Does botulinum toxin A reduce adductor muscle spasticity in children with cerebral palsy?

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Abstract

BACKGROUND

Botulinum toxin is an established antispastic treatment for children with cerebral palsy (CP), but its effect on adductor spasticity-an important risk factor for hip dislocation-has not been investigated in a clinical trial.

OBJECTIVE

To examine whether treatment with botulinum toxin A (BTX-A) reduces adductor muscle spasticity in children with CP.

DESIGN AND INTERVENTION

This placebo-controlled, randomized, double-blind trial was conducted at nine centers in Germany and one center in Austria. The study included 61 children (mean age 6 years and 1 month; range 1 year and 11 months to 10 years and 10 months) with CP who had bilateral adductor spasticity without hip dislocation (Reimer's Migration Index <50%). Patients were excluded if they had received BTX-A within the previous 9 months, or if they had undergone surgery of the injected muscles or associated ligaments. The children were randomized to one dose of BTX-A (Dysport®, Ipsen Inc., Milford, MA; 30 U per kg body weight) or placebo. Two-thirds of the dose was injected into adductor muscles and one-third into medial hamstrings. At baseline, and 4 weeks and 12 weeks post-injection, the treatment effect was evaluated by assessing the distance between the knees ('fast catch'), hip adduction (range of passive movement), spasticity of the adductors and hamstrings (modified Ashworth Scale) and motor function (Gross Motor Function Measure, GMFM). In addition, the investigators determined achievement of predetermined treatment goals related to functional ability (Goal Attainment Scaling, GAS). GAS takes into account a patient's severity of disease and sets patient-specific goals such as improvement in walking or personal care, or reduced use of analgesics.

OUTCOME MEASURES

The primary outcome measure was the knee-knee distance; secondary measures were hip adduction, muscle spasticity, motor function and achievement of pretreatment goals.

RESULTS

After 4 weeks, BTX-A-treated patients had a greater knee-knee distance than placebo-treated patients (P=0.002); in addition, BTX-A reduced the spasticity of the adductor muscles and improved progress towards individual treatment goals (P=0.001 and P=0.037, respectively, compared with placebo). These treatment effects remained significant at 12 weeks (fast catch P=0.019, Ashworth Scale P=0.079, GAS P=0.045). BTX-A treatment had no significant effect on motor function (GMFM score) when compared with placebo, however. The most frequently observed adverse events in this study were muscular weakness (five BTX-A, two placebo), dysphagia (two BTX-A, one placebo), pollakiuria (one BTX-A) and urinary incontinence (one BTX-A).

CONCLUSION

In most children with CP, adductor muscle tone can be reduced by injections with BTX-A. Treatment reduced the extent of impairment and helped patients to achieve personal goals such as improvement in walking or personal care. The GMFM, however, failed to detect an improvement of motor function.

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