Will pediatric botulinum toxin expansion improve function in cerebral palsy-related spasticity?

Does botulinum toxin actually improve function, or just reduce spasticity?

The short answer is: it can, but the evidence is stronger for reducing spasticity than for automatically translating into better function. A 2026 meta-analysis of 18 randomized controlled trials found that botulinum toxin type A (BoNT-A) significantly reduced ankle spasticity (a pooled mean difference of -0.31 on the Modified Ashworth Scale), but functional gains were only seen when injections were combined with structured rehabilitation [1]. This means the injection alone relaxes the muscle, but the child still needs therapy to turn that relaxation into new movement skills.

When rehabilitation is part of the picture, functional improvements do show up. A 2022 study of 200 children with bilateral cerebral palsy who received repeated BoNT-A injections within a rehabilitation program over five years found that 33.5% improved their Gross Motor Function Classification System (GMFCS) level—a measure of overall mobility—and about half improved their functional mobility scores at 5 and 50 meters [3]. Another study of 116 children found that BoNT-A combined with physiotherapy and electrical stimulation significantly improved gross motor function, especially in children under 72 months old [4]. So the message is: injections are a tool, not a cure—they create the opportunity for function, but therapy is what turns that opportunity into real-world gains.

Which children are most likely to see functional gains?

Age and baseline function matter a lot. The 2023 study of 116 children found that younger children (under 72 months, or 6 years) showed greater reductions in spasticity and more improvement in gross motor skills than older children [4]. This makes sense—younger brains and bodies are more plastic, and there's more time to build on the window of reduced spasticity.

The same study also found that children with milder involvement (GMFCS levels I–III) improved in sitting, standing, and walking, while children with more severe involvement (levels IV–V) improved in posture and mobility [4]. So even children with significant disability can benefit, but the type of functional gain looks different. For children with severe spasticity, a 2021 pilot study found that repeated injections into the hip adductors reduced muscle tone by up to 53% and halted the progression of hip dislocation—a major complication that affects comfort and quality of life [5]. That's a functional benefit in terms of preventing deterioration, even if it doesn't show up as a new walking milestone.

What are the limits and caveats?

The biggest limitation is that the effect is temporary. The 2026 meta-analysis noted that spasticity reduction attenuates by about 12 weeks, meaning injections need to be repeated regularly to maintain benefits [1]. This isn't a one-time fix—it's an ongoing treatment strategy.

Upper limb function is a mixed bag. A 2023 systematic review of 24 studies found that BoNT-A improved spasticity in the upper limbs in about half of the studies, and improved activity limitations in 6 out of 11 studies, but no study found an improvement in quality of life [2]. This suggests that for the upper limbs, injections can help with specific tasks (like reaching or grasping) but may not change the child's overall sense of well-being. The same review emphasized that improvements are most likely when 'reasonable objectives are established'—meaning the goals need to be specific and realistic, like 'improve hand hygiene' or 'make dressing easier,' rather than 'normalize arm function.'

Finally, the evidence is not unanimous. The 2026 meta-analysis found that functional data were too sparse to pool quantitatively, and the 2023 review noted that only a minority of studies showed functional gains [1][2]. This inconsistency likely reflects differences in injection protocols, rehabilitation intensity, and outcome measures. But the overall picture is clear: when injections are combined with therapy and targeted at achievable goals, they can improve function—especially in younger children and in the lower limbs.

About These Sources

This answer is built on 5 peer-reviewed studies — published from 2021 to 2026, 1 from 2024 or later, 1 in Q1 journals — selected as the most relevant from 6 studies that passed quality screening, drawn from 48 papers retrieved from a database of over 500 million.

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