Biomedical device for spasticity quantification based on the velocity dependence of 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 validation, in clinical environment, of a mechatronic medical device, dedicated, and specially designed and constructed for spasticity quantification, in joint of ankle, elbow and knees. This approach is based on the velocity-dependent of the Stretch Reflex threshold. The relevant variables, the measurement range and the adequate measurement systems are indicated. The reliability of the developed mechatronic medical system is confirmed by data acquisition and analysis, following a systematic methodology, also presented in the paper

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

Development, Test and Validation of a Mechatronic Device for Spasticity Quantification

Abstract Spasticity is a common pathological phenomenon in clinical practices, frequently expressed as a stroke, multiple sclerosis or cerebral palsy. The accurate quantification of spasticity allows early action to prevent the potentially irreversible consequences. The aim of this work is to develop and implement a mechatronic device for the accurate quantification of spasticity, which is able to differentiate spasticity from other motor disorders. The proposed method is based on the quantification of the tonic stretch reflex threshold (TSRT) for the assessment of the range of motion of the limb affected by spasticity. In order to validate the developed device, experimental trials have been conducted, considering the flexor muscle of the elbow joint. The developed device was tested, first in a laboratory environment with healthy subjects and secondly, in a clinical environment with the collaboration of patients with spasticity. The evaluations in th clinical environment were performed on three different days in order to evaluate the reproducibility of the obtained results. The experimental trials confirm the sensibility, reproducibility and reliability of spasticity quantification based on the TSRT method. This project has been developed in cooperation with the Hospital of Braga and Fisimaia rehabilitation clinic, both in Portugal

Robot-Aided Systems for Improving the Assessment of Upper Limb Spasticity: A Systematic Review

This article belongs to the Special Issue Sensors Technology for Medical Robotics.Spasticity is a motor disorder that causes stiffness or tightness of the muscles and can interfere with normal movement, speech, and gait. Traditionally, the spasticity assessment is carried out by clinicians using standardized procedures for objective evaluation. However, these procedures are manually performed and, thereby, they could be influenced by the clinician’s subjectivity or expertise. The automation of such traditional methods for spasticity evaluation is an interesting and emerging field in neurorehabilitation. One of the most promising approaches is the use of robot-aided systems. In this paper, a systematic review of systems focused on the assessment of upper limb (UL) spasticity using robotic technology is presented. A systematic search and review of related articles in the literature were conducted. The chosen works were analyzed according to the morphology of devices, the data acquisition systems, the outcome generation method, and the focus of intervention (assessment and/or training). Finally, a series of guidelines and challenges that must be considered when designing and implementing fully-automated robot-aided systems for the assessment of UL spasticity are summarized

Manually controlled instrumented spasticity assessments: a systematic review of psychometric properties

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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

Quantifying Spasticity: A Review

A precise method to measure spasticity is fundamental in improving the quality of life of spastic patients. The measurement methods that exist for spasticity have long been considered scarce and inadequate, which can partly be explained by a lack of consensus in the definition of spasticity. Spasticity quantification methods can be roughly classified according to whether they are based on neurophysiological or biomechanical mechanisms, clinical scales, or imaging techniques. This article reviews methods from all classes and further discusses instrumentation, dimensionality, and EMG onset detection methods. The objective of this article is to provide a review on spasticity measurement methods used to this day in an effort to contribute to the advancement of both the quantification and treatment of spasticity

Position as Well as Velocity Dependence of Spasticity—Four-Dimensional Characterizations of Catch Angle

We investigated the muscle alterations related to spasticity in stroke quantitatively using a portable manual spasticity evaluator.Methods: Quantitative neuro-mechanical evaluations under controlled passive elbow stretches in stroke survivors and healthy controls were performed in a research laboratory of a rehabilitation hospital. Twelve stroke survivors and nine healthy controls participated in the study. Spasticity and catch angle were evaluated at 90°/s and 270°/s with the velocities controlled through real-time audiovisual feedback. The elbow range of motion (ROM), stiffness, and energy loss were determined at a slow velocity of 30°/s. Four-dimensional measures including joint position, torque, velocity and torque change rate were analyzed jointly to determine the catch angle.Results: The catch angle was dependent on the stretch velocity and occurred significantly later with increasing velocity (p < 0.001), indicating position dependence of spasticity. The higher resistance felt by the examiner at the higher velocity was also due to more extreme joint position (joint angle) since the spastic joint was moved significantly further to a stiffer elbow position with the higher velocity. Stroke survivors showed smaller ROM (p < 0.001), higher stiffness (p < 0.001), and larger energy loss (p = 0.005). Compared to the controls, stroke survivors showed increased reflex excitability with higher reflex-mediated torque (p < 0.001) and at higher velocities (p = 0.02).Conclusion: Velocity dependence of spasticity is partially due to joint angle position dependence with the joint moved further (to a stiffer position where higher resistance was felt) at a higher velocity. The “4-dimensional characterization” including the joint angle, velocity, torque, and torque change rate provides a systematic tool to characterize catch angle and spasticity quantitatively

Development of an equipment to detect and quantify muscular spasticity

Dissertação para obtenção do Grau de Mestre em Engenharia BiomédicaSpasticity consists of a muscular tonus alteration caused by a flawed central nervous system which results in a hypertonic phenomenon. The presence of spasticity is normally noticeable by the appearance of a denoted velocity dependent “rigidity” throughout the passive mobilization of an affected limb which can be a potential source of constraints in subject independency by negatively affecting the accomplishment of daily basic tasks. Spasticity treatment usually comprises high cost methods and materials. There is also a strict relation between the spasticity grade and the dose that has to be applied to attain the desired effective result. These two facts justify the need for a more precise equipment to detect and quantify muscular spasticity. In the present days, three main groups of spasticity quantification methods coexist: the clinical scales, electrophysiological measurements and the biomechanical measurements. The most used ones are the clinical scales, especially the Modified Ashworth Scale. These scales quantify spasticity based on the perception of muscular response sensed by an operator. In a different field of approach, many instruments have been built to quantify biomechanical magnitudes that have shown direct relation with spasticity. Unfortunately, most of these instruments had either inappropriate size for clinical use, weak result correlation both inter and intra-subject, or a noticeable result dependence on the operator. The objective of this project was to create a reliable method for spasticity detection and quantification that could: be of easy and fast application, have no need for a specialized operator, be portable and present good repeatability and independency from the operator in the produced results. The resulting prototype, named SpastiMed, is a motorized and electronically controlled device which through analysis of the produced signal presented irrefutable proof of its capacity to detect and possibly quantify spasticity while gathering the important characteristics mentioned