Nicolas Bayle

Spastic cocontraction in hemiparesis: effects of botulinum toxin.

Introduction: In this study of spastic hemiparesis we evaluated cocontraction during sustained agonist/antagonist efforts, before and after botulinum toxin (BoNT) injection in 1 agonist. Methods: Nineteen hemiparetic subjects performed maximal isometric elbow flexion/extension efforts with the elbow at 100° (extensors stretched). Using flexor and extensor surface electromyography we calculated agonist recruitment/cocontraction indices from 500‐ms peak voluntary agonist recruitment, before and 1 month after onabotulinumtoxinA injection (160 U) into biceps brachii. Results: Before injection, agonist recruitment and cocontraction indices were higher in extensors than flexors [0.74 ± 0.15 vs. 0.59 ± 0.10 (P < 0.01) and 0.43 ± 0.25 vs. 0.25 ± 0.13 (P < 0.05), respectively]. Biceps injection decreased extensor cocontraction index (−35%, P < 0.05) while increasing flexor agonist recruitment and cocontraction indices. Conclusions: In spastic hemiparesis, stretch may facilitate agonist recruitment and spastic cocontraction. In the non‐injected antagonist, cocontraction may be reduced by enhanced reciprocal inhibition from a more relaxed, and therefore stretched, agonist, or through decreased recurrent inhibition from the injected muscle. Muscle Nerve, 2012

Influence of effort intensity and gastrocnemius stretch on co-contraction and torque production in the healthy and paretic ankle

OBJECTIVEnSpastic co-contraction is a misdirected supraspinal command in spastic paresis. We quantified the influence of effort and gastrocnemius stretch on plantar flexor co-contraction and torque during dorsiflexion efforts in hemiparetic and healthy subjects.nnnMETHODSnEighteen healthy and 18 hemiparetic subjects produced light, medium and maximal isometric dorsi- and plantar flexion efforts in two gastrocnemius positions, stretched (knee extended) and slack (knee flexed), ankle at 90°. Measuring ankle torque and soleus and medial gastrocnemius surface EMG, we calculated the co-contraction index (CCI) as the ratio of the EMG root mean square (RMS) from the muscle acting as antagonist over its RMS when acting as agonist in a maximal effort, in each knee position.nnnRESULTSnCo-contraction was abnormally high in hemiparetic subjects at all effort levels, e.g. for soleus in the knee extended position (CCI(SO) 0.37±0.08 in hemiparesis vs 0.18±0.02 in healthy subjects, p<0.05). In hemiparetic subjects knee extended, dorsiflexion torque, (i) was reversed or canceled in 26% trials; and (ii) correlated negatively with plantar flexor CCI.nnnSIGNIFICANCEnMajor dynamometric impact of co-contraction with stretched position of the cocontracting muscle may justify muscle length modifications (e.g. through aggressive stretch programs) to improve function in spastic paresis.

Contribution of Step Length to Increase Walking and Turning Speed as a Marker of Parkinson's Disease Progression.

When increasing ambulation speed in Parkinson’s disease, step cadence increases more than stride length, indicating movement scaling difficulties that affect step generation in particular. We investigated whether step length variation when increasing ambulation speed was related to disease progression. Patients with Parkinson’s disease (N = 39) and controls (N = 152) performed two timed ambulation tasks: at a free (self-selected) pace and then at maximal speed. The total number of steps (including during turns) and time to complete the task were clinically measured. The relative contribution of step length and cadence to increased ambulation speed was determined using two methods: the ratios of change in step length or in cadence to the change in ambulation speed, and the step length index. While the relative contribution of step length and cadence to increased ambulation speed was independent of age in both control and patient groups, in Parkinson’s disease there was a negative correlation between time from diagnosis and the ratio of change in step length to change in ambulation speed (R = 0.54; p = 0.0004) and the step length index (R = 0.56, p = 0.0002). In parallel, there was a positive correlation between time since diagnosis and the ratio of change in cadence to change in ambulation speed (R = 0.57; p = 0.0002). The relative contribution of step length and cadence to increased ambulation speed is age invariant but a marker of Parkinsons disease advancement, and can be easily determined in the clinical setting.

Stretch-sensitive paresis and effort perception in hemiparesis

In spastic paresis, stretch applied to the antagonist increases its inappropriate recruitment during agonist command (spastic co-contraction). It is unknown whether antagonist stretch: (1) also affects agonist recruitment; (2) alters effort perception. We quantified voluntary activation of ankle dorsiflexors, effort perception, and plantar flexor co-contraction during graded dorsiflexion efforts at two gastrocnemius lengths. Eighteen healthy (age 41xa0±xa013) and 18 hemiparetic (age 54xa0±xa012) subjects performed light, medium and maximal isometric dorsiflexion efforts with the knee flexed or extended. We determined dorsiflexor torque, Root Mean Square EMG and Agonist Recruitment/Co-contraction Indices (ARI/CCI) from the 500xa0ms peak voluntary agonist recruitment in a 5-s maximal isometric effort in tibialis anterior, soleus and medial gastrocnemius. Subjects retrospectively reported effort perception on a 10-point visual analog scale. During gastrocnemius stretch in hemiparetic subjects, we observed: (1) a 25xa0±xa07xa0% reduction of tibialis anterior voluntary activation (maximum reduction 98xa0%; knee extended vs knee flexed; pxa0=xa00.007, ANOVA); (2) an increase in dorsiflexion effort perception (pxa0=xa00.03, ANCOVA). Such changes did not occur in healthy subjects. Effort perception depended on tibialis anterior recruitment only (βARITAxa0=xa00.61, pxa0<xa00.01) in healthy subjects (not on gastrocnemius medialis co-contraction) while it depended on both tibialis anterior agonist recruitment (βARITAxa0=xa00.41, pxa0<xa00.001) and gastrocnemius medialis co-contraction (βCCIMGxa0=xa00.43, pxa0<xa00.001) in hemiparetic subjects. In hemiparesis, voluntary ability to recruit agonist motoneurones is impaired—sometimes abolished—by antagonist stretch, a phenomenon defined here as stretch-sensitive paresis. In addition, spastic co-contraction increases effort perception, an additional incentive to evaluate and treat this phenomenon.

Time, touch and temperature affect perceived finger position and ownership in the grasp illusion

The brains internal model of the body and the sense of body ownership are fundamental to interaction with the world. It is thought that temporally congruent, repetitive multisensory stimuli are required to elicit a sense of body ownership. Here we investigate the ability of static cutaneous stimuli – passively grasping an artificial finger – to induce body ownership and alter perceived body position; we also investigate how physical characteristics of grasped objects alter these senses. We show that static cutaneous stimuli can alter perceived body position and induce an illusion of ownership and also that signals of temperature, texture and shape of grasped finger‐sized objects influence body ownership. Thus, these aspects of human proprioception can be altered by a single sustained sensory stimulus and by the physical characteristics of held objects.

Pattern of improvement in upper limb pointing task kinematics after a 3-month training program with robotic assistance in stroke

BackgroundWhen exploring changes in upper limb kinematics and motor impairment associated with motor recovery in subacute post stroke during intensive therapies involving robot-assisted training, it is not known whether trained joints improve before non-trained joints and whether target reaching capacity improves before movement accuracy.MethodsTwenty-two subacute stroke patients (mean delay post-stroke at program onset 63xa0±xa029xa0days, M2) underwent 50xa0±xa017 (meanxa0±xa0SD) 45-min sessions of robot-assisted (InMotion™) shoulder/elbow training over 3xa0months, in addition to conventional occupational therapy. Monthly evaluations (M2 to M5) included Fugl-Meyer Assessment (FM), with subscores per joint, and four robot-based kinematic measures: mean target distance covered, mean velocity, direction accuracy (inverse of root mean square error from straight line) and movement smoothness (inverse of mean number of zero-crossings in the velocity profile). We assessed delays to reach statistically significant improvement for each outcome measure.ResultsAt M5, all clinical and kinematic parameters had markedly improved: Fugl-Meyer, +65% (median); distance covered, +87%; mean velocity, +101%; accuracy, +134%; and smoothness, +96%. Delays to reach statistical significance were M3 for the shoulder/elbow Fugl-Meyer subscore (+43%), M4 for the hand (+80%) and M5 for the wrist (+133%) subscores. For kinematic parameters, delays to significant improvements were M3 for distance (+68%), velocity (+65%) and smoothness (+50%), and M5 for accuracy (+134%).ConclusionsAn intensive rehabilitation program combining robot-assisted shoulder/elbow training and conventional occupational therapy was associated with improvement in shoulder and elbow movements first, which suggests focal behavior-related brain plasticity. Findings also suggested that recovery of movement quantity related parameters (range of motion, velocity and smoothness) might precede that of movement quality (accuracy).Trial registrationEudraCT 2016–005121-36. Date of Registration: 2016–12-20. Date of enrolment of the first participant to the trial: 2009–11-24 (retrospective data).

Movement Smoothness Differentiates Voluntary from Parkinsonian Bradykinesia

Objective: While considered a key symptom, bradykinesia is not specific to Parkinsons disease (PD). Measuring movement smoothness may help distinguish PD-induced from volitional bradykinesia. Methods: Eight PD patients and 12 healthy subjects performed alternating, maximal speed, small and large elbow flexion-extension movements. Six of the healthy subjects also performed the task while matching the average speed of PD patients. From angular displacement, we derived speed, acceleration, jerk measures and the power spectrum of acceleration frequencies. Acceleration variability was evaluated using the Normalized Average Rectified Jerk (NARJ) and the fast-frequency to movement-frequency (FF/MF) ratio. Ratios of maximal velocities and accelerations in large to those in small movements (L/S velocity and acceleration ratios) were also measured. Results: NARJ in PD was 189 ± 17% of controls and 151 ± 14% of speed-matched controls (p=0.004; pairwise p=0.003, p=0.051 respectively) in large movements and 146 ± 11% of controls and 139 ± 11% of speed-matched controls (p=0.012; pairwise p=0.011, p=0.067 respectively) in small movements. FF/MF ratio in PD was 277 ± 45% of controls and 200 ± 32% of speed-matched controls (p=0.032; pairwise p=0.028, non-significant, respectively) in large movements and 613 ± 73% of controls and 246 ± 29% of speed-matched controls (p<0.001; pairwise p<0.001, p<0.001 respectively) in small movements. Time since diagnosis, but not age, was correlated with NARJ (p<0.05) and FF/MF ratio (p<0.01) for all movements. L/S ratios did not differentiate PD from speed-matched movements in the study sample. Conclusion: The two smoothness metrics, NARJ and FF/MF ratio, distinguished PD from volitional slowness and correlated with time since diagnosis. They are candidate physiological markers of PD-induced bradykinesia.

Beliefs of rehabilitation professionals towards guided self-rehabilitation contracts for post stroke hemiparesis

Abstract Purpose To investigate the beliefs of physiotherapy students (ST), professionals (PT) and physicians (MD) about engaging patients with post-stroke hemiparesis into Guided Self-Rehabilitation Contracts (GSC), to increase their exercise intensity and responsibility level. Method A survey examining beliefs about post-stroke rehabilitation was completed by first (n = 95), second (n = 105), and third (n = 48) year STs; PTs (n = 129) and MDs (n = 65) in France. Results The belief about whether a patient may exercise alone varied between the professional groups with more STs and MDs finding it acceptable: 62% of PTs vs. 74% of STs (p = 0.005) and 79% of MDs (p = 0.02). For 93% of therapists (STs and PTs together), the caregiver may take part in physical therapy sessions. The appropriate weekly duration of exercises in chronic hemiparesis should be over 5 h for 19% of PTs, 37% of STs, and 51% of MDs (MDs vs. PTs, p < 0.005). After stroke, functional progress through rehabilitation is possible all lifelong for 11% of STs, 19% of PTs (p < 0.05, STs vs. PTs), and 29% of MDs (MD vs. PT, NS). Conclusions The strategy of asking patients to perform exercises alone, in the practice or at home, is still not accepted by a large proportion of physical therapy professionals as compared with students or with physicians. Most therapists still see a <5-h weekly duration of exercise as sufficient after stroke. Few therapists are ready to utilize the persistence of behavior-induced brain plasticity regardless of age or delay after the lesion.

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

Abstract 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.

Effect on Passive Range of Motion and Functional Correlates After a Long-Term Lower Limb Self-Stretch Program in Patients With Chronic Spastic Paresis

In current health care systems, long‐duration stretching, performed daily, cannot be obtained through prescriptions of physical therapy. In addition, the short‐term efficacy of the various stretching techniques is disputed, and their long‐term effects remain undocumented.