A mechatronic device for spasticity quantification

Spasticity is a common and complex motor disorder that affects more than 12 million persons in the world. There are several studies on spasticity quantification in the literature but there is still a need for measurement improvements. This paper presents the design of a mechatronic device for spasticity quantification, in joint of ankle, elbow and knees. This approach is based on the velocity dependent of the tonic stretch reflexes. The relevant variables, the measurement range and the adequate measurement systems are selected. The data acquisition system, board and software, are also defined and tested in laboratory. The proposed system was tested in rehabilitation clinical environment and the corresponding results are presented in this article.The authors are grateful to Portuguese Research Centers Algoritmi and CT2M for financial support. The authors are also grateful to Fisimaia rehabilitation clinic in Maia and his patients

An examination of muscle and tendon properties in children with spastic cerebral palsy and their response to stretch: a theoretical basis for evidence-based clinical practice

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Cerebral palsy (CP) is a heterogeneous disorder in which movement and posture are affected. Increased excitation of the central nervous system leads to neural symptoms, which can cause spasticity and muscle weakness. These neural abnormalities result in secondary CP-related mechanical adaptations of muscles and tendons, which can lead to muscle contracture, joint deformities and pain. Therapeutic interventions are therefore essential to treat CP-induced abnormalities. Passive stretching in particular is a popular treatment method in clinical practice. However, due to a lack of scientific evidence, clinicians often have to make assumptions about the mechanical adaptability of muscles and tendons. Currently, the mechanical properties of muscles and tendons in children with CP and their adaptability are not well understood, which makes it difficult to implement evidence-based practice in clinical settings. Therefore, the overall purpose of this research was to examine the mechanical properties of the medial gastrocnemius muscle and Achilles tendon in children with spastic CP, and the adaptations of the muscle and tendon to acute and long-term passive stretching. The first experimental Chapter (3) was carried out in healthy adults, to assess the agreement between two methods of deriving Achilles tendon stiffness (i) active contraction of the triceps surae muscles to elongate the Achilles tendon, or (ii) passive rotation of the ankle joint. Taking into consideration the tendon’s viscoelastic response, the effects of strain-rate on Achilles tendon stiffness were also described. Results revealed that tendon stiffness measured using the “active method” was 6% greater than the “passive method”. There was also a significant increase in Achilles tendon stiffness in response to increased strain-rate. As the more commonly used active method is problematic to be used in children with CP, due to muscle weakness and excessive co-contraction, the passive method of deriving tendon stiffness was used in subsequent experimental studies. In experimental Chapter 4, differences in the mechanical properties of the Achilles tendon and triceps surae muscles between children with CP and their typically developing (TD) peers, were investigated. The results revealed that estimates of triceps surae muscle stiffness were significantly greater in children with CP compared to TD children. The results also showed that despite a smaller tendon cross-sectional area in children with CP, Achilles tendon stiffness was not different between groups. In addition, children with CP had a steeper tendon stiffness-strain-rate relationship compared to TD children. These results have significant clinical implications regarding the diagnosis of spasticity using the current clinical methods. Experimental Chapters 5 and 6 examined the muscle’s and tendon’s response to stretch. Passive stretching, implemented by a clinician or by the children themselves, is a commonly used intervention for children with CP with the aim of inducing structural alterations in muscles and tendons to improve function. In order for these alterations to take place, elongation of the muscle and fascicles would presumably need to occur with acute stretching. To date, this assumption has not been tested. Thus, the purpose of Chapter 5 was to investigate the medial gastrocnemius and muscle fascicle response to acute stretching, using two commonly used stretch techniques. Results of this study revealed that 100 s of stretching caused a transient increase in tendon (1.0 cm), muscle (0.8 cm) and fascicle lengths (0.6 cm). This effect was independent of stretch technique. These results provide evidence that the muscle and fascicles are capable of elongating in response to stretch in children with spastic CP. They provide a basis for the hypothesis that the spastic muscle may be able to adapt in response to long-term stretching. Thus, the purpose of the final experimental Chapter (6) was to assess the effects of a six week passive stretching intervention (four days per week, 15 minutes per day) on muscle and tendon properties, and gait parameters in children with CP. Results revealed there was a significant reduction in joint stiffness in the experimental group following six weeks of stretching. This was accompanied by a reduction in muscle stiffness, but with no alterations in Achilles tendon stiffness. Additionally, there were no positive effects of passive stretching on gait parameters. Together, the results of the present series of investigations demonstrates how fundamental knowledge of muscle and tendon mechanics in children with spastic CP, can be implemented to support evidence-based clinical practice

An approach for spasticity quantification based on the stretch reflex threshold

Spasticity is a common and complex motor disorder that affects more than 12 million persons in the world. There are several studies on spasticity quantification in the literature but there is still a need for measurement improvements. This paper presents the design of a mechatronic device for spasticity quantification, in joint of ankle, elbow and knees. This approach is based on the velocity dependent of the tonic stretch reflexes. The relevant variables, the measurement range and the adequate measurement systems are selected. The data acquisition system, board and software, are also defined and tested in laboratory. Next step consists of the system validation in clinical environment

Cerebral spasticity modeled as disorded equilibrium point control

Spasticity is a highly complex phenomenon, which has not been defined in precise and quantifiable terms. Although the muscle stretch reflex is thought to play an important role in spasticity generation, the pathophysiologic basis of spasticity is not completely understood. A valid measure of spasticity is one that is chosen within the context of a theory describing the physiological mechanisms underlying the control of posture and movement in healthy individuals and possible impairments of these mechanisms leading to motor disorders. This research’s goal was to determine the role of stretch reflex threshold in the regulation of impaired motor control through the exploration of the following research questions: Can experimental measures be produced leading to the development of a model of spasticity that can be interpreted within the framework of a general theory of motor control? Can the underlying motor control framework provide unique parameters capable of describing both normal and altered/abnormal movement? Can the model be robust enough to explain active as well as passive movement? The research method outlined in this dissertation takes the novel approach of incorporating the equilibrium point hypothesis into a trajectory-based analysis of pendulum knee motion. The Equilibrium Point Hypothesis (EPH) of motor control theorizes that the central nervous system (CNS) provides a virtual trajectory of joint motion, representing space and time. A forward dynamic model has been developed that can reproduce kinematic data through the using optimized model parameters. The incorporation of the equilibrium point hypothesis in forward model was not only recognition that examination of the entire trajectory of the limb, rather than just the first amplitude of swing, was necessary, but also, that movement can be characterized by the simple extraction of three parameters: a relative damping coefficient, relative stiffness coefficient and mathematical function which can act as an approximation CNS the virtual trajectory described in the EPH. This research produced a model of passive motion with the ability to produce parameter values that not only differentiate subjects with spasticity from subjects with no clinical signs of spasticity but that can separate subjects based on severity of spastic condition. Research which began as an endeavor to model the passive motion of the pendulum knee test, led to the development of a unifying model of motor control that is robust enough to describe both active and passive movements

The effect of therapeutic vibration on increasing erect and symmetrical sitting behaviors in multiply handicapped children

Thesis (M.S. Ed.)--University of Kansas, Special Education, 1984

Neuromuscular Treatments for Speech and Swallowing: A Tutorial

Despite the proliferation of oral motor therapies, much controversy exists regarding the application and benefit of neuromuscular treatments (NMTs) such as strength training for alleviating dysarthria and/or dysphagia. Not only is limited empirical support available to validate the use of NMTs, but clinicians may also lack the foundational information needed to judge the theoretical soundness of unstudied treatment strategies. This tutorial reviews the theoretical foundations for several NMTs, including active exercises, passive exercises, and physical modalities. It highlights how these techniques have been used to address neuromuscular impairments in the limb musculature and explores potential applications to the speech and swallowing musculature. Key issues discussed in relation to active exercise are the selection of treatment targets (e.g., strength, endurance, power, range of motion), specificity of training, progression, and recovery. Factors influencing the potential effectiveness of passive exercises and physical modalities are presented, along with discussion of additional issues contributing to the controversy surrounding oral motor therapies

Shear wave elastography to assess the effect of botulinum toxin in muscle hypertonia following stroke

Introduction Sonoelastography is a method capable of evaluating the mechanical properties of soft tissues by ultrasound (US). A further development of this technique is shear wave elastography (SWE), which provides a quantitative evaluation of the elastic properties - in terms of tissutal stiffness - by measuring the propagation velocities of the directional shear waves, produced by an ultrasound pulse. Spasticity often appears in stroke patients in the affected limbs. It corresponds to velocity-dependent muscle hypertonia in relation to the hyperexcitability of the stretch reflex. Over time, the paretic muscles develop intrinsic alterations with consequent muscle shortening and increased fibrosis related to reduced use and immobilization. Intramuscular injections of botulinum toxin A (BoNT-A) is an effective treatment which reduces muscle activity by inhibiting the release of acetylcholine at the neuromuscular junction level and is therefore able to reduce neuromediated muscle hypertonicity. The study aims to evaluate the effectiveness of SWE to appreciate changes in stiffness in spastic muscles after treatment with BoNT-A and possibly detect differences between affected muscles and unaffected contralateral ones related to fibrous-fatty remodeling. Materials & Methods 14 adult patients (5F; age: 58,4\ub114,1 years, m\ub1SD; range:46-78) affected by spasticity were recruited after ischemic or hemorrhagic stroke diagnosed for at least 3 months and with a time interval from the last injection of at least 4 months, if already treated with BoNT-A. They patients underwent a physical examination in which muscle hypertonia was assessed using the modified Ashworth scale (MAS). The assessments were carried out on a sample muscle among the spastic ones favoring the greater volume and better accessibility to the ultrasound probe. SWE was also performed on the homologue non-paretic contralateral muscle. Spasticity was measured as the average electromyographic activity recorded during stretching (reflex by stretching) of the selected muscle at a reproducible speed, according to a previously validated methodology. The SWE evaluation was carried out with US scans across and along the direction of muscular fibers - as assessed by conventional US - covering the entire belly of the selected muscle to obtain a comprehensive estimate of the muscle stiffness both with the maximum shortened and elongated muscle position. Muscle fibrosis was also estimated on conventional B-mode US using the modified Heckmatt scale. All evaluations were performed shortly before botulinum toxin infiltration (T0) and one month later (T1). Clinical, electromyographic and ultrasound evaluation were performed by three different blinded examiners. Depending on data distribution, non-parametric statistical tests for paired data were performed for comparison; Spearman\u2019s r was calculated to assess data correlations. Results A total of 224 SWE values resulted considering both time points. Overall, SWE measurements on paretic muscles assessed with a longitudinal positioning of the probe showed statistically significant reduction at T1 versus T0 both in non stretched conditions (p=0.001) and in stretched conditions (p=0.0029). After BoNT-A injection, a significant reduction in MAS (p=0.009), spastic dystonia (p=0.0043), spasticity (p=0.0019) and longitudinal SWE measurements, both in non stretched conditions (p=0.001) and in stretched conditions (p=0.0029), was observed. No significant changes in SWE parameters were observed on non-paretic versus contralateral muscle . All SWE measurements were higher in the paretic limb than in the contralateral one (p<0.01); higher SWE measurements resulted along the direction of muscular fibers versus across them (p<0.01). Cohen\u2019s d estimate a larger effect on EMG values than longitudinal SWE ones (either in non stretched and in stretched condition), with narrower 95%CI for SWE measurements. No changes resulted by the modified Heckmatt scale US assessments; there was a positive correlation (r: 0.46-0.84) between MHS scores and SWE values. Conclusion This is the first study evaluating the effect of BoNT-A on muscle hypertonia following stroke, assessed by mean of SWE and compared with the stretch reflex. The treatment resulted in a reduction of MAS, stretch reflex and muscular stiffness, in relation to the reduction of the neuro-mediated hypertonia. We have therefore shown that SWE is able to appreciate a reduction in neuro-mediated stiffness. Abolishing the neuro-mediated contribution by keeping the limb in a shortened position and moreover after BoNT-A injection, the SWE values resulted higher in the paretic muscle than in the healthy muscle in the same position. Hence, SWE-driven comparison between the spastic muscle and the contralateral unaffected homologous one is able to disclose the amount of stiffness due only to intrinsic muscular involutive remodeling. Alongside sEMG, SWE could therefore constitute an added-value to clinicians who manage spasticity for the assessment of responses to treatments and monitoring therapeutic interventions

Biomechanics and Exercise

Children develop lower levels of muscle force, and at slower rates, than adults. Whilst strength training in children is expected to reduce this differential, a synchronous adaptation in the tendon must be achieved to ensure forces continue to be transmitted to the skeleton with efficiency whilst minimizing the risk of strain-related tendon injury. We hypothesized that resistance training (RT) would alter tendon mechanical properties in children concomitantly with changes in force production characteristics. Twenty prepubertal children (8.9 ± 0.3 years) were equally divided into control (non-training) and experimental (training) groups. The training group completed a 10-week RT intervention consisting of 2-3 sets of 8-15 plantar flexion contractions performed twice-weekly on a recumbent calf raise machine. Achilles tendon properties (cross-sectional area, elongation, stress, strain, stiffness and Young’s modulus), electromechanical delay (EMD; time between the onset of muscle activity and force), rate of force development (RFD; slope of the force-time curve) and rate of EMG increase (REI; slope of the EMG-time curve) were measured before and after RT. Tendon stiffness and Young’s modulus increased significantly after RT in the experimental group only (~29% and ~25%, respectively); all other tendon properties were not significantly altered, although there were mean decreases in both peak tendon strain and strain at a given force level (14% and 24%, respectively (n.s)) which may have implications for tendon injury risk and muscle fiber mechanics. A ~13% decrease in EMD was found after RT for the experimental group which paralleled the increase in tendon stiffness (r = -0.59), however RFD and REI were unchanged. The present data show that the Achilles tendon adapts to RT in prepubertal children and is paralleled by a change in EMD, although the magnitude of this change did not appear to be sufficient to influence RFD. These findings are of potential importance within the context of the efficiency and execution of movement