Pathophysiology of spastic paresis. II: Emergence of muscle overactivity

Muscle mass gain is positively associated with functional recovery in patients with sarcopenia after stroke

OBJECTIVE

Intervention for treating sarcopenia is of great concern in clinical settings. The aim of this study was to investigate the relationship between changes in skeletal muscle mass and functional outcomes in patients with sarcopenia after stroke.

METHODS

A retrospective cohort study of stroke patients with sarcopenia consecutively admitted to a single center's convalescent rehabilitation wards was conducted from 2015 to 2018. Sarcopenia was defined as a loss of skeletal muscle mass index (SMI) with bioelectrical impedance and decreased muscle strength as measured by handgrip strength; cut-off values were adopted from the 2019 Asian Working Group for Sarcopenia. Changes in SMI during hospitalization were measured. Outcomes included the motor domain of Functional Independence Measure at discharge and its gain. Multivariate analysis determined whether the changes in SMI were associated with these outcomes.

RESULTS

During the study period, 272 stroke patients were enrolled. Of those, 120 patients (44%) (mean age 79 years, 70 females) were diagnosed with sarcopenia. The mean (SD) for changes in SMI was 0.2 (0.5) kg/m². Multiple linear regression analysis showed that changes in SMI were significantly associated with Functional Independence Measure - motor at discharge (β=0.175, P=0.003) and Functional Independence Measure - motor gain (β=0.247, P=0.003).

CONCLUSIONS

Muscle mass gain may be positively associated with functional recovery in patients with sarcopenia after stroke. Exercise and nutritional therapy to increase skeletal muscle mass, in addition to conventional stroke rehabilitation, is needed for these patients.

Treatment Response to Botulinum Neurotoxin-A in Children With Cerebral Palsy Categorized by the Type of Stretch Reflex Muscle Activation

While Botulinum NeuroToxin-A (BoNT-A) injections are frequently used to reduce the effects of hyperactive stretch reflexes in children with cerebral palsy (CP), the effects of this treatment vary strongly. Previous research, combining electromyography (EMG) with motion analysis, defined different patterns of stretch reflex muscle activation in muscles, those that reacted more to a change in velocity (velocity dependent -VD), and those that reacted more to a change in length (length dependent -LD). The aim of this study was to investigate the relation between the types of stretch reflex muscle activation in the semitendinosus with post-BoNT-A outcome as assessed passively and with 3D gait analysis in children with spastic CP. Eighteen children with spastic CP (10 bilaterally involved) between the ages of 12 and 18 years were assessed before and on average, 8 weeks post-treatment. EMG and motion analysis were used to assess the degree and type of muscle activation dependency in the semitendinosus during passive knee extensions performed at different joint angular velocities. Three-dimensional gait analysis was used to assess knee gait kinematics as a measure of functional outcome. Pre-treatment, 9 muscles were classified as VD and 9 as LD, but no differences between the groups were evident in the baseline knee gait kinematics. Post-treatment, stretch reflex muscle activation decreased significantly in both groups but the reduction was more pronounced in those muscles classified pre-treatment as VD (-72% vs. -50%, p = 0.005). In the VD group, these changes were accompanied by greater knee extension at initial contact and during the swing phase of gait. In the LD group, there was significantly increased post-treatment knee hyperextension in late stance. Although results vary between patients, the reduction of stretch reflex muscle activation in the semitendinosus generally translated to an improved functional outcome, as assessed with 3D gait analysis. However, results were less positive for those muscles with pre-treatment length-dependent type of stretch reflex muscle activation. The study demonstrates the relevance of categorizing the type of stretch reflex muscle activation as a possible predictor of treatment response.

Composite active range of motion (CXA) and relationship with active function in upper and lower limb spastic paresis

OBJECTIVE

The aim of this study is to evaluate a novel composite measure of active range of motion (X_A) and determine whether this measure correlates with active function.

DESIGN

Post hoc analysis of two randomized, placebo-controlled, double-blind studies with open-label extensions exploring changes in active function with abobotulinumtoxinA.

SETTING

Tertiary rehabilitation centers in Australia, Europe, and the United States.

SUBJECTS

Adults with upper (n = 254) or lower (n = 345) limb spastic paresis following stroke or brain trauma.

INTERVENTIONS

AbobotulinumtoxinA (⩽5 treatment cycles) in the upper or lower limb.

MAIN MEASURES

X_A was used to calculate a novel composite measure (CX_A), defined as the sum of X_A against elbow, wrist, and extrinsic finger flexors (upper limb) or soleus and gastrocnemius muscles (lower limb). Active function was assessed by the Modified Frenchay Scale and 10-m comfortable barefoot walking speed in the upper limb and lower limb, respectively. Correlations between CX_A and active function at Weeks 4 and 12 of open-label cycles were explored.

RESULTS

CX_A and active function were moderately correlated in the upper limb (P < 0.0001-0.0004, r = 0.476-0.636) and weakly correlated in the lower limb (P < 0.0001-0.0284, r = 0.186-0.285) at Weeks 4 and 12 of each open-label cycle. Changes in CX_A and active function were weakly correlated only in the upper limb (Cycle 2 Week 12, P = 0.0160, r = 0.213; Cycle 3 Week 4, P = 0.0031, r = 0.296). Across cycles, CX_A improvements peaked at Week 4, while functional improvements peaked at Week 12.

CONCLUSION

CX_A is a valid measure for functional impairments in spastic paresis. CX_A improvements following abobotulinumtoxinA injection correlated with and preceded active functional improvements.

Experienced consequences of spasticity and effects of botulinum toxin injections: a qualitative study amongst patients with disabling spasticity after stroke

Purpose: Chronic spasticity poses a major burden on patients after stroke. Intramuscular botulinum toxin injections constitute an important part of the treatment for patients suffering from troublesome focal spasticity. This study explores the experienced consequences of chronic spasticity amongst patients after stroke regarding physical impairments and activities, the experienced effects of botulinum toxin treatment on these domains, and whether current spasticity management addresses patients' needs.Materials and methods: Fourteen participants with chronic spasticity after stroke who were treated with cyclical botulinum toxin injections in the upper and/or lower extremity muscles were interviewed. Inductive thematic analysis generated representative themes.Results: Analyses of the interviews revealed three themes: (1) spasticity-related impairments and activity limitations; (2) fluctuations in spasticity related to botulinum toxin; (3) need for professional support and feedback. Besides motor impairments, participants experienced activity limitations in many domains of everyday life, with considerable day-to-day fluctuations. Moreover, treatment with botulinum toxin led to cyclical fluctuations in spasticity-related symptoms, which differed across participants. The participants called for shared responsibility for treatment, particularly regarding optimising the timing of injections.Conclusion: Incorporating patient-relevant outcomes into the current assessment of spasticity and monitoring these outcomes may improve spasticity management, particularly regarding the timing of botulinum toxin injections.Implications for rehabilitationBecause chronic spasticity after stroke impacts on almost all domains of everyday life, professionals should identify and target the most relevant problems in each individual patient.Monitoring patient-reported outcomes may help patients and professionals to get insight in the fluctuations of spasticity-related symptoms and may help to evaluate the effects of botulinum toxin injections from the patient's perspective.Patient education and providing insight in the fluctuations of spasticity-related symptoms may support self-management and shared decision-making in spasticity management.

In-Vivo Study of Passive Musculotendon Mechanics in Chronic Hemispheric Stroke Survivors

We characterized the passive mechanical properties of the affected and contralateral musculotendon units in 9 chronic stroke survivors as well as in 6 neurologically-intact controls. Using a position-controlled motor, we precisely indented the distal tendon of the biceps brachii to a 20 mm depth from skin, recording both its sagittal motion using ultrasound movies and the compression force at the tip of the indenter. Length changes of 8 equally-spaced features along the aponeurosis axis were quantified using a pixel-tracking protocol. We report that, on the aggregate and with respect to contralateral and control, respectively, the affected side initiates feature motion at a shorter indentation distance by 61% and 50%, travels further by 15% and 9%, at a lower rate of 28% and 15%, and is stiffer by 40% and 57%. In an extended analysis including the spatial location of the 8 designated features, we report that in contrast to the contralateral and control muscles, the affected musculotendon unit does not strain measurably within the imaging window. These results confirm that chronic stroke-induced spasticity changes musculotendon unit passive mechanics, causing it to not strain under stretch. The mechanisms responsible for altered passive mechanics may lie within extracellular matrix fibrosis.

Spastic co-contraction is directly associated with altered cortical beta oscillations after stroke

OBJECTIVE

Spastic co-contraction is a motor-disabling form of muscle overactivity occurring after a stroke, contributing to a limitation in active movement and a certain level of motor impairment. The cortical mechanisms underlying spastic co-contraction remain to be more fully elucidated, the present study aimed to investigate the role of the cortical beta oscillations in spastic co-contraction after a stroke.

METHOD

We recruited fifteen post-stroke participants and nine healthy controls. The participants were asked to perform active elbow extensions. In the study, multimodal analysis was performed to combine the evaluation of three-dimensional elbow kinematics, the elbow muscles electromyographic activations, and the cortical oscillatory activity.

RESULTS

The movement-related beta desynchronization was significantly decreased in post-stroke participants compared to healthy participants. We found a significant correlation between the movement-related beta desynchronization and the elbow flexors activation during the active elbow extension in post-stroke participants. When compared to healthy participants, post-stroke participants exhibited significant alterations in the elbow kinematics and greater muscle activation levels.

CONCLUSIONS

Cortical beta oscillation alterations may reflect an important neural mechanism underlying spastic co-contraction after a stroke.

SIGNIFICANCE

Measuring the cortical oscillatory activity could be useful to further characterize neuromuscular plasticity induced by recovery or therapeutic interventions.

Are There Trigger Points in the Spastic Muscles? Electromyographical Evidence of Dry Needling Effects on Spastic Finger Flexors in Chronic Stroke

The purpose was to examine the immediate effects of dry needling to spastic finger muscles in chronic stroke. Ten chronic stroke patients with spasticity in finger flexors participated in this experiment. Dry needling to the flexor digitorum superficialis (FDS) muscle was performed under ultrasound guidance for about 30 s (about 100 times). Clinical assessment and intramuscular needle EMG readings were made before and immediately after dry needling. Immediately after needling, the FDS muscle was felt less tight to palpation and the proximal phalangeal joint rested in a less flexed position (p = 0.036). The MAS score decreased for FDS (p = 0.017) and flexor digitorum profundus (FDP) (p = 0.029). Motor unit action potential (MUAP) spikes decreased from 41.6 ± 5.5 to 6.7 ± 2.2 spikes/s (p = 0.002), an 84% reduction after dry needling. However, the pre-needling spike frequency was not correlated to MAS or resting position of the FDS muscles. Dry needling to the spastic finger flexors leads to immediate spasticity reduction, increased active range of motion, and decreased frequency of motor unit spontaneous firing spikes. The results suggest that latent trigger points possibly exist in spastic muscles and they contribute partly to spastic hypertonia of finger flexors in chronic stroke.

Ghost spasticity in multiple sclerosis

Spasticity is the velocity-dependent hypertonia frequently encountered in patients affected by Upper Motor Neuron Syndrome. It is due to a tonic stretch reflex, which is evoked in patients at rest. The aim of this study, performed using surface electromyography (EMG), was to investigate stretch reflex excitability in the hamstrings muscles of patients affected by progressive Multiple Sclerosis (MS) and to correlate EMG results with clinical findings. Thirty patients and 20 age-matched healthy controls were investigated. EMG activity was recorded from biceps femoris muscle with the patient at rest. To stretch hamstrings muscles, the patient's leg was manually moved from maximal flexion to maximal extension at 3 different velocities to investigate both phasic and tonic stretch reflex. Only 7 patients were affected by hypertonia of the hamstrings; 4 of them showed muscle contracture. A tonic stretch reflex was present in the vast majority of the recruited patients, whether they presented hypertonia of the hamstrings or not. Tonic stretch reflex is often present in the hamstrings muscles of progressive MS patients without producing increased muscle tone. This "ghost spasticity" is likely to be, for its intrinsic features, an important risk factor for the development of contractures in the hamstrings muscles.

Prevalence of Spasticity in Nursing Home Residents

OBJECTIVES

To determine the prevalence, rate of underdiagnosis and undertreatment, and association with activities of daily living dependency of spasticity in a nursing home setting.

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

This study is an analysis of a deidentified data set generated by a prior quality improvement project at a 240-bed nursing home for residents receiving long-term care or skilled nursing care services.

METHODS

Each resident was examined by a movement disorders specialist neurologist to determine whether spasticity was present and, if so, the total number of spastic postures present in upper and lower limbs was recorded. Medical records, including the Minimum Data Set, were reviewed for neurologic diagnoses associated with spasticity, activities of daily living (ADL) dependency, and prior documentation of diagnosis and past or current treatments. Ordinary least squares linear regression models were used to evaluate the association between spasticity and ADL dependency.

RESULTS

Two hundred nine residents (154 women, 81.9 ± 10.9 years) were included in this analysis. Spasticity was present in 22% (45/209) of residents examined by the neurologist. Only 11% of residents (5/45) had a prior diagnosis of spasticity and were receiving treatment. Presence of spasticity was associated with greater ADL dependency (χ² = 51.72, P < .001), which was driven by lower limb spasticity (χ² = 14.56, P = .006).

CONCLUSIONS AND IMPLICATIONS

These results suggest that spasticity (1) is common in nursing homes (1 of 5 residents), (2) is often not diagnosed or adequately treated, and (3) is associated with worse ADL dependency. Further research is needed to enhance the rates of diagnosis and treatment of spasticity in long-term care facilities.

Impact of the EMG normalization method on muscle activation and the antagonist-agonist co-contraction index during active elbow extension: Practical implications for post-stroke subjects

Electromyographic (EMG) raw signals are sensitive to intrinsic and extrinsic factors. Consequently, EMG normalization is required to draw proper interpretations of standardized data. Specific recommendations are needed regarding a relevant EMG normalization method for participants who show atypical EMG patterns, such as post-stroke subjects. This study compared three EMG normalization methods ("isometric MVC", "isokinetic MVC", "isokinetic MVC kinematic-related") on muscle activations and the antagonist-agonist co-contraction index. Fifteen post-stroke subjects and fifteen healthy controls performed active elbow extensions, followed by isometric and isokinetic maximum voluntary contractions (MVC). Muscle activations were obtained by normalizing EMG envelopes during active movement using a reference value determined for each EMG normalization method. The results showed no significant difference between the three EMG normalization methods in post-stroke subjects on muscle activation and the antagonist-agonist co-contraction index. We highlighted that the antagonist-agonist co-contraction index could underestimate the antagonist co-contraction in the presence of atypical EMG patterns. Based on its practicality and feasibility, we recommend the use of isometric MVC as a relevant procedure for EMG normalization in post-stroke subjects. We suggest combined analysis of the antagonist-agonist co-contraction index and agonist and antagonist activations to properly investigate antagonist co-contraction in the presence of atypical EMG patterns during movement.

A new method to elicit and measure movement illusions in stroke by means of muscle tendon vibration: the Standardized Kinesthetic Illusion Procedure (SKIP)

Purpose: Muscle tendon vibration (MTV) strongly activates muscle spindles and can evoke kinaesthetic illusions. Although potentially relevant for sensorimotor rehabilitation in stroke, MTV is scarcely used in clinical practice, likely because of the absence of standardised procedures to elicit and characterise movement illusions. This work developed and validated a Standardised Kinaesthetic Illusion Procedure (SKIP) to favour the use of MTV-induced illusions in clinical settings.Materials and methods: SKIP scores were obtained in 15 individuals with chronic stroke and 18 age- and gender-matched healthy counterparts. A further 13 healthy subjects were tested to provide more data with the general population. MTV was applied over the Achilles tendon and SKIP scoring system characterised the clearness and direction of the illusions of ankle dorsiflexion movements.Results: All healthy and stroke participants perceived movement illusions. SKIP scores on the paretic side were significantly lower compared to the non paretic and healthy. Illusions were less clear and sometimes in unexpected directions with the impaired ankle, but still possible to elicit in the presence of sensorimotor deficits.Conclusions: SKIP represents an ancillary and potentially useful clinical method to elicit and characterise illusions of movements induced by MTV. SKIP could be relevant to further assess the processing of proprioceptive afferents in stroke and their potential impact on motor control and recovery. It may be used to guide therapy and improve sensorimotor recovery. Future work is needed to investigate the metrological properties of our method (reliability, responsiveness, etc.), and also the neurophysiological underpinnings of MTV-induced illusions.

Sensorimotor Strategies in Individuals With Poststroke Hemiparesis When Standing Up Without Vision

This study investigated the sensorimotor strategies for dynamic balance control in individuals with stroke by restricting sensory input that might influence task accomplishment. Sit-to-stand movements were performed with restricted vision by participants with hemiparesis and healthy controls. The authors evaluated the variability in the position of participants’ center of mass and velocity, and the center-of-pressure position, in each orthogonal direction at the lift-off point. When vision was restricted, the variability in the mediolateral center-of-pressure position decreased significantly in individuals with hemiparesis, but not in healthy controls. Participants with hemiparesis adopted strategies that explicitly differed from those used by healthy individuals. Variability may be decreased in the direction that most requires accuracy. Individuals with hemiparesis have been reported to have asymmetrical balance deficits, and that meant they had to prioritize mediolateral motion control to prevent falling. This study suggests that individuals with hemiparesis adopt strategies appropriate to their characteristics.

Effect of music listening on hypertonia in neurologically impaired patients-systematic review

Background

As music listening is able to induce self-perceived and physiological signs of relaxation, it might be an interesting tool to induce muscle relaxation in patients with hypertonia. To this date effective non-pharmacological rehabilitation strategies to treat hypertonia in neurologically impaired patients are lacking. Therefore the aim is to investigate the effectiveness of music listening on muscle activity and relaxation.

Methodology

The search strategy was performed by the PRISMA guidelines and registered in the PROSPERO database (no. 42019128511). Seven databases were systematically searched until March 2019. Six of the 1,684 studies met the eligibility criteria and were included in this review. Risk of bias was assessed by the PEDro scale. In total 171 patients with a variety of neurological conditions were included assessing hypertonia with both clinicall and biomechanical measures.

Results

The analysis showed that there was a large treatment effect of music listening on muscle performance (SMD 0.96, 95% CI [0.29–1.63], I² = 10%, Z = 2.82, p = 0.005). Music can be used as either background music during rehabilitation (dual-task) or during rest (single-task) and musical preferences seem to play a major role in the observed treatment effect.

Conclusions

Although music listening is able to induce muscle relaxation, several gaps in the available literature were acknowledged. Future research is in need of an accurate and objective assessment of hypertonia.

The beneficial aspects of spasticity in relation to ambulatory ability in mice with spinal cord injury

STUDY DESIGN

Experimental study with mice.

OBJECTIVES

Spasticity is a common complication after spinal cord injury (SCI) and has detrimental aspects, such as persistent pain and involuntary muscle spasms. This study aimed to assess the influence of antispastic therapy on locomotor function after SCI.

SETTING

University-based laboratory in Fukuoka, Japan.

METHODS

A mouse model of spasticity was developed by producing incomplete SCI at the 9th thoracic level. At 8 weeks after SCI, an antispastic drug, baclofen, was intraperitoneally administered to six injured and two sham-operated mice. The severity of spasticity was evaluated by the modified Ashworth scoring (MAS) system, and locomotor function was evaluated by the Basso-Beattie-Bresnahan (BBB) scale/Basso mouse score (BMS).

RESULTS

The administration of baclofen significantly improved spasticity in the SCI mice and the mean MAS decreased to from 6.2 to 2.8. However, at the same time, it significantly exacerbated the locomotor dysfunction of the SCI mice and the mean BMS decreased from 4.7 to 2.3. The time-course of the changes in locomotor function coincided with the time-course of the spasticity score. We also confirmed that the administration of baclofen was not associated with any changes in either locomotor function or spasticity of the sham-operated control mice.

CONCLUSIONS

Our results suggest that spasticity has a certain beneficial effect on ambulation ability. It is important to note that antispastic treatments may be associated with a risk of impairing the preserved function of chronic SCI patients.

Advanced quantitative estimation methods for spasticity: a literature review

Post-stroke spasticity seriously affects patients’ quality of life. Spasticity is considered to involve both neural and non-neural factors. Current clinical scales, such as the Modified Ashworth Scale and the Modified Tardieu Scale, lack reliability and reproducibility. These scales are also unable to identify the neural and non-neural contributions to spasticity. Surface electromyography and biomechanical and myotonometry measurement methods for post-stroke spasticity are discussed in this report. Surface electromyography can provide neural information, while myotonometry can estimate muscular properties. Both the neural and non-neural contributions can be estimated by biomechanical measurement. These laboratory methods can quantitatively assess spasticity. They can provide more valuable information for further study on treatment and rehabilitation than clinical scales.

Sustained involuntary muscle activity in cerebral palsy and stroke: same symptom, diverse mechanisms

Individuals with lesions of central motor pathways frequently suffer from sustained involuntary muscle activity. This symptom shares clinical characteristics with dystonia but is observable in individuals classified as spastic. The term spastic dystonia has been introduced, although the underlying mechanisms of involuntary activity are not clarified and vary between individuals depending on the disorder. This study aimed to investigate the nature and pathophysiology of sustained involuntary muscle activity in adults with cerebral palsy and stroke. Seventeen adults with cerebral palsy (Gross Motor Function Classification System I–V), 8 adults with chronic stroke and 14 control individuals participated in the study. All individuals with cerebral palsy or stroke showed increased resistance to passive movement with Modified Ashworth Scale >1. Two-minute surface EMG recordings were obtained from the biceps muscle during attempted rest in three positions of the elbow joint; a maximally flexed position, a 90-degree position and a maximally extended position. Cross-correlation analysis of sustained involuntary muscle activity from individuals with cerebral palsy and stroke, and recordings of voluntary isometric contractions from control individuals were performed to examine common synaptic drive. In total, 13 out of 17 individuals with cerebral palsy and all 8 individuals with stroke contained sustained involuntary muscle activity. In individuals with cerebral palsy, the level of muscle activity was not affected by the joint position. In individuals with stroke, the level of muscle activity significantly (P < 0.05) increased from the flexed position to the 90 degree and extended position. Cumulant density function indicated significant short-term synchronization of motor unit activities in all recordings. All groups exhibited significant coherence in the alpha (6–15 Hz), beta (16–35 Hz) and early gamma band (36–60 Hz). The cerebral palsy group had lower alpha band coherence estimates, but higher gamma band coherence estimates compared with the stroke group. Individuals with increased resistance to passive movement due to cerebral palsy or stroke frequently suffer sustained involuntary muscle activity, which cannot exclusively be described by spasticity. The sustained involuntary muscle activity in both groups originated from a common synaptic input to the motor neuron pool, but the generating mechanisms could differ between groups. In cerebral palsy it seemed to originate more from central mechanisms, whereas peripheral mechanisms likely play a larger role in stroke. The sustained involuntary muscle activity should not be treated simply like the spinal stretch reflex mediated symptom of spasticity and should not either be treated identically in both groups.

Effects of a 3D-printed orthosis compared to a low-temperature thermoplastic plate orthosis on wrist flexor spasticity in chronic hemiparetic stroke patients: a randomized controlled trial

Objective:

The aim of this study was to compare the effects of two kinds of wrist-hand orthosis on wrist flexor spasticity in chronic stroke patients.

Design:

This is a randomized controlled trial.

Setting:

The study was conducted in a rehabilitation center.

Participants:

A total of 40 chronic hemiparetic stroke patients with wrist flexor spasticity were involved in the study.

Interventions:

Patients were randomly assigned to either an experimental group (conventional rehabilitation therapy + 3D-printed orthosis, 20 patients) or a control group (conventional rehabilitation therapy + low-temperature thermoplastic plate orthosis, 20 patients). The time of wearing orthosis was about 4–8 hours per day for six weeks.

Main measures:

Primary outcome measure: Modified Ashworth Scale was assessed three times (at baseline, three weeks, and six weeks). Secondary outcome measures: passive range of motion, Fugl-Meyer Assessment score, visual analogue scale score, and the swelling score were assessed twice (at baseline and six weeks). The subjective feeling score was assessed at six weeks.

Results:

No significant difference was found between the two groups in the change of Modified Ashworth Scale scores at three weeks (15% versus 25%, P = 0.496). At six weeks, the Modified Ashworth Scale scores (65% versus 30%, P = 0.02), passive range of wrist extension ( P < 0.001), ulnar deviation ( P = 0.028), Fugl-Meyer Assessment scores ( P < 0.001), and swelling scores ( P < 0.001) showed significant changes between the experimental group and the control group. No significant difference was found between the two groups in the change of visual analogue scale scores ( P = 0.637) and the subjective feeling scores ( P = 0.243).

Conclusion:

3D-printed orthosis showed greater changes than low-temperature thermoplastic plate orthosis in reducing spasticity and swelling, improving motor function of the wrist and passive range of wrist extension for stroke patients.

Shear Waves Reveal Viscoelastic Changes in Skeletal Muscles After Hemispheric Stroke

We investigated alterations in material properties such as elasticity and viscoelasticity of stroke-affected muscles using ultrasound induced shear waves and mechanical models. We used acoustic radiation force to generate shear waves along fascicles of biceps muscles and measured their propagation velocity. The shear wave data were collected in muscles of 13 hemiplegic stroke survivors under passive conditions at 90°, 120°, and 150° elbow flexion angles. In a viscoelastic medium, as opposed to a purely elastic medium, the shear wave propagation velocity depends on the frequency content of the induced wave. Therefore, in addition to the shear wave group velocity (GpV), we also estimated a frequency-dependent phase velocity (PhV). We found significantly higher GpVs and PhVs in stroke-affected muscles ( ). The velocity data were used to estimate shear elasticity and viscosity using an elastic and viscoelastic material models. A pure elastic model showed increased shear elasticity in stroke-affected muscles ( ). The Voigt model estimates of viscoelastic properties were also significantly different between the stroke-impaired and non-impaired muscles. We observed significantly larger model-estimated viscosity values on the stroke-affected side at elbow flexion angles of 120° and 150°. Furthermore, the creep behavior (tissue strain resulting from the application of sudden constant stress) of the model was also different between muscles of the paretic and non-paretic side. We speculate that these changes are associated with the structural disruption of muscles after stroke and may potentially affect force generation from muscle fibers as well as transmission of force to tendons.

Detection of pronator muscle overactivity in children with unilateral spastic cerebral palsy: Development of a semi-automatic method using EMG data

BACKGROUND

The pronator teres and pronator quadratus muscles are frequently injected with neuromuscular blocking agents to improve supination in children with spastic cerebral palsy and limited active elbow supination. However, determining by simple clinical examination whether these muscles are overactive during active movement is difficult.

OBJECTIVE

This study aimed to develop a semi-automatic method to detect pronator muscle overactivity by using surface electromyography (EMG) during active supination movements in children with cerebral palsy.

METHODS

In total, 25 children with unilateral spastic cerebral palsy (10 males; mean [SD] age 10.6 [3.0] years) and 12 typically developing children (7 males; mean age 11.0 [3.0] years) performed pronation-supination movements at 0.50Hz. Kinematic parameters and surface EMG signals were recorded for both pronator muscles. Three experts visually assessed muscle overactivity in the EMG signals of the children with cerebral palsy, in comparison with the reference group. The reliability and discrimination ability of the visual assessments were analysed. Overactivity detection thresholds for the semi-automatic method were adjusted by using the visual assessment by the EMG experts. The positive and negative predictive values of the semi-automatic detection method were calculated.

RESULTS

Intra-rater reliability of visual assessment by EMG experts was excellent and inter-rater reliability was moderate. For the 25 children with unilateral spastic cerebral palsy, EMG experts could discriminate different profiles of pronator overactivity during active supination: no pronator overactivity, one overactive pronator, or overactivity of both pronators. The positive and negative predictive values were 96% and 91%, respectively, for this semi-automatic detection method.

CONCLUSIONS

Detection of pronator overactivity by using surface EMG provides an important complement to the clinical examination. This method can be used clinically, with the condition that clinicians be aware of surface EMG limitations. We believe use of this method can increase the accuracy of treatment for muscle overactivity, resulting in improved motor function and no worsening of paresis.

Application of upper-limb dynamic pseudoelastic splinting in the treatment of stroke chronic patient: a pilot assessment

PURPOSE

The chronic sequelae of stroke are often a strong limitation to patient's quality of life. New non-invasive elective treatments are required to support postural and functional improvements long after the primary insult. This study is an uncontrolled pilot evaluation of pseudoelastic orthotics for post-stroke upper-limb rehabilitation.

MATERIALS AND METHODS

Six chronic hemiplegic patients (3.8 ± 1.7 years since stroke) were evaluated with clinical scales, covering the ICF domains of body functions and structures (Modified Ashworth Score [MAS], Medical Research Council Scale for Muscle Strength, Fugl-Meyer [FM], Motricity Index [MI]), activities (Wolf Motor Function Test [WMF], Motor Activity Log [MAL]) and participation (quality of life questionnaires); sensors applied to the orthosis were used to assess changes in the articular and functional domains over a month's treatment.

RESULTS

Significant gains were achieved in elbow spasticity (MAS, p = .020), upper-limb motor function (FM, p = .005), reaching task (p = .035), and gait (p = .00046) speed. Most patients improved in functional tasks (WMF), but this did not reflect in daily-life activities as measured with MAL. Some patients reported an improved quality of life, especially the quality of sleep.

CONCLUSIONS

Pseudoelastic orthoses could be a comfortable and useful adjunct in the long-term management of stroke. Broader trials will have to confirm these preliminary observations.Implications for rehabilitationUse of new materials in neuromuscular rehabilitation.Customised and adjustable therapeutic action obtained with dynamic personalised orthoses.Non-invasive interventions could be of help for patients with chronic disability.

Unilateral Strength Training and Mirror Therapy in Patients With Chronic Stroke: A Pilot Randomized Trial

OBJECTIVE

The aim of the study was to investigate the feasibility and potential effectiveness of mirror-aided cross-education compared with cross-education alone in poststroke upper limb recovery.

DESIGN

A pilot randomized controlled parallel group study was carried out. Thirty-two patients with chronic stroke followed a 4-wk isometric strength training program performed with the less-affected upper limb three times per week. Participants in the mirror and strength training group observed the reflection of the exercising arm in the mirror. Participants in the strength training only group exercised without a mirror entirely. Participant compliance, adverse effects, and suitability of outcome measures assessed feasibility. Effectiveness outcomes included maximal isometric strength measured with the Biodex Dynamometer, the Modified Ashworth Scale, and the Chedoke Arm and Hand Activity Inventory.

RESULTS

Compliance was high with no adverse effects. The use of the Biodex Dynamometer must be reviewed. Mirror therapy did not augment the cross-education effect (P > 0.05) in patients with chronic stroke when training isometrically.

CONCLUSIONS

This pilot trial established the feasibility of a randomized controlled trial comparing mirror-aided cross-education with cross-education alone for poststroke upper limb recovery. Mirror therapy did not augment cross-education when training isometrically. However, results indicate that the combination of interventions should be investigated further applying an altered training protocol.

Development of muscle contractures and spasticity during subacute rehabilitation after severe acquired brain injury: a prospective cohort study

Objective: This study investigated the development of contractures, passive stiffness, and spasticity in the ankle joint in patients with severe acquired brain injury (ABI) from admission to rehabilitation unit until 1-year post-injury compared to healthy controls. Design: An observational longitudinal cohort study Methods and procedures: Nineteen patients (26 affected ankle joints) with severe ABI >17 years old and with paresis of a lower limb admitted to sub-acute neurorehabilitation were compared to 14 healthy controls (28 ankle joints). Passive and reflex-mediated ankle joint stiffness was obtained measuring torque, range of motion, velocity and acceleration of the ankle movements. Data was collected at inclusion, after 4-5 weeks, after 8-9 weeks and at 1-year follow-up. Outcomes and results: At admittance to rehabilitation range of motion and stiffness was significantly lower compared to controls. Range of motion decreased by one degree in three weeks and passive ankle joint stiffness increased significantly by 1% per week. More patients than controls had no stretch reflex. Conclusion: Patients with severe ABI show reduced mobility and increased passive stiffness despite less spasticity in the ankle joint compared to healthy controls. Research and clinical practice should therefore focus intensively on the prevention of contractures in the ankle joint. ISRCTN17910097.

Unilateral dorsiflexor strengthening with mirror therapy to improve motor function after stroke: A pilot randomized study

BACKGROUND

Independently, cross-education, the performance improvement of the untrained limb following unilateral training, and mirror therapy have shown to improve lower limb functioning poststroke. Mirror therapy has shown to augment the cross-education effect in healthy populations. However, this concept has not yet been explored in a clinical setting.

OBJECTIVES

This study set out to investigate the feasibility and potential efficacy of applying cross-education combined with mirror therapy compared with cross-education alone for lower limb recovery poststroke.

METHODS

Thirty-one chronic stroke participants (age 61.7 ± 13.3) completed either a unilateral strength training (ST; n = 15) or unilateral strength training with mirror-therapy (MST; n = 16) intervention. Both groups isometrically strength trained the less-affected ankle dorsiflexors three times per week for 4 weeks. Only the MST group observed the mirror reflection of the training limb. Patient eligibility, compliance, treatment reliability, and outcome measures were assessed for feasibility. Maximal voluntary contraction (MVC; peak torque, rate of torque development, and average torque), 10-m walk test, timed up and go (TUG), Modified Ashworth Scale (MAS), and the London Handicap Scale (LHS) were assessed at pretraining and posttraining.

RESULTS

Treatment and assessments were well tolerated without adverse effects. No between group differences were identified for improvement in MVC, MAS, TUG, or LHS. Only the combined treatment was associated with functional improvements with the MST group showing an increase in walking velocity.

CONCLUSION

Cross-education plus mirror therapy may have potential for improving motor function after stroke. This study demonstrates the feasibility of the combination treatment and the need for future studies with larger sample sizes to investigate the effectiveness of the treatment.

Numerical study of patient-specific ankle-foot orthoses for drop foot patients using shape memory alloy

Drop foot is a nerve-muscle disorder that affects the muscles that lift the foot. The two main side effects of drop foot are slapping/kicking the foot after heel strike (foot) and dragging the foot during the swing (toe drag). Treatment methods such as ankle-foot orthoses (AFO) have some biomechanical benefits, but are not applicable to all walking conditions and cannot mitigate significant gait complications. This study introduces the design of a passive AFO system, which combines an ordinary AFO and a shape memory alloy (SMA) element. OpenSim was used to simulate patients with muscle weakness and to calculate the torque needed to imitate normal ankle joint stiffness. The calculated torque was then reproduced for different levels of muscle weakness by the superelasticity of SMAs. The study showed that the normal joint stiffness profile for each patient with a certain level of muscle weakness can be restored by designing a patient-specific orthosis.

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.

Cortical and spinal excitability changes after repetitive transcranial magnetic stimulation combined to physiotherapy in stroke spastic patients

OBJECTIVE

Repetitive Transcranial Magnetic Stimulation (rTMS) has been used to treat post-stroke upper limb spasticity (ULS) in addition to physiotherapy (PT). To determine whether rTMS associated with PT modulates cortical and spinal cord excitability as well as decreases ULS of post-stroke patients.

METHODS

Twenty chronic patients were randomly assigned to either the intervention group-1 Hz rTMS on the unaffected hemisphere and PT, or control group-sham stimulation and PT, for ten sessions. Before and after sessions, ULS was measured using the modified Ashworth scale and cortical excitability using the output intensity of the magnetic stimulator (MSO). The spinal excitability was measured by the Hmax/Mmax ratio of the median nerve at baseline, at the end of treatment, and at the 4-week follow-up.

RESULTS

The experimental group showed at the end of treatment an enhancement of cortical excitability, i.e., lower values of MSO, compared to control group (p = 0.044) and to baseline (p = 0.028). The experimental group showed a decreased spinal cord excitability at the 4-week follow-up compared to control group (p = 0.021). ULS decreased by the sixth session in the experimental group (p < 0.05).

CONCLUSION

One-hertz rTMS associated with PT increased the unaffected hemisphere excitability, decreased spinal excitability, and reduced post-stroke ULS.

Spastic dystonia in stroke subjects: prevalence and features of the neglected phenomenon of the upper motor neuron syndrome

OBJECTIVE

Spastic dystonia is one of the positive phenomena of the upper motor neuron syndrome (UMNS). It is characterised by the inability to relax a muscle leading to a spontaneous, although stretch-sensitive, tonic contraction. Although spastic dystonia is a recognized cause of muscle hypertonia, its prevalence among hypertonic muscles of stroke subjects has never been investigated. Differently from spasticity, which is an exaggerated stretch reflex, spastic dystonia is viewed as an efferent phenomenon, due to an abnormal central drive to motoneurons.

METHODS

In 23 hemiparetic stroke subjects showing increased muscle tone of wrist flexors, surface EMG was used to investigate the presence of spontaneous, stretch-sensitive EMG activity in flexor carpi radialis.

RESULTS

Spontaneous, stretch-sensitive EMG activity was found in 17 subjects. In the remaining 6 subjects, no spontaneous EMG activity was found.

CONCLUSIONS

The majority of stroke subjects is affected by spastic dystonia in their hypertonic wrist flexor muscles. Only a minority of subjects is affected by spasticity.

SIGNIFICANCE

To stop spastic dystonia from being the neglected aspect of UMNS, it is essential to link its definition to increased muscle tone, as occurred for spasticity. Recognizing the real phenomena underling muscle hypertonia could improve its management.

Kinematics can help to discriminate the implication of iliopsoas, hamstring and gastrocnemius contractures to a knee flexion gait pattern

BACKGROUND

Excessive Knee Flexion Gait Pattern (KFGP) is a common gait deviation in many pathological conditions. The contractures of the muscles that have been identified as being responsible of KFGP are: iliopsoas, hamstring and gastrocnemius.

RESEARCH QUESTION

How do isolated contractures of the iliopsoas, hamstrings and gastrocnemius impact knee flexion during gait?

METHODS

Three levels of contracture (mild, moderate and severe) were simulated bilaterally using an exoskeleton on 10 healthy participants for iliopsoas, hamstring and gastrocnemius muscles. A gait analysis session was performed to evaluate the joint kinematics according to the different simulated contractures. Thirty one parameters were chosen to analyze the kinematics of the thorax, pelvis, hip, knee and ankle. A principal component analysis (PCA) was used to determine the kinematic parameters influenced by contractures.

RESULTS

In addition to a permanent knee flexion observed for the three muscles with contracture: the contracture of the iliopsoas induces a large hip flexion with pronounced anterior pelvis tilt; the contracture of the hamstrings induces an ankle dorsiflexion during the support phase with a posterior pelvis tilt; the contracture of the gastrocnemius induces an absence of first and second rocker of the ankle with a slight flexion of hip and a slight anterior pelvis tilt.

SIGNIFICANCE

These results support the identification of the muscles responsible for a KFGP. A better knowledge of the interactions between contractures and associated joint kinematics of the same and adjacent joints will support the interpretation of gait analyses by more precisely and faster targeting the concerned muscle.

Effectiveness of Robot-Assisted Upper Limb Training on Spasticity, Function and Muscle Activity in Chronic Stroke Patients Treated With Botulinum Toxin: A Randomized Single-Blinded Controlled Trial

Background: The combined use of Robot-assisted UL training and Botulinum toxin (BoNT) appear to be a promising therapeutic synergism to improve UL function in chronic stroke patients.

Objective: To evaluate the effects of Robot-assisted UL training on UL spasticity, function, muscle strength and the electromyographic UL muscles activity in chronic stroke patients treated with Botulinum toxin.

Methods: This single-blind, randomized, controlled trial involved 32 chronic stroke outpatients with UL spastic hemiparesis. The experimental group (n = 16) received robot-assisted UL training and BoNT treatment. The control group (n = 16) received conventional treatment combined with BoNT treatment. Training protocols lasted for 5 weeks (45 min/session, two sessions/week). Before and after rehabilitation, a blinded rater evaluated patients. The primary outcome was the Modified Ashworth Scale (MAS). Secondary outcomes were the Fugl-Meyer Assessment Scale (FMA) and the Medical Research Council Scale (MRC). The electromyographic activity of 5 UL muscles during the “hand-to-mouth” task was explored only in the experimental group and 14 healthy age-matched controls using a surface Electromyography (EMGs).

Results: No significant between-group differences on the MAS and FMA were measured. The experimental group reported significantly greater improvements on UL muscle strength (p = 0.004; Cohen's d = 0.49), shoulder abduction (p = 0.039; Cohen's d = 0.42), external rotation (p = 0.019; Cohen's d = 0.72), and elbow flexion (p = 0.043; Cohen's d = 1.15) than the control group. Preliminary observation of muscular activity showed a different enhancement of the biceps brachii activation after the robot-assisted training.

Conclusions: Robot-assisted training is as effective as conventional training on muscle tone reduction when combined with Botulinum toxin in chronic stroke patients with UL spasticity. However, only the robot-assisted UL training contributed to improving muscle strength. The single-group analysis and the qualitative inspection of sEMG data performed in the experimental group showed improvement in the agonist muscles activity during the hand-to-mouth task.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT03590314

Mirror therapy and treadmill training for patients with chronic stroke: a pilot randomized controlled trial

BACKGROUND

Previous lower-limb mirror therapy research has focused on non-weight bearing interventions.

OBJECTIVES

The primary aim of this study was to investigate the effect and feasibility of a combination of mirror therapy and treadmill training on post-stroke lower-limb recovery compared to a placebo intervention.

METHODS

All patients (N = 30) walked on a treadmill for 30 min per day, 3 days per week, for 4 weeks. The mirror therapy and treadmill training group (n = 15) walked on the treadmill while viewing a reflection of their non-paretic limb in a mirror positioned in their mid-sagittal plane. The placebo group (n = 15) received no mirror visual feedback due to an altered mirror position.

PRIMARY OUTCOME MEASURES

Ten Metre Walk Test (10MWT) and Six Minute Walk Test (6MWT).

SECONDARY OUTCOME MEASURES

Modified Ashworth Scale (MAS) and Fugl-Meyer Assessment-Lower Extremity (FMA-LE). Feasibility was appraised by examining participant compliance and any adverse events.

RESULTS

No significant between group differences were demonstrated for the 10MWT, 6MWT or FMA-LE at post-training or 3-month follow-up assessment. A significant between group difference on the MAS was demonstrated in the reduction of ankle dorsiflexion muscle tone (p = 0.006) and ankle plantarflexion muscle tone (p = 0.01) in the mirror therapy group compared to the placebo group at post-training assessment but not at 3-month follow-up.

CONCLUSION

Our study reveals that in our group of patients with chronic stroke, mirror therapy combined with treadmill training facilitated significant reductions in ankle muscle tone (p < 0.05) compared to a placebo intervention.

Clinical and electrophysiological investigation of spastic muscle overactivity in patients with disorders of consciousness following severe brain injury

OBJECTIVE

The clinical and electrophysiological profile of spastic muscle overactivity (SMO) is poorly documented in patients with disorders of consciousness (DOC) following severe cortical and subcortical injury. We aim at investigating the link between the clinical observations of SMO and the electrophysiological spastic over-reactivity in patients with prolonged DOC.

METHODS

We prospectively enrolled adult patients with DOC at least 3 months post traumatic or non-traumatic brain injury. The spastic profile was investigated using the Modified Ashworth Scale and the Hmax/Mmax ratio. T1 MRI data and impact of medication were analyzed as well.

RESULTS

21 patients were included (mean age: 41 ± 11 years; time since injury: 4 ± 5 years; 9 women; 10 traumatic etiologies). Eighteen patients presented signs of SMO and 11 had an increased ratio. Eight patients presented signs of SMO but no increased ratio. We did not find any significant correlation between the ratio and the MAS score for each limb (all ps > 0.05). The presence of medication was not significantly associated with a reduction in MAS scores or Hmax/Mmax ratios.

CONCLUSIONS

In this preliminary study, the Hmax/Mmax ratio does not seem to reflect the clinical MAS scores in patients with DOC. This supports the fact they do not only present spasticity but other forms of SMO and contracture.

SIGNIFICANCE

Patients with DOC are still in need of optimized tools to evaluate their spastic profile and therapeutic approaches should be adapted accordingly.

[Spasticity: from pathophysiology to treatment]

The article presents modern views on the pathophysiology of spasticity, which is a frequent disabling consequence to the upper motor neuron (UMN) damage. Morphological and functional system of motion organization and the changes after the UMN damage is considered. The authors analyze existing definitions of spasticity. Stages of spasticity development are described in the context of neuroplasticity as well as in the framework of pathogenesis and sanogenesis. Existing ideas of its pathogenesis are compared with the typical clinical symptoms. The occurring pathological processes in muscles, tendons and joints that can aggravate the development of spasticity and complicate the diagnosis are considered. In addition, the main pathological spasticity patterns are described and the current development of diagnostic techniques is estimated. A review of main methods of spasticity treatment is presented. Special attention is paid to the botulinum neurotoxin type A (BoNT) preparations and central action muscle relaxants. The pathophysiological basement for complex treatment of spasticity as a part of the general rehabilitation process is given, so that the BoNT can be considered as the obligatory element of standard rehabilitation programs.

The neurophysiology of deforming spastic paresis: A revised taxonomy

This paper revisits the taxonomy of the neurophysiological consequences of a persistent impairment of motor command execution in the classic environment of sensorimotor restriction and muscle hypo-mobilization in short position. Around each joint, the syndrome involves 2 disorders, muscular and neurologic. The muscular disorder is promoted by muscle hypo-mobilization in short position in the context of paresis, in the hours and days after paresis onset: this genetically mediated, evolving myopathy, is called spastic myopathy. The clinician may suspect it by feeling extensibility loss in a resting muscle, although long after the actual onset of the disease. The neurologic disorder, promoted by sensorimotor restriction in the context of paresis and by the muscle disorder itself, comprises 4 main components, mostly affecting antagonists to desired movements: the first is spastic dystonia, an unwanted, involuntary muscle activation at rest, in the absence of stretch or voluntary effort; spastic dystonia superimposes on spastic myopathy to cause visible, gradually increasing body deformities; the second is spastic cocontraction, an unwanted, involuntary antagonist muscle activation during voluntary effort directed to the agonist, aggravated by antagonist stretch; it is primarily due to misdirection of the supraspinal descending drive and contributes to reducing movement amplitude; and the third is spasticity, one form of hyperreflexia, defined by an enhancement of the velocity-dependent responses to phasic stretch, detected and measured at rest (another form of hyperreflexia is "nociceptive spasms", following flexor reflex afferent stimulation, particularly after spinal cord lesions). The 3 main forms of overactivity, spastic dystonia, spastic cocontraction and spasticity, share the same motor neuron hyperexcitability as a contributing factor, all being predominant in the muscles that are more affected by spastic myopathy. The fourth component of the neurologic disorder affects the agonist: it is stretch-sensitive paresis, which is a decreased access of the central command to the agonist, aggravated by antagonist stretch. Improved understanding of the pathophysiology of deforming spastic paresis should help clinicians select meaningful assessments and refined treatments, including the utmost need to preserve muscle tissue integrity as soon as paresis sets in.

Frequency Dependence of Shear Wave Velocity in Stroke-Affected Muscles During Isometric Contraction- Preliminary Data

In addition to changes in the central nervous system, many changes can occur in the composition and structure of skeletal muscles after a hemispheric stroke. The mechanical behavior of skeletal muscles is linked to the density and structural arrangement of key constituents. Yet, little is known about changes in post-stroke muscle mechanical properties such as viscoelasticity. The aim of this study was to explore the frequency-dependent changes in shear wave (SW) velocity as a potentially informative feature accompanying changes in muscle viscoelastic properties under passive and active conditions in hemiplegic stroke. We used the ultrasound SuperSonic Imaging technique to induce and measure SW propagation in the biceps brachii muscle for both the paretic and contralateral limbs in three hemiplegic stroke survivors during passive and submaximal voluntary muscle contractions. We found that for all subjects, the muscles on both the paretic and non-paretic sides demonstrated large dispersion (i.e., a change in SW phase velocities as a function of frequency within each contraction level) under both passive and active conditions, although muscles on the paretic side displayed larger dispersion. In addition, for a range of frequencies from 108-756 Hz, the SW phase velocity was higher in active nonparetic muscles compared to those of paretic side with an increase of 42% at 756 Hz. This is in contrast with the muscle response under passive condition where the SW phase velocity exhibited a 97 % increase at 765Hz on the paretic side compared to the non-paretic side. These results suggest the mechanical properties are altered for stroke-affected muscles, which may be a result of changes in the muscle extracellular matrix composition. Further, this study provides evidence that there are changes in tissue mechanical properties and that may consequently influence muscle function.

Early movement restriction leads to maladaptive plasticity in the sensorimotor cortex and to movement disorders

Motor control and body representations in the central nervous system are built, i.e., patterned, during development by sensorimotor experience and somatosensory feedback/reafference. Yet, early emergence of locomotor disorders remains a matter of debate, especially in the absence of brain damage. For instance, children with developmental coordination disorders (DCD) display deficits in planning, executing and controlling movements, concomitant with deficits in executive functions. Thus, are early sensorimotor atypicalities at the origin of long-lasting abnormal development of brain anatomy and functions? We hypothesize that degraded locomotor outcomes in adulthood originate as a consequence of early atypical sensorimotor experiences that induce developmental disorganization of sensorimotor circuitry. We showed recently that postnatal sensorimotor restriction (SMR), through hind limb immobilization from birth to one month, led to enduring digitigrade locomotion with ankle-knee overextension, degraded musculoskeletal tissues (e.g., gastrocnemius atrophy), and clear signs of spinal hyperreflexia in adult rats, suggestive of spasticity; each individual disorder likely interplaying in self-perpetuating cycles. In the present study, we investigated the impact of postnatal SMR on the anatomical and functional organization of hind limb representations in the sensorimotor cortex and processes representative of maladaptive neuroplasticity. We found that 28 days of daily SMR degraded the topographical organization of somatosensory hind limb maps, reduced both somatosensory and motor map areas devoted to the hind limb representation and altered neuronal response properties in the sensorimotor cortex several weeks after the cessation of SMR. We found no neuroanatomical histopathology in hind limb sensorimotor cortex, yet increased glutamatergic neurotransmission that matched clear signs of spasticity and hyperexcitability in the adult lumbar spinal network. Thus, even in the absence of a brain insult, movement disorders and brain dysfunction can emerge as a consequence of reduced and atypical patterns of motor outputs and somatosensory feedback that induce maladaptive neuroplasticity. Our results may contribute to understanding the inception and mechanisms underlying neurodevelopmental disorders, such as DCD.

Considerations in the Management of Upper Extremity Spasticity

Spasticity is a movement disorder characterized by a velocity-dependent increase in muscle tone and a hyperexcitable stretch reflex. Common causes of spasticity include cerebral palsy, spinal cord injury, and stroke. Surgical treatment plans for spasticity must be highly individualized and based on the characteristics of patients and the spasticity in order to maximize functional gains. Candidates for surgery must be carefully selected. In this article, the authors review the pathophysiology of spasticity and discuss general considerations for surgical management with an emphasis on patient factors and spasticity characteristics. Specific considerations for the common causes of spasticity are presented.

Patterns of upper limb muscle activation in children with unilateral spastic cerebral palsy: Variability and detection of deviations

BACKGROUND

The aim of this study was two-fold: (1) to quantify the variability of upper limb electromyographic patterns during elbow movements in typically developing children and children with unilateral spastic cerebral palsy, and to compare different amplitude normalization methods; (2) to develop a method using this variability to detect (a) deviations in the patterns of a child with unilateral spastic cerebral palsy from the average patterns of typically developing children, and (b) changes after treatment to reduce muscle activation.

METHODS

Twelve typically developing children ([6.7-15.9yo]; mean 11.0 SD 3.0yo) and six children with unilateral spastic cerebral palsy ([7.9-17.4yo]; mean 12.4 SD 4.0yo) attended two sessions during which they performed elbow extension-flexion and pronation-supination movements. Surface electromyography of the biceps, triceps, brachioradialis, pronator teres, pronator quadratus, and brachialis muscles was recorded. The Likelihood method was used to estimate the inter-trial, inter-session, and inter-subject variability of the electromyography patterns for each time point in the movement cycle. Deviations in muscle patterns from the patterns of typically developing children and changes following treatment were evaluated in a case study of a child with cerebral palsy.

FINDINGS

Normalization of electromyographic amplitude by the mean peak yielded the lowest variability. The variability data were then used in the case study. This method detected higher levels of activation in specific muscles compared with typically developing children, and a reduction in muscle activation after botulinum toxin A injections.

INTERPRETATION

Upper limb surface electromyography pattern analysis can be used for clinical applications in children with cerebral palsy.

Common Etiologies of Upper Extremity Spasticity

Spasticity is a motor disorder that manifests as a component of the upper motor neuron syndrome. It is associated with paralysis and can cause significant disability. The most common causes leading to spasticity include stroke, traumatic brain injury, multiple sclerosis, spinal cord injury, and cerebral palsy. This article discusses the pathophysiology and clinical findings associated with each of the most common etiologies of upper extremity spasticity.

Botulinum Toxin Injections and Electrical Stimulation for Spastic Paresis Improve Active Hand Function Following Stroke

Botulinum toxin type A (BTX-A) injections improve muscle tone and range of motion (ROM) among stroke patients with upper limb spasticity. However, the efficacy of BTX-A injections for improving active function is unclear. We aimed to determine whether BTX-A injections with electrical stimulation (ES) of hand muscles could improve active hand function (AHF) among chronic stroke patients. Our open-label, pilot study included 15 chronic stroke patients. Two weeks after BTX-A injections into the finger and/or wrist flexors, ES of finger extensors was performed while wearing a wrist brace for 4 weeks (5 days per week; 30-min sessions). Various outcomes were assessed at baseline, immediately before BTX-A injections, and 2 and 6 weeks after BTX-A injections. After the intervention, we noted significant improvements in Box and Block test results, Action Research Arm Test results, the number of repeated finger flexions/extensions, which reflect AHF, and flexor spasticity. Moreover, significant improvements in active ROM of wrist extension values were accompanied by marginally significant changes in Medical Research Council wrist extensor and active ROM of wrist flexion values. In conclusion, BTX-A injections into the finger and/or wrist flexors followed by ES of finger extensors improve AHF among chronic stroke patients.

Orthopaedic surgery for patients with central nervous system lesions: Concepts and techniques

Since ancient times, the aim of orthopedic surgery has been to correct limb and joint deformities, including those resulting from central nervous system lesions. Recent developments in the treatment of spasticity have led to changes in concepts and management strategies. The increase in life expectancy has increased the functional needs of patients. Orthopedic surgery, along with treatments for spasticity, improves the functional capacity of patients with neuro-orthopaedic disorders, improving their autonomy. In this paper, we describe key moments in the history of orthopedic surgery regarding the treatment of patients with central nervous system lesions, from poliomyelitis to stroke-related hemiplegia, from the limbs to the spine, and from contractures to heterotopic ossification. A synthesis of the current surgical techniques is then provided, and the importance of multidisciplinary evaluation and management is highlighted, along with indications for medical, rehabilitation and surgical treatments and their combinations. We explain why it is essential to consider patients' expectations and to set achievable goals, particularly before surgery, which is by nature irreversible. More recently, specialized surgical teams have begun to favor the use of soft-tissue techniques over bony and joint procedures, except for spinal disorders. We highlight that orthopedic surgery is no longer the end-point of treatment. For example, lengthening a contractured muscle improves the balance around a joint, improving mobility and stability but may be only part of the problem. Further medical treatment and rehabilitation, or additional surgery, are often necessary to continue to improve the function of the limb. Despite the recognized effectiveness of orthopedic surgery for neuro-orthopedic disorders, few studies have formally evaluated them. Hence, there is a need for research to provide evidence to support orthopedic surgery for treating neuro-orthopedic disorders.

Evaluation of a toolkit for standardizing clinical measures of muscle tone

OBJECTIVE

To evaluate a new portable toolkit for quantifying upper and lower extremity muscle tone in patients with upper motor neuron syndrome (UMNS).

APPROACH

Cross-sectional, multi-site, observational trial to test and validate a new technology.

SETTING

Neurorehabilitation clinics at tertiary care hospitals.

PARTICIPANTS

Four cohorts UMNS patient, >6 mo post acquired brain injury, spinal cord injury, multiple sclerosis and cerebral palsy, and a sample of healthy age-matched adult controls.

MEASURES

Strength: grip, elbow flexor and extensor, and knee extensor; range of motion (ROM): passive ROM (contracture) and passive-active ROM (paresis); objective spasticity: stretch-reflex test for elbow, and pendulum test for knee; subjective spasticity: modified Ashworth scale scores for elbow and knee flexors and extensors.

RESULTS

Measures were acquired for 103 patients from three rehabilitation clinics. Results for patient cohorts were consistent with the literature. Grip strength correlated significantly with elbow muscle strength and all patient populations were significantly weaker in upper- and lower-extremity compared to controls. Strength and paresis were correlated for elbow and knee but neither correlated with contracture. Elbow spasticity correlated with strength and paresis but not contracture. Knee spasticity correlated with strength, and subjective spasticity correlated with contracture.

SIGNIFICANCE

The BioTone^™ toolkit provided comprehensive objective measures for assessing muscle tone in patients with UMNS. The toolkit could be useful for standardizing outcomes measures in clinical trials and for routine practice.

Post-stroke Hemiplegic Gait: New Perspective and Insights

Walking dysfunction occurs at a very high prevalence in stroke survivors. Human walking is a phenomenon often taken for granted, but it is mediated by complicated neural control mechanisms. The automatic process includes the brainstem descending pathways (RST and VST) and the intraspinal locomotor network. It is known that leg muscles are organized into modules to serve subtasks for body support, posture and locomotion. Major kinematic mechanisms are recognized to minimize the center of gravity (COG) displacement. Stroke leads to damage to motor cortices and their descending corticospinal tracts and subsequent muscle weakness. On the other hand, brainstem descending pathways and the intraspinal motor network are disinhibited and become hyperexcitable. Recent advances suggest that they mediate post-stroke spasticity and diffuse spastic synergistic activation. As a result of such changes, existing modules are simplified and merged, thus leading to poor body support and walking performance. The wide range and hierarchy of post-stroke hemiplegic gait impairments is a reflection of mechanical consequences of muscle weakness, spasticity, abnormal synergistic activation and their interactions. Given the role of brainstem descending pathways in body support and locomotion and post-stroke spasticity, a new perspective of understanding post-stroke hemiplegic gait is proposed. Its clinical implications for management of hemiplegic gait are discussed. Two cases are presented as clinical application examples.