Tonic Stretch Reflex Threshold Research Articles

Maturation of short-interval inhibitory and excitatory circuits in the human primary motor cortex

s / Brain Stimulation 8 (2015) 360e377 372 spasticity in 4 post-stroke subjects that affected tonic stretch reflex threshold (TSRT) [2], i.e., the joint angle at which the stretch reflex begins to act due to the descending and segmental influences on motoneurons. The rectangular (4.5 cm 9 cm) electrodes were placed on each side of the spine (5 cm apart) over the paravertebral skin at the twelfth thoracic and first lumbar vertebral levels [3]. We found that only the high frequency (2100 Hz) sinusoidal stimulation (HFSS) and not the low frequency sinusoidal stimulation (LFSS) (20Hz) significantly affected the TSRT during tsACS application (45mins). LFSS showed significant aftereffects only after 45mins of tsACS application. Therefore, HFSS and LFSS may involve different mechanisms based on the ion channel distributions and their response properties in the neural tissue of the dorsal column [1].

Effects of transcutaneous lumbar spinal cord alternating current stimulation on tonic stretch reflex threshold in stroke - a case series

Effects of transcutaneous lumbar spinal cord alternating current stimulation on tonic stretch reflex threshold in stroke - a case series

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.

Portable measurement system for the objective evaluation of the spasticity of hemiplegic patients based on the tonic stretch reflex threshold

The clinical scales used for the evaluation of the spasticity have some drawbacks, in spite of their simplicity and ease of assessment, and their inter- and intra-rater reliability remains controversial. The aim of this study is to develop a portable system for the objective and reliable evaluation of the spasticity based on the K-means clustering of the tonic stretch reflex threshold (TSRT) and to compare the discrimination performance of the level of spasticity determined by our method with that by the conventional modified Ashworth scale (MAS). Fifteen hemiplegic patients (7 males and 8 females, age: 63.5 ± 15.6) participated in the study. The average and standard deviation values of the TSRTs were 127.9 ± 1.6, 121.8 ± 1.5 and 117.9 ± 1.3 in groups G1, G2 and G3, respectively, and there were significant differences between the TSRTs of each group ( p < 0.05). Also, our groups classified by the criteria of the TSRT had a strong negative correlation ( r = −0.95, r 2 = 0.90, p < 0.05) between the level of spasticity and TSRTs. These results demonstrated that our system could be clinically more useful for the quantitative and reliable discrimination of the spasticity than the conventional MAS.

Clinical Effectiveness of New Portable System for Measuring Spasticity of the Stroke Patients

Spasticity is a motor disorder characterized by a velocity dependent increase in muscle tone with exaggerated tendon jerks, resulting from hyper-excitability of the stretch reflex. The aim of this study is to develop a portable system for quantifying the grade of spasticity which could calculate the biomechanical as well as neurophysiologic parameters, and for determining the relationship between the Tonic Stretch Reflex Threshold (TSRT) and Modified Ashworth Scale (MAS). Eleven patients with stroke participated in the study (6 males and 5 females, the average age of years). As a results, the mean and standard deviation values of the TSRT were , and in the MAS 1, MAS 1+ and MAS 2 groups, respectively. Also, there was a negative correlation between the TSRT and MAS (rho=-0.72, p

Tonic Stretch Reflex Threshold as a Measure of Spasticity: Implications for Clinical Practice

Lance’s definition of spasticity states: (1) the excitability of the tonic stretch reflex threshold is the conceptual unit of measure of spasticity; (2) because spasticity is a velocity-dependent phenomenon, different velocities of stretch should be used to evaluate spasticity; and (3) measures should provide insight into the role of spasticity in disordered motor control. This article reviews studies of clinical and laboratory-based methods to evaluate spasticity. There is a lack of consensus regarding the conceptual unit that best captures spasticity. Several biomechanical variables and parameters such as stretch reflex gain, stretch reflex threshold, and/or suprathreshold phenomena are often measured alone or in combination without a unifying conceptual framework. Most studies do not establish links between spasticity and other motor deficits and adhere only partly to Lance’s definition. A promising alternative to current measures is offered by the lambda model that uses the tonic stretch reflex threshold as the descriptor of spasticity. The lambda model also provides a framework in which spasticity and the presence of disorders in muscle activation can be described and explained. We introduce a portable device to measure spasticity, based on the measurement of the tonic stretch reflex threshold, which is more closely related to Lance’s definition.

Spasticity measurement based on tonic stretch reflex threshold in stroke using a portable device

Objectives We investigated intra- and inter-evaluator reliability to quantify spasticity based on the tonic stretch reflex threshold (TSRT) and the correlation between TSRT and resistance to stretch. Methods Spasticity was evaluated in 20 subjects with chronic stroke-related spasticity using a portable device and the Modified Ashworth Scale (MAS). Evaluations were done on 2 days, by three evaluators. Biceps brachii EMG signals and elbow displacement were recorded during 20 elbow stretches applied at different velocities for each evaluation. Velocity-dependent dynamic stretch reflex thresholds (angle where EMG signal increased in the biceps for a given velocity of stretch) were recorded. These values were used to compute TSRT (excitability of motoneurons at 0°/s). Spasticity was also measured with MAS. Results Reliability was moderately good for subjects with moderate to high spasticity (intra-evaluator: 0.46–0.68, and inter-evaluator: 0.53–0.68). The TSRT measure of spasticity did not correlate with resistance to stretch (MAS). Conclusions TSRT may be a more representative measure for subjects with moderate to high spasticity. Further improvements are suggested for the portable device in order to quantify all the levels of spasticity. Significance TSRT may be an alternative clinical measure to current clinical scales.

Regulation of stretch reflex threshold in elbow flexors in children with cerebral palsy: a new measure of spasticity

The tonic stretch reflex threshold in children with cerebral palsy (CP) was measured to determine its test-retest reliability and its concurrent validity as a potential measure of spasticity. Fourteen children with spastic CP aged 6 to 18 years were tested on three separate occasions for clinical spasticity and stretch reflex thresholds of affected elbow flexors. Electromyographic (EMG) recordings were obtained by surface electrodes for elbow flexors and extensors during mechanical displacements of the passive joint towards extension. Displacements were produced by a torque motor at seven velocities which randomly varied from trial to trial. EMG activity was measured in the stretched flexor muscles to determine threshold angles and velocities for each velocity of stretch. These were plotted on a velocity-angle-phase diagram and regression analysis was used to determine the static stretch reflex threshold for each participant. The measure showed good test-retest reliability for the group (ICC 0.73, p<0.001) whereas a significant correlation between the measure and the clinical spasticity scale was not found. This technique is a potential outcome variable for measuring the efficacy of treatments aimed at decreasing spasticity in children with CP.

Regulation of stretch reflex threshold in elbow flexors in children with cerebral palsy: a new measure of spasticity

The tonic stretch reflex threshold in children with cerebral palsy (CP) was measured to determine its test‐retest reliability and its concurrent validity as a potential measure of spasticity. Fourteen children with spastic CP aged 6 to 18 years were tested on three separate occasions for clinical spasticity and stretch reflex thresholds of affected elbow flexors. Electromyographic (EMG) recordings were obtained by surface electrodes for elbow flexors and extensors during mechanical displacements of the passive joint towards extension. Displacements were produced by a torque motor at seven velocities which randomly varied from trial to trial. EMG activity was measured in the stretched flexor muscles to determine threshold angles and velocities for each velocity of stretch. These were plotted on a velocity‐angle‐phase diagram and regression analysis was used to determine the static stretch reflex threshold for each participant. The measure showed good test‐retest reliability for the group (ICC 0.73,p&lt;0.001) whereas a significant correlation between the measure and the clinical spasticity scale was not found. This technique is a potential outcome variable for measuring the efficacy of treatments aimed at decreasing spasticity in children with CP.

Effect of emotional stress on spasticity and rigidity

To determine inter-rater reliability, minimal detectable change and responsiveness of Tonic Stretch Reflex Threshold (TSRT) as a quantitative measure of elbow flexor spasticity.Elbow flexor spasticity was assessed in 55 patients with sub-acute stroke by determining TSRT, the angle of spasticity onset at rest (velocity = 0°/s). Elbow flexor muscles were stretched 20 times at different velocities. Dynamic stretch-reflex thresholds, the elbow angles corresponding to the onset of elbow flexor EMG at each velocity, were used for TSRT calculation. Spasticity was also measured with the Modified Ashworth Scale (MAS). In a sub-group of 44 subjects, TSRT and MAS were measured before and after two weeks of an upper-limb intervention.The intraclass correlation coefficient was 0.65 and the 95% minimal detectable change was 32.4°. In the treated sub-group, TSRT, but not MAS significantly changed. TSRT effect size and standardized response mean were 0.40 and 0.35, respectively. Detection of clinically meaningful improvements in upper-limb motor impairment by TSRT change scores ranged from poor to excellent.Evaluation of stroke-related elbow flexor spasticity by TSRT has good inter-rater reliability. Test responsiveness is low, but better than that of the MAS.TSRT may be used to complement current scales of spasticity quantification.