points (range 1-9, higher scores for higher RoB). Studies predominantly used the Charlson Comorbidity Index (CCI), or the Modified CCI to measure MCC burden, and the modified Rankin scale to measure FO. Half of the studies reported a significant negative association between MCC and FO, which was also found by the meta-analysis with a pooled OR of 1.11 (95% CI 1.05-1.18). CONCLUSIONS: The current review supports that increased MCC is associated with worse poststroke FO although population-based studies of this association are lacking. Future research should aim to develop more refined measures of MCC that consider the severity and interactions of comorbid conditions reflective of the broader stroke population and to understand the relationship between MCC and poststroke FO with thorough adjustment for confounding factors.

Reliability and minimal detectable change of stiffness and other mechanical properties of the ankle joint in standing and walking.

BACKGROUND: Ankle joint stiffness and viscosity are fundamental mechanical descriptions that govern the movement of the body and impact an individual's walking ability. Hence, these internal properties of a joint have been increasingly used to evaluate the effects of pathology (e.g., stroke) and in the design and control of robotic and prosthetic devices. However, the reliability of these measurements is currently unclear, which is important for translation to clinical use. RESEARCH QUESTION: Can we reliably measure the mechanical impedance parameters of the ankle while standing and walking? METHODS: Eighteen able-bodied individuals volunteered to be tested on two different days separated by at least 24 h. Participants received several small random ankle dorsiflexion perturbations while standing and during the stance phase of walking using a custom-designed robotic platform. Three-dimensional motion capture cameras and a 6-component force plate were used to quantify ankle joint motions and torque responses during normal and perturbed conditions. Ankle mechanical impedance was quantified by computing participant-specific ensemble averages of changes in ankle angle and torque due to perturbation and fitting a second-order parametric model consisting of stiffness, viscosity, and inertia. The test-retest reliability of each parameter was assessed using intraclass correlation coefficients (ICCs). We also computed the minimal detectable change (MDC) for each impedance parameter to establish the smallest amount of change that falls outside the measurement error of the instrument. RESULTS: In standing, the reliability of stiffness, viscosity, and inertia was good to excellent (ICCs=0.67-0.91). During walking, the reliability of stiffness and viscosity was good to excellent (ICCs=0.74-0.84) while that of inertia was fair to good (ICCs=0.47-0.68). The MDC for a single subject ranged from 20%- 65% of the measurement mean but was higher (>100%) for inertia during walking. SIGNIFICANCE: Results indicate that dynamic measures of ankle joint impedance were generally reliable and could serve as an adjunct clinical tool for evaluating gait impairments.

Rest the Brain to Learn New Gait Patterns after Stroke.

Background: The ability to relearn a lost skill is critical to motor recovery after a stroke. Previous studies indicate that stroke typically affects the processes underlying motor control and execution but not the learning of those skills. However, these prior studies could have been confounded by the presence of significant motor impairments and/or have not focused on motor acuity tasks (i.e., tasks focusing on the quality of executed actions) that have direct functional relevance to rehabilitation. Methods: Twenty-five participants (10 stroke; 15 controls) were recruited for this prospective, case-control study. Participants learned a novel foot-trajectory tracking task on two consecutive days while walking on a treadmill. On day 1, participants learned a new gait pattern by performing a task that necessitated greater hip and knee flexion during the swing phase of the gait. On day 2, participants repeated the task with their training leg to test retention. An average tracking error was computed to determine online and offline learning and was compared between stroke survivors and uninjured controls. Results: Stroke survivors were able to improve their tracking performance on the first day (p=0.033); however, the amount of learning in stroke survivors was lower in comparison with the control group on both days (p≤0.05). Interestingly, the offline gains in motor learning were higher in stroke survivors when compared with uninjured controls (p=0.011). Conclusions: The results suggest that even high-functioning stroke survivors may have difficulty acquiring new motor skills related to walking, which may be related to the underlying neural damage caused at the time of stroke. Furthermore, it is likely that stroke survivors may require longer training with adequate rest to acquire new motor skills, and rehabilitation programs should target motor skill learning to improve outcomes after stroke.

Teaching Motor Skills Without a Motor: A Semi-Passive Robot to Facilitate Learning.

Semi-passive rehabilitation robots resist and steer a patient's motion using only controllable passive force elements (e.g., controllable brakes). Contrarily, passive robots use uncontrollable passive force elements (e.g., springs), while active robots use controllable active force elements (e.g., motors). Semi-passive robots can address cost and safety limitations of active robots, but it is unclear if they have utility in rehabilitation. Here, we assessed if a semi-passive robot could provide haptic guidance to facilitate motor learning. We first performed a theoretical analysis of the robot's ability to provide haptic guidance, and then used a prototype to perform a motor learning experiment that tested if the guidance helped participants learn to trace a shape. Unlike prior studies, we minimized the confounding effects of visual feedback during motor learning. Our theoretical analysis showed that our robot produced guidance forces that were, on average, 54° from the current velocity (active devices achieve 90). Our motor learning experiment showed, for the first time, that participants who received haptic guidance during training learned to trace the shape more accurately (97.57% error to 52.69%) than those who did not receive guidance (81.83% to 78.18%). These results support the utility of semi-passive robots in rehabilitation.

How Does Ankle Mechanical Stiffness Change as a Function of Muscle Activation in Standing and During the Late Stance of Walking?

OBJECTIVE: Ankle joint stiffness is known to be modulated by co-contraction of the ankle muscles; however, it is unclear to what extent changes in agonist muscle activation alone affect ankle joint stiffness. This study tested the effects of varying levels of ankle muscle activation on ankle joint mechanical stiffness in standing and during the late stance phase of walking. METHODS: Dorsiflexion perturbations were applied at various levels of ankle muscle activation via a robotic platform in standing and walking conditions. In standing, muscle activation was modulated by having participants perform an EMG target matching task that required varying levels of plantarflexor activation. In walking, muscle activation was modulated by changing walking speeds through metronome-based auditory feedback. Ankle stiffness was evaluated by performing a Least-squares system identification using a parametric model consisting of stiffness, damping, and inertia. The association between ankle muscle activation and joint stiffness was evaluated using correlation analyses. Linear regression models were used to determine the extent to which muscle activation contributed to ankle stiffness. An inclusive statistical approach (both classical and Bayesian analyses) was adopted to measure the statistical significance (p-value) and Bayes Factor (BF10). RESULTS: Results indicate that plantarflexor activity was positively correlated with ankle stiffness in both standing and walking (p<0.001, BF10>900), whereas dorsiflexor activity was negatively correlated with ankle stiffness in walking (p = 0.014, BF10 = 3.9) but not in standing (p = 0.725). Regression analyses indicated that ankle muscle activation predicted about 84% of the variation in ankle stiffness in standing and 45% in walking (p<0.001, BF10>100). CONCLUSION: Ankle muscle activation significantly contributes to ankle stiffness during standing and walking. SIGNIFICANCE: The results highlight the role of muscle activation on maintaining joint stiffness and underscore the importance of accounting for muscle activation when measuring ankle stiffness in healthy as well as patient populations.

Functional decline in hospitalized patients with COVID-19 in the early months of the pandemic.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) survivors are at risk of functional decline. To address the current gap in knowledge about post-acute needs of those infected by COVID-19, we examined discharge function data to better prepare patients, providers, and health systems to return patients to optimal levels of functioning. OBJECTIVE: To examine the prevalence of functional decline and related rehabilitation needs at hospital discharge. DESIGN: Prospective chart review. SETTING: Academic tertiary care hospital. PARTICIPANTS: Hospitalized adults with a laboratory confirmed COVID-19 diagnosis, with admission dates between March 4, 2020 and May 1, 2020. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Discharge location; need for outpatient physical, occupational, or speech therapy; need for durable medical equipment at discharge; presence of dysphagia at discharge; functional decline. RESULTS: Three hundred eleven potential cases were reviewed. The final number of cases included in analysis was N = 288; patient ages ranged from 20 to 95 years old (mean 66.80 ± 15.31 years). Nearly 20 % of COVID-19 survivors were discharged to a location other than their home. Forty-five percent of survivors experienced functional decline impacting their discharge. Eighty-seven survivors (80.6%) who showed functional change during hospitalization were referred for additional therapy at discharge. At least 73 (67.6%) of these patients required durable medical equipment at discharge (in 12 cases this was not clearly documented). Twenty-nine (26.7%) of the survivors who showed functional changes had ongoing dysphagia at the time of hospital discharge. Ninety-seven of the survivors (40.6%) were never assessed by a PM&R physician, physical therapist, occupational therapist, or speech language pathologist during their hospitalization. CONCLUSIONS: COVID-19 mortality rates are frequently reported in the media, whereas the effects on function are not as well described. The information provided here highlights the need for rehabilitative services during and after hospitalization for COVID-19.

Hospitalized Patients With COVID-19 and Neurological Complications Experience More Frequent Decline in Functioning and Greater Rehabilitation Needs.

ABSTRACT: The coronavirus disease 2019 has been reported to cause various serious neurological sequelae. However, there is little information available about the impact of the disease and its complications on patients' functional status and their postacute needs. Hence, this study was performed to address the current gap in knowledge about the function and postacute needs of those with neurological complications of coronavirus disease 2019. A prospective chart review was completed for 319 patients admitted with coronavirus disease 2019 between March 4 and May 1, 2020. Primary outcomes included rate of new functional decline, discharge location, need for outpatient physical/occupational/speech therapy, need for durable medical equipment at discharge, and presence of dysphagia at discharge. Patients with neurological complications were compared with patients without neurological complications. Two hundred ninety-six cases were included in the final analysis, and 81 (27.4%) of these patients experienced neurological complications. Results indicated that hospitalized coronavirus disease 2019 patients with neurological complications exhibit a significantly longer length of stay, higher frequency of functional decline, higher mortality rate, and more frequent discharge to a subacute rehabilitation facility (all P < 0.0001). The findings of this study are expected to better prepare patients, providers, and health systems for the postacute needs of those with coronavirus disease 2019 and neurological complications.

Motor slacking during resisted treadmill walking: Can visual feedback of kinematics reduce this behavior?

BACKGROUND: Functional resistance training is frequently applied to rehabilitate individuals with neuromusculoskeletal injuries. It is performed by applying resistance in conjunction with a task-specific training, such as walking. However, the benefits of this training may be limited by motor slacking, a phenomenon in which the human body attempts to reduce muscle activation levels or movement excursions to minimize metabolic- or movement-related costs. While kinematic feedback could reduce one's tendency to minimize effort during training, this has not been verified experimentally. RESEARCH QUESTION: Does functional resistance training during walking lead to motor slacking, and can techniques such as visual feedback be used to reduce these effects? METHODS: Fourteen able-bodied individuals participated in this experiment. Participants were trained by walking on a treadmill while a bidirectional resistance was applied to the knee using a robotic knee exoskeleton. During training, participants were either instructed to walk in a manner that felt natural or were provided real-time visual feedback of their kinematics. Electromyography and knee kinematics were measured to determine if adding resistance to the limb induced slacking and if feedback could reduce slacking behavior. Kinematic aftereffects were measured after training bouts to gauge adaptation. RESULTS: Functional resistance training without feedback significantly reduced knee flexion when compared to baseline walking, indicating that participants were slacking. This reduction in knee flexion did not improve with continued training. Providing visual feedback of knee joint kinematics during training significantly increased knee muscle activation and kinematic aftereffects. SIGNIFICANCE: The findings indicate that individuals are susceptible to motor slacking during functional resistance training, which could affect outcomes of this training. However, motor slacking can be reduced if training is provided in conjunction with a feedback paradigm. This finding underscores the importance of using additional methods that externally motivate motor adaptation when the body is not intrinsically motivated to do so.

New Index for Multiple Chronic Conditions Predicts Functional Outcome in Ischemic Stroke.

OBJECTIVE: To determine whether a new index for multiple chronic conditions (MCCs) predicts poststroke functional outcome (FO), we developed and internally validated the new MCC index in patients with ischemic stroke. METHODS: A prospective cohort of patients with ischemic stroke (2008-2017) was interviewed at baseline and 90 days in the Brain Attack Surveillance in Corpus Christi Project. An average of 22 activities of daily living (ADL)/instrumental ADL (IADL) items measured the FO score (range 1-4) at 90 days. A FO score >3 (representing a lot of difficulty with ADL/IADLs) was considered unfavorable FO. A new index was developed using machine learning techniques to select and weight conditions and prestroke impairments. RESULTS: Prestroke modified Rankin Scale (mRS) score, age, congestive heart failure (CHF), weight loss, diabetes, other neurologic disorders, and synergistic effects (dementia × age, CHF × renal failure, and prestroke mRS × prior stroke/TIA) were identified as important predictors in the MCC index. In the validation dataset, the index alone explained 31% of the variability in the FO score, was well-calibrated (p = 0.41), predicted unfavorable FO well (area under the receiver operating characteristic curve 0.81), and outperformed the modified Charlson Comorbidity Index in predicting the FO score and poststroke mRS. CONCLUSIONS: A new MCC index was developed and internally validated to improve the prediction of poststroke FO. Novel predictors and synergistic interactions were identified. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that in patients with ischemic stroke, an index for MCC predicts FO at 90 days.

Associations of Self-Reported History of Depression and Antidepressant Use Before Stroke Onset With Poststroke Post-Acute Rehabilitation Care-An Exploratory Study: The BASIC (Brain Attack Surveillance in Corpus Christi) Project.

Background Prestroke depression status and post-acute rehabilitation care (PARC) are determinants of poststroke depression and function. However, little is known on how prestroke depression status affects PARC placement, a possible pathway for upstream intervention. We examined how prestroke depression status affects PARC in a population-based study. Methods and Results Incident ischemic stroke cases were from the BASIC (Brain Attack Surveillance in Corpus Christi) Project from 2008 to 2012. Prestroke depression status was self-reported and categorized as (1) never depressed, (2) history of depression without antidepressant use before stroke onset, or (3) antidepressant use before stroke onset. PARC included home, a skilled nursing facility, or an inpatient rehabilitation facility. Confounder-adjusted multinomial regression models were used to examine the association between prestroke depression status and PARC. Adjustment for stroke severity was deferred in the main analyses because it may lie on the causal pathway. There were 548 stroke survivors (mean age 65.3 years, 48.3% female, 62.6% Mexican-American). The adjusted odds ratios comparing home discharge to a skilled nursing facility were 1.88 (95% CI: 0.86-4.11) for those with a history of depression and 2.55 (95% CI: 1.11-5.83) for those using an antidepressant at stroke onset, relative to those never depressed. The adjusted odds ratios comparing an inpatient rehabilitation facility to a skilled nursing facility were 1.17 (95% CI 0.40-3.42) and 3.28 (95% CI 1.24-8.67) for those with a history of depression and those using an antidepressant at stroke onset, respectively, relative to those never depressed. Conclusions Antidepressant use before stroke onset may increase odds of home and inpatient rehabilitation facility discharge compared with skilled nursing facility discharge.

Zolpidem for the Treatment of Neurologic Disorders: A Systematic Review.

Importance: Given its selective action on the ω1 subtype of the γ-aminobutyric acid A receptor, zolpidem tartrate presents a potential treatment mechanism for other neurologic disorders. Objective: To synthesize studies that used zolpidem to treat neurologic disorders. Evidence Review: Eligibility criteria included any published English-language article that examined the use of zolpidem for noninsomnia neurologic disorders in humans for all dates up to March 20, 2015. Searched databases included PubMed, Scopus, Web of Science Core Collection, the Cochrane Library, EMBASE, CENTRAL, and clinicaltrials.gov. Publication bias was mitigated by searching clinicaltrials.gov for unpublished studies. Two rounds of screening were performed based on title and then abstract, and coding was performed by 2 coders. All methods followed the PRISMA Reporting Guidelines for systematic reviews of the literature. Findings: The initial search produced 2314 articles after removing duplicates. After exclusion based on a review of abstracts, 67 articles remained for full manuscript review. Thirty-one studies treated movement disorders, 22 treated disorders of consciousness, and 14 treated other neurologic conditions, including stroke, traumatic brain injury, encephalopathy, and dementia. Study designs included case reports (n = 28), case series (n = 8), single-patient interventional (n = 13), pretest and posttest (n = 9), randomized clinical trials (n = 9), and crossover studies (n = 5). Only 11 studies had more than 10 participants. Effects of zolpidem were wide ranging (eg, improvement on the JFK Coma Recovery Scale-Revised, the Unified Parkinson Disease Rating Scale, and the Burke-Fahn-Marsden Dystonia Rating Scale) and generally lasted 1 to 4 hours before the participant returned to baseline. Sedation was the most common adverse effect. Conclusions and Relevance: Zolpidem has been observed to transiently treat a large variety of neurologic disorders, most often related to movement disorders and disorders of consciousness. Much of what is known comes from case reports and small interventional trials. These findings may represent a new treatment mechanism for these disorders.

Validity and repeatability of inertial measurement units for measuring gait parameters.

Inertial measurement units (IMUs) are small wearable sensors that have tremendous potential to be applied to clinical gait analysis. They allow objective evaluation of gait and movement disorders outside the clinic and research laboratory, and permit evaluation on large numbers of steps. However, repeatability and validity data of these systems are sparse for gait metrics. The purpose of this study was to determine the validity and between-day repeatability of spatiotemporal metrics (gait speed, stance percent, swing percent, gait cycle time, stride length, cadence, and step duration) as measured with the APDM Opal IMUs and Mobility Lab system. We collected data on 39 healthy subjects. Subjects were tested over two days while walking on a standard treadmill, split-belt treadmill, or overground, with IMUs placed in two locations: both feet and both ankles. The spatiotemporal measurements taken with the IMU system were validated against data from an instrumented treadmill, or using standard clinical procedures. Repeatability and minimally detectable change (MDC) of the system was calculated between days. IMUs displayed high to moderate validity when measuring most of the gait metrics tested. Additionally, these measurements appear to be repeatable when used on the treadmill and overground. The foot configuration of the IMUs appeared to better measure gait parameters; however, both the foot and ankle configurations demonstrated good repeatability. In conclusion, the IMU system in this study appears to be both accurate and repeatable for measuring spatiotemporal gait parameters in healthy young adults.

A Novel Application of Eddy Current Braking for Functional Strength Training During Gait.

Functional strength training is becoming increasingly popular when rehabilitating individuals with neurological injury such as stroke or cerebral palsy. Typically, resistance during walking is provided using cable robots or weights that are secured to the distal shank of the subject. However, there exists no device that is wearable and capable of providing resistance across the joint, allowing over ground gait training. In this study, we created a lightweight and wearable device using eddy current braking to provide resistance to the knee. We then validated the device by having subjects wear it during a walking task through varying resistance levels. Electromyography and kinematics were collected to assess the biomechanical effects of the device on the wearer. We found that eddy current braking provided resistance levels suitable for functional strength training of leg muscles in a package that is both lightweight and wearable. Applying resistive forces at the knee joint during gait resulted in significant increases in muscle activation of many of the muscles tested. A brief period of training also resulted in significant aftereffects once the resistance was removed. These results support the feasibility of the device for functional strength training during gait. Future research is warranted to test the clinical potential of the device in an injured population.

Low-level intermittent quadriceps activity during transcranial direct current stimulation facilitates knee extensor force-generating capacity.

Anodal transcranial direct current stimulation (tDCS) is known to increase the force-generating capacity of the skeletal muscles. However, when tDCS is concurrently combined with a motor task, interference may occur that hinders tDCS effects. Here, we tested the interaction and time course of tDCS effects on force production when paired with a low-level force-matching task. Twenty-two subjects were randomized into two groups: tDCS-Matching and tDCS-Resting. Each group received tDCS and a sham stimulation, separated by one week. Maximal knee extensor and flexor torques were measured before and up to twenty-five minutes following the stimulation. The tDCS-Matching group produced greater knee extension torques relative to sham when compared with the tDCS-Resting group. There was no significant effect for knee flexion. This suggests that interference does not occur for force production tasks when tDCS is combined with a motor task. Rather, the task appears to aid and isolate the effects to the muscle groups involved in the task.

Effect of Continuous Positive Airway Pressure on Stroke Rehabilitation: A Pilot Randomized Sham-Controlled Trial.

STUDY OBJECTIVES: Obstructive sleep apnea (OSA) predicts poor functional outcome after stroke and increases the risk for recurrent stroke. Less is known about continuous positive airway pressure (CPAP) treatment on stroke recovery. METHODS: In a pilot randomized, double-blind, sham-controlled trial, adult stroke rehabilitation patients were assigned to auto-titrating or sham CPAP without diagnostic testing for OSA. Change in Functional Independence Measure (FIM), a measure of disability, was assessed between rehabilitation admission and discharge. RESULTS: Over 18 months, 40 patients were enrolled and 10 withdrew from the study: 7 from active and 3 from sham CPAP (p > 0.10). For the remaining 30 patients, median duration of CPAP use was 14 days. Average CPAP use was 3.7 h/night, with at least 4 h nightly use among 15 patients. Adherence was not influenced by treatment assignment or stroke severity. In intention-to-treat analyses (n = 40), the median change in FIM favored active CPAP over sham but did not reach statistical significance (34 versus 26, p = 0.25), except for the cognitive component (6 versus 2.5, p = 0.04). The on-treatment analyses (n = 30) yielded similar results (total FIM: 32 versus 26, p = 0.11; cognitive FIM: 6 versus 2, p = 0.06). CONCLUSIONS: A sham-controlled CPAP trial among stroke rehabilitation patients was feasible in terms of recruitment, treatment without diagnostic testing and adequate blinding-though was limited by study retention and CPAP adherence. Despite these limitations, a trend towards a benefit of CPAP on recovery was evident. Tolerance and adherence must be improved before the full benefits of CPAP on recovery can be assessed in larger trials.

Emerging treatments for motor rehabilitation after stroke.

Although numerous treatments are available to improve cerebral perfusion after acute stroke and prevent recurrent stroke, few rehabilitation treatments have been conclusively shown to improve neurologic recovery. The majority of stroke survivors with motor impairment do not recover to their functional baseline, and there remains a need for novel neurorehabilitation treatments to minimize long-term disability, maximize quality of life, and optimize psychosocial outcomes. In recent years, several novel therapies have emerged to restore motor function after stroke, and additional investigational treatments have also shown promise. Here, we familiarize the neurohospitalist with emerging treatments for poststroke motor rehabilitation. The rehabilitation treatments covered in this review will include selective serotonin reuptake inhibitor medications, constraint-induced movement therapy, noninvasive brain stimulation, mirror therapy, and motor imagery or mental practice.