The role of botulinum toxin injections in the management of muscle overactivity of the lower limb

Stretching exercises in managing spasticity: effectiveness, risks, and adjunct therapies

Spasticity is a component of upper motor neuron disorders and can be seen in neurological conditions like stroke and multiple sclerosis. Although the incidence rate of spasticity is unknown, it can put pressure on the health condition of those with spasticity, and there is no absolute effective way to control it. In the past, stretching exercises were an accessible tool for physical therapists to manage and control spasticity, but opinions on the optimal dose, aftereffects, and mechanism of effects were controversial. Therefore, this article tries to provide an overview of the effectiveness and risks of stretching exercises. Furthermore, there are several adjunct therapies, such as brain stimulation and botulinum injection, that can increase the effectiveness of a simple stretch by increasing cortical excitability and reducing muscle tone and their role is evaluated in this regard. The results of this study propose that several prospective and case studies have demonstrated the benefits of stretching to control spasticity, but it seems that other methods such as casting can be more effective than a simple stretch. Therefore, it is better to use stretching in combination with other therapeutic regimes to increase its effectivity of it.

Botulinum Toxin Intervention in Cerebral Palsy-Induced Spasticity Management: Projected and Contradictory Effects on Skeletal Muscles

Spasticity, following the neurological disorder of cerebral palsy (CP), describes a pathological condition, the central feature of which is involuntary and prolonged muscle contraction. The persistent resistance of spastic muscles to stretching is often followed by structural and mechanical changes in musculature. This leads to functional limitations at the respective joint. Focal injection of botulinum toxin type-A (BTX-A) is effectively used to manage spasticity and improve the quality of life of the patients. By blocking acetylcholine release at the neuromuscular junction and causing temporary muscle paralysis, BTX-A aims to reduce spasticity and hereby improve joint function. However, recent studies have indicated some contradictory effects such as increased muscle stiffness or a narrower range of active force production. The potential of these toxin- and atrophy-related alterations in worsening the condition of spastic muscles that are already subjected to changes should be further investigated and quantified. By focusing on the effects of BTX-A on muscle biomechanics and overall function in children with CP, this review deals with which of these goals have been achieved and to what extent, and what can await us in the future.

Do gait parameters improve after botulinum toxin injections in post stroke patients? A prospective study

The intramuscular injection of botulinum toxin is one of the most efficient ways to treat localized spasticity in patients suffering from Central Nervous System lesions like stroke, cerebral palsy and multiple sclerosis. The gait analysis based on kinetics and kinematics is a recognized way of measurement of the effect of intramuscular injection of botulinum toxin in spastic patients suffering from chronic stroke. The aim of this study is to provide evidence of the beneficial effect of botulinum toxin on characteristics of gait pattern on patients suffering from chronic stroke. So, thirteen patients with spasticity due to chronic stroke were included in the protocol and were treated by botulinum toxin injections in the lower extremity. All patients were evaluated before the injection as well as one month after the botulinum injection on a foot pressure sensitive walkway with a power plate and by the readings of seven inertial measurements units which recorded spatio-temporal specific parameters during walking, and the spasticity was measured according to modified Ashworth Scale. While all spatio-temporal parameters of motion analysis and balance improved for most of the patients after botulinum toxin injection, only one parameter, the normal to hemiplegic step length, reached statistical significant improvement (p < 0.03). Moreover the modified Ashworth score was statistically improved post injection (p < 0.001). In conclusion the use of botulinum toxin injections is beneficial in post stroke patients as this is depicted in gait parameters improvement which accompanies the spasticity reduction.

Long-Term Effects With Potential Clinical Importance of Botulinum Toxin Type-A on Mechanics of Muscles Exposed

Botulinum toxin type-A (BTX-A) is widely used for spasticity management and mechanically aims at reducing passive resistance at the joint and widening joint range of movement. However, recent experiments on acute BTX-A effects showed that the injected rat tibialis anterior (TA) muscle’s passive forces increased, and the length range of active force exertion (l_range) did not change. Additionally, BTX-A was shown to spread into non-injected muscles in the compartment and affect their mechanics. Whether those effects persist in the long term is highly important, but unknown. The aim was to test the following hypotheses with experiments conducted in the anterior crural compartment of the rat: In the long term, BTX-A (1) maintains l_range, (2) increases passive forces of the injected TA muscle, and (3) spreads into non-injected extensor digitorum longus (EDL) and the extensor hallucis longus (EHL) muscles, also affecting their active and passive forces. Male Wistar rats were divided into two groups: BTX-A and Control (0.1 units of BTX-A or only saline was injected into the TA). Isometric forces of the muscles were measured simultaneously 1-month post-injection. The targeted TA was lengthened, whereas the non-targeted EDL and EHL were kept at constant length. Hydroxyproline analysis was done to quantify changes in the collagen content of studied muscles. Two-way ANOVA test (for muscle forces, factors: TA length and animal group) and unpaired t or Mann-Whitney U test (for l_range and collagen content, where appropriate) were used for statistical analyses (P < 0.05). BTX-A caused significant effects. TA: active forces decreased (maximally by 75.2% at short and minimally by 48.3%, at long muscle lengths), l_range decreased (by 22.9%), passive forces increased (by 12.3%), and collagen content increased (approximately threefold). EDL and EHL: active forces decreased (up to 66.8%), passive force increased (minimally by 62.5%), and collagen content increased (approximately twofold). Therefore, hypothesis 1 was rejected and 2 and 3 were confirmed indicating that previously reported acute BTX-A effects persist and advance in the long term. A narrower l_range and an elevated passive resistance of the targeted muscle are unintended mechanical effects, whereas spread of BTX-A into other compartmental muscles indicates the presence of uncontrolled mechanical effects.

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.

Estimation of tissue stiffness, reflex activity, optimal muscle length and slack length in stroke patients using an electromyography driven antagonistic wrist model

BACKGROUND

About half of all chronic stroke patients experience loss of arm function coinciding with increased stiffness, reduced range of motion and a flexed wrist due to a change in neural and/or structural tissue properties. Quantitative assessment of these changes is of clinical importance, yet not trivial. The goal of this study was to quantify the neural and structural properties contributing to wrist joint stiffness and to compare these properties between healthy subjects and stroke patients.

METHODS

Stroke patients (n=32) and healthy volunteers (n=14) were measured using ramp-and-hold rotations applied to the wrist joint by a haptic manipulator. Neural (reflexive torque) and structural (connective tissue stiffness and slack lengths and (contractile) optimal muscle lengths) parameters were estimated using an electromyography driven antagonistic wrist model. Kruskal-Wallis analysis with multiple comparisons was used to compare results between healthy subjects, stroke patients with modified Ashworth score of zero and stroke patients with modified Ashworth score of one or more.

FINDINGS

Stroke patients with modified Ashworth score of one or more differed from healthy controls (P<0.05) by increased tissue stiffness, increased reflexive torque, decreased optimal muscle length and decreased slack length of connective tissue of the flexor muscles.

INTERPRETATION

Non-invasive quantitative analysis, including estimation of optimal muscle lengths, enables to identify neural and non-neural changes in chronic stroke patients. Monitoring these changes in time is important to understand the recovery process and to optimize treatment.

Are gait and mobility measures responsive to change following botulinum toxin injections in adults with lower limb spasticity?

PURPOSE

To determine whether gait and mobility measures are responsive to change following botulinum toxin (BoNT) injections in adults with lower limb spasticity.

METHOD

Independently ambulant adults who attended a spasticity clinic for lower limb BoNT injections were eligible to participate. The 10 m walk test (shoes on and off), timed up and go test and 6-min walk test were performed before injection and 1 month later. Participants completed a global rating of change scale (GRCS) at follow up. Comparisons were made between participants' ratings of change and change in walking performance. Effect sizes (ES) and standard error of measurement (SEM) were calculated for each outcome.

RESULTS

Thirty-nine patients (22 female, 17 male; mean age 51 ± 12 years; range 26-74 years) with a median spasticity duration of 53 months participated. Statistically significant changes were found in all gait and mobility measures at 1 month following injection. All ES were small (<0.2) and SEM for each measure was large. The global rating of change scale (GRCS) indicated that 66% of participants perceived that their walking had improved. However, there was a significant relationship between GRCS and performance on walking tests for the 10 m walk test with shoes off (p = 0.01) and timed up and go test (p = 0.02) only.

CONCLUSION

Commonly used walking tests may not be responsive to change following BoNT injection. The small ES suggest that BoNT has a modest effect on walking ability. Tests of walking performance may not be sufficient to capture all clinically relevant changes in walking ability following BoNT injection of the lower limb.

A prospective, multicentre, randomized, double-blind, placebo-controlled trial of onabotulinumtoxinA to treat plantarflexor/invertor overactivity after stroke

OBJECTIVE

To examine the safety and efficacy of onabotulinumtoxinA (Botox) for plantarflexor overactivity following stroke.

DESIGN

Double-blind randomized controlled trial, open-label extension phase.

SETTING

Neurology rehabilitation facilities.

SUBJECTS

Eighty-five subjects with lower limb hypertonia received 200 U (n = 28) or 300 U (n = 28) of onabotulinumtoxinA or saline (n = 29) injection.

PRIMARY MEASURES

Plantarflexor Ashworth scores at 12 weeks post injection and adverse events. Secondary measures: self-reported spasm frequency and pain, physician rating of hypertonia severity, gait quality and active dorsiflexion.

RESULTS

Differences were not seen between onabotulinumtoxinA groups; hence data were pooled. Incidence of adverse events was not different between groups (P = 0.61). Reduction in hypertonia was not different between groups at 12 weeks (P = 0.53); however for subjects with Ashworth scores of >3 at baseline, 14/31 in the onabotulinumtoxinA group demonstrated a reduction of >1 grade versus 1/17 receiving placebo injection (P = 0.01). Overall, onabotulinumtoxinA-injected subjects demonstrated significantly greater improvement in spasm frequency (22/54 versus 4/29, P = 0.01), pain reduction (8/54 versus 1/29, P = 0.02), active dorsiflexion (8/54 versus 1/29 P = 0.03) and gait quality (17/54 versus 6/29, P = 0.02) than controls. In the open-label phase, a second onabotulinumtoxinA injection was associated with greater hypertonia reduction (P = 0.005) and gait quality (P = 0.002) compared with single injection.

CONCLUSIONS

OnabotulinumtoxinA injection for ankle flexor overactivity after stroke was safe and well tolerated but did not alter local spasticity at 12 weeks; it did reduce spasms and improve gait quality. There were no detectable differences between higher and lower doses. A second injection may be associated with greater change.

Does the treatment of spastic equinovarus deformity following stroke with botulinum toxin increase gait velocity? A systematic review and meta-analysis

While botulinum toxin-A (BT-A) has been used to treat lower-limb focal spasticity successfully, its effect on characteristics of gait has not been well defined. The objective of this systematic review was to establish the treatment effect associated with the use of BT-A for equinovarus to improve gait velocity following stroke, using a meta-analytic technique. Relevant studies were identified through a literature search encompassing the years 1985 to November 2009. Studies were included if (i) the sample was composed of adult subjects recovering from either first or subsequent stroke, presenting with spastic equinovarus deformity of the ankle preventing full active dorsiflexion, and (ii) subjects who received BT-A were compared with subjects who had received a placebo, or (iii) in the absence of a placebo-controlled condition, subject had received BT-A and was assessed before and after treatment. A standardized mean difference (SMD) ± standard error and 95% confidence interval (CI) for gait velocity between the treatment and control group was calculated for each study, using Hedges's g, and the results pooled. Eight trials, five randomized controlled trials, and three single group intervention studies were included. Data representing 228 subjects were available for pooled analysis. Treatment with BT-A was associated with a small improvement in gait velocity (Hedge's g = 0.193 ± 0.081; 95% CI: 0.033 to 0.353, P < 0.018) representing an increase of 0.044 meters/s. The use of BT-A for lower-limb post-stroke equinovarus because of spasticity was associated with a small, but statistically significant increase in gait velocity.

Botulinum toxin injection to facilitate rehabilitation of muscle imbalance syndromes in sports medicine

Intramuscular injection of Botulinum toxin to produce reduction of focal muscle overactivity, and localized muscle spasm, has been utilized therapeutically for almost two decades. Muscle overactivity in neurologically normal muscle, where an imbalance exists between a relatively overactive muscle and its less active synergist or antagonist, can inhibit control of the antagonist producing a functional muscle imbalance. This brief review provides an overview of the role of muscle imbalance in sports-related pain and dysfunction, and outlines the potential for intramuscular injection of Botulinum toxin to be used as an adjunct to specific muscle re-education and functional rehabilitation in this patient group. A comprehensive understanding of normal movement and the requirements of the sporting activity are essential to allow accurate diagnosis of abnormal motor patterns and to re-educate more appropriate movement strategies. Therapeutic management of co-impairments may include stretching of tight soft tissues, specific re-education aimed at isolation of the non-dominant weak muscles and improvement in their activation, 'unlearning' of faulty motor patterns, and eventual progression onto functional exercises to anticipate gradual return to sporting activity. Intramuscular injection of Botulinum toxin, in carefully selected cases, provides short term reduction of focal muscle overactivity, and may facilitate activation of relatively 'inhibited' muscles and assist the restoration of more appropriate motor patterns.