Evaluation of Spasticity in Adults

Neuromuscular electrical stimulation reduces spinal excitability in Multiple Sclerosis patients with spasticity symptoms

BACKGROUND

The use of neuromuscular electrical stimulation (NMES) has been recently proposed in patients with neurological diseases, such as spinal cord injuries and stroke, to improve symptoms of spasticity, resulting in both increased control of voluntary movements and improved functional ability in daily activities. Despite several authors suggest that these results could be related to a reduced spinal excitability, which is known to be higher in spastic patients, no previous studies investigated the neurophysiological mechanisms underlying the effect of NMES in reducing spasticity. In addition, there are no studies in the literature adopting NMES to improve spasticity in patients with Multiple Sclerosis (MS). Therefore, this study aims at comparing acute responses in spinal excitability, as measured by H-reflex, between MS patients with and without spasticity, following three experimental conditions: 1) isometric voluntary contraction (ISO) of the ankle plantar flexor muscles; 2) NMES passively applied (pNMES) to the ankle plantar flexor muscles; and 3) NMES superimposed onto isometric voluntary contraction (NMES+) of the same muscles.

METHODS

15 MS patients with spasticity (MS+) and 15 MS patients without spasticity (MS-) took part in a single experimental session, which consisted in the application of NMES to the ankle plantar-flexor muscles in the most spastic and compromised leg. Following the assessment of maximum voluntary isometric contraction (MVIC), participants were asked to perform 15 repetitions of 6 s at 20 % of MVIC, with 6 s of recovery between repetitions, during the three experimental conditions (ISO, pNMES, NMES+). Before and after each condition, soleus (SOL) H-reflex amplitudes were recorded by using surface electromyography (sEMG).

RESULTS

In MS+, H-reflex amplitude significantly decreased after both pNMES (p = 0.007) and NMES+ (p = 0.003), while it was unaltered after ISO (p = 0.829). In MS-, H-reflex amplitude did not change under any experimental condition (ISO: p = 0.383; pNMES: p = 0.328; NMES+: p = 0.087).

CONCLUSION

The reduction of H-reflex after pNMES and NMES+ can be attributed to a reduced spinal excitability in spastic MS patients, which may be attributed to presynaptic inhibition, recurrent inhibition, gamma-aminobutyric acid activity and persistent inward current. These results are highly relevant from both neurophysiological and clinical point of views, suggesting new approaches to manage spasticity symptoms in neurological patients.

The effects of concurrent M1 anodal tDCS and physical therapy interventions on function of ankle muscles in patients with stroke: a randomized, double-blinded sham-controlled trial study

One of the most common symptoms in stroke patients is spasticity. The aims were to investigate the effects of anodal trans-cranial direct current stimulation (a-tDCS) over the affected primary motor cortex (M1) on ankle plantar flexor spasticity and dorsiflexor muscle activity in stroke patients. The design of this study was a randomized sham-controlled clinical trial. Thirty-two participants with stroke were randomly assigned to three groups (experimental, sham, control groups). Participants in the experimental and sham groups received 10-session 20-min M1 a-tDCS concurrent with physical therapy (PT), while the control group only received 10-session PT. All groups were instructed to perform home stretching exercises and balance training. Berg Balance Scale (BBS), Modified Ashworth Scale (MAS) of plantar flexors, and EMG activity of lateral gastrocnemius (LG) and tibialis anterior (TA) were recorded during active and passive ankle dorsiflexion immediately and 1 month after interventions. A significant reduction was shown in MAS and EMG activity of LG during dorsiflexion, immediately and 1 month after intervention in the M1 a-tDCS group (p <0.001). BBS also significantly increased only in the M1 a-tDCS group (p <0.001). In addition, EMG activity of TA during active dorsiflexion increased immediately and 1 month after intervention in the M1 a-tDCS group (p <0.001). However, in the sham and control groups, EMG activity of TA increased immediately (p<0.001), while this was not maintained 1 month after intervention (p >0.05). PT concurrent with M1 a-tDCS can significantly prime lasting effects of decreasing LG spasticity, increasing TA muscle activity, and also balance in stroke patients.

Objective assessment of spasticity by pendulum test: a systematic review on methods of implementation and outcome measures

Background

Instrumented pendulum test is an objective and repeatable biomechanical method of assessment for spasticity. However, multitude of sensor technologies and plenty of suggested outcome measures, confuse those interested in implementing this method in practice. Lack of a standard agreement on the definition of experimental setup and outcome measures adds to this ambiguity and causes the results of one study not to be directly attainable by a group that uses a different setup. In this systematic review of studies, we aim to reduce the confusion by providing pros and cons of the available choices, and also by standardizing the definitions.

Methods

A literature search was conducted for the period of 1950 to the end of 2019 on PubMed, Science Direct, Google Scholar and IEEE explore; with keywords of “pendulum test” and “Spasticity”.

Results

Twenty-eight studies with instrumented pendulum test for assessment of spasticity met the inclusion criteria. All the suggested methods of implementation were compared and advantages and disadvantages were provided for each sensor technology. An exhaustive list categorized outcome measures in three groups of angle-based, angular velocity-based, and angular acceleration-based measures with all different names and definitions.

Conclusions

With the aim of providing standardized methodology with replicable and comparable results, sources of dissimilarity and ambiguity among research strategies were found and explained with the help of graphical representation of pendulum movement stages and corresponding parameters on the angular waveforms. We hope using the provided tables simplify the choices when implementing pendulum test for spasticity evaluation, improve the consistency when reporting the results, and disambiguate inconsistency in the literature.

Effects of transcutaneous electrical nerve stimulation alone or as additional therapy on chronic post-stroke spasticity: systematic review and meta-analysis of randomized controlled trials

Purpose: To evaluate the effects and to compare transcutaneous electrical nerve stimulation protocols, alone or as additional therapy in chronic post-stroke spasticity through a systematic review and meta-analysis of randomized clinical trials.Methods: Search was conducted in MEDLINE, Cochrane Library, EMBASE and Physiotherapy Evidence Database through November 2017 (CRD42015020146). Two independent reviewers performed articles selection, data extraction and methodological quality assessment using the Cochrane Collaboration's risk of bias tool. The main outcome was spasticity assessed with Modified Ashworth Scale or other valid scale. Meta-analysis was conducted using random effects method, and pooled-effect results are mean difference with 95% confidence interval.Results: Of 6506 articles identified, 10 studies with 360 subjects were included in the review. Transcutaneous electrical nerve stimulation alone or as additional therapy is superior to placebo TENS to reduce post-stroke spasticity assessed with Modified Ashworth Scale (-0.52 [-0.74 to -0.30] p < 0.0001, 6 studies), especially in lower limbs (-0.58 [-0.82 to -0.34] p < 0.0001, 5 studies), which is in accordance with the studies that used other scales. Low frequency TENS showed a slightly larger improvement than high-frequency, but without significant difference between subgroups. Most studies present low or unclear risk of bias.Conclusion: Transcutaneous electrical nerve stimulation can provide additional reduction in chronic post-stroke spasticity, mainly as additional therapy to physical interventions. Studies with better methodological quality and larger sample are needed to increase evidence power.Implications for RehabilitationTranscutaneous electrical nerve stimulation as additional treatment to physical interventions can lead to additional reduction in chronic post-stroke spasticity.High and low frequency transcutaneous electrical nerve stimulation showed similar results, with a smaller numerical superiority of low frequency TENS.More studies are needed to substantiate the best protocol of transcutaneous electrical nerve stimulation to the treatment of spasticity.

Correlation of Resting Elbow Angle with Spasticity in Chronic Stroke Survivors

OBJECTIVE

To evaluate whether resting joint angle is indicative of severity of spasticity of the elbow flexors in chronic stroke survivors.

METHODS

Seventeen hemiparetic stroke subjects (male: n = 13; female: n = 4; age: 37-89 years; 11 right and 6 left hemiplegia; averaged 54.8 months after stroke, ranging 12-107 months) participated in the study. The number of subjects with modified Ashworth scale score (MAS) = 0, 1, 1+, 2, and 3 was 3, 3, 5, 3, and 3, respectively. In a single experimental session, resting elbow joint angle, MAS, and Tardieu scale score (Tardieu R1) were measured. A customized motorized stretching device was used to stretch elbow flexors at 5, 50, and 100°/s, respectively. Biomechanical responses (peak reflex torque and reflex stiffness) of elbow flexors were quantified. Correlation analyses between clinical and biomechanical assessments were performed.

RESULTS

Resting elbow joint angle showed a strong positive correlation with Tardieu R1 (r = 0.77, p < 0.01) and a very strong negative correlation with MAS (r = -0.89, p < 0.01). The resting angle also had strong correlations with biomechanical measures (r = -0.63 to -0.76, p < 0.01).

CONCLUSION

Our study provides experimental evidence for anecdotal observation that the resting elbow joint angle correlates with severity of spasticity in chronic stroke. Resting angle observation for spasticity assessment can and will be an easy, yet a valid way of spasticity estimation in clinical settings, particularly for small muscles or muscles which are not easily measurable by common clinical methods.

Quantifying the deep tendon reflex using varying tendon indentation depths: applications to spasticity

The deep tendon reflex (DTR) is often utilized to characterize the neuromuscular health of individuals because it is cheap, quick to implement, and requires limited equipment. However, DTR assessment is unreliable and assessor-dependent improve the reliability of the DTR assessment, we devised a novel standardization procedure. Our approach is based on the hypothesis that the neuromuscular state of a muscle changes systematically with respect to the indentation depth of its tendon. We tested the hypothesis by progressively indenting the biceps tendons on each side of nine hemiplegic stroke survivors to different depths, and then superimposing a series of brief controlled taps at each indentation depth to elicit a reflex response. Our results show that there exists a unique indentation depth at which reflex responses are consistently recorded (termed the Reflex Threshold) with increasing amplitude along increasing indentation depth. We further show that the reflex threshold depth is systematically smaller on the affected side of stroke survivors and that it is negatively correlated with the Modified Ashworth Score (VAF 70%). Our procedure also enables measurement of passive mechanical properties at the indentation location. In conclusion, our study shows that controlling for the indentation depth of the tendon of a muscle alters its reflex response predictably. Our novel device and method could be used to estimate neuromuscular changes in muscle (e.g., spasticity). Although some refinement is needed, this method opens the door to more reliable quantification of the DTR.