Toward improving the specificity of perturbation-based training through assessment of dynamic balancing responses: a series of N-of-1 studies in subacute stroke.

Perturbation-based balance training (PBT) has been shown to improve reactive balancing abilities in chronic stroke. To inform future investigations in the subacute phase of stroke, the objective of this series of N-of-1 studies was to investigate the range of balancing responses to unexpected mechanical perturbations applied to the pelvis during walking on an instrumented treadmill before and after PBT training. Three subacute stroke subjects were assessed on each occasion with clinical tests and biomechanical measurements following perturbations applied in forward, backward, inward and outward directions. After 15 daily sessions of PBT, most clinical mobility outcomes showed improvements in all three subjects. Assessment of reactive balancing also showed improvements in all subjects when responding to perturbations in backward and inward directions whereas the changes following perturbations in forward and outward directions were subject-specific. The results suggest that PBT should be individually tailored to target balance deficiencies identified through a serial biomechanical assessment.

Assessment of dynamic balancing responses following perturbations during slow walking in relation to clinical outcome measures for high-functioning post-stroke subjects.

BACKGROUND: Generating appropriate balancing reactions in response to unexpected loss of balance during walking is important to prevent falls. The purpose of this study was to assess dynamic balancing responses following pushes to the pelvis in groups of post-stroke and healthy subjects. METHODS: Forty-one post-stroke subjects and forty-three healthy subjects participated in the study. Dynamic balancing responses to perturbations triggered at heel strike of the left or right leg, directed in the forward, backward, inward and outward directions during slow treadmill walking were assessed. Responses of the healthy group provided reference values used to classify responses of the post-stroke group into two subgroups; one within the reference responses ("inside" subgroup) and the other that falls out ("outside" subgroup). A battery of selected clinical outcome measures (6-Minute Walk Test, 10-Meter Walk Test, Timed-Up-and-Go test, Four Square Step Test, Functional Gait Assessment, Functional Independence Measure and One-legged stance test) was additionally assessed in the post-stroke group. RESULTS: The "inside" subgroup of post-stroke subjects was able to appropriately modulate centre-of-pressure and ground-reaction-force both under the impaired and non-impaired leg in response to perturbations. The "outside" subgroup of post-stroke subjects showed limited modulation of centre-of-pressure and ground-reaction-force under the impaired leg; instead stepping strategy was used in which the non-impaired leg was placed such as to make a longer step (forward perturbation), to make a shorter step (backward perturbation) or to make a cross-step (outward perturbation). Consequently, peak centre-of-mass displacements following perturbations were significantly higher in the "outside" subgroup compared to the "inside" subgroup. Responses in both subgroups following inward perturbations did not differ. Majority of clinical outcome measures moderately correlated with the peak centre-of-mass displacements for forward perturbations and exhibited weak correlations for other perturbation directions. CONCLUSIONS: Substantial number of post-stroke subjects, that were considered to be independent walkers, have reduced capabilities to execute appropriate balancing responses following perturbations commencing on the hemiparetic leg and may thus benefit from perturbation-based training. Timed-Up-and-Go and Functional Independence Measure tests may provide an indication on the abilities of each subject to counteract unexpected loss of balance. However, a reliable assessment should be done through perturbation-based measures.

Clinical risk factors for post-stroke urinary incontinence during rehabilitation.

Urinary incontinence (UI) is a common problem after stroke. Risk factors for UI seem to be multifactorial. There is still controversy in which risk factors contribute to UI. The aim of this study was to investigate risk factors for UI in stroke patients during rehabilitation. Study investigated 150 participants after the first stroke consecutively admitted to a post-acute inpatient rehabilitation program. They were divided into continence and incontinence group according to continence status on rehabilitation admission. Data about sociodemographic factors, functional status, comorbidities, current medications, type and localisation of stroke were collected. Compared with the continence group, incontinent participants had significantly worse cognitive status and upper limb function (P ≤ 0.005), more common global aphasia, neglect, visual field defect, agitation/confusion and deficits in somatic sensation (P ≤ 0.014). There were no differences between the groups regarding comorbidities, but incontinent participants received a larger number of current medications (P = 0.020). Incontinent participants had stroke located more common in the right hemisphere, corticosubcortical region and in the total anterior circulation region (P ≤ 0.051). In the multivariate analysis, Brunnstrom recovery stages of the affected upper limb [odds ratio (95% confidence interval: 1.61 (1.27-2.03)], agitation/confusion [5.36 (1.74-16.54)], global aphasia [5.06 (1.40-18.26)] and faecal impaction [3.41 (1.15-10.09)] were independent risk factors for UI. Findings suggest that communicative and cognitive problems, affected upper limb function and faecal impaction are the most important clinical risk factors for UI after stroke. Knowledge of these risk factors may help in the management of UI during rehabilitation of stroke patients.

Algorithm for selection of balance assessment tools in post-stroke patients.

The aim of the study was to design an algorithm of selecting the balance assessment tool in patients after stroke, which could be used in a subacute rehabilitation setting. A retrospective study was carried out to analyse results of standardized balance measurements in three groups of stroke patients classified by Functional Ambulation Category (FAC) (FAC 1 or 2, non-functional ambulation; FAC 3 or 4, ambulatory dependent; FAC 5 or 6, ambulatory independent). Balance functions were evaluated in 62 out of 70 patients (88.6%) at admission and discharge with at least with one standardized assessment tool. In 21 patients (30%), two or more assessment tools were used. From admission to discharge significant changes in balance functions in the non-functional ambulatory group were detected by Postural Assessment Scale for Stroke (PASS) (P = 0.003), in the ambulatory dependent group with PASS (P = 0.025) and Berg Balance Scale (BBS) (P = 0.009) and in the ambulatory independent group with the Timed Up and Go Test (P = 0.002) and Functional Gait Assessment (P = 0.029). In a post-stroke rehabilitation most commonly used BBS and PASS are sensitive enough in non-functional ambulatory and ambulatory dependent patients, though they do not reflect the overall balance function. In ambulatory independent patients, significant changes in balance functions can be detected only with the assessment tools that include the measurements of dynamic balance. Based on the findings, the algorithm for the selection of balance assessment tools in post-stroke rehabilitation setting was formulated according to FAC.

Pain and outcome prediction in muscle strength rehabilitation after knee injury in recreational athletes.

Effects of rehabilitation on knee function, activity and health-related quality of life after soft-tissue knee injury have been widely studied in clinical trials, but there is still a lack of data on the relation between knee muscle strength and athlete's perceived performance to identify sports-risk modifiers. We performed a prospective observational clinical study of knee muscle strength and self-reported health during rehabilitation after unilateral knee soft-tissue injury in recreational sports. Forty-three patients performed isokinetic dynamometry and filled in the Short form Health Survey (SF-36) and the Oxford Knee Score questionnaires before and after 4 months of instructed home strengthening program. We observed significant improvement in peak torque deficit between two limbs during concentric extension (PTDE) and flexion, dynamic control ratio of the involved knee, most of the SF-36 subscales and the Oxford Knee Score values (P ≤ 0.001). Dynamic control ratio of the uninvolved knee values remained below referential values and unchanged. Improvement of PTDE correlated positively with improvement of the bodily pain subscale of SF-36 score (r = 0.51, P < 0.001). Receiver operating characteristic analysis indicated that reduction of pain by at least nine points predicts at least 10% reduction in PTDE, whereby the bodily pain change achieved poor (56%) sensitivity and good (86%) specificity as a rehabilitation success measure for recreational athletes after knee injury. Primary inferior eccentric strength of noninjured knee hamstrings might indicate increased risk of knee injury. Diminished perceived pain predicts strength improvement of the injured knee extensors with poor sensitivity and good specificity.

A novel robot-assisted training approach for improving gait symmetry after stroke.

Gait asymmetry as a consequence of hemiparesis is known as a serious long-term disability, where typical compensatory gait movements are used by stroke subjects in order to cope with their daily activities. This study presents a gait symmetry training approach consisting of the adaptive robot assistance with the combination of the visual feedback integrated in Balance Assessment Robot for treadmill walking (BAR-TM). The support algorithm is based on gait temporal parameters that change the level of assistive support, which was triggered at different gait subphase events. The presented approach was evaluated on a post-stroke subject in a large number of training sessions. The results have shown significant improvement of gait symmetry indicating that the proposed rehabilitation method has significant potential that should be explored in further studies.

Overground gait training using a motorized assistive device in patients with severe disabilities after stroke.

Regaining of the patient's ability to walk after stroke is an important goal of rehabilitation programmes. The ultimate goal of gait rehabilitation is to empower patients for overground walking. We have previously developed a prototype of a therapist-controlled mobile platform with compliant pelvis support mechanism that enables balance training during overground walking (device E-go). The aim of this pilot randomized controlled study was to explore the usefulness of the E-go in reducing the number of therapists needed during walking training, and to explore the effectiveness of the E-go on walking abilities in severely affected stroke patients. The study included 19 subacute poststroke patients divided into two groups. The experimental group (nine patients) trained to walk with the E-go and the control group trained within conventional physiotherapy programs for 3 weeks. Outcome measures were walking distance and speed, Fugl-Meyer Assessment, Berg Balance Scale, Functional Ambulation Category and the number of therapists needed during training. At the end of the training both groups significantly improved in walking speed, walking distance, Berg Balance Scale and Fugl-Meyer Assessment (P≤0.001), but there were no between-group differences. The experimental group on average needed a lower number of therapists (P=0.040). These findings highlight the potential of the E-go for overground walking training in severely disabled subacute stroke patients.

Decreased movement-related beta desynchronization and impaired post-movement beta rebound in amyotrophic lateral sclerosis.

OBJECTIVE: This study explored event-related desynchronization (ERD) and synchronization (ERS) in amyotrophic lateral sclerosis (ALS) to quantify cortical sensorimotor processes during volitional movements. We furthermore compared ERD/ERS measures with clinical scores and movement-related cortical potential (MRCP) amplitudes. METHODS: Electroencephalograms were recorded while 21 ALS patients and 19 controls performed two self-paced motor tasks: sniffing and right index finger flexion. Based on Wavelet analysis the alpha and beta frequency bands were selected for subsequent evaluation. RESULTS: Patients generated significantly smaller resting alpha spectral power density (SPD) and smaller beta ERD compared to controls. Additionally patients exhibited merely unilateral post-movement ERS (beta rebound) whereas this phenomenon was bilateral in controls. ERD/ERS amplitudes did not correlate with corresponding MRCPs for either patients or controls. CONCLUSIONS: The smaller resting alpha SPD and beta ERD and asymmetrical appearance of beta ERS in patients compared to controls could be the result of pyramidal cell degeneration and/or corpus callosum involvement in ALS. SIGNIFICANCE: These results support the notion of reduced movement preparation in ALS involving also areas outside the motor cortex. Furthermore post-movement cortical inhibition seems to be impaired in ALS. ERD/ERS and MRCP are found to be independent measures of cortical motor functions in ALS.

Movement-related cortical potentials in ALS increase at lower and decrease at higher upper motor neuron burden scores.

Our aim was to investigate changes in movement-related cortical potentials (MRCPs) in ALS patients with different degrees of upper motor neuron (UMN) involvement. Since respiratory failure is the main cause of death in ALS, changes in inspiratory-related (sniffing) potentials were studied in addition to finger-flexion-related potentials. Subjects (21 ALS, 19 controls) performed two self-paced motor tasks while their EEGs were recorded. The first task required flexions of the right index finger and the second, brisk nasal inspirations. The early (BP1), late (BP2) and motor potential (MP) components of MRCPs were evaluated. Results showed that patients generated higher MRCPs than controls. However, this effect was most significant in the subgroup of patients with low UMN burden (LUB). The high UMN burden (HUB) subgroup did not differ from controls, but had significantly lower MP amplitudes than the LUB subgroup. Progressive UMN deterioration was associated with an initial increase, followed by a later decrease, in MP amplitudes in ALS. In conclusion, the increased MRCPs in LUB compared to HUB patients indicate different processes of ALS pathophysiology that force opposing changes in MRCP amplitudes.

Inspiratory- and finger-flexion-related cortical potentials in patients with amyotrophic lateral sclerosis--an exploratory study.

OBJECTIVE: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by degeneration of the upper and lower motor neurons. Each voluntary movement, including inspiration, is preceded by movement-related cortical potential (MRCP) that can be recorded from the scalp. MRCPs of ALS patients with severe upper motor neuron involvement are smaller. Our aim was to explore whether the inspiratory-(sniffing)-related cortical potentials (SRCPs) and index-finger-flexion MRCPs (FFRCPs) can be used as markers of cortical involvement in ALS. METHODS: Thirteen ALS patients and 15 healthy volunteers were assessed for their hand dexterity and strength, respiratory function, speech capacity, spasticity, electromyographic parameters and functional rating scales. EEG was recorded during self-paced sniffing and the right index finger flexion. The MRCP amplitudes were assessed at the relevant electrode positions. RESULTS: No statistically significant difference was found between the MRCP amplitudes of the ALS patients and the control subjects. However, patients with more severely affected upper limb functions generated smaller FFRCPs and those with more affected respiratory functions generated smaller SRCPs. Excessively high FFRCPs were associated with better while excessively low FFRCPs with worse scores on some of the clinical measures of the upper limb function. CONCLUSION: Our preliminary results demonstrate that it is feasible to record SRCP in ALS patients, which combined with FFRCP, may be useful to determine the spectrum of motor control changes in this population.

Rehabilitation of critical illness polyneuropathy and myopathy patients: an observational study.

Critical illness polyneuropathy and myopathy (CIPNM) frequently develops in patients hospitalized in intensive care units. The number of patients with CIPNM admitted to inpatient rehabilitation is increasing. The aim of this study was to comprehensively evaluate the outcome of their rehabilitation. Twenty-seven patients with CIPNM were included in the study. The diagnosis was established clinically and confirmed electrophysiologically. Manual muscle testing was used for the assessment of function. Activity was assessed using the functional independence measure and two walking tests. The patients were also assessed using an adapted International Classification of Functioning, Disability and Health (ICF) checklist. All assessments were performed at admission and discharge. Clinically important and statistically significant improvements were found in all observed measures. High and significant correlations were found between the measures, except between muscle strength and the results of walking tests. Improvement in body functions during rehabilitation decreased as the time from established diagnosis to the start of rehabilitation increased, but it was not related to rehabilitation duration. Improvements in terms of the ICF mainly corresponded to the gain in functional independence measure scores. Major improvement regarding body functions and activities/participation was achieved in patients with CIPNM with a relatively short rehabilitation. Rehabilitation of such patients should start as early as possible once the diagnosis has been established. Comprehensive assessment of such patients combining established scales, objective clinical tests, and the ICF is recommended.

Variable structure pantograph mechanism with spring suspension system for comprehensive upper-limb haptic movement training.

Numerous haptic devices have been developed for upper-limb neurorehabilitation, but their widespread use has been largely impeded because of complexity and cost. Here, we describe a variable structure pantograph mechanism combined with a spring suspension system that produces a versatile rehabilitation robot, called Universal Haptic Pantograph, for movement training of the shoulder, elbow, and wrist. The variable structure is a 5-degree-of-freedom (DOF) mechanism composed of 7 joints, 11 joint axes, and 3 configurable joint locks that reduce the number of system DOFs to between 0 and 3. The resulting device has eight operational modes: Arm, Wrist, ISO (isometric) 1, ISO 2, Reach, Lift 1, Lift 2, and Steer. The combination of available work spaces (reachable areas) shows a high suitability for movement training of most upper-limb activities of daily living. The mechanism, driven by series elastic actuators, performs similarly in all operational modes, with a single control scheme and set of gains. Thus, a single device with minimal setup changes can be used to treat a variety of upper-limb impairments that commonly afflict veterans with stroke, traumatic brain injury, or other direct trauma to the arm. With appropriately selected design parameters, the developed multimode haptic device significantly reduces the costs of robotic hardware for full-arm rehabilitation while performing similarly to that of single-mode haptic devices. We conducted case studies with three patients with stroke who underwent clinical training using the developed mechanism in Arm, Wrist, and/or Reach operational modes. We assessed outcomes using Fugl-Meyer Motor Assessment and Wolf Motor Function Test scores showing that upper-limb ability improved significantly following training sessions.