Effect of early and late rehabilitation onset in a chronic rat model of ischemic stroke- assessment of motor cortex signaling and gait functionality over time

Gait assessment in a female rat Sprague Dawley model of disc-associated low back pain

PURPOSE

Gait disturbances are common in human low back pain (LBP) patients, suggesting potential applicability to rodent LBP models. This study aims to assess the influence of disc-associated LBP on gait in female Sprague Dawley rats and explore the utility of the open-source Gait Analysis Instrumentation and Technology Optimized for Rodents (GAITOR) suite as a potential alternative tool for spontaneous pain assessment in a previously established LBP model.

MATERIALS AND METHODS

Disc degeneration was surgically induced using a one-level disc scrape injury method, and microcomputed tomography was used to assess disc volume loss. After disc injury, axial hypersensitivity was evaluated using the grip strength assay, and an open field test was used to detect spontaneous pain-like behavior.

RESULTS

Results demonstrated that injured animals exhibit a significant loss in disc volume and reduced grip strength. Open field test did not detect significant differences in distance traveled between sham and injured animals. Concurrently, animals with injured discs did not display significant gait abnormalities in stance time imbalance, temporal symmetry, spatial symmetry, step width, stride length, and duty factor compared to sham. However, comparisons with reference values of normal gait reported in prior literature reveal that injured animals exhibit mild deviations in forelimb and hindlimb stance time imbalance, forelimb temporal symmetry, and hindlimb spatial symmetry at some time points.

CONCLUSIONS

This study concludes that the disc injury may have very mild effects on gait in female rats within 9 weeks post-injury and recommends future in depth dynamic gait analysis and longer studies beyond 9 weeks to potentially detect gait.

Porcine Model of Cerebral Ischemic Stroke Utilizing Intracortical Recordings for the Continuous Monitoring of the Ischemic Area

PURPOSE

Our aim was to use intracortical recording to enable the tracking of ischemic infarct development over the first few critical hours of ischemia with a high time resolution in pigs. We employed electrophysiological measurements to obtain quick feedback on neural function, which might be useful for screening, e.g., for the optimal dosage and timing of agents prior to further pre-clinical evaluation.

METHODS

Micro-electrode arrays containing 16 (animal 1) or 32 electrodes (animal 2-7) were implanted in the primary somatosensory cortex of seven female pigs, and continuous electrical stimulation was applied at 0.2 Hz to a cuff electrode implanted on the ulnar nerve. Ischemic stroke was induced after 30 min of baseline recording by injection of endothelin-1 onto the cortex adjacent to the micro-electrode array. Evoked responses were extracted over a moving window of 180 s and averaged across channels as a measure of cortical excitability.

RESULTS

Across the animals, the cortical excitability was significantly reduced in all seven 30 min segments following endothelin-1 injection, as compared to the 30 min preceding this intervention. This difference was not explained by changes in the anesthesia, ventilation, end-tidal CO2, mean blood pressure, heart rate, blood oxygenation, or core temperature, which all remained stable throughout the experiment.

CONCLUSIONS

The animal model may assist in maturing neuroprotective approaches by testing them in an accessible model of resemblance to human neural and cardiovascular physiology and body size. This would constitute an intermediate step for translating positive results from rodent studies into human application, by more efficiently enabling effective optimization prior to chronic pre-clinical studies in large animals.

Does frequent use of an exoskeletal upper limb robot improve motor function in stroke patients?

PURPOSE

To determine how differences in frequency of the single-joint hybrid assistive limb (HAL-SJ) use affect the improvement of upper limb motor function and activities of daily living (ADL) in stroke patients.

MATERIALS AND METHODS

Subacute stroke patients were divided into the high or low frequency of HAL-SJ use groups. The two groups were matched by propensity score, and the degree of changes 30 days after initiating HAL-SJ use was compared. A logistic regression analysis was performed to examine whether frequent use would increase the number of subjects experiencing the efficacy of more than the minimal clinically important difference (MCID) of Fugl-Meyer assessment (FMA).

RESULTS

Twenty-five stroke patients were matched by propensity score, and nine pairs were matched. The high-frequency group showed a significantly superior increase to total FMA shoulder, elbow, forearm, and Barthel index compared with the low-frequency group. Logistic regression analysis revealed no significant associations between frequent use and MCID.

CONCLUSIONS

The frequency of HAL-SJ use may affect the improvement of motor function and ADL ability of the upper limb with exception of the fingers and wrist. However, the frequency of intervention was not effective enough to further increase the number of subjects with clinically meaningful changes in upper limb motor function.IMPLICATIONS FOR REHABILITATIONThe current study aimed to clarify how differences in the frequency of single-joint hybrid assistive limb (HAL-SJ) use can affect the improvement of upper-limb motor functions and ADL in subacute stroke patients.Our results implied that the frequency of HAL-SJ use may influence the recovery of upper limb function.However, even if HAL-SJ is used frequently, it does not mean that more patients will achieve clinically meaningful recovery.

A Decoding Prediction Model of Flexion and Extension of Left and Right Feet from Electroencephalogram

Detection of limb motor functions utilizing brain signals is a significant technique in the brain signal gain model (BSM) that can be effectively employed in various biomedical applications. Our research presents a novel technique for prediction of feet motor functions by applying a deep learning model with cascading transfer learning technique to use the electroencephalogram (EEG) in the training stage. Our research deduces the electroencephalogram data (EEG) of stroke incidence to propose functioning high-tech interfaces for predicting left and right foot motor functions. This paper presents a transfer learning with several source input domains to serve a target domain with small input size. Transfer learning can reduce the learning curve effectively. The correctness of the presented model is evaluated by the abilities of motor functions in the detection of left and right feet. Extensive experiments were performed and proved that a higher accuracy was reached by the introduced BSM-EEG neural network with transfer learning. The prediction of the model accomplished 97.5% with less CPU time. These accurate results confirm that the BSM-EEG neural model has the ability to predict motor functions for brain-injured stroke therapy.

A Deep Learning Model for Stroke Patients’ Motor Function Prediction

Deep learning models are effectively employed to transfer learning to adopt learning from other areas. This research utilizes several neural structures to interpret the electroencephalogram images (EEG) of brain-injured cases to plan operative imagery-computerized interface models for controlling left and right hand movements. This research proposed a model parameter tuning with less training time using transfer learning techniques. The precision of the proposed model is assessed by the aptitudes of motor imagery detection. The experiments depict that the best performance is attained with the incorporation of the proposed EEG-DenseNet and the transfer model. The prediction accuracy of the model reached 96.5% with reduced time computational cost. These high performance proves that the EEG-DenseNet model has high prospective for motor imagery brain-injured therapy systems. It also productively exhibited the effectiveness of transfer learning techniques for enhancing the accuracy of electroencephalogram brain-injured therapy models.

Very Early Exercise Rehabilitation After Intracerebral Hemorrhage Promotes Inflammation in the Brain

BACKGROUND

Very early exercise has been reported to exacerbate motor dysfunction; however, its mechanism is largely unknown.

OBJECTIVE

This study examined the effect of very early exercise on motor recovery and associated brain damage following intracerebral hemorrhage (ICH) in rats.

METHODS

Collagenase solution was injected into the left striatum to induce ICH. Rats were randomly assigned to receive placebo surgery without exercise (SHAM) or ICH without (ICH) or with very early exercise within 24 hours of surgery (ICH+VET). We observed sensorimotor behaviors before surgery, and after surgery preexercise and postexercise. Postexercise brain tissue was collected 27 hours after surgery to investigate the hematoma area, brain edema, and Il1b, Tgfb1, and Igf1 mRNA levels in the striatum and sensorimotor cortex using real-time reverse transcription polymerase chain reaction. NeuN, PSD95, and GFAP protein expression was analyzed by Western blotting.

RESULTS

We observed significantly increased skillful sensorimotor impairment in the horizontal ladder test and significantly higher Il1b mRNA levels in the striatum of the ICH+VET group compared with the ICH group. NeuN protein expression was significantly reduced in both brain regions of the ICH+VET group compared with the SHAM group.

CONCLUSION

Our results suggest that very early exercise may be associated with an exacerbation of motor dysfunction because of increased neuronal death and region-specific changes in inflammatory factors. These results indicate that implementing exercise within 24 hours after ICH should be performed with caution.

Mobilization within 24 hours of new-onset stroke enhances the rate of home discharge at 6-months follow-up: a prospective cohort study

BACKGROUND/OBJECTIVE

Previous research indicates a better improvement of functional independence measure (FIM) at discharge in acute-stroke patients who received physiatrist and registered therapist operating rehabilitation (PROr) within 24 hrs compared with those who received after 24 hrs was reported. The aim of this prospective cohort study was to determine whether PROr provided within 24 hrs for new-onset stroke patients affects home-discharge rate at 6 months later.

METHODS

Acute new-onset stroke patients admitted to our hospital and received PROr (n = 227) and were conducted into 3 categories based on the time until starting PROr; within 24 hrs (very early mobilization; VEM; n = 47), 24-48 hrs (early mobilization; EM; n = 77) and >48 hrs (later mobilization; LM; n = 103). Home-discharge rates as well as changes in FIM, and rates of recurrence and mortality during the 6-month follow-up were assessed.

RESULTS

A total of 139 patients [VEM (n = 32), EM (n = 43), LM (n = 64)] could be followed throughout the 6-month period. The home-discharge rate was ∼80% and significantly higher by ∼20% in VEM than EM. The gains in the motor subscale of FIM at 6 months were significantly higher in VEM than LM, while the mortality and recurrent rates were not significantly different among the categories.

CONCLUSIONS

Starting PROr within 24 hrs of new-onset stroke may help to increase home-discharge rates at 6-month follow-up, simultaneously with a higher FIM. Very early mobilization in our hospital did not increase the risks of recurrence or death.

F. CARACTERIZACIÓN TEMPORO-ESPACIAL DEL PATRÓN DE MARCHA EN ROEDORES COMO MODELO ANIMAL DE LESIÓN CEREBRAL CEREBROVASCULAR

En la investigación sobre movimiento, la experimentación animal ha proporcionado fundamentación científica para la investigación clínica, mejorando procedimientos diagnósticos y de rehabilitación. Lesiones cerebrales en roedores pueden ser usadas para modelar síntomas locomotores, sensoriales y/o cognitivos. Con el propósito de determinar la funcionalidad locomotriz y sensorial en roedores, se han propuesto varios métodos de evaluación y pronóstico clínico para identificar y evaluar adaptaciones estructurales y mecanismos de neuro-recuperación. Esto ha permitido que métodos de intervención terapéutica, como el ejercicio físico, sean utilizados para restaurar funciones sensitivo-motoras y cognitivas en roedores y humanos. La extrapolación (translación) de los resultados de investigaciones en ciencias básicas a áreas clínicas supone la continua cooperación y retroalimentación entre investigadores y profesionales de la salud, favoreciendo la formulación de intervenciones terapéuticas más eficaces basadas en resultados obtenidos de la experimentación animal. El objetivo de esta revisión es exponer las principales deficiencias motoras y los métodos empleados para determinar la dificultad motriz en la marcha en roedores con lesión cerebrovascular, para lo cual se realizó una revisión de literatura, sobre términos definidos (MeSH), en las bases de datos PsychINFO, Medline y Web of Science, entre enero de 2000 y enero de 2017. Se excluyeron artículos de carácter cualitativo o narrativo, sin revisión por pares, disertaciones, tesis o trabajos de grado y resúmenes de conferencias. Se revisan algunas manifestaciones clínicas, su efecto en la locomotricidad en roedores, algunas metodologías usadas para generar lesiones y para estudiar la función motriz, los principales métodos de medición y algunos aspectos translacionales. 

The Effects of Early Exercise on Motor, Sense, and Memory Recovery in Rats With Stroke

OBJECTIVE

Exercise is an effective, inexpensive, home-based, and accessible intervention strategy for stroke treatment, and early exercise after stroke has attracted a great deal of attention in recent years. However, the effects of early exercise on comprehensive functional recovery remain poorly understood. The present study investigated the effect of early exercise on motor, sense, balance, and spatial memory recovery.

DESIGN

Adult Sprague-Dawley rats were subjected to unilateral middle cerebral artery occlusion (MCAO) and were randomly divided into early exercise group (EE), non-exercise group (NE), and sham group. EE group received 2 weeks of exercise training initiated at 24 hours after operation. The recovery of motor, sense, and balance function was evaluated every 3 days after MCAO. Spatial memory recovery was detected from 21 to 25 days after MCAO.

RESULTS

The results showed that early exercise significantly promoted the motor and spatial memory recovery with statistical differences. The rats in EE group have a better recovery in sense and balance function, but there is no statistically significant difference about these results.

CONCLUSION

Our results showed that early moderate exercise can significantly promote motor and spatial memory recovery, but not the sense and balance functions.

Low-Frequency Intracortical Electrical Stimulation Decreases Sensorimotor Cortex Hyperexcitability in the Acute Phase of Ischemic Stroke

Ischemic stroke causes a series of complex pathophysiological events in the brain. Electrical stimulation of the brain has been considered as a novel neuroprotection intervention to save the penumbra. However, the effect on the cells' responsiveness and their ability to survive has yet to be established. The objective of the present study was to investigate the effects of low-frequency intracortical electrical stimulation (lf-ICES) applied to the ischemia-affected sensorimotor cortex immediately following ischemic stroke. Twenty male Sprague-Dawley rats were instrumented with an intracortical microelectrode array (IC MEA) and a cuff-electrode around the sciatic nerve. Photothrombosis intervention was performed within the sensorimotor cortex and the electrophysiological changes were assessed by analysis of the neural responses to stimulation of the sciatic nerve. Neuroprotection intervention consisted of eight 23 min lf-ICES blocks applied to the IC MEA during the initial 4 h following photothrombosis. Our results revealed that the area and magnitude of the sensorimotor cortex response significantly increased if ischemic stroke was allowed to progress uninterrupted, whereas this was not observed for the group of rats subjected to lf-ICES. Our findings indicate that low-frequency electrical stimulation is able to minimize hyperexcitability and may therefore be a candidate as neuroprotection intervention in the future.

Defining Optimal Aerobic Exercise Parameters to Affect Complex Motor and Cognitive Outcomes after Stroke: A Systematic Review and Synthesis

Although poststroke aerobic exercise (AE) increases markers of neuroplasticity and protects perilesional tissue, the degree to which it enhances complex motor or cognitive outcomes is unknown. Previous research suggests that timing and dosage of exercise may be important. We synthesized data from clinical and animal studies in order to determine optimal AE training parameters and recovery outcomes for future research. Using predefined criteria, we included clinical trials of stroke of any type or duration and animal studies employing any established models of stroke. Of the 5,259 titles returned, 52 articles met our criteria, measuring the effects of AE on balance, lower extremity coordination, upper limb motor skills, learning, processing speed, memory, and executive function. We found that early-initiated low-to-moderate intensity AE improved locomotor coordination in rodents. In clinical trials, AE improved balance and lower limb coordination irrespective of intervention modality or parameter. In contrast, fine upper limb recovery was relatively resistant to AE. In terms of cognitive outcomes, poststroke AE in animals improved memory and learning, except when training was too intense. However, in clinical trials, combined training protocols more consistently improved cognition. We noted a paucity of studies examining the benefits of AE on recovery beyond cessation of the intervention.

The Effect of Body Weight Support Treadmill Training on Gait Recovery, Proximal Lower Limb Motor Pattern, and Balance in Patients with Subacute Stroke

Objective. Gait performance is an indicator of mobility impairment after stroke. This study evaluated changes in balance, lower extremity motor function, and spatiotemporal gait parameters after receiving body weight supported treadmill training (BWSTT) and conventional overground walking training (CT) in patients with subacute stroke using 3D motion analysis. Setting. Inpatient department of rehabilitation medicine at a university-affiliated hospital. Participants. 24 subjects with unilateral hemiplegia in the subacute stage were randomized to the BWSTT (n = 12) and CT (n = 12) groups. Parameters were compared between the two groups. Data from twelve age matched healthy subjects were recorded as reference. Interventions. Patients received gait training with BWSTT or CT for an average of 30 minutes/day, 5 days/week, for 3 weeks. Main Outcome Measures. Balance was measured by the Brunel balance assessment. Lower extremity motor function was evaluated by the Fugl-Meyer assessment scale. Kinematic data were collected and analyzed using a gait capture system before and after the interventions. Results. Both groups improved on balance and lower extremity motor function measures (P < 0.05), with no significant difference between the two groups after intervention. However, kinematic data were significantly improved (P < 0.05) after BWSTT but not after CT. Maximum hip extension and flexion angles were significantly improved (P < 0.05) for the BWSTT group during the stance and swing phases compared to baseline. Conclusion. In subacute patients with stroke, BWSTT can lead to improved gait quality when compared with conventional gait training. Both methods can improve balance and motor function.

Phase Synchronization Between Motor Cortices During Gait Movement in Patients With Spinal Cord Injury

Spinal cord injury (SCI) frequently leads to generalized locomotor disability and gait disturbances which cause serious discomfort among patients. Human gait is a complex process in the central nervous system that results from the integration of various mechanisms which remain unclear. Therefore, it is of great theoretical and practical significance to investigate the cortical activity patterns during gait movement in SCI. In this study, brain activity was recorded by electroencephalogram (EEG) during two kinds of gait-like movements. Phase synchronization between motor cortices was investigated through source analysis and phase locking. Results revealed that diverse neural networks with different resonance-like frequencies exist in the brain. Further, we found that the premotor cortex played an important role in the control of passive gait-like movement. In attempted/active movement, spatial function and multimodal integration with somatosensory information are crucial aspects of posterior parietal cortex function which need to be considered separately in different EEG bands. Our results further confirmed that neural system control patterns in passive gait-like movement differ from those in attempted or active gait-like movement. Novel insights into human gait will provide a basis for improvements in future neurorehabilitation applications.

Neuroprotection of Early Locomotor Exercise Poststroke: Evidence From Animal Studies

Early locomotor exercise after stroke has attracted a great deal of attention in clinical and animal research in recent years. A series of animal studies showed that early locomotor exercise poststroke could protect against ischemic brain injury and improve functional outcomes through the promotion of angiogenesis, inhibition of acute inflammatory response and neuron apoptosis, and protection of the blood-brain barrier. However, to date, the clinical application of early locomotor exercise poststroke was limited because some clinicians have little confidence in its effectiveness. Here we review the current progress of early locomotor exercise poststroke in animal models. We hope that a comprehensive awareness of the early locomotor exercise poststroke may help to implement early locomotor exercise more appropriately in treatment for ischemic stroke.

Assessment of functional and behavioral changes sensitive to painful disc degeneration

The development of an in vivo rodent discogenic pain model can provide insight into mechanisms for painful disc degeneration. Painful disc degeneration in rodents can be inferred by examining responses to external stimuli, observing pain-related behaviors, and measuring functional performance. This study compared the sensitivity of multiple pain and functional assessment methods to disc disruption for identifying the parameters sensitive to painful disc degeneration in rats. Disc degeneration was induced in rats by annular injury with saline injection. The severity of disc degeneration, pain sensitivity, and functional performance were compared to sham and naïve control rats. Saline injection induced disc degeneration with decreased disc height and MRI signal intensity as well as more fibrous nucleus pulposus, disorganized annular lamellae and decreased proteoglycan. Rats also demonstrated increased painful behaviors including decreased hindpaw mechanical and thermal sensitivities, increased grooming, and altered gait patterns with hindpaw mechanical hyperalgesia and duration of grooming tests being most sensitive. This is the first study to compare sensitivities of different pain assessment methods in an in vivo rat model of disc degeneration. Hindpaw mechanical sensitivity and duration of grooming were the most sensitive parameters to surgically induced degenerative changes and overall results were suggestive of disc degeneration associated pain.

Adult cortical plasticity following injury: Recapitulation of critical period mechanisms?

A primary goal of research on developmental critical periods (CPs) is the recapitulation of a juvenile-like state of malleability in the adult brain that might enable recovery from injury. These ambitions are often framed in terms of the simple reinstatement of enhanced plasticity in the growth-restricted milieu of an injured adult brain. Here, we provide an analysis of the similarities and differences between deprivation-induced and injury-induced cortical plasticity, to provide for a nuanced comparison of these remarkably similar processes. As a first step, we review the factors that drive ocular dominance plasticity in the primary visual cortex of the uninjured brain during the CP and in adults, to highlight processes that might confer adaptive advantage. In addition, we directly compare deprivation-induced cortical plasticity during the CP and plasticity following acute injury or ischemia in mature brain. We find that these two processes display a biphasic response profile following deprivation or injury: an initial decrease in GABAergic inhibition and synapse loss transitions into a period of neurite expansion and synaptic gain. This biphasic response profile emphasizes the transition from a period of cortical healing to one of reconnection and recovery of function. Yet while injury-induced plasticity in adult shares several salient characteristics with deprivation-induced plasticity during the CP, the degree to which the adult injured brain is able to functionally rewire, and the time required to do so, present major limitations for recovery. Attempts to recapitulate a measure of CP plasticity in an adult injury context will need to carefully dissect the circuit alterations and plasticity mechanisms involved while measuring functional behavioral output to assess their ultimate success.

The value of robotic systems in stroke rehabilitation

In this paper, we discuss robot-mediated neurorehabilitation as a significant emerging field in clinical medicine. Stroke rehabilitation is advancing toward more integrated processes, using robotics to facilitate this integration. Rehabilitation approaches have tremendous value in reducing long-term impairments in stroke patients during hospitalization and after discharge, of which robotic systems are a new modality that can provide more effective rehabilitation. The function of robotics in rehabilitative interventions has been examined extensively, generating positive yet not completely satisfactory clinical results. This article presents state-of-the-art robotic systems and their prospective function in poststroke rehabilitation of the upper and lower limbs.