Time Course Analysis of the Effects of Botulinum Toxin Type A on Elbow Spasticity Based on Biomechanic and Electromyographic Parameters

Hyperselective neurectomy of thoracodorsal nerve for treatment of the shoulder spasticity: anatomical study and preliminary clinical results

BACKGROUND

Hyperselective neurectomy is a reliable treatment for spasticity. This research was designed to quantify the surgical parameters of hyperselective neurectomy of thoracodorsal nerve for shoulder spasticity through anatomical studies, as well as to retrospectively assess patients who underwent this procedure to provide an objective basis for clinical practice.

METHODS

On nine embalmed adult cadavers (18 shoulders), we dissected and observed the branching patterns of thoracodorsal nerve, counted the number of nerve branches, measured the distribution of branch origin point, and determined the length of the surgical incision. Next, we selected five patients who underwent this procedure for shoulder spasticity and retrospectively evaluated (ethic committee: 2022-37) their shoulder function with active/passive range of motion (AROM/PROM) and modified Ashworth scale (MAS).

RESULTS

The anatomical study revealed that the main trunk of thoracodorsal nerve sends out one to three medial branches, with the pattern of only one medial branch being the most common (61.1%); there were significant variations in the branch numbers and nerve distributions; the location of thoracodorsal nerve branches' entry points into the muscle varied from 27.2 to 67.8% of the length of the arm. Clinical follow-up data showed significant improvement in shoulder mobility in all patients. AROM of shoulder abduction increased by 39.4° and PROM increased by 64.2° (P < 0.05). AROM and PROM of shoulder flexion increased by 36.6° and 54.4°, respectively (P < 0.05). In addition, the MAS of shoulder abduction (1.8) and flexion (1.2) was both significantly reduced in all patients (P < 0.05).

CONCLUSION

Hyperselective neurectomy of thoracodorsal nerve is effective and stable in the treatment of shoulder spasticity. Intraoperative attention is required to the numbers of the medial branch of thoracodorsal nerve. We recommend an incision in the mid-axillary line that extends from 25 to 70% of the arm length to fully expose each branch.

Anomalies of motor unit amplitude and territory after botulinum toxin injection

OBJECTIVE

Botulinum toxin (BT) induced cholinergic denervation of hyperactive motor units is a clinically accepted and extensively practiced way of managing focal spasticity after stroke. The denervation potentially initiates a temporary reorganization of the motor unit (MU) structure by inducing the emergence of a large number of newly innervated muscle fibers. In this study, we quantify the effect of the BT on motor unit action potential (MUAP) amplitudes and on the motor unit territory areas (MUTA) as seen on the surface of the skin over the biceps brachii (BB) muscle.

APPROACH

We have used a 128 channel high-density electromyography (HDsEMG) grid on the spastic and contralateral BB muscle and recorded the myoelectric activity along with the contraction force during isometric contraction of elbow muscles. We have decomposed the recorded EMG signal into individual MU potentials and estimated the MUAP amplitudes and territory areas before and two weeks after a BT injection.

MAIN RESULT

We found that there were significantly larger median (47±9%) MUAP amplitudes as well as reduction of MUTA (20±2%) two weeks after the injection compared to the respective pre-injection recording.

SIGNIFICANCE

The observed covariation of the amplitude and the territory area indicates that the large amplitude MUs that appeared after the BT injection have a relatively smaller territory area. We discuss the potential contributing factors to these changes subsequent to the injection in the context of the investigated subject cohort.

Surface EMG in Clinical Assessment and Neurorehabilitation: Barriers Limiting Its Use

This article addresses the potential clinical value of techniques based on surface electromyography (sEMG) in rehabilitation medicine with specific focus on neurorehabilitation. Applications in exercise and sport pathophysiology, in movement analysis, in ergonomics and occupational medicine, and in a number of related fields are also considered. The contrast between the extensive scientific literature in these fields and the limited clinical applications is discussed. The "barriers" between research findings and their application are very broad, and are longstanding, cultural, educational, and technical. Cultural barriers relate to the general acceptance and use of the concept of objective measurement in a clinical setting and its role in promoting Evidence Based Medicine. Wide differences between countries exist in appropriate training in the use of such quantitative measurements in general, and in electrical measurements in particular. These differences are manifest in training programs, in degrees granted, and in academic/research career opportunities. Educational barriers are related to the background in mathematics and physics for rehabilitation clinicians, leading to insufficient basic concepts of signal interpretation, as well as to the lack of a common language with rehabilitation engineers. Technical barriers are being overcome progressively, but progress is still impacted by the lack of user-friendly equipment, insufficient market demand, gadget-like devices, relatively high equipment price and a pervasive lack of interest by manufacturers. Despite the recommendations provided by the 20-year old EU project on "Surface EMG for Non-Invasive Assessment of Muscles (SENIAM)," real international standards are still missing and there is minimal international pressure for developing and applying such standards. The need for change in training and teaching is increasingly felt in the academic world, but is much less perceived in the health delivery system and clinical environments. The rapid technological progress in the fields of sensor and measurement technology (including sEMG), assistive devices, and robotic rehabilitation, has not been driven by clinical demands. Our assertion is that the most important and urgent interventions concern enhanced education, more effective technology transfer, and increased academic opportunities for physiotherapists, occupational therapists, and kinesiologists.

Precise quantification of the time course of voluntary activation capacity following Botulinum toxin injections in the biceps brachii muscles of chronic stroke survivors

Background

Spasticity is a key motor impairment that affects many hemispheric stroke survivors. Intramuscular botulinum toxin (BT) injections are used widely to clinically manage spasticity-related symptoms in stroke survivors by chemically denervating muscle fibers from their associated motor neurons. In this study, we sought to understand how BT affects muscle activation, motor unit composition and voluntary force generating capacity over a time period of 3 months. Our purpose was to characterize the time course of functional changes in voluntary muscle activity in stroke survivors who are undergoing BT therapy as part of their physician-prescribed clinical plan.

Method

Our assessment of the effects of BT was based on the quantification of surface electromyogram (sEMG) recordings in the biceps brachii (BB), an upper arm muscle and of voluntary contraction force. We report here on voluntary force and sEMG responses during isometric elbow contractions across consecutive recording sessions, spread over 12 weeks in three segments, starting with a preliminary session performed just prior to the BT injection. At predetermined time points, we conducted additional clinical assessments and we also recorded from the contralateral limbs of our stroke cohort. Eight subjects were studied for approximately 86 experimental recording sessions on both stroke-affected and contralateral sides.

Results

We recorded an initial reduction in force and sEMG in all subjects, followed by a trajectory with a progressive return to baseline over a maximum of 12 weeks, although the minimum sEMG and minimum force were not always recorded at the same time point. Three participants were able to complete only one to two segments. Slope values of the sEMG-force relations were also found to vary across the different time segments. While sEMG-force slopes provide assessments of force generation capacity of the BT injected muscle, amplitude histograms from novel sEMG recordings during the voluntary tasks provide additional insights about differential actions of BT on the overall motor unit (MU) population over time.

Conclusions

The results of our study indicate that there are potential short term as well as long term decrements in muscle control and activation properties after BT administration on the affected side of chronic stroke survivors. Muscle activation levels as recorded using sEMG, did not routinely return to baseline even at three months’ post injection. The concurrent clinical measures also did not follow the same time course, nor did they provide the same resolution as our experimental measures. It follows that even 12 weeks after intramuscular BT injections muscle recovery may not be complete, and may thereby contribute to pre-existing paresis.

Characterization of Differences in the Time Course of Reflex and Voluntary Responses Following Botulinum Toxin Injections in Chronic Stroke Survivors

Spasticity is a major impairment that can occur following a hemispheric stroke and is often treated with injections of botulinum toxin, a neurotoxin that impairs transmission at the neuromuscular junction. Hyperreflexia is a defining feature of spasticity. Our main objective here was to quantify the time course of changes in the deep tendon reflex (DTR) responses and voluntary activation capacity following BT injection as well as to track changes in a clinical assessment of spasticity. Four chronic stroke survivors, scheduled to receive BT in their Biceps Brachii(BB) as part of their clinical care plan, were recruited for repeated testing sessions over the course of 4 months post injection. Both surface BB EMG reflex response to bicipital tendon taps as well as signals of applied tendon tap forces were recorded before and up to 18 weeks post-BT. Voluntary force and biceps EMG signals were also recorded during maximum voluntary (isometric) contractions (MVC) at each testing session. Our results show major reductions (up to 75%) in voluntary sEMG and force arising between 11 to 35 days post-BT-injection. The stretch reflex gain declined two weeks after the maximal reductions in voluntary EMG and force. Paradoxically, there was a short-term increase in stretch reflex gain, in three out of four participants, approximately 11-35 days post BT. The time course of recovery of voluntary MVC and reflex responses varied considerably with a longer recovery time for the reflex responses.

Stretch reflex excitability in contralateral limbs of stroke survivors is higher than in matched controls

Background

Spasticity, characterized by hyperreflexia, is a motor impairment that can arise following a hemispheric stroke. While the neural mechanisms underlying spasticity in chronic stroke survivors are unknown, one probable cause of hyperreflexia is increased motoneuron (MN) excitability. Potential sources of increased spinal MN excitability after a stroke include increased vestibulospinal (VS) and/or reticulospinal (RS) drive. Spasticity, as clinically assessed in stroke survivors, is highly lateralized, thus RS contributions to stroke-induced spasticity are more difficult to reconcile, as RS nuclei routinely project bilaterally to the spinal cord. Yet studies in stroke survivors suggest that there may also be changes in neuromodulation at the spinal level, indicative of RS tract influence. We hypothesize that after hemispheric stroke, alterations in the excitability of the RS nuclei affect both sides of the spinal cord, and thereby contribute to increased MN excitability on both paretic/spastic and contralateral sides of stroke survivors, as compared to neurologically intact subjects.

Methods

We estimated stretch reflex thresholds of the biceps brachii (BB) muscle using a position-feedback controlled linear motor to progressively indent the BB distal tendon in both spastic and contralateral limbs of hemispheric stroke survivors and in age-matched intact subjects.

Results

Our previously reported results show a significant difference between reflex thresholds of spastic and contralateral limbs of stroke survivors recorded from BB-medial (p < 0.005) and BB-lateral (p < 0.001). For this study, we report that there is also a significant difference between the reflex thresholds in the contralateral limb of stroke subjects and the dominant arm of intact subjects, again measured from both BB-medial (p < 0.05) and BB-lateral (p < 0.05).

Conclusion

The reduction in stretch reflex thresholds in the contralateral limb of stroke survivors, based here on comparisons with thresholds of intact subjects, suggests an increased MN excitability on contralateral sides of stroke survivors as compared to intact subjects. This in turn supports our contention that RS tract activation, which has bilateral descending influences, is at least partially responsible for increased stretch reflex excitability, post-stroke, as both contralateral and affected sides show increased MN excitability as compared to intact subjects. Still, spasticity, presently diagnosed only on the affected side, with increased MN excitability on the affected side as compared to the contralateral side (our previous study), may be due to a different strongly lateralized pathway, such as the VS tract, which has not been directly tested here. Currently available clinical methods of spasticity assessment, such as the Modified Ashworth Scale, lack the resolution to quantify this phenomenon of a bilateral increase in MN excitability.

Nonsurgical Treatment Options for Upper Limb Spasticity

There are many nonsurgical treatment options for patients with upper limb spasticity. This article presents an algorithmic approach to management, encompassing evidence-based rehabilitation therapies, medications, and promising new orthotic and robotic innovations.

Co-Expression Network Approach to Studying the Effects of Botulinum Neurotoxin-A

Botulinum Neurotoxin A (BoNT-A) is a potent neurotoxin with several clinical applications. The goal of this study was to utilize co-expression network theory to analyze temporal transcriptional data from skeletal muscle after BoNT-A treatment. Expression data for 2000 genes (extracted using a ranking heuristic) served as the basis for this analysis. Using weighted gene co-expression network analysis (WGCNA), we identified 19 co-expressed modules, further hierarchically clustered into five groups. Quantifying average expression and co-expression patterns across these groups revealed temporal aspects of muscle's response to BoNT-A. Functional analysis revealed enrichment of group 1 with metabolism; group 5 with contradictory functions of atrophy and cellular recovery; and groups 2 and 3 with extracellular matrix (ECM) and non-fast fiber isoforms. Topological positioning of two highly ranked, significantly expressed genes-Dclk1 and Ostalpha-within group 5 suggested possible mechanistic roles in recovery from BoNT-A induced atrophy. Phenotypic correlations of groups with titin and myosin protein content further emphasized the effect of BoNT-A on the sarcomeric contraction machinery in early phase of chemodenervation. In summary, our approach revealed a hierarchical functional response to BoNT-A induced paralysis with early metabolic and later ECM responses and identified putative biomarkers associated with chemodenervation. Additionally, our results provide an unbiased validation of the response documented in our previous work.

Changes in the Neural and Non-neural Related Properties of the Spastic Wrist Flexors After Treatment With Botulinum Toxin A in Post-stroke Subjects: An Optimization Study

Quantifying neural and non-neural contributions to the joint resistance in spasticity is essential for a better evaluation of different intervention strategies such as botulinum toxin A (BoTN-A). However, direct measurement of muscle mechanical properties and spasticity-related parameters in humans is extremely challenging. The aim of this study was to use a previously developed musculoskeletal model and optimization scheme to evaluate the changes of neural and non-neural related properties of the spastic wrist flexors during passive wrist extension after BoTN-A injection. Data of joint angle and resistant torque were collected from 21 chronic stroke patients before, and 4 and 12 weeks post BoTN-A injection using NeuroFlexor, which is a motorized force measurement device to passively stretch wrist flexors. The model was optimized by tuning the passive and stretch-related parameters to fit the measured torque in each participant. It was found that stroke survivors exhibited decreased neural components at 4 weeks post BoNT-A injection, which returned to baseline levels after 12 weeks. The decreased neural component was mainly due to the increased motoneuron pool threshold, which is interpreted as a net excitatory and inhibitory inputs to the motoneuron pool. Though the linear stiffness and viscosity properties of wrist flexors were similar before and after treatment, increased exponential stiffness was observed over time which may indicate a decreased range of motion of the wrist joint. Using a combination of modeling and experimental measurement, valuable insights into the treatment responses, i.e., transmission of motoneurons, are provided by investigating potential parameter changes along the stretch reflex pathway in persons with chronic stroke.

Quantitative assessment for flexed-elbow deformity during gait following botulinum toxin A treatment

BACKGROUND

The effect of botulinum toxin A (BoNTA) injection on flexed-elbow deformity is usually evaluated using the Modified Ashworth Scale (MAS), but only with the muscle tone at rest. Some patients show the flexed-elbow deformity during gait despite low muscle tone at rest.

OBJECTIVE

This study aimed to evaluate the effect of BoNTA injection on flexed-elbow deformity during gait using a three-dimensional motion analysis system.

METHODS

Twenty stroke patients with spastic flexed-elbow deformity during gait received BoNTA injections into the upper limb muscles. The MAS score of the elbow flexors, passive elbow range of motion, comfortable overground gait velocity, and elbow flexion angle during treadmill gait were evaluated just before and 2, 6, and 12 weeks after the injection. Twenty-five healthy subjects were also recruited to provide a normal reference of the elbow flexion angle.

RESULTS

The MAS scores at 2, 6 and 12 weeks after the injection were significantly lower than that before the injection. Some patients showed no spasticity at rest but an obviously flexed elbow during gait. The elbow flexion angles during gait at 2 and 6 weeks after the injection were significantly lower than that before the injection.

CONCLUSIONS

BoNTA injections to the upper limb muscles reduced muscle tone at rest and flexed-elbow deformity during gait. However, the elbow flexion angle during gait returned to its pre-injection level sooner than the muscle tone at rest. We strongly recommend evaluating muscle tone during motion and at rest, preferably using three-dimensional motion analysis since it can objectively detect small changes.

Total knee arthroplasty in multiple sclerosis

We present a case report of total knee arthroplasty complicated by spasticity and contractures in a patient with multiple sclerosis (MS). Four previous case reports in the literature describe adverse outcomes after total knee arthroplasty in persons with MS secondary to severe spasticity. Preoperative, intraoperative, and postoperative considerations for persons with MS, which may help to improve functional outcomes, are discussed. Prospective research is needed among persons with MS to help determine the timing and selection of persons for arthroplasty and to minimize complications related to spasticity.

Instrumented assessment of the effect of Botulinum Toxin-A in the medial hamstrings in children with cerebral palsy

This study examined the sensitivity of an instrumented spasticity assessment of the medial hamstrings (MEH) in children with cerebral palsy (CP). Nineteen children received Botulinum Toxin type A (BTX-A) injections in the MEH. Biomechanical (position and torque) and electrophysiological (surface electromyography, EMG) signals were integrated during manually-performed passive stretches of the MEH at low, medium and high velocity. Signals were examined at each velocity and between stretch velocities, and compared pre and post BTX-A (43 ± 16 days). Average change between pre and post BTX-A was interpreted in view of the minimal detectable change (MDC) calculated from previously published reliability results. Improvements greater than the MDC were found for nearly all EMG-parameters and for torque parameters at high velocity and at high versus low velocity (p<0.03), however large inter-subject variability was noted. Moderate correlations were found between the improvement in EMG and in torque (r=0.52, p<0.05). Biomechanical and electrophysiological parameters proved to be adequately sensitive to assess the response to treatment with BTX-A. Furthermore, studying both parameters at different velocities improves our understanding of spasticity and of the physiological effect of selective tone-reduction. This not only provides a clinical validation of the instrumented assessment, but also opens new avenues for further spasticity research.

OnabotulinumtoxinA muscle injection patterns in adult spasticity: a systematic literature review

Background

OnabotulinumtoxinA has demonstrated significant benefit in adult focal spasticity. This study reviews the injection patterns (i.e., muscle distribution, dosing) of onabotulinumtoxinA for treatment of adult spasticity, as reported in published studies.

Methods

A systematic review of clinical trials and observational studies published between 1990 and 2011 reporting data on muscles injected with onabotulinumtoxinA in adult patients treated for any cause of spasticity.

Results

28 randomized, 5 nonrandomized, and 37 single-arm studies evaluating 2,163 adult patients were included. The most frequently injected upper-limb muscles were flexor carpi radialis (64.0% of patients), flexor carpi ulnaris (59.1%), flexor digitorum superficialis (57.2%), flexor digitorum profundus (52.5%), and biceps brachii (38.8%). The most frequently injected lower-limb muscles were the gastrocnemius (66.1% of patients), soleus (54.7%), and tibialis posterior (50.5%). The overall dose range reported was 5–200 U for upper-limb muscles and 10–400 U for lower-limb muscles.

Conclusions

The reviewed evidence indicates that the muscles most frequently injected with onabotulinumtoxinA in adults with spasticity were the wrist, elbow, and finger flexors and the ankle plantar flexors. OnabotulinumtoxinA was injected over a broad range of doses per muscle among the studies included in this review, but individual practitioners should be mindful of local regulatory approvals and regulations.

Feasibility of video clip analysis on effect of botulinum toxin-A injection for post-stroke upper limb spasticity

Existing functional evaluation tools do not accurately reveal the improved function following botulinum toxin A (BTX-A) injection for post-stroke upper limb spasticity. With the aim of developing an alternate method of measuring functional improvement following BTX-A injection, this study tested the feasibility, validity and reliability of video clip analysis performed by the clinicians. Seventy-nine patients administered BTX-A due to post-stroke upper limb spasticity, were retrospectively evaluated using video clip analysis. Pre- and post-injection video clips recorded at 1-month intervals were randomly allocated and sent to three blinded physician evaluators who were asked to choose the one that seemed more improved in terms of hand motion and associated upper limb reaction during gait. The three physicians chose the post-injection video clip as depicting improved hand motion (82.3%, 79.7%, and 72.2%) and associated upper limb reaction during gait (73.4%, 70.9%, and 70.9%). Kappa and intraclass correlation coefficient as a measure of interrater reliability among the three physicians was 0.86 and 0.79 for the hand, and 0.92 and 0.92 for associated upper limb reaction during gait, respectively. The percent overall agreement of the physicians was 78.1% and 71.7% for hand function and associated upper limb reaction, respectively. Retrospective pre- and post-BTX-A injection video clip analyses is a clinically feasible alternative method to evaluate the improvement following BTX-A injection for post-stroke upper limb spasticity, especially in busy clinical practice setting.

The gap between clinical gaze and systematic assessment of movement disorders after stroke

Background

Movement disorders after stroke are still captured by clinical gaze and translated to ordinal scores of low resolution. There is a clear need for objective quantification, with outcome measures related to pathophysiological background. Neural and non-neural contributors to joint behavior should be separated using different measurement conditions (tasks) and standardized input signals (force, position and velocity).

Methods

We reviewed recent literature for the application of biomechanical and/or elektromyographical (EMG) outcome measures under various measurement conditions in clinical research.

Results

Since 2005, 36 articles described the use of biomechanical and/or EMG outcome measures to quantify post-stroke movement disorder. Nineteen of the articles strived to separate neural and non-neural components. Only 6 of the articles measured biomechanical and EMG outcome measures simultaneously, while applying active and passive tasks and multiple velocities.

Conclusion

The distinction between neural and non-neural components to separately assess paresis, stiffness and muscle overactivity is not commonplace yet, while a large gap is to be bridged to attain reproducible and comparable results. Pathophysiologically clear concepts, substantiated with a comprehensive and concise measuring protocol will help professionals to identify and treat limiting factors in movement capabilities of post-stroke patients.

Care management of spasticity with botulinum toxin-A in patients with severe acquired brain injury: a 1-year follow-up prospective study

OBJECTIVE

To evaluate the efficacy and the safety of repeated botulinum toxin type A (BT-A) injections in patients with severe acquired brain injury (ABI) and to gain a better knowledge of possible clinical or demographic characteristics associated with a better rehabilitation outcome.

DESIGN

Prospective study with a 1-year follow-up period.

SUBJECTS

Twenty-one patients with spasticity due to severe ABI and no further improving with rehabilitation treatment and oral anti-spastic drugs.

INTERVENTION

Repeated BT-A injections associated to a rehabilitation programme.

MAIN MEASURES

Barthel Index (BI), Modified Ashworth Score (MAS) and VAS score for pain subjective perception were recorded.

RESULTS

At the end of the follow-up study, MAS, BI and VAS significantly improved. Despite the number of BT-A injections, a shorter interval between severe ABI onset and first BT-A treatment correlated to a better BI improvement. None of the patients experienced adverse events attributable to BT-A.

CONCLUSION

BT-A was effective and safe in the treatment of spasticity in severe ABI patients, with a better functional outcome in those subjects treated earlier after spasticity onset. The lack of correlation between clinical outcome and number of injections suggests, in addition to a direct inhibition at the neuromuscular junction, a more distant BT-A long-term effect.

Assessing the neurophysiological effects of botulinum toxin treatment for adults with focal limb spasticity: a systematic review

To examine effectiveness of botulinum toxin therapy (BoNT), accurate quantification of the neurological component of underlying spasticity is needed.

PURPOSE

Systematically identify and summarize literature on neurophysiological methods to test the effectiveness of BoNT, discuss methodological aspects, and recommend best techniques for clinical and research settings.

METHODS

Electronic databases were searched using specific keywords. Reviews and reference lists were hand-checked to find relevant studies. Studies in adults with focal limb spasticity were included.

RESULTS

Over 300 articles were scanned for relevance, and a list of 90 relevant articles was made. After excluding reviews and studies in healthy controls or non-spasticity related BoNT, 22 articles were reviewed. Neurophysiological techniques included electromyography (EMG; n = 11), electrical nerve stimulation (n = 13), transcranial magnetic stimulation (TMS; n = 1), functional magnetic resonance imaging (fMRI; n = 1), reflex threshold (n = 4), Achilles tendon reflex (n = 1), reflex latency (n = 1).

DISCUSSION

Maximum M-wave amplitude (M-max) and stretch reflex threshold techniques were successfully used to measure the neurophysiological effects of BoNT and have high test-retest reliability. EMG techniques require effective magnitude normalization techniques and establishing test-retest reliability.

CONCLUSION

Serial electrical nerve stimulation can be incorporated into clinical practice to assist in follow-up. We recommend using M-max and stretch reflex threshold techniques to assess the neurophysiological effects.