Antagonist Activation Measurement in Triceps Surae Using High-Density and Bipolar Surface EMG in Chronic Hemiparesis.

After a stroke, antagonist muscle activation during agonist command impedes movement. This study compared measurements of antagonist muscle activation using surface bipolar EMG in the gastrocnemius medialis (GM) and high-density (HD) EMG in the GM and soleus (SO) during isometric submaximal and maximal dorsiflexion efforts, with knee flexed and extended, in 12 subjects with chronic hemiparesis. The coefficients of antagonist activation (CAN) of GM and SO were calculated according to the ratio of the RMS amplitude during dorsiflexion effort to the maximal agonist effort for the same muscle. Bipolar CAN (BipCAN) was compared to CAN from channel-specific (CsCAN) and overall (OvCAN) normalizations of HD-EMG. The location of the CAN centroid was explored in GM, and CAN was compared between the medial and lateral portions of SO. Between-EMG system differences in GM were observed in maximal efforts only, between BipCAN and CsCAN with lower values in BipCAN (p < 0.001), and between BipCAN and OvCAN with lower values in OvCAN (p < 0.05). The CAN centroid is located mid-height and medially in GM, while the CAN was similar in medial and lateral SO. In chronic hemiparesis, the estimates of GM hyperactivity differ between bipolar and HD-EMGs, with channel-specific and overall normalizations yielding, respectively, higher and lower CAN values than bipolar EMG. HD-EMG would be the way to develop personalized rehabilitation programs based on individual antagonist activations.

Hidden Markov Model for Parkinson's Disease Patients Using Balance Control Data.

Understanding the behavior of the human postural system has become a very attractive topic for many researchers. This system plays a crucial role in maintaining balance during both stationary and moving states. Parkinson's disease (PD) is a prevalent degenerative movement disorder that significantly impacts human stability, leading to falls and injuries. This research introduces an innovative approach that utilizes a hidden Markov model (HMM) to distinguish healthy individuals and those with PD. Interestingly, this methodology employs raw data obtained from stabilometric signals without any preprocessing. The dataset used for this study comprises 60 subjects divided into healthy and PD patients. Impressively, the proposed method achieves an accuracy rate of up to 98% in effectively differentiating healthy subjects from those with PD.

Comparing the Effect of Implanted Peroneal Nerve Stimulation and Ankle-Foot Orthosis on Gait Kinematics in Chronic Hemiparesis: A Randomized Controlled Trial.

OBJECTIVE: Impaired ankle dorsiflexion in hemiparesis may be treated with ankle-foot orthosis or functional electrical stimulation. Semi-implanted selective functional electrical stimulation uses independent stimulations of deep and superficial peroneal nerves. The aim of this study was to compare gait kinematics using ankle-foot orthosis or semi-implanted selective functional electrical stimulation over 6 months in hemiparesis. METHODS: Subjects with chronic hemiparesis, randomized into ankle-foot orthosis or semi-implanted selective functional electrical stimulation groups, underwent comfortable gait analysis without and with device OFF and ON, before, and 3 and 6 months after treatment onset. The effects of condition, visit and group on gait kinematics (analysis of variance; ANOVA) were analysed. RESULTS: A total of 27 subjects were included (ankle-foot orthosis, n = 13; semi-implanted selective functional electrical stimulation, n = 14). The only between-group difference in changes from OFF to ON conditions was a deteriorated ankle dorsiflexion speed with ankle-foot orthosis at month 6 (condition*group, p = 0.04; ankle-foot orthosis, -60%, p = 0.02; semi-implanted selective functional electrical stimulation, non significant). Both groups pooled, from OFF to ON gait speed (+ 0.07 m/s; + 10%), cadence (+ 4%), step length (+ 6%) and peak ankle dorsiflexion (+ 6°) increased, and peak ankle inversion (-5°) and peak knee flexion (-2°) decreased (p < 0.001); finally, peak knee flexion in the OFF condition increased (+ 2°, p = 0.03). CONCLUSION: Semi-implanted selective functional electrical stimulation and ankle-foot orthosis similarly impacted gait kinematics in chronic hemiparesis after 6 months of use. Ankle dorsiflexion speed in swing deteriorated markedly with ankle-foot orthosis.

Reliability of the Modified Frenchay Scale for the Assessment of Upper Limb Function in Adults With Hemiparesis.

OBJECTIVES: To investigate the reliability of the Modified Frenchay Scale (MFS) in adults with hemiparesis. DESIGN: Prospective analysis of videos. SETTING: Study conducted in a Neurorehabilitation Unit of a University Hospital. PARTICIPANTS: Fifty-one patients (17 women [33%], age 46±15, time since injury 5.2±6.7 years) with hemiparesis secondary to stroke (N=47), tumor (N=3), or spinal cord injury (N=1) were enrolled. INTERVENTION: The MFS measures active upper limb function in spastic hemiparesis based on a video recording of 10 daily living tasks, each rated from 0 to 10. Six tasks are bimanual and 4 are unimanual with the paretic hand. MFS videos performed in routine care of patients with hemiparesis between 2015 and 2021 were collected. After a 3-hour group training session, each MFS video was assessed twice, 1 week apart by 4 rehabilitation professionals with various levels of experience in using the scale. MAIN OUTCOME MEASURES: Internal consistency was determined using Cronbach's alpha. Intra- and inter-rater reliability was measured using intraclass correlation coefficients (ICC, mean [95% CI]), mean differences between ratings and minimal detectable change (MDC). Bland-Altman plots were also performed for inter-rater assessments. RESULTS: The mean overall MFS score was 4.95±1.20 with no floor or ceiling effect. Cronbach's α was 0.97. For the overall MFS score, intra- and inter-rater ICCs were 0.99[0.99;1.00] and 0.97[0.95;0.98], respectively; mean intra- and inter-rater differences were 0.10±0.04 and 0.24±0.12, respectively; and MDC were 0.17 and 0.37, respectively. CONCLUSIONS: The MFS is an internally consistent and reliable scale to assess upper limb function in adults with hemiparesis.

Test-Retest and Inter-Rater Reliability of the 20-Meter Ambulation Test in Patients with Parkinson's Disease.

OBJECTIVE: In patients with Parkinson's disease, limited sit-to-stand, walk and turn contribute to decreased independence and quality of life. The 20-meter Ambulation Test (AT20) evaluates walking a total of 20 m, over a 10-m distance, back and forth between 2 chairs, starting and ending in a seated position. The aim of this study was to evaluate test-retest and inter-rater reliability of the AT20 in patients with Parkinson's disease. METHODS: Patients with idiopathic Parkinson's disease performed the AT20 in 3 conditions: free speed, fast speed, and with large steps, twice 1 week apart. The total number of steps and the time to complete the task were recorded manually by 4 independent raters. The main outcome criteria were the test-retest and inter-rater intraclass correlation coefficients and coefficients of variation for speed, step length and cadence in the 3 conditions. RESULTS: Twenty participants completed the 2 visits. Across all conditions, test-retest and inter-rater intraclass correlation coefficients for step length and speed were > 95%. Test-retest and inter-rater coefficients of variation were < 0.08. CONCLUSION: The AT20 is a reliable ambulation test in Parkinson's disease, with excellent test-retest and inter-rater reliability for step length and speed in all 3 conditions: at free speed, fast speed, and with large steps. The AT20 might be useful to assess ambulation in parkinsonism in clinical practice.

EMD-Based Method for Supervised Classification of Parkinson's Disease Patients Using Balance Control Data.

There has recently been increasing interest in postural stability aimed at gaining a better understanding of the human postural system. This system controls human balance in quiet standing and during locomotion. Parkinson's disease (PD) is the most common degenerative movement disorder that affects human stability and causes falls and injuries. This paper proposes a novel methodology to differentiate between healthy individuals and those with PD through the empirical mode decomposition (EMD) method. EMD enables the breaking down of a complex signal into several elementary signals called intrinsic mode functions (IMFs). Three temporal parameters and three spectral parameters are extracted from each stabilometric signal as well as from its IMFs. Next, the best five features are selected using the feature selection method. The classification task is carried out using four known machine-learning methods, KNN, decision tree, Random Forest and SVM classifiers, over 10-fold cross validation. The used dataset consists of 28 healthy subjects (14 young adults and 14 old adults) and 32 PD patients (12 young adults and 20 old adults). The SVM method has a performance of 92% and the Dempster-Sahfer formalism method has an accuracy of 96.51%.

Do Muscle Changes Contribute to the Neurological Disorder in Spastic Paresis?

Background: At the onset of stroke-induced hemiparesis, muscle tissue is normal and motoneurones are not overactive. Muscle contracture and motoneuronal overactivity then develop. Motor command impairments are classically attributed to the neurological lesion, but the role played by muscle changes has not been investigated. Methods: Interaction between muscle and command disorders was explored using quantified clinical methodology-the Five Step Assessment. Six key muscles of each of the lower and upper limbs in adults with chronic poststroke hemiparesis were examined by a single investigator, measuring the angle of arrest with slow muscle stretch (XV1) and the maximal active range of motion against the resistance of the tested muscle (XA). The coefficient of shortening CSH = (XN-XV1)/XN (XN, normally expected amplitude) and of weakness CW = (XV1-XA)/XV1) were calculated to estimate the muscle and command disorders, respectively. Composite CSH (CCSH) and CW (CCW) were then derived for each limb by averaging the six corresponding coefficients. For the shortened muscles of each limb (mean CSH > 0.10), linear regressions explored the relationships between coefficients of shortening and weakness below and above their median coefficient of shortening. Results: A total of 80 persons with chronic hemiparesis with complete lower limb assessments [27 women, mean age 47 (SD 17), time since lesion 8.8 (7.2) years], and 32 with upper limb assessments [18 women, age 32 (15), time since lesion 6.4 (9.3) years] were identified. The composite coefficient of shortening was greater in the lower than in the upper limb (0.12 ± 0.04 vs. 0.08 ± 0.04; p = 0.0002, while the composite coefficient of weakness was greater in the upper limb (0.28 ± 0.12 vs. 0.15 ± 0.06, lower limb; p < 0.0001). In the lower limb shortened muscles, the coefficient of weakness correlated with the composite coefficient of shortening above the 0.15 median CSH (R = 0.43, p = 0.004) but not below (R = 0.14, p = 0.40). Conclusion: In chronic hemiparesis, muscle shortening affects the lower limb particularly, and, beyond a threshold of severity, may alter descending commands. The latter might occur through chronically increased intramuscular tension, and thereby increased muscle afferent firing and activity-dependent synaptic sensitization at the spinal level.

Quantified clinical measures linked to ambulation speed in hemiparesis.

BACKGROUND: In spastic paresis, the respective contributions to active function of antagonist hypoextensibility, spasticity, and impaired descending command remain unknown. Objectives: We explored correlations between ambulation speed and coefficients of shortening, spasticity and, weakness for three lower limb extensors. METHODS: This retrospective study identified 140 subjects with chronic hemiparesis (>6 months since injury) assessed during a single visit with barefoot 10-meter ambulation at comfortable and fast speed, and measurements of passive range of motion (XV1), angle of catch at fast stretch (XV3) and active range of motion (XA) against the resistance of gastrocnemius, rectus femoris, and gluteus maximus. Coefficients of shortening (CSH=[XN-XV1]/XN; XN, normal expected amplitude based on anatomical values), spasticity (CSP=[XV1-XV3]/XV1), and weakness (CWK=[XV1-XA]/XV1) were derived. For each muscle, multivariable analysis explored CSH, CSP, and CWK as potential predictors of ambulation speed. RESULTS: Ambulation speed was 0.62±0.28m/s (mean±SD, comfortable) and 0.84±0.38m/s (fast) and was correlated with CSH and CWK against gastrocnemius (CSH, comfortable, ns; fast, ß=-0.20, p=.03; CWK, comfortable, ß=-0.21, p=.010; fast, ß=-0.21, p =.012), rectus femoris (CSH, comfortable, ß=-0.41, p=6E-7; fast, ß=-0.43, p=5E-7; CWK, comfortable, ß=-0.36, p=5E-5; fast, ß=-0.33, p=.0003) and gluteus maximus (CSH, comfortable, ß=-0.19, p=.02; fast, ß=-0.26, p=.002; CWK, comfortable, ß=-0.26, p=.002; fast, ß=-0.22, p=.010). Ambulation speed was not correlated with CSP. CONCLUSIONS: In chronic hemiparesis, ambulation speed correlates with coefficients of shortening and of weakness in lower limb extensors, but not with their spasticity level. This may encourage therapists to focus treatment primarily on muscle shortening by stretching programs and on impaired descending command by active training.

Agonist and antagonist activation at the ankle monitored along the swing phase in hemiparetic gait.

BACKGROUND: Descending command in hemiparesis is reduced to agonists and misdirected to antagonists. We monitored agonist and antagonist activation along the swing phase of gait, comparing paretic and non-paretic legs. METHODS: Forty-two adults with chronic hemiparesis underwent gait analysis with bilateral EMG from tibialis anterior, soleus and gastrocnemius medialis. We monitored ankle and knee positions, and coefficients of agonist activation in tibialis anterior and of antagonist activation in soleus and gastrocnemius medialis over the three thirds of swing phase. These coefficients were defined as the ratio of the root-mean-square EMG from one muscle over any period to the root-mean-square EMG from the same muscle over 100 ms of its maximal voluntary isometric contraction. FINDINGS: As against the non-paretic side, the paretic side showed lesser ankle dorsiflexion and knee flexion (P < 1.E-5), with higher coefficients of agonist activation in tibialis anterior (+100 ± 28%, P < 0.05), and of antagonist activation in soleus (+224 ± 41%, P < 0.05) and gastrocnemius medialis (+276 ± 49%, P < 0.05). On the paretic side, coefficient of agonist activation in tibialis anterior decreased from mid-swing on; coefficients of antagonist activation in soleus and gastrocnemius medialis increased and ankle dorsiflexion decreased in late swing (P < 0.05). INTERPRETATION: During the swing phase in hemiparesis, normalized tibialis anterior recruitment is higher on the paretic than on the non-paretic leg, failing to compensate for a marked increase in plantar flexor activation (cocontraction). The situation deteriorates along swing with a decrease in tibialis anterior recruitment in parallel with an increase in plantar flexor activation, both likely related to gastrocnemius stretch during knee re-extension. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT03119948.

Guided Self-rehabilitation Contract vs conventional therapy in chronic stroke-induced hemiparesis: NEURORESTORE, a multicenter randomized controlled trial.

BACKGROUND: After discharge from hospital following a stroke, prescriptions of community-based rehabilitation are often downgraded to "maintenance" rehabilitation or discontinued. This classic therapeutic behavior stems from persistent confusion between lesion-induced plasticity, which lasts for the first 6 months essentially, and behavior-induced plasticity, of indefinite duration, through which intense rehabilitation might remain effective. This prospective, randomized, multicenter, single-blind study in subjects with chronic stroke-induced hemiparesis evaluates changes in active function with a Guided Self-rehabilitation Contract vs conventional therapy alone, pursued for a year. METHODS: One hundred and twenty four adult subjects with chronic hemiparesis (> 1 year since first stroke) will be included in six tertiary rehabilitation centers. For each patient, two treatments will be compared over a 1-year period, preceded and followed by an observational 6-month phase of conventional rehabilitation. In the experimental group, the therapist will implement the diary-based and antagonist-targeting Guided Self-rehabilitation Contract method using two monthly home visits. The method involves: i) prescribing a daily antagonist-targeting self-rehabilitation program, ii) teaching the techniques involved in the program, iii) motivating and guiding the patient over time, by requesting a diary of the work achieved to be brought back by the patient at each visit. In the control group, participants will benefit from conventional therapy only, as per their physician's prescription. The two co-primary outcome measures are the maximal ambulation speed barefoot over 10 m for the lower limb, and the Modified Frenchay Scale for the upper limb. Secondary outcome measures include total cost of care from the medical insurance point of view, physiological cost index in the 2-min walking test, quality of life (SF 36) and measures of the psychological impact of the two treatment modalities. Participants will be evaluated every 6 months (D1/M6/M12/M18/M24) by a blinded investigator, the experimental period being between M6 and M18. Each patient will be allowed to receive any medications deemed necessary to their attending physician, including botulinum toxin injections. DISCUSSION: This study will increase the level of knowledge on the effects of Guided Self-rehabilitation Contracts in patients with chronic stroke-induced hemiparesis. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02202954 , July 29, 2014.

Ultrasound Structural Changes in Triceps Surae After a 1-Year Daily Self-stretch Program: A Prospective Randomized Controlled Trial in Chronic Hemiparesis.

INTRODUCTION: The effects of long-term stretching (>6 months) in hemiparesis are unknown. This prospective, randomized, single-blind controlled trial compared changes in architectural and clinical parameters in plantar flexors of individuals with chronic hemiparesis following a 1-year guided self-stretch program, compared with conventional rehabilitation alone. METHODS: Adults with chronic stroke-induced hemiparesis (time since lesion >1 year) were randomized into 1 of 2, 1-year rehabilitation programs: conventional therapy (CONV) supplemented with the Guided Self-rehabilitation Contract (GSC) program, or CONV alone. In the GSC group, specific lower limb muscles, including plantar flexors, were identified for a diary-based treatment utilizing daily, high-load, home self-stretching. Blinded assessments included (1) ultrasonographic measurements of soleus and medial gastrocnemius (MG) fascicle length and thickness, with change in soleus fascicle length as primary outcome; (2) maximum passive muscle extensibility (XV1, Tardieu Scale); (3) 10-m maximal barefoot ambulation speed. RESULTS: In all, 23 individuals (10 women; mean age [SD], 56 [±12] years; time since lesion, 9 [±8] years) were randomized into either the CONV (n = 11) or GSC (n = 12) group. After 1 year, all significant between-group differences favored the GSC group: soleus fascicle length, +18.1mm [9.3; 29.9]; MG fascicle length, +6.3mm [3.5; 9.1]; soleus thickness, +4.8mm [3.0; 7.7]; XV1 soleus, +4.1° [3.1; 7.2]; XV1 gastrocnemius, +7.0° [2.1; 11.9]; and ambulation speed, +0.07m/s [+0.02; +0.16]. CONCLUSIONS: In chronic hemiparesis, daily self-stretch of the soleus and gastrocnemius over 1 year using GSC combined with conventional rehabilitation increased muscle fascicle length, extensibility, and ambulation speed more than conventional rehabilitation alone.

Intra- and inter-rater reliability of the 10-meter ambulation test in hemiparesis is better barefoot at maximal speed.

Objectives Reliability of clinical tests to evaluate ambulation in chronic hemiparesis may vary according to the testing condition. The 10-meter ambulation test (AT10) assesses walking speed and step length over 10 m, starting and ending in seated position. In the present study, we compared the intra- and inter-reliability of AT10 in chronic hemiparesis in four different conditions: with shoes and barefoot, at free and maximal safe speed. Methods Ten patients with hemiparesis, >1 year post-stroke (age 45 ± 12, time since stroke 16 ± 9 months, mean ± SD) participated in the reliability study (registration, ID-RCB-2017-A00090-53). All patients performed the AT10 twice, one week apart, in each of the four conditions. The number of steps and time to complete the task were manually recorded by four independent raters. The main outcome measurements were the intraclass correlation coefficients (ICC), coefficients of variation (CV), and mean raw differences (DIFF) of the three parameters of AT10 (speed, step length, and cadence) in each of the four conditions. Effects of wearing shoes and speed condition were explored using ANOVA. Results Across all conditions, mean intra- and inter-rater ICCs were, respectively, 98.5 ± 0.1 and 99.9 ± 0.1% for speed, 98.3 ± 0.1 and 99.7 ± 0.2% for step length, and 96.5 ± 0.1 and 98.9 ± 0.6% for cadence. Mean intra- and inter-rater CV for speed were 0.051 ± 0.016 and 0.022 ± 0.002, respectively. Intra-rater reliability of speed assessments was higher at maximal than at free speed (ICC, CV, DIFF, p < 0.05). At free speed, intra-rater ICCs were higher barefoot than with shoes (p < 0.05). Discussion Performing the 10-meter ambulation test barefoot at maximal speed optimizes its reliability.

Postural stability in young healthy subjects - Impact of reduced base of support, visual deprivation, dual tasking.

OBJECTIVE: To provide normative postural stability data in young subjects. METHODS: Ninety-six healthy participants (58W, 28±6y) stood on a force plate during 60s. We measured effects of support width (feet apart, FA; feet together, FT), vision (eyes open, EO; closed, EC), and cognitive load (single task, ST; dual tasking, DT) on anteroposterior (AP) and medio-lateral (ML) ranges, area and planar velocity of center of pressure (COP) trajectory. RESULTS: All variables increased with FT (AP range, +15%; ML, +185%; area, +242%; velocity, +50%, p<0.0002 for all, MANOVA). Visual deprivation increased COP ranges with added constraints (FT or DT, p=0.002) and increased velocity in all conditions (FA/ST, +16%; DT, +18%; FT/ST, +29%; DT, +23%, p<0.0002 for all). Dual tasking reduced COP displacements with FT (AP range, EO, -15%; EC, -11%; ML range, EO, -19%; EC, -13%; area, EO, -40%; EC, -28%, p<0.0002 for all) and increased velocity in most conditions (FA/EO, +15%; FA/EC, +16%; FT/EO, +7%, p<0.0002 for all). CONCLUSION: In young healthy adults, base of support reduction increases COP displacements. Vision particularly affects postural stability with feet together or dual tasking. Dual tasking increases velocity but decreases COP displacements in challenging postural tasks, potentially by enhanced lower limb stiffness.

Wireless, accelerometry-triggered functional electrical stimulation of the peroneal nerve in spastic paresis: A randomized, controlled pilot study.

In hemiparesis, Wireless, Accelerometry-Triggered Functional Electrical Stimulation (WAFES) of the common peroneal nerve may hold intrinsic rehabilitative properties. The present pilot study analyzes WAFES against conventional therapy. Twenty adults with chronic hemiparesis (time since lesion 7(6) years; median (interquartile range)) were randomized into 2 10-week rehabilitation programs: a 45-minute (min) daily walk using WAFES (n = 10) and conventional physical therapy (CPT), 3 × 45 min per week (n = 10). The outcomes were 3D sagittal speed measurements, step length, cadence, maximal amplitude and velocity of hip, knee, and ankle during gait at free and fast speed without WAFES and clinical assessments of plantar flexor angles of shortening, spasticity, and weakness, before (D1) and after the program (W10). Kinematic and spasticity improvements occurred in the WAFES group only: (i) ankle dorsiflexion velocity (D1 versus W10, free speed, WAFES, +4(5)°/sec, p = 0.002; CPT, -3(8)°/sec, p = 0.007; fast, WAFES, +8(6)°/sec, p = 0.03; CPT, -1(4)°/sec, NS); (ii) maximal passive ankle dorsiflexion (WAFES,+26(85)%; CPT,+0(27)%; group-visit, p = 0.007) and knee flexion (WAFES, +13(17)%; CPT, -1(11)%; group-visit, p = 0.006) at fast speed only; (iii) 15% plantar flexor spasticity grade reduction with WAFES. Over 10 weeks, gait training using WAFES improved ankle and knee kinematics and reduced plantar flexor spasticity compared with CPT. Studies with longer WAFES use should explore functional effects.