Treating spastic equinus foot from cerebral palsy with botulinum toxin type A: what factors influence the results?: an analysis of 189 consecutive cases

A consensus statement on the use of botulinum toxin in pediatric patients

Botulinum toxin has been used in medicine for the past 30 years. However, there continues to be controversy about the appropriate uses and dosing, especially in the pediatric population. A panel of nine pediatric physiatrists from different regions and previous training programs in the United States were nominated based on institutional reputation and botulinum toxin (BoNT) experience. Based on a review of the current literature, the goal was to provide the rationale for recommendations on the administration of BoNT in the pediatric population. The goal was not only to review safety, dosing, and injection techniques but also to develop a consensus on the appropriate uses in the pediatric population. In addition to upper and lower limb spasticity, the consensus also provides recommendations for congenital muscular torticollis, cervical dystonia, sialorrhea, and brachial plexus palsies.

Over 25 Years of Pediatric Botulinum Toxin Treatments: What Have We Learned from Injection Techniques, Doses, Dilutions, and Recovery of Repeated Injections?

Botulinum toxin type A (BTXA) has been used for over 25 years in the management of pediatric lower and upper limb hypertonia, with the first reports in 1993. The most common indication is the injection of the triceps surae muscle for the correction of spastic equinus gait in children with cerebral palsy. The upper limb injection goals include improvements in function, better positioning of the arm, and facilitating the ease of care. Neurotoxin type A is the most widely used serotype in the pediatric population. After being injected into muscle, the release of acetylcholine at cholinergic nerve endings is blocked, and a temporary denervation and atrophy ensues. Targeting the correct muscle close to the neuromuscular junctions is considered essential and localization techniques have developed over time. However, each technique has its own limitations. The role of BTXA is flexible, but limited by the temporary mode of action as a focal spasticity treatment and the restrictions on the total dose deliverable per visit. As a mode of treatment, repeated BTXA injections are needed. This literature reviewed BTXA injection techniques, doses and dilutions, the recovery of muscles and the impact of repeated injections, with a focus on the pediatric population. Suggestions for future studies are also discussed.

Efficacy of Repeated Botulinum Toxin Type A Injections for Spastic Equinus in Children with Cerebral Palsy-A Secondary Analysis of the Randomized Clinical Trial

Botulinum toxin A is considered an important tool to control spasticity in children with cerebral palsy. Several factors are known to affect the efficacy of botulinum toxin, such as dosage, appropriate muscle selection and application, age, and accompanying therapy. A multicenter, double-blind, randomized, prospective phase III clinical trial of botulinum toxin A for the treatment of dynamic equinus in 144 children with cerebral palsy was performed to compare the efficacies of letibotulinumtoxin A and onabotulinumtoxin A. Secondary analyses were performed to evaluate factors that affected the outcome, focusing on the number of times injections were repeated. Effectiveness was defined as a change of 2 or more in the physician’s rating scale. Multivariate regression analyses were performed with multiple variables. The first injection of botulinum toxin A significantly improved D subscale of Gross Motor Function Measure-88 scores at 3 months compared to repeated injections (p < 0.05). After 6 months, patients who had one injection or none before the study showed significantly better outcomes than those who had more than one injection in terms of observational gait scores.

The WE-Study: does botulinum toxin A make walking easier in children with cerebral palsy?: Study protocol for a randomized controlled trial

BACKGROUND

Intramuscular injections of botulinum toxin A (BoNT-A) have been a cornerstone in the treatment of spasticity for the last 20 years. In Norway, the treatment is now offered to two out of three children with spastic cerebral palsy (CP). However, despite its common use, the evidence for its functional effects is limited and inconclusive. The objective of this study is to determine whether BoNT-A makes walking easier in children with CP. We hypothesize that injections with BoNT-A in the calf muscles will reduce energy cost during walking, improve walking capacity, increase habitual physical activity, reduce pain and improve self-perceived performance and satisfaction.

METHODS/DESIGN

This randomized, double-blinded, placebo-controlled, multicenter trial is conducted in a clinical setting involving three health regions in Norway. Ninety-six children with spastic CP, referred for single-level injections with BoNT-A in the calf muscles, will be invited to participate. Those who are enrolled will be randomized to receive either injections with BoNT-A (Botox®) or 0.9% saline in the calf muscles. Stratification according to age and study center will be made. The allocation ratio will be 1:1. Main inclusion criteria are (1) age 4 - 17.5 years, (2) Gross Motor Function Classification System levels I and II, (3) no BoNT-A injections in the lower limbs during the past 6 months and (4) no orthopedic surgery to the lower limbs during the past 2 years. The outcome measures will be made at baseline and 4, 12 (primary endpoint) and 24 weeks after injections. Primary outcome is change in energy cost during walking. Secondary outcomes are change in walking capacity, change in activity, perceived change in performance and satisfaction in mobility tasks, and pain. The primary analysis will use a linear mixed model to test for difference in change in the outcome measures between the groups. The study is approved by the Regional Ethical Committee and The Norwegian Medicines Agency. Recruitment started in September 2015.

DISCUSSION

The evaluation of effect is comprehensive and includes objective standardized tests and measures on both impairment and activity level. Results are to be expected by spring 2019.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02546999 . Registered on 9 September 2015.

[Therapeutic outcome of onabotulinum toxin type A in patients with upper limb spasticity]

Onabotulinum toxin type A treatment for post-stroke upper limb spasticity was investigated to contribute to establishing a standard dosage for Japanese patients. A total of 100 patients participated in the study. The outcome one month (33.6±6.5 days) after the treatment was assessed by the Modified Ashworth Scale (MAS) to estimate the mean effect with a 10-unit injection and the standard dosage expected to improve MAS 1 degree. Average improvement of 263 muscles treated with a higher concentration of 10 units diluted in 0.2 ml was 0.207±0.414 degrees, and that of 231 muscles treated with a lower concentration of 10 units in 0.4 ml was 0.149±0.244 degrees without significant difference among diluted concentrations. To improve MAS 1 degree, 64.6±31.1 units were required for the pectoralis major, 51.2±21.3 units for the teres major, 111.7±48.0 units for the biceps brachii, 51.6±26.8 units for the brachioradialis, 54.1±23.2 units for the brachialis, 34.4±10.7 units for the pronator teres, 64.6±27.9 units for the flexor carpi radialis, 62.4±26.8 units for the flexor carpi ulnalis, 58.5±31.1 units for the flexor digitorum profundus, 69.7±35.1 units for the flexor digitorum superficialis, 24.6±13.4 units for the flexor pollicis longus, and 15.6±11.3 units for the adductor pollicis. Although the results shown here had no significant differences among concentrations, increasing the volume would disturb injection into small muscles, so we considered that a lower volume with a higher concentration should assure larger benefits. It is difficult to make effective injections into all spastic muscles within the officially permitted health insurance dosage of 240 units. Hence, it is advisable to increase the applicable upper limit based on safely achieved cumulative experience.

Comparison of treatment effects between children with spastic cerebral palsy under and over five years after botulinum toxin type a injection

OBJECTIVE

To evaluate whether age influences a change in the spasticity of the ankle plantar flexor after botulinum toxin type A (BTA) injection in children with spastic cerebral palsy (CP).

METHODS

Sixteen children with spastic CP were enrolled in the study. Seven children (group 1) were under 5 years of age, and nine (group 2) were over 5 years of age. They all received BTA injection in the gastrocnemius muscle (GCM) under ultrasound guidance. Passive range of motion (PROM) of ankle dorsiflexion, Modified Ashworth Scale (MAS) of the ankle plantar flexor, Gross Motor Function Measure (GMFM) and median red pixel intensity (RPI) of the medial GCM on real-time sonoelastography were measured at baseline (pre-injection) and 1-, 3-, and 6-month post-injection.

RESULTS

In both groups, the mean PROM, MAS, and RPI were significantly improved after injection until 6-month post-injection. The change of PROM of ankle dorsiflexion in group 1 was significantly greater than that in group 2, until 6-month post-injection. The change in the MAS and GMFM between baseline and 6-month post-injection in group 1 was greater than that in group 2. The changes in the median RPI between baseline and 3- and 6-month post-injections were greater in group 1 than in group 2.

CONCLUSION

Our pilot study demonstrated the different changes in spasticity of the ankle plantar flexor after BTA injection based on age. Therefore, age may be considered when establishing a treatment plan using BTA injection for children with spastic CP.

Efficacy and safety of serial injections of botulinum toxin A in children with spastic cerebral palsy

BACKGROUND

Botulinum toxin A (BTX-A) has been successfully used as a treatment for children with spastic cerebral palsy; however, the effect of BTX-A on reducing spasticity only lasts a few months, thus serial injections are required. The present study was to evaluate the efficacy and safety of serial injections of BTX-A in children with spastic cerebral palsy.

METHODS

Fifty-two pediatric patients with spastic cerebral palsy, 2-12 years of age (mean age, 4.79 ± 2.70), were retrospectively analyzed. Muscle tone was assessed with the Modified Ashworth Scale, and gait was assessed with the Physician Rating Scale. Assessments were undertaken at baseline, 3 months, and 6 months after serial injections of BTX-A.

RESULTS

The beneficial effects of BTX-A occurred 1 week after the injection, whereas the adverse side-effects appeared within 1 week and lasted <2 weeks. BTX-A significantly improved muscle tone and gait 3 and 6 months after its serial injections compared to baseline (P <0.05).

CONCLUSIONS

Serial injections of BTX-A are effective and safe for children with spastic cerebral palsy. The sideeffects of serial injections of BTX-A are mild and selflimited.