Biomechanical Assessment Methods Used in Chronic Stroke: A Scoping Review of Non-Linear Approaches.

Non-linear and dynamic systems analysis of human movement has recently become increasingly widespread with the intention of better reflecting how complexity affects the adaptability of motor systems, especially after a stroke. The main objective of this scoping review was to summarize the non-linear measures used in the analysis of kinetic, kinematic, and EMG data of human movement after stroke. PRISMA-ScR guidelines were followed, establishing the eligibility criteria, the population, the concept, and the contextual framework. The examined studies were published between 1 January 2013 and 12 April 2023, in English or Portuguese, and were indexed in the databases selected for this research: PubMed®, Web of Science®, Institute of Electrical and Electronics Engineers®, Science Direct® and Google Scholar®. In total, 14 of the 763 articles met the inclusion criteria. The non-linear measures identified included entropy (n = 11), fractal analysis (n = 1), the short-term local divergence exponent (n = 1), the maximum Floquet multiplier (n = 1), and the Lyapunov exponent (n = 1). These studies focused on different motor tasks: reaching to grasp (n = 2), reaching to point (n = 1), arm tracking (n = 2), elbow flexion (n = 5), elbow extension (n = 1), wrist and finger extension upward (lifting) (n = 1), knee extension (n = 1), and walking (n = 4). When studying the complexity of human movement in chronic post-stroke adults, entropy measures, particularly sample entropy, were preferred. Kinematic assessment was mainly performed using motion capture systems, with a focus on joint angles of the upper limbs.

Usability of Functional Electrical Stimulation in Upper Limb Rehabilitation in Post-Stroke Patients: A Narrative Review.

Stroke leads to significant impairment in upper limb (UL) function. The goal of rehabilitation is the reestablishment of pre-stroke motor stroke skills by stimulating neuroplasticity. Among several rehabilitation approaches, functional electrical stimulation (FES) is highlighted in stroke rehabilitation guidelines as a supplementary therapy alongside the standard care modalities. The aim of this study is to present a comprehensive review regarding the usability of FES in post-stroke UL rehabilitation. Specifically, the factors related to UL rehabilitation that should be considered in FES usability, as well a critical review of the outcomes used to assess FES usability, are presented. This review reinforces the FES as a promising tool to induce neuroplastic modifications in post-stroke rehabilitation by enabling the possibility of delivering intensive periods of treatment with comparatively less demand on human resources. However, the lack of studies evaluating FES usability through motor control outcomes, specifically movement quality indicators, combined with user satisfaction limits the definition of FES optimal therapeutical window for different UL functional tasks. FES systems capable of integrating postural control muscles involving other anatomic regions, such as the trunk, during reaching tasks are required to improve UL function in post-stroke patients.

Methodological Considerations in Assessing Interlimb Coordination on Poststroke Gait: A Scoping Review of Biomechanical Approaches and Outcomes.

Objective: To identify and summarize biomechanical assessment approaches in interlimb coordination on poststroke gait. Introduction: Interlimb coordination involves complex neurophysiological mechanisms that can be expressed through the biomechanical output. The deepening of this concept would have a significant contribution in gait rehabilitation in patients with an asymmetric neurological impairment as poststroke adults. Inclusion criteria: Poststroke adults (>19 years old), with assessment of interlimb coordination during gait, in an open context, according to the Population, Concept, Context framework. Methods: A literature search was performed in PubMed, Web of Science™, Scopus, and gray literature in Google Scholar™, according to the PRISMA-ScR recommendations. Studies written in Portuguese or English language and published between database inception and 14 November 2021 were included. Qualitative studies, conference proceedings, letters, and editorials were excluded. The main conceptual categories were "author/year", "study design", "participant's characteristics", "walking conditions", "instruments" and "outcomes". Results: The search identified 827 potentially relevant studies, with a remaining seven fulfilling the established criteria. Interlimb coordination was assessed during walking in treadmill (n = 3), overground (n = 3) and both (n = 1). The instruments used monitored electromyography (n = 2), kinetics (n = 2), and kinematics (n = 4) to assess spatiotemporal parameters (n = 4), joint kinematics (n = 2), anteroposterior ground reaction forces (n = 2), and electromyography root mean square (n = 2) outcomes. These outcomes were mostly used to analyze symmetry indices or ratios, to calculate propulsive impulse and external mechanical power produced on the CoM, as well as antagonist coactivation. Conclusions: Assessment of interlimb coordination during gait is important for consideration of natural auto-selected overground walking, using kinematic, kinetic, and EMG instruments. These allow for the collection of the main biomechanical outcomes that could contribute to improve better knowledge of interlimb coordination assessment in poststroke patients.

Healthcare, Clinical Factors and Rehabilitation Predicting Quality of Life in First-time Stroke Patients: A 12-month Longitudinal Study.

OBJECTIVES: One of the long-term rehabilitation goals in stroke survivors is to achieve the best health-related quality of life (HRQoL). This study analyzes the evolution of HRQoL one-year post-stroke to establish the main pre-stroke, clinical, health care and rehabilitation predictors. MATERIALS AND METHODS: This study uses patient-level data from a one-year single-center prospective cohort study of first stroke patients, assessed at baseline, 3, 6 and 12 months. A generalized linear model with a linear response determined independent predictors of HRQol with EQ-5D-3L and SF-6D. The model included age, gender, scholarity, monthly income, residence, occupation, National Institute of Health Stroke Scale (NIHSS), Modified Rankin Scale (mRS), Barthel Index (BI), Mini-Mental State Examination (MMSE), length of stay, door-to-neurological examination time, access, frequency, and satisfaction with rehabilitation care. RESULTS: A total of 391 acute stroke patients, with a mean disability of 3.7 and severity of 11.7 participated. A decline of HRQoL was observed from baseline to the first three months in both indexes, with an increase in HRQoL at 3 months until 12 months. Scores were significantly lower compared to corresponding population norms throughout follow-up, mostly affected by stroke severity, disability, rehabilitation access and frequency. Higher HRQoL was associated with lower mRS, NIHSS, age, length of stay, and with higher BI, MMSE, scholarity, occupation, and rehabilitation care. CONCLUSION: Clinical measures and rehabilitation care were the strongest HRQoL predictors of stroke survivors regardless of severity levels. These findings may contribute to the development of future health policies that focus on post-stroke recovery.

Optimal multi-field functional electrical stimulation parameters for the "drinking task - reaching phase" and related upper limb kinematics repeatability in post stroke subjects.

BACKGROUND: No specific guidelines for the management of functional electrical stimulation (FES) parameters in post stroke patients have been defined yet, despite its frequent use. The purpose of this study is to characterize the optimal FES parameters that assist the reaching phase of drinking task ("drinking task - reaching phase") on post stroke subjects and to analyze the related upper limb (UL) movement quality indicators repeatability. METHODS: An observational study with a test and re-test design involving ten post stroke subjects with UL dysfunction was performed. End-point and joint kinematics of contralesional UL were assessed during the "drinking task - reaching phase" with FES through a test and retest design. FES parameters were adjusted to improve UL function according to a consensus between physiotherapists and patients' perspective. FINDINGS: It was possible to establish reliable FES parameters that assisted the "drinking task - reaching phase". All FES parameters presented high to very high repeatability and led to moderate to very high repeatability in almost UL movement quality indicators during the "drinking task - reaching phase". INTERPRETATION: These findings show that the main characteristics of FES parameters that improves patient perception of change are quite stable, which facilitate its implementation in clinical practice by allowing consistence between intervention sessions.

Optimal Multifield Functional Electrical Stimulation Parameters for the "Turn on the Light" Task and Related Upper Limb Kinematics Repeatability in Poststroke Subjects.

OBJECTIVE: To characterize the optimal functional electrical stimulation (FES) parameters that assist the turn on the light task (TOTL) on poststroke participants and to analyze the related upper limb (UL) kinematics repeatability. DESIGN: Cross-sectional study. SETTING: Human movement research center. PARTICIPANTS: Poststroke individuals (N=11) with history of a single unilateral stroke that resulted in a motor control dysfunction of the contralesional UL. INTERVENTIONS: FES based on surface multifield technology applied to the contralesional wrist and finger extensors during the TOTL. MAIN OUTCOME MEASURES: FES outcome metrics (virtual electrodes, stimulation duration, intensity) and kinematic metrics (end-point kinematics [absolute and relative duration, mean and peak velocities, relative instant of peak velocity, index of curvature, number of movement units] and joint kinematics [shoulder, elbow, wrist end position and range of movement]). Outcome measures were assessed 2 times with a 72-hour maximum time interval. CONCLUSION: It was possible to establish reliable FES parameters that assisted the TOTL on poststroke participants. These stimulation parameters led to high to very high repeatability in terms of UL kinematics for most of the cases.

Stroke rehabilitation and research: consideration of the role of the cortico-reticulospinal system.

A cerebrovascular accident, otherwise known as stroke, has the potential to damage multiple areas within the brain affecting descending motor control via a multitude of pathways resulting in a wide variety of movement problems. The cortico-reticulospinal system, one of the largest motor systems, is frequently affected, compromising its output, resulting in postural control deficits. The identification of clinically relevant instruments and scales to document and evaluate recovery in post-stroke patients is vital. However, the availability of such measures and scales which take into consideration the role of postural control as an integral component of functional movement performance are scarce. This paper will critically discuss the importance of integrating current neuroscience and motor control knowledge in order to better understand and describe the clinical presentation of persons post-stroke such that the effectiveness of stroke rehabilitation can be appropriately measured.

The role of the ipsilesional side in the rehabilitation of post-stroke subjects.

Most stroke lesions occur in the middle cerebral artery territory, presenting a high probability of damage of pathways with predominant ipsilesional disposition, mainly related to postural control. Despite the high probability of bilateral postural control dysfunction based on neuroanatomical fundaments, both research and clinical rehabilitation involving stroke subjects have been focused on contralesional side (also named affected side) impairments, while ipsilesional side (also named non-affected side) impairments have been attributed to an adaptive strategy. This paper aims to present a critical understanding about the state-of-the-art that sustains the hypothesis that stroke subjects with middle cerebral artery territory lesion at the subcortical level show an atypical behaviour in the ipsilateral side associated with the lesion itself and the possible implications.

Ankle antagonist coactivation in the double-support phase of walking: Stroke vs. healthy subjects.

INTRODUCTION: Lesions in ipsilateral systems related to postural control in the ipsilesional side may justify the lower performance of stroke subjects during walking. PURPOSE: To analyze bilateral ankle antagonist coactivation during double support in stroke subjects. METHODS: Sixteen (8 females; 8 males) subjects with a first isquemic stroke and 22 controls (12 females; 10 males) participated in this study. The double-support phase was assessed through ground reaction forces and the electromyography of ankle muscles was assessed in both limbs. RESULTS: The ipsilesional limb presented statistically significant differences from the control when assuming specific roles during double support. The tibialis anterior and soleus pair was the one in which this atypical behavior was more pronounced. CONCLUSION: The ipsilesional limb presents a dysfunctional behavior when a higher postural control activity was demanded.

Reliability of Two Methods for Identifying the Postural Phase of Gait Initiation in Healthy and Poststroke Subjects.

This study aims to compare 2 methods of assessing the postural phase of gait initiation, in regard to intrasession reliability, in healthy and poststroke subjects. As a secondary aim, this study aims to analyze anticipatory postural adjustments during gait initiation based on the center of pressure (CoP) displacements in poststroke participants. The CoP signal was acquired during gait initiation in 15 poststroke subjects and 23 healthy controls. Postural phase was identified through a baseline-based method and a maximal displacement-based method. In both healthy and poststroke participants, higher intraclass correlation coefficient and lower coefficient of variation values were obtained with the baseline-based method when compared with the maximal displacement-based method. Poststroke participants presented decreased CoP displacement backward and toward the first swing limb compared with controls when the baseline-based method was used. With the maximal displacement based method, there were differences between groups only regarding backward CoP displacement. Postural phase duration in medial-lateral direction was also increased in poststroke participants when using the maximal displacement based method. The findings obtained indicate that the baseline-based method is more reliable detecting the onset of gait initiation in both groups, while the maximal displacement-based method presents greater sensitivity for poststroke participants.

Assessing Postural Control From Birth to Adulthood Among Individuals Born Preterm: A Systematic Review.

Premature life exposure, meaning an immature central nervous system, presents a significant challenge for the development of postural control and, in turn, overall motor development. Preventing motor delay thus requires identifying, characterizing, and quantifying deficit in postural control as early as possible. In our study, we reviewed the procedures used in past studies to assess postural control among individuals born preterm, specifically the characterization of participants, the instruments and motor tasks involved, the types of data collected and analyzed, and the outcomes. To that end, we performed a literature search on PubMed, Wiley Online Library, Web of Science, and Scopus using Boolean logic and assessed the quality of the studies with a standardized assessment based on the Strengthening the Reporting of Observational Studies in Epidemiology guidelines and the Cochrane Handbook for Systematic Reviews of Interventions. Of 35 potential studies, 24 were included; all evaluated infants born preterm, but six did not include a control group of full-term infants. Although the heterogeneity of measurements, variability of instruments, and divergence in motor tasks examined limit definitive conclusions based on quantitative synthesis and the generalization of the results, most studies revealed dysfunctional postural control among individuals born preterm.

Activation timing of soleus and tibialis anterior muscles during sit-to-stand and stand-to-sit in post-stroke vs. healthy subjects.

INTRODUCTION: Sit-to-stand (SitTS) and stand-to-sit (StandTS) are very important functional tasks that become compromised in stroke patients. As in other voluntary movements, they require an adequate postural control (PC) involving the generation of anticipatory postural adjustments (APAs). In order to give clues for more efficient and directed rehabilitation programs, a deeper knowledge about APAs during challenging and daily life movements is essential. PURPOSE: To analyze the activation timing of tibialis anterior (TA) and soleus (SOL) muscles during SitTS and StandTS in healthy subjects and in post-stroke patients. METHODS: Two groups participated in this study: one composed of ten healthy subjects and the other by ten subjects with a history of stroke and increased H-reflex. Electromyographic activity (EMGa) of SOL and TA was analyzed during SitTS and StandTS in the ipsilateral (IPSI) and the contralateral (CONTRA) limb to the side lesion in stroke subjects, and in one limb in healthy subjects. A force plate was used to identify the movement onset. RESULTS: In both sequences, in the stroke group SOL activation timing occurred prior to movement onset, contrary to the pattern observed in the healthy subjects. Statistically significant differences were found in SOL activation timings between each lower limb of the stroke and healthy groups, but no significant differences were found between the IPSI and the CONTRA limb. The TA activation timing seems to be delayed in the CONTRA limb when compared to the healthy subjects and showed a better organization of TA timing activation in StandTS when compared to SitTS. CONCLUSION: Compared to healthy subjects, APAs seem to be altered in both limbs of the post-stroke subjects, with the SOL activation timing being anticipated in both SitTS and StandTS.

Interlimb coordination during the stance phase of gait in subjects with stroke.

OBJECTIVE: To analyze the relation between contralesional and ipsilesional limbs in subjects with stroke during step-to-step transition of walking. DESIGN: Observational, transversal, analytical study with a convenience sample. SETTING: Physical medicine and rehabilitation clinic. PARTICIPANTS: Subjects (n=16) with poststroke hemiparesis with the ability to walk independently and healthy controls (n=22). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Bilateral lower limbs electromyographic activity of the soleus (SOL), gastrocnemius medialis, tibialis anterior, biceps femoris, rectus femoris, and vastus medialis (VM) muscles and the ground reaction force were analyzed during double-support and terminal stance phases of gait. RESULTS: The propulsive impulse of the contralesional trailing limb was negatively correlated with the braking impulse of the leading limb during double support (r=-.639, P=.01). A moderate functional relation was observed between thigh muscles (r=-.529, P=.035), and a strong and moderate dysfunctional relation was found between the plantar flexors of the ipsilesional limb and the vastus medialis of the contralesional limb, respectively (SOL-VM, r=-.80, P<.001; gastrocnemius medialis-VM, r=-.655, P=.002). Also, a functional moderate negative correlation was found between the SOL and rectus femoris muscles of the ipsilesional limb during terminal stance and between the SOL (r=-.506, P=.046) and VM (r=-.518, P=.04) muscles of the contralesional limb during loading response, respectively. The trailing limb relative impulse contribution of the contralesional limb was lower than the ipsilesional limb of subjects with stroke (P=.02) and lower than the relative impulse contribution of the healthy limb (P=.008) during double support. CONCLUSIONS: The findings obtained suggest that the lower performance of the contralesional limb in forward propulsion during gait is related not only to contralateral supraspinal damage but also to a dysfunctional influence of the ipsilesional limb.

Interlimb relation during the double support phase of gait: an electromyographic, mechanical and energy-based analysis.

The purpose of this study is to analyse the interlimb relation and the influence of mechanical energy on metabolic energy expenditure during gait. In total, 22 subjects were monitored as to electromyographic activity, ground reaction forces and VO2 consumption (metabolic power) during gait. The results demonstrate a moderate negative correlation between the activity of tibialis anterior, biceps femoris and vastus medialis of the trailing limb during the transition between mid-stance and double support and that of the leading limb during double support for the same muscles, and between these and gastrocnemius medialis and soleus of the trailing limb during double support. Trailing limb soleus during the transition between mid-stance and double support was positively correlated to leading limb tibialis anterior, vastus medialis and biceps femoris during double support. Also, the trailing limb centre of mass mechanical work was strongly influenced by the leading limbs, although only the mechanical power related to forward progression of both limbs was correlated to metabolic power. These findings demonstrate a consistent interlimb relation in terms of electromyographic activity and centre of mass mechanical work, being the relations occurred in the plane of forward progression the more important to gait energy expenditure.

Biomechanical and neurophysiological mechanisms related to postural control and efficiency of movement: a review.

Understanding postural control requires considering various mechanisms underlying a person's ability to stand, to walk, and to interact with the environment safely and efficiently. The purpose of this paper is to summarize the functional relation between biomechanical and neurophysiological perspectives related to postural control in both standing and walking based on movement efficiency. Evidence related to the biomechanical and neurophysiological mechanisms is explored as well as the role of proprioceptive input on postural and movement control.

Ankle dynamic in stroke patients: agonist vs. antagonist muscle relations.

INTRODUCTION: Atypical ankle patterns of muscle activity during gait are commonly reported in patients with stroke. These findings can be due to changes between tibialis anterior (TA) and soleus (SOL) coactivation mechanisms. OBJECTIVE: To compare the electromyographic activity (EMGa) of SOL and TA muscles and antagonist coactivation (C) level in the contralateral (CONTRA) and ipsilateral (IPSI) limbs to the side of the stroke lesion during the stance phase of the gait cycle. METHODS: Twelve subjects with a stroke episode participated in this study. The electromyographic signal of TA and SOL and ground reaction forces were acquired while subjects walked at their self-selected speed. Values of ground reaction forces were used to divide the stance phase of gait into initial contact, midstance, and terminal stance. In each sub-phase, the magnitude of TA and SOL was calculated as well as the level of the antagonist C. RESULTS: Although no statistical differences were found, mean values of SOL EMGa were lower in the IPSI limb in all stance phases in relation to the CONTRA limb, and the opposite was observed in the TA EMGa. Moreover, higher mean levels of antagonist C were only found during the initial contact sub-phase in the CONTRA limb and in the other sub-phases in the IPSI limb. Besides, statistical differences were observed only during midstance. CONCLUSION: In stroke subjects, the antagonist C level during midstance of gait may reflect the dysfunction of the neuronal system over the IPSI limb.

Soleus activity in post-stroke subjects: movement sequence from standing to sitting.

INTRODUCTION: The beginning of the movement sequence from standing to sitting requires the modulation of plantar flexors activity, including the soleus muscle (SOL), to allow the forward translation of the tibia in relation to the foot, preserving its antigravity function. PURPOSE: To analyze the SOL activity during the initial phase of standing to sitting in stroke subjects. METHODS: Two groups of ten subjects each participated in this study, one composed of healthy subjects and the other with subjects with a history of stroke. Electromyographic activity (EMGa) of SOL was analyzed in the ipsilateral (IPSI) and contralateral (CONTRA) limb to side lesion in stroke subjects, and in one limb in healthy subjects during the initial phase of standing to sitting. A force plate was used to identify the movement sequence phase. RESULTS: The mean values of SOL EMGa were higher in healthy subjects than the ones obtained in the IPSI and CONTRA limb in stroke subjects. Significant differences were only observed between the IPSI and healthy limb (p=0.035). CONCLUSION: When compared to the healthy subjects, stroke subjects showed a decreased SOL EMGa in the IPSI limb, which suggests that therapeutic decisions must consider the need to promote a better postural control also in the IPSI limb.

Postural control during turn on the light task assisted by functional electrical stimulation in post stroke subjects.

Postural control mechanisms have a determinant role in reaching tasks and are typically impaired in post-stroke patients. Functional electrical stimulation (FES) has been demonstrated to be a promising therapy for improving upper limb (UL) function. However, according to our knowledge, no study has evaluated FES influence on postural control. This study aims to evaluate the influence of FES UL assistance, during turning on the light task, in the related postural control mechanisms. An observational study involving ten post-stroke subjects with UL dysfunction was performed. Early and anticipatory postural adjustments (EPAs and APAs, respectively), the weight shift, the center of pressure and the center of mass (CoM) displacement were analyzed during the turning on the light task with and without the FES assistance. FES parameters were adjusted to improve UL function according to a consensus between physiotherapists' and patients' perspectives. The ANOVA repeated measures, Paired sample t and McNemar tests were used to compare postural control between the assisted and non-assisted conditions. When the task was assisted by FES, the number of participants that presented APAs increased (p = 0.031). UL FES assistance during turning on the light task can improve postural control in neurological patients with UL impairments.

Ankle Intrinsic Stiffness in Subcortical Poststroke Subjects.

The authors' purpose was to evaluate bilateral ankle intrinsic stiffness in subcortical poststroke subjects. Ten subcortical poststroke subjects and 10 healthy controls participated in this study. The ankle passive stiffness at 3 different speeds and the electromyographic activity of the soleus, the gastrocnemius, and the tibialis anterior muscles of poststroke contralesional (CONTRA) and ipsilesional (IPSI) limbs and of one limb of healthy subjects were assessed. Ankle electromyographic activity was collected to ensure that reflexive or voluntary muscle activity was not being elicited during the passive movements. A significant interaction was observed between the effects of the limb (IPSI vs. CONTRA vs. control) and ankle position, F(4, 28) = 3.285, p = .025, and between the effects of the limb and the velocity of stretch, F(2, 14) = 4.209, p = .037. While increased intrinsic stiffness was observed in the CONTRA limb of poststroke subjects at ankle neutral position when the passive stretch was applied with a velocity of 1°/s (p = .021), the IPSI limb of poststroke subjects presented increased stiffness at 20º of plantar flexion when the stretch was applied with a velocity of 5°/s (p = .009) when compared to healthy group. Subcortical poststroke subjects present increased intrinsic stiffness in both the CONTRA and IPSI limbs in specific ankle amplitudes.

Subserous Eosinophilic Gastroenteritis: A Rare Cause of Ascites.

Eosinophilic gastroenteritis is an inflammatory gastrointestinal disease characterized by eosinophilic infiltration of the digestive tract. The subserous type is the rarest form and diagnosis is challenging because the symptoms are heterogeneous and endoscopy may be non-diagnostic. The authors describe the clinical case of a 41-year-old female patient who was diagnosed with subserous eosinophilic gastroenteritis. This case highlights the importance of clinical suspicion of eosinophilic gastroenteritis in patients in the third to fifth decades of life with gastrointestinal symptoms, ascites and eosinophilia. LEARNING POINTS: Subserous eosinophilic gastroenteritis is an uncommon inflammatory gastrointestinal disease with a challenging diagnosis because the symptoms are heterogeneous and endoscopy may be non-diagnostic.The diagnosis should be suspected in the presence of gastrointestinal symptoms, and peripheral eosinophilia is confirmed by the presence of eosinophilic infiltration of the gastrointestinal tract or ascites with a predominance of eosinophils, after the exclusion of other causes of eosinophilia.Automated cell counting analysis of the ascitic fluid can wrongly identify eosinophils as neutrophils, which can delay the diagnosis.