Upper limb motor dysfunction is associated with fragmented kinetics after brain injury.

BACKGROUND: Characterization of motor deficits after brain injury is important for rehabilitation personalization. While studies reported abnormalities in the kinematics of paretic and non-paretic elbow extension for patients with brain injuries, kinematic analysis is not sufficient to explore how patients deal with musculoskeletal redundancy and the energetic aspect of movement execution. Conversely, interarticular coordination and movement kinetics can reflect patients' motor strategies. This study investigates motor strategies of paretic and non-paretic upper limb after brain injury to highlight motor deficits or compensation strategies. METHODS: 26 brain-injured hemiplegic patients and 24 healthy controls performed active elbow extensions in the horizontal plane, with both upper limbs for patients and, with the dominant upper limb for controls. Elbow and shoulder kinematics, interarticular coordination, net joint kinetics were quantified. FINDINGS: Results show alterations in kinematics, and a strong correlation between elbow and shoulder angles, as well as time to reach elbow and shoulder peak angular velocity in both upper limbs of patients. Net joint kinetics were lower for paretic limb and highlighted a fragmented motor strategy with increased number of transitions between concentric and eccentric phases. INTERPRETATION: In complement to kinematic results, our kinetic results confirmed patients' difficulties to manage both spatially and temporally the joint degrees of freedom redundancy but revealed a fragmented compensatory motor strategy allowing patients upper limb extension despite quality alteration and decrease in energy efficiency. Motor rehabilitation should improve the management of this fragmentation strategy to improve the performance and the efficiency of active movement after brain injury.

Functional outcomes following surgery for spastic hip adductor muscles in ambulatory and non-ambulatory adults.

OBJECTIVE: To evaluate functional outcomes of surgery of spastic hip adductor muscles (obturator neurotomy with or without adductor longus tenotomy) in ambulatory and non-ambulatory patients, using preoperatively defined personalized goals. DESIGN: Retrospective observational descriptive study. PATIENTS: Twenty-three patients with adductor spasticity who underwent obturator neurotomy between May 2016 and May 2021 at the Clinique des Cèdres, Cornebarrieu, France, were included. METHODS: Postoperative functional results were evaluated in accordance with the Goal Attainment Scaling method. Patients were considered "responders" if their score was ≥ 0. Secondary outcomes included spasticity, strength, hip range of motion and change in ambulatory capacity. When data were available, a comparison of pre- and postoperative 3-dimensional instrumented gait analysis was also performed. RESULTS: Among the 23 patients only 3 were non-walkers. Seventeen/22 patients achieved their main goal and 14/23 patients achieved all their goals. Results were broadly similar for both walking goals (inter-knee contact, inter-feet contact, fluidity, walking perimeter, toe drag) and non-walking goals (intimacy, transfer, pain, posture, dressing). CONCLUSION: Surgery of spastic hip adductor muscles results in functional improvement in ambulation, hygiene, dressing and posture and can be offered to patients with troublesome adductor overactivity. The use of a motor nerve block is recommended to define relevant goals before the surgery.

ToulGaitViz: a tool for the systematic description of lower limb clearance during the swing phase of hemiparetic gait after stroke. A cohort study.

BACKGROUND: In post-stroke hemiparetic subjects, a systematic and quantified description of the shortening default and compensatory movements during the swing phase of gait is essential to guide treatments and assess the impact of therapeutic interventions. However, such a systematic approach does not exist in the current clinical practice. AIM: The aim of this study was to present a method improving the quantification and visualization of the kinematics of both lower limbs during the swing phase of gait, more specifically the origin of shortening default and the weight of compensations, based on a tool specifically developed: ToulGaitViz. DESIGN: Observational cohort study. SETTING: Three-dimensional kinematic gait analyses of outpatients evaluated in Toulouse university hospital. POPULATION: ToulGaitViz was applied to 151 post-stroke hemiparetic participants and 48 healthy control participants. METHODS: ToulGaitViz is a standalone software allowing to compute 1) limb clearance as the sum of the shortening related to hip, knee and ankle flexion in the sagittal plane; 2) compensations related to the abduction of the limb and hip hiking at mid-swing. Both centimetric and angular values of the clearance were reported as well as their correlations with walking speed. RESULTS: Overall, the contribution of compensations in clearance was higher in post-stroke hemiparetic subjects than in healthy control participants with both centimetric (130% vs. 33%; P<0.001) and angular methods (23% vs. 1.4%; P<0.001). The centimetric method better represents the specific contribution of each segment to the clearance than the angular method. Symbolically, mean kinematic data from the cohort supports the claim that 2° of pelvic obliquity is equivalent to 10° of knee flexion to increase clearance by 1 cm, emphasizing the non-proportionality between the angular values and the actual contribution to the shortening. ToulGaitViz allows visualization of clearance, segmental shortening and compensation evolution before and after any therapeutic intervention with quantitative and comprehensive data. CONCLUSIONS: The ToulGaitViz could be systematically used in clinical practice to extract relevant kinematic data from the origin of shortening default and the weight of compensations. CLINICAL REHABILITATION IMPACT: This tool allows better understanding of the mechanisms of action of treatments to better link them to the subjects' needs.

Assessing Spatiotemporal and Quality Alterations in Paretic Upper Limb Movements after Stroke in Routine Care: Proposal and Validation of a Protocol Using IMUs versus MoCap.

Accurate assessment of upper-limb movement alterations is a key component of post-stroke follow-up. Motion capture (MoCap) is the gold standard for assessment even in clinical conditions, but it requires a laboratory setting with a relatively complex implementation. Alternatively, inertial measurement units (IMUs) are the subject of growing interest, but their accuracy remains to be challenged. This study aims to assess the minimal detectable change (MDC) between spatiotemporal and quality variables obtained from these IMUs and MoCap, based on a specific protocol of IMU calibration and measurement and on data processing using the dead reckoning method. We also studied the influence of each data processing step on the level of between-system MDC. Fifteen post-stroke hemiparetic subjects performed reach or grasp tasks. The MDC for the movement time, index of curvature, smoothness (studied through the number of submovements), and trunk contribution was equal to 10.83%, 3.62%, 39.62%, and 25.11%, respectively. All calibration and data processing steps played a significant role in increasing the agreement. The between-system MDC values were found to be lower or comparable to the between-session MDC values obtained with MoCap, meaning that our results provide strong evidence that using IMUs with the proposed calibration and processing steps can successfully and accurately assess upper-limb movement alterations after stroke in clinical routine care conditions.

Corticomuscular and intermuscular coherence are correlated after stroke: a simplified motor control?

During movement, corticomuscular coherence is a measure of central-peripheral communication, while intermuscular coherence is a measure of the amount of common central drive to the muscles. Although these two measures are modified in stroke subjects, no author has explored a correlation between them, neither in stroke subjects nor in healthy subjects. Twenty-four chronic stroke subjects and 22 healthy control subjects were included in this cohort study, and they performed 20 active elbow extension movements. The electroencephalographic and electromyographic activity of the elbow flexors and extensors were recorded. Corticomuscular and intermuscular coherence were calculated in the time-frequency domain for each limb of stroke and control subjects. Partial rank correlations were performed to study the link between these two variables. Our results showed a positive correlation between corticomuscular and intermuscular coherence only for stroke subjects, for their paretic and non-paretic limbs (P < 0.022; Rho > 0.50). These results suggest, beyond the cortical and spinal hypotheses to explain them, that stroke subjects present a form of simplification of motor control. When central-peripheral communication increases, it is less modulated and more common to the muscles involved in the active movement. This motor control simplification suggests a new way of understanding the plasticity of the neuromuscular system after stroke.

Selection criteria for surgical correction of equinovarus foot in adults with brain damage: A systematic scoping review.

OBJECTIVE: To report on preoperative outcomes that guide the choice of surgical techniques to correct equinovarus foot in adults with brain injury. METHODS: Four databases (PubMed, MEDLINE, Cochrane, PEDro) were searched according to the PRISMA guidelines. Studies were included regardless of their level of proof, with no limitation on date of publication, and their quality was assessed with the Methodological Index for Non-Randomized Studies score. RESULTS: We analysed 61 studies (n = 2,293 participants); 523 participants underwent neurotomy, 437 calf musculotendinous lengthening, and 888 tibialis anterior transfer or alternative anterior transfers with the flexor digitorum/hallucis longus (n = 249), the extensor hallucis longus (n = 102), the tibialis posterior (n = 41) and the peroneus longus (n = 41). Two studies were dedicated to osteoarticular surgeries (n = 12 participants). Ankle dorsiflexors motricity was assessed before 70% of neurotomies as compared with 29% before isolated calf lengthening studies, their strength being at least 3/5 in 33% and 50% of the studies concerned, respectively. Passive ankle dorsiflexion was assessed before surgery in 87% of neurotomy studies, with 62% of studies investigating non-retracted spastic equinovarus foot. Before anterior tendon transfer with the tibialis anterior or another muscle, passive ankle dorsiflexion was reported in only 20% and 46% of studies, respectively, and dynamic tibialis anterior activation during gait in 46% and 56%. Although voluntary recruitment of the tibialis anterior produced a better functional result, the presence/correction of varus justified its transfer in 60% of studies as compared with 30% in other transfers, which were justified by hyperactivity or voluntary recruitment of transferred muscle. CONCLUSIONS: This review highlights the poor level of preoperative assessment and the absence of formal criteria to indicate the different surgical approaches in the management of equinovarus foot. It reinforces the interest of a systematic standardized preoperative assessment such as selective motor block and dynamic electromyography to choose the most suitable surgical procedure.

Task and ecologically based assessment of upper-limb passive function before and after botulinum injections in adults with stroke using the Upper-Limb Performance Assessment: French cross-cultural adaptation and feasibility pilot study.

PURPOSE: To test feasibility of a French translation and cross-cultural adaptation of the Upper-Limb Performance Assessment (ULPA) for task and ecologically based assessment of individualized passive function of upper-limb (UL) performance in adults treated with botulinum toxin-A. MATERIALS AND METHODS: A case series with seven adults with stroke (29-74 years) for spastic hypertonia management with passive use objectives (hygiene or positioning) established through Goal Attainment Scaling (GAS). Scores on ULPA Task Performance Mastery (TPM) were obtained through clinical and home-based performances before and after treatment. RESULTS: Time administration per task ranged from 5-10 min. Median (range) ULPA, Task Performance Mastery (ULPA-TPM) scores pre-intervention of 58 mastery (35-71) improved to 75 (58-88). Tau-U demonstrated significant large effect sizes (≥.65) for five participants. Complementary measures demonstrated improvement of passive performance for five participants and improvements in GAS for six participants. Testing indicates excellent intra-rater (ICC = 0.90) and moderate inter-rater (ICC = 0.64) reliability, with SDC of 10.16 and 18.23%, respectively. CONCLUSIONS: French use of ULPA is a promising standardized, objective and ecologically based assessment of passive performance in adults with stroke. Preliminary findings after TCCA support feasibility for measurement of individualized goals for UL passive use. Future studies may explore other tasks and environments. Implications for rehabilitationULPA is a performance-based, criterion-referenced and ecological measure of individualized goals based on task-analysis of upper-limb (UL) performance in real-life situations providing an interest for individualized assessment of activity and participation.The measure provides a standardized and quantitative approach, applicable to passive use of UL across environments, promoting ecological validity of assessment.Preliminary data will support clinical interpretation of change before and after botulinum injections of UL passive performance.Access to a transculturally validated French version of ULPA complements standardized assessment of UL impairment, perceived performance and goal attainment.

Changes in intermuscular connectivity during active elbow extension reveal a functional simplification of motor control after stroke.

Background: Stroke alters muscle co-activation and notably leads to exaggerated antagonist co-contraction responsible for impaired motor function. However, the mechanisms underlying this exaggerated antagonist co-contraction remain unclear. To fill this gap, the analysis of oscillatory synchronicity in electromyographic signals from synergistic muscles, also called intermuscular coherence, was a relevant tool. Objective: This study compares functional intermuscular connectivity between muscle pairs of the paretic and non-paretic upper limbs of stroke subjects and the dominant limb of control subjects, concomitantly between two muscle pairs with a different functional role, through an intermuscular coherence analysis. Methods: Twenty-four chronic stroke subjects and twenty-four healthy control subjects were included. Subjects performed twenty elbow extensions while kinematic data and electromyographic activity of both flexor and extensor elbow muscles were recorded. Intermuscular coherence was analyzed in the beta frequency band compared to the assessment of antagonist co-contraction. Results: Intermuscular coherence was higher in the stroke subjects' paretic limbs compared to control subjects. For stroke subjects, the intermuscular coherence of the antagonist-antagonist muscle pair (biceps brachii-brachioradialis) was higher than that of the agonist-antagonist muscle pair (triceps brachii-brachioradialis). For the paretic limb, intermuscular coherence of the antagonist-antagonist muscle pair presented a negative relationship with antagonist co-contraction. Conclusion: Differences in intermuscular coherence between the paretic limbs of stroke subjects and control subjects suggest a higher common central drive during movement. Furthermore, results highlight the association between stroke-related alteration of intermuscular functional connectivity and the alteration of motor function.

Respective Contributions of Instrumented 3D Gait Analysis Data and Tibial Motor Nerve Block on Presurgical Spastic Equinus Foot Assessment: A Retrospective Study of 40 Adults.

Spastic equinus foot is a common deformity in neurologic patients who compromise walking ability. It is related to the imbalance between weak dorsiflexion and overactive plantar flexor muscles. To achieve the best functional results after surgical management, the challenge is to identify the relevant components involved in the deformity using several methods, namely, examination in the supine position, motor nerve blocks allowing transient anesthesia of suspected overactive muscles, and kinematic and electromyographic data collected during an instrumented 3D gait analysis. The procedure is not standardized; its use varies from one team to another. Access to gait analysis laboratories is limited, and some teams do not perform motor nerve blocks. When both examinations are available, instrumental data from the instrumented 3D gait analysis can be used to specify muscle targets for motor blocks, but data collected from both examinations are sometimes considered redundant. This retrospective cohort analysis compared examination in the supine position, temporary motor nerve blocks, and instrumented 3D gait analysis data in 40 adults after brain or spinal cord injuries. Clinical data collected before motor nerve block was not associated with instrumental data to assess calf muscle's overactivity and tibialis anterior function. Improvement of ankle dorsiflexion in the swing phase after tibial motor nerve block was associated with soleus spastic co-contraction during this phase corroborating its involvement in ankle dorsiflexion defects. This study showed the relevance of tibial motor nerve block to remove spastic calf dystonia and facilitate the assessment of calf contracture. It also underlined the need for complementary and specific analyses of the tibialis anterior abnormal activation pattern after motor nerve block to confirm or deny their pathological nature.

Botulinum toxin combined with rehabilitation decrease corticomuscular coherence in stroke patients.

OBJECTIVE: Stroke results in limitation of active range of motion involving antagonist co-contraction. The analysis of brain-muscle connectivity can be used to deepen understanding of motor control alterations associated with the loss of motor function after stroke. This preliminary study aims to investigate the combined effects of botulinum toxin and rehabilitation on corticomuscular coherence to better understand the altered functional reorganization of the central-peripheral network. METHODS: Kinematic, electromyographic and electroencephalographic data were recorded during twenty active elbow extensions in eleven chronic stroke patients and nine healthy control subjects. Active range of motion, antagonist co-contraction and corticomuscular coherence were calculated. RESULTS: The initial increase in corticomuscular coherence in stroke patients was significantly reduced five weeks after the first botulinum toxin injection and twenty weeks away from the third injection, in both agonist and antagonist muscles, with moderate to large effect sizes, concomitantly with a decrease in antagonist co-contraction and an improvement in the active range of motion. CONCLUSIONS: This study highlights for the first time an effect of botulinum toxin injections combined with rehabilitation on corticomuscular coherence in stroke patients. SIGNIFICANCE: Notwithstanding the relatively small sample, the results provide original evidence supporting treatment-induced effective functional reorganization of the central-peripheral network.