Influence of positional changes on spasticity of the upper extremity in poststroke hemiplegic patients

Quantitative assessment of spasticity: a narrative review of novel approaches and technologies

Spasticity is a complex neurological disorder, causing significant physical disabilities and affecting patients' independence and quality of daily lives. Current spasticity assessment methods are questioned for their non-standardized measurement protocols, limited reliabilities, and capabilities in distinguishing neuron or non-neuron factors in upper motor neuron lesion. A series of new approaches are developed for improving the effectiveness of current clinical used spasticity assessment methods with the developing technology in biosensors, robotics, medical imaging, biomechanics, telemedicine, and artificial intelligence. We investigated the reliabilities and effectiveness of current spasticity measures employed in clinical environments and the newly developed approaches, published from 2016 to date, which have the potential to be used in clinical environments. The new spasticity scales, taking advantage of quantified information such as torque, or echo intensity, the velocity-dependent feature and patients' self-reported information, grade spasticity semi-quantitatively, have competitive or better reliability than previous spasticity scales. Medical imaging technologies, including near-infrared spectroscopy, magnetic resonance imaging, ultrasound and thermography, can measure muscle hemodynamics and metabolism, muscle tissue properties, or temperature of tissue. Medical imaging-based methods are feasible to provide quantitative information in assessing and monitoring muscle spasticity. Portable devices, robotic based equipment or myotonometry, using information from angular, inertial, torque or surface EMG sensors, can quantify spasticity with the help of machine learning algorithms. However, spasticity measures using those devices are normally not physiological sound. Repetitive peripheral magnetic stimulation can assess patients with severe spasticity, which lost voluntary contractions. Neuromusculoskeletal modeling evaluates the neural and non-neural properties and may gain insights into the underlying pathology of spasticity muscles. Telemedicine technology enables outpatient spasticity assessment. The newly developed spasticity methods aim to standardize experimental protocols and outcome measures and enable quantified, accurate, and intelligent assessment. However, more work is needed to investigate and improve the effectiveness and accuracy of spasticity assessment.

Flexor carpi radialis H-reflex in different body positions in patients with post-stroke

Background

Spinal stretch reflex (SSR) hyperexcitability reflected by the H-reflex has been reported in more strongly affected extremities after stroke. The H-reflex in the lower extremities is modulated by body position normally and alternatively modulated post-stroke.

Objective

This study aimed to preliminarily explore how upper extremity (UE) H-reflexes are modulated by body position after stroke, which remains unknown.

Materials and methods

Three patients after stroke with hemiparesis/hemiplegia were included. Bilateral flexor carpi radialis (FCR) H-reflexes were examined in the supine position while standing. Other clinical evaluations include the modified Ashworth scale (MAS) and postural stability measurement.

Results

The three cases herein showed that (1) SSR excitability was higher in more strongly affected UEs than less-affected UEs, (2) down-modulation of SSR excitability occurred in less-affected UEs in static standing compared with the supine position, but modulation of SSR excitability in more-affected UEs varied, and (3) bilateral UE SSR excitability in case 3 was down-modulated the most. Moreover, case 3 showed no difference in muscle tone of the more affected UE between supine and standing positions, and case 3 showed the best postural stability.

Conclusion

Spinal stretch reflex hyperexcitability in strongly affected UEs could commonly occur in different phases of recovery after stroke. Down-modulation of SSR excitability could occur in less-affected UEs in the standing position compared with the supine position, while modulation of SSR excitability might be altered in strongly affected UEs and vary in different phases of recovery. There could be some correlation between postural control and UE SSR hyperexcitability. The H-reflex may help to offer a new perspective on rehabilitation evaluation and interventions to promote UE motor control after stroke.

Validity and reliability of the Modified Tardieu Scale as a spasticity outcome measure of the upper limbs in adults with neurological conditions: a systematic review and narrative analysis

PURPOSE

To evaluate published evidence on the Modified Tardieu Scale (MTS) as a tool to assess spasticity in the upper limbs of adults with neurological conditions.

DATA SOURCES

A systematic search of six electronic databases (PubMed/MEDLINE, CINAHL, EMBASE, the Cochrane Library, Web of Science and Physiotherapy Evidence Database) from inception to 31 December 2020. A search strategy was developed using key elements of the research question: population, intervention (action), outcome.

STUDY ELIGIBILITY CRITERIA

Inclusion criteria: (1) adult participants with neurological conditions; (2) upper limb muscles/joints as tested elements; (3) studies testing the MTS and (4) reliability or validity reported.

EXCLUSION CRITERIA

(1) non-English articles; (2) non-empirical articles and (3) studies testing the Tardieu Scale.

STUDY APPRAISAL

Evidence quality was evaluated using the US National Heart, Lung, Blood Institute quality assessment tool for observational cohort and cross-sectional studies.

RESULTS

Six reliability studies met the inclusion criteria. Overall, most articles reported good-to-excellent levels of inter-rater, intrarater and test-retest reliability. However, limitations, such as study design weaknesses, statistical misuses and reporting biases, undermine confidence in reported conclusions. The validity of the MTS also remained questionable based on the results of one study.

CONCLUSIONS AND IMPLICATIONS

This review did not find sufficient evidence to either support or reject the use of the MTS in assessing spasticity in the upper limbs of adults with neurological conditions. Despite the paucity of research evidence, the MTS may still remain a clinically useful tool to measure the motor aspect of spasticity. Future research would benefit from a focus on test standardisation, while the wider field would require the development of a consensual definition of spasticity.

Soleus H-Reflex Change in Poststroke Spasticity: Modulation due to Body Position

Purpose

This study is aimed at exploring how soleus H-reflex change in poststroke patients with spasticity influenced by body position.

Materials and Methods

Twenty-four stroke patients with spastic hemiplegia and twelve age-matched healthy controls were investigated. Maximal Hoffmann-reflex (Hmax) and motor potential (Mmax) were elicited at the popliteal fossa in both prone and standing positions, respectively, and the Hmax/Mmax ratio at each body position was determined. Compare changes in reflex behavior in both spastic and contralateral muscles of stroke survivors in prone and standing positions, and match healthy subjects in the same position.

Results

In healthy subjects, Hmax and Hmax/Mmax ratios were significantly decreased in the standing position compared to the prone position (Hmax: p = 0.000, Hmax/Mmax: p = 0.016). However, Hmax/Mmax ratios were increased in standing position on both sides in poststroke patients with spasticity (unaffected side: p = 0.006, affected side: p = 0.095). The Hmax and Hmax/Mmax ratios were significantly more increased on the affected side than unaffected side irrespective of the position.

Conclusions

The motor neuron excitability of both sides was not suppressed but instead upregulated in the standing position in subjects with spasticity, which may suggest that there was abnormal regulation of the Ia pathway on both sides.

A New Definition of Poststroke Spasticity and the Interference of Spasticity With Motor Recovery From Acute to Chronic Stages

The relationship of poststroke spasticity and motor recovery can be confusing. "True" motor recovery refers to return of motor behaviors to prestroke state with the same end-effectors and temporo-spatial pattern. This requires neural recovery and repair, and presumably occurs mainly in the acute and subacute stages. However, according to the International Classification of Functioning, Disability and Health, motor recovery after stroke is also defined as "improvement in performance of functional tasks," i.e., functional recovery, which is mainly mediated by compensatory mechanisms. Therefore, stroke survivors can execute motor tasks in spite of disordered motor control and the presence of spasticity. Spasticity interferes with execution of normal motor behaviors ("true" motor recovery), throughout the evolution of stroke from acute to chronic stages. Spasticity reduction does not affect functional recovery in the acute and subacute stages; however, appropriate management of spasticity could lead to improvement of motor function, that is, functional recovery, during the chronic stage of stroke. We assert that spasticity results from upregulation of medial cortico-reticulo-spinal pathways that are disinhibited due to damage of the motor cortex or corticobulbar pathways. Spasticity emerges as a manifestation of maladaptive plasticity in the early stages of recovery and can persist into the chronic stage. It coexists and shares similar pathophysiological processes with related motor impairments, such as abnormal force control, muscle coactivation and motor synergies, and diffuse interlimb muscle activation. Accordingly, we propose a new definition of spasticity to better account for its pathophysiology and the complex nuances of different definitions of motor recovery.

Effects of Self-Assisted Shoulder Elevation of the Affected Side Combined with Balance Training on Associated Reactions of Upper Limb and Walking Function in Chronic Stroke Patients: A Randomized Controlled Trial

Background

Associated reactions of the upper limb are frequently seen in stroke patients, especially during dynamic activities, such as walking. The aim of this study was to assess the effect of a method to inhibit the affected upper limb flexors combined with balance training on associated reactions of the affected upper limb and walking function in chronic stroke patients.

Material/Methods

60 patients were randomly allocated into 3 groups (n=20 per group): control group (no upper limb intervention), back group (the unaffected hand assists the affected upper limb in the low back and keep it in an extended position) and shoulder elevation group using the inhibition method (the unaffected hand assists the affected shoulder to elevate above 90°). Before and after the four-week balance training, the surface electromyography was used to evaluate the rate of contraction of affected elbow flexors. Fugl-Meyer Assessment of Upper Extremity (FMA-UE), 10 Meter Walking Test (10MWT) and Barthel Index (BI) were used to measure functional status.

Results

The shoulder elevation group had significant improvement in the percentage changes in the rate of contraction of the affected elbow flexors, 10WMT and FMA-UE (p<0.05) compared with back group and control group. We found no significant difference of 10WMT and FMA-UE between back group and control group.

Conclusions

The combination of the new inhibition method and the standing balance training could reduce the abnormal activity of affected elbow flexors during walking, increase walking speed, and improve the affected upper limb motor function.

Flexors activity of affected upper extremity in stroke patients during different standing conditions and their relationships with clinical scales: a cross-sectional study

Purpose: To explore the flexors activity of affected upper extremity in stroke patients during different standing conditions and their relationships with clinical scales.Materials and methods: Sixteen stroke patientswere recruited, all subjects stood on balance equipment with four different standing postures. The electromyogram (EMG) simultaneously recorded the muscle activity of bilateral biceps brachii, triceps brachii, flexor carpi radialis and extensor carpi radialis and their integrated electromyogram were figured out the contraction rate of elbow flexors(biceps brachii/triceps brachii) and wrist flexors(flexor carpi radialis/extensor carpi radialis). All subjects were assessed using Fugl-Meyer Assessment of the Upper Extremity (FMA-UE), Berg Balance Scale (BBS), Barthel Index (BI) and Modified Ashworth Scale (MAS).Results: The contraction rate of affected elbow flexors in the condition of feet together on soft surface was significantly higher than that in the condition of feet separatedon hard surface (P < 0.05). The contraction rate of affected elbow flexors in four standing conditions tended to increase, all the values of which were greater than numerical value1. The difference in the contraction rate of elbow flexor between the affected side and the unaffected side was statistically significant (P < 0.05). No correlation was observed between the contraction rate of the elbow flexor and the results of MAS, FMA-UE, BBS and BI regardless of the standing conditions.Conclusions: The contraction rates of elbowflexor in the affected side increase with the difficulty in different standing postures,and it may be a good index to reflect the changes of muscle tone in postural control.