Safety of high-dose botulinum toxin type A therapy for the treatment of pediatric spasticity

The updated European Consensus 2009 on the use of Botulinum toxin for children with cerebral palsy

An interdisciplinary European group of clinical experts in the field of movement disorders and experienced Botulinum toxin users has updated the consensus for the use of Botulinum toxin in the treatment of children with cerebral palsy (CP). A problem-orientated approach was used focussing on both published and practice-based evidence. In part I of the consensus the authors have tabulated the supporting evidence to produce a concise but comprehensive information base, pooling data and experience from 36 institutions in 9 European countries which involves more than 10,000 patients and over 45,000 treatment sessions during a period of more than 280 treatment years. In part II of the consensus the Gross Motor Function Measure (GMFM) and Gross Motor Function Classification System (GMFCS) based Motor Development Curves have been expanded to provide a graphical framework on how to treat the motor disorders in children with CP. This graph is named "CP(Graph) Treatment Modalities - Gross Motor Function" and is intended to facilitate communication between parents, therapists and medical doctors concerning (1) achievable motor function, (2) realistic goal-setting and (3) treatment perspectives for children with CP. The updated European consensus 2009 summarises the current understanding regarding an integrated, multidisciplinary treatment approach using Botulinum toxin for the treatment of children with CP.

Safety of botulinum toxin type A in children younger than 2 years

BACKGROUND

Botulinum toxin type A (BoNT-A) has been used in many indications and is licensed for the treatment of spasticity in children older than 2 years. However, there are few reports of BoNT-A treatment in patients younger than 2 years of age.

AIMS

To review retrospectively the safety data from all infants treated with botulinum toxin type A (BoNT-A) before 2 years of age in a paediatric neurology unit.

METHODS

There were 74 infants: 28 received the first dose before 1 year of age, and 46 between the ages of 1 and 2 years.

RESULTS

In the first year of life, the most frequent indication was obstetric brachial palsy (OBP) (71.4% of cases) and in the second year, cerebral palsy (CP) (73.9%). Both Botox and Dysport, the two commercially-available BoNT-A products in Spain, were used. The average starting dose by session was 6.55 U/kg body weight Botox in infants in their first year of life, and 8.4 U/kg body weight Botox and 21.1 U/kg body weight Dysport in the second year of life. Only 3.6% of cases treated in the first year and 6.5% of those treated in the second experienced adverse events (AEs), which consisted of mild weakness or tiredness lasting 1-4 days.

CONCLUSIONS

BoNT-A has a good safety profile in infants younger than 2 years old. AEs are similar to those found in older children.

Long-term use of botulinum toxin type A in children with cerebral palsy: treatment consistency

At the University Hospital of Pellenberg (Belgium), more than 1000 patients have been treated with Botulinum toxin type A (BTX-A) over the last decade. Ten percent of these patients (n=106) received multiple (at least four times), multi-level, high-dosage treatments. The aim of this study was to evaluate the stability of dosage and treatment intervals in long-term, multi-level, high-dosage treated children with cerebral palsy and to evaluate the evidence for a safe and stable response to this treatment. Data on disease, age, dosage and target muscles were extracted for each treatment session of 106 patients who received multiple BTX-A treatment sessions. Patients had a follow-up of 4y 6mo (range 1y 8mo-8y 9mo) on average and received 4 to 12 BTX-A treatments within the period of January 1996 and December 2005. Patients received a mean dosage of 23.5+/-5.2U/kgbw at first treatment with stable subsequent values. Mean dosages for children with diplegia, hemiplegia and quadriplegia were 24.5+/-4.7U/kgbw, 15.9+/-3.7U/kgbw and 22.0+/-4.8U/kgbw, respectively. Mean age at first treatment was 4y 6mo (range 1y 11mo-18y 10mo) with a majority of patients (76.4%) first treated within 2 and 4y of age. Treatment intervals of approximately 1y remained stable within four, five and six subsequent treatments. Long-term, high-dosage, multi-level BTX-A applications can be considered as a safe and stable treatment option for children with cerebral palsy and the formation of antibodies, responsible for secondary non-response, can be indirectly precluded.

Contralateral weakness and fatigue after high-dose botulinum toxin injection for management of poststroke spasticity

A 53-yr-old woman developed contralateral weakness and fatigue, without autonomic symptoms, 2 wks after receiving an injection with 800 units of botulinum toxin A for management of her poststroke spasticity. Although the patient reported resolution 4 wks later, clinical evaluations suggested an even longer time course. The patient then experienced the same contralateral symptoms again more than a year later, after a 500-unit injection, which took a similar length of time to resolve. We report the first known case of repeated contralateral weakness and fatigue after high-dose botulinum toxin A injection. Currently, dosage is largely titrated by the practitioner based on individual patient response. Before performing botulinum toxin A injections for therapeutic purposes, the expected risks and benefits for each patient must be carefully considered.

Management of spasticity and dystonia in children with acquired brain injury with rehabilitation and botulinum toxin A

OBJECTIVE

To investigate the effect of a combination of botulinum toxin A (BTX-A) and rehabilitation on spasticity, pain and motor functioning in children with acquired brain injury (ABI).

METHODS

All children and adolescents with ABI, aged 2-20 years, consecutively treated in the department over a 22-month period, were prospectively followed-up and clinically assessed pre- and post-treatment. They had spasticity and/or dystonia leading to impairment in activities of daily living, orthopaedic deformations and/or pain. Injections were performed using electro-stimulation. Doses of BTX-A (Botox) were administered using recent recommendations.

RESULTS

Twenty-five children (mean age 6.3 years) participated in the study (51 injection sessions). All patients received BTX-A injections, followed with physical and/or occupational therapy. Significant improvement was achieved for spasticity reduction (p < 0.0001), command on antagonist muscles (p = 0.03 for the tibialis anterior) and goniometry assessment (p < 0.05). Pain relief was achieved in patients in a minimally responsive state. Functional goals were achieved, such as improving transfers or gait, grasping and releasing abilities, with significant transfer in activities of daily living (p < 0.0001).

CONCLUSION

A combination of BTX-A injection with rehabilitation is an interesting option for treatment of muscle tone disorders in children with ABI.

Prospective study examining remote effects of botulinum toxin a in children with cerebral palsy

We examined the remote effects on muscle strength and functional decline of lower-extremity botulinum toxin A injections in children with cerebral palsy. This prospective study enrolled 34 children (19 boys, 15 girls; mean age, 7.7 years) diagnosed with spastic cerebral palsy. Patients were examined at baseline and 1 month to determine if they experienced a change in upper-extremity strength (handheld dynamometry) or function (Pediatric Outcomes Data Collection Instrument). Subjects were analyzed in aggregate and by dosing group (low dose, 0-10 U/kg body weight; high dose, 11-25 U/kg) to determine if injection dose was associated with a change in remote muscle strength or function. We measured baseline and 1-month postinjection strength in shoulder flexor, shoulder abductor, elbow flexor, elbow extensor, and finger flexor muscles. None of these remote muscle groups was significantly weaker at 1 month after injection. No correlation was evident between change in muscle strength and toxin dose. These findings indicate that doses of botulinum toxin A in the lower extremities, at up to 21 U/kg, do not affect upper-extremity strength. This information can help guide dosages of botulinum toxin A in the management of spasticity in children with cerebral palsy.

A dose-response relationship research on botulinum toxin type A local intramuscular injections of lower extremity spasticity in children with cerebral palsy

OBJECTIVES

To observe the dose-response relationship of intramuscular injections of botulinum toxin A (BTX-A) in the spastic cerebral palsy.

METHODS

One hundred fifty cases (age between 2 and 12 years) were randomly divided into three groups. The patients were injected with different dose of BTX-A. The movement function was evaluated with modified Ashworth scale (MAS) and physician's rating scale (PRS) at entry and 1 month after injection. The analyses were conducted with one-way analysis of variance and chi (2) test.

RESULTS

The evaluation of MAS and PRS revealed a significant increase of movement function. No statistically significant differences of the side effects among three groups could be demonstrated.

CONCLUSIONS

The study suggested that the movement function was more significantly improved with relatively higher dose of BTX-A, which was safe and effective.

Treatment of the spasticity in children with cerebral palsy

Botulinum toxin is a natural purified protein and one of the strongest biological poisons--neurotoxin. It is produced by the bacterium Clostridium botulinum. Its medical usage started in USA in 1981 and in Europe in 1992. There are seven different immune types of the toxin: A, B, C1, D, E, F and G. Toxin types A and B are used to decrease muscular spasticity. Botulinum toxin prevents the formation of acetylcholine from cholinergic nerve tissues in muscles, which in the end irreversibly destroys neuromuscular synapses. It is called temporary local chemodenervation. It does not affect the synthesis of acetylcholine. As it affects neuromuscular bond it also affects one of the symptoms of cerebral palsy--spasticity. Decreasing the spasticity of children with cerebral palsy leads to the improvement of conscious movements, muscles are less toned, passive mobility is improved, orthosis tolerance is also improved, and the child is enabled to perform easier and better motor functions such as crawling, standing and walking. Since the action of Botulinum toxin is limited to 2-6 months, new neural collaterals are formed and neuromuscular conductivity is reestablished which in the end once again develops a muscular spasm. This leads to a conclusion that botulinum toxin should again be applied into spastic muscles. It is very important for good effect of Botulinum toxin to set the goals of the therapy in advance. The goals include improvement of a function, prevention of contractions and deformities, ease of care and decrease of pain for children with cerebral palsy. After application of botulinum toxin, it is necessary to perform adequate and intensive physical treatment with regular monitoring of effects. This work shows a case of a boy with spastic form of cerebral palsy. After being rehabilitated using Vojta therapy and Bobath concept and the conduct of certain physical procedures, botulinum toxin is administered into his lower limbs' muscles and kinesiotherapy is intensified. After the administration of botulinum toxin significant functional improvement is noted.

Iatrogenic botulism due to therapeutic botulinum toxin a injection in a pediatric patient

Botulinum toxin A is commonly used to reduce spasticity and dystonia in children with cerebral palsy. We report a pediatric patient who developed systemic botulism as a result of a severe overdose of the injected toxin (40 U/kg). This case highlights the importance of physicians having adequate knowledge of primate and human literature on the lethal dose, 50% of botulinum toxin A before injecting children.

High dose botulinum toxin A for the treatment of lower extremity hypertonicity in children with cerebral palsy

The aim of this study was to determine the safety profile of high dose (15-25 units/kg) of botulinum toxin A (BTX-A) in children with cerebral palsy (CP) and increased lower extremity muscle tone. We performed a retrospective review of 929 patient encounters at the Movement Disorders Center at Washington University. A total of 261 patients (105 females; 156 males) were treated during these visits, ages 6 months to 21 years (mean 8 y 4 mo [SD 4 y 8 mo]). Ambulatory ability at the time of BTX-A injection was independent ambulation (36.4%, n=95), ambulation with a walker (27.6%, n=72), and non-ambulatory (31.8%, n=83). A few patients (4.2%, n=11) were able to ambulate with a cane or crutch at the time of injection. Participants were characterized according to BTX-A dose, CP etiology, motor involvement pattern, muscles injected, ambulatory ability, and use of oral tone medications. Follow-up records were searched for reported adverse events (AEs), with a mean time to AE assessment of 6.5 weeks (SD 3.38). The AE occurrence was determined for doses of 0 to 4.9 units/kg, 5 to 9.9 units/kg, 10 to 14.9 units/kg, 15 to 19.9 units/kg, and 20 to 25 units/kg. The overall AE occurrence was 4.2%. Standard doses of BTX-A had side-effect occurrences of 3.9% for 5 to 10 units/kg and 7.6% for 10 to 15 units/kg. Among higher doses (15-20 units/kg and 20-25 units/kg) the AE occurrence was 3.5% and 8.6% respectively. No patient developed botulism. AEs were randomly distributed across dosing groups, CP etiologies, clinical phenotypes, ambulatory status, and treatment duration. All doses were associated with a significant increase in passive range of motion using the Tardieu scale. We conclude that higher dose BTX-A is safe in children with a spectrum of CP phenotypes and are well tolerated over time.

Repeat injection of botulinum toxin A is safe and effective for upper limb movement and function in children with cerebral palsy

The efficacy of repeated botulinum toxin A (BTX-A) injections in two and three dose regimes, together with occupational therapy, on upper limb movement and function, was studied using an evaluator blinded, randomized, controlled two-group trial. Forty-two children (31 males, 11 females; range 2-8 y, mean 4 y [SD 1 y 7 mo]) with hemiplegic cerebral palsy (Gross Motor Function Classification System Level I) longitudinally participated for 30 months, with the first 6 months reported earlier (Lowe et al. 2006). The BTX-A group (n=21) received three injections (0, 6, and 18 mo), while the delayed group had two (6 and 18 mo; dose 0.5-2.1 units/kg, mean 1.5 [SD 0.18]; dilution 100 units/0.5 ml). At 30 months, no difference existed between groups on any standardized measures. First and second injections showed significant treatment effect sizes, on Quality of Upper Extremity Skills Test (5.5 p=0.01: 4.5 p=0.03); parent Goal Attainment Scaling (GAS; 3.5 p=0.02: 3.9 p=0.01; therapist GAS 7.8 p=0.00: 4.0 p=0.03); Canadian Occupational Performance Measure (performance 0.4 p=0.05: 0.4 p=0.02; satisfaction 0.4 p=0.05: 0.37 p=0.08); and Pediatric Evaluation of Disability Inventory functional skills (1.8 p=0.00: 2.3 p=0.04). BTX-A was not linked to adverse events, suggesting repeated upper limb injections in children with hemiplegia receiving occupational therapy were safe and effective for improvement of movement and function.

Iatrogenic botulism in a child with spastic quadriparesis

Botulinum toxins are potent neurotoxins used in a variety of neurological disorders. Few pediatric reports have been published to date regarding the potential hazards of therapeutic use of botulinum toxins. We describe the case of a 10-year-old boy who developed systemic weakness following treatment of spasticity with botulinum toxin type B. The patient developed iatrogenic botulism with ptosis, facial diplegia, neck flexor and extensor weakness, and profound hypopharyngeal laxity with respiratory compromise from which he eventually recovered. Clinicians should be mindful of the risk for systemic botulism when using local injections of the neurotoxin.

Nonoperative management of spasticity in children

Central to the longitudinal management of childhood hypertonia are nonsurgical treatments. These include physical and occupational therapy, electrical stimulation, orthotics, botulium toxin, and drugs. This manuscripts reviews these treatment modalities as well as evaluation tools available to assess their impact on a child's hypertonia.

[Multimuscle treatment of spasticity in adults patients with botulinum toxin]

Some recent studies in children with spasticity demonstrated the safety of multimuscle injections of botulinum toxin (BT) type A with doses markedly higher than those recommended. Data about efficacy and safety of multifocal injections of BT in adult patients with spasticity are very limited. However numerous clinical situations for example, spinal cord injury, multiple sclerosis, brain injury, stroke or cerebral palsy seem to justify this type of patient management. Controlled studies are expected in the future to evaluate the efficacy and safety of multisite injections of BT. They may encourage physicians to perform such multifocal injections with high doses of BT. A better understanding of distant spread of BT is also warranted.

Place des doses élevées dans les injections de toxine botulique

OBJECTIVE

To bring general elements of reflection on the use of the high doses of botulinum toxin in spastic children and adults.

MATERIAL AND METHODS

Review of the literature on the high doses and the benefit-risk associated with botulinum toxin injections.

RESULTS

The medical literature exclusively relates to the use of the high doses in children and adolescents. Comparative work with conventional doses suggests a relative interest, but with a risk of increased side effects. Several articles report on treatments with high and even very high doses in series of patient, with a documented effectiveness. But their justification remains partial and the study of the possible side effects is limited. Reflections are brought to contribute to the debate on the use of high doses, taking into account the local physiological effect of botulinum toxin, the risk of regional and general diffusion, the need for a progressive strategy, the variability of effects, the cost of the treatment and the need for obtaining an informed consent of the patient and of significant others.

CONCLUSION

The use of high doses of botulinum toxin increases progressively, but must remain very careful.

Utilisation de fortes doses de toxine botulique de type A chez l'enfant: intérêt et sécurité en pratique clinique

The purpose of this article is to examine the current state of administering high doses botulinum toxin type A for the treatment of childhood spasticity, particularly Cerebral Palsy. The inter-relationship between the Cerebral Palsy neurological maturation and the early management is discussed, including identification of common gait patterns and the choice of target muscles for focal or multi focal spasticity management. High doses of botulinum toxin type A, when multilevel and integrated management approach is indicated, appear to be a safe, efficacious treatment for multi focal Cerebral Palsy spasticity. A review of literature guides the clinician about necessary adaptation of botulinum toxin doses and found no evidence that higher doses result in a increase of complications. Further studies would be interesting in order to evaluate long term safety and efficacy of this therapy in Cerebral Palsy.