Botox treatment for muscle spasticity

Botulinum Toxin A (BTA) is used with people who may have high muscle tone (tight muscles) because of conditions like cerebral palsy.

Botox for tight muscles

BTA is a muscle relaxant derived from the bacterium Clostridium Botulinum, which can be poisonous.

When used in small, controlled doses, Botox can provide safe, effective relief from several conditions. It has treated muscular conditions in children and adults for over 20 years. Clinical studies and trials have indicated positive and helpful results.

Botox is effective on muscle tone in various parts of the body such as:

  • the arms and hands, if grip is an issue
  • around the orbital (eye) area
  • the lower limbs to aid standing and walking

Many children who have difficulty with movement due to tight muscle tone will walk on the balls of their feet with the heel off the ground. The feet may also turn inwards. This makes it difficult or impossible to place the foot flat on the floor.

When injected into the calf or lower leg muscles, BTA can relax these muscles. This makes walking easier and more comfortable. It can also improve balance and reduce falls.

Tightness in the hamstring muscles at the back of the thigh makes it difficult to straighten legs. This can result in a crouch or squat gait.

Injection with BTA can help straighten the legs and improve walking, sitting and transferring.

Botox also works well on the adductor muscles in the hip and groin area. This is a common problem area for children with spastic CP.

High muscle tone

High muscle tone in the hip and groin makes it difficult to keep the legs apart. This is called scissoring. For those with upper limb spasticity, Botox can reduce muscle tone around the elbow, wrist and thumb areas, enabling the arm to straighten. This can help with personal care and hygiene. It can also improve pinching, grasping and releasing movements.

Botox can also reduce secondary problems. Spasticity can create an imbalance in muscle tone across a joint that not only interferes with movement but can also lead to:

  • fixed contractures (permanent shortening of the muscle and tendon)
  • bony abnormalities
  • joint instability, such as hip dislocation


If surgery occurs too early, the child may need to have repeat or other surgery as they grow. Lowering the tone of the more active muscles can:

  • restore balance across the joint
  • increase the stretch of the muscle
  • and promote growth

This can avoid or minimise potential damage to that joint and the need for surgery. It's rare to have orthopaedic surgery without trying Botox first.

BTA has also been used for:

  • pain relief
  • improved positioning
  • tremor and spasm control
  • drooling
  • facilitation of personal care

Treatment may delay or reduce the need for orthopaedic surgery. If used before adductor release surgery, it can reduce post-operative pain and the length of stay in hospital. Many surgeons use BTA to reduce painful spasms after operations. It can protect soft tissue from involuntary movement until the healing process is complete.

As well as the comfort from reduction of tone and spasm, many teenagers and adults with CP report a cosmetic improvement in their appearance too.

Tiredness can often be a problem for disabled people due to the increased effort required in moving around. As movement becomes more fluid following treatment, this can reduce energy consumption.

How Botox works

Muscles contract and relax as a result of chemical messages from the brain. Problems can occur when the chemical messengers are blocked or do not connect with specific muscles. This chemical is called acetylcholine.

When BTA is injected into the muscle, the release of acetylcholine is blocked, resulting in a relaxation of overactive muscles. The injections generally take effect within a few days and last for several months.

Physiotherapy is also part of the treatment and aids the injection's effectiveness.

Suitability for Botox

Usually the assessment team may include a consultant, paediatrician, paediatric neurologist or orthopaedic surgeon, and a physiotherapist. An orthotist or occupational therapist may also be present.

If you walk on tip toe or turn your feet inward, the assessment may involve a detailed movement study (gait analysis). This is often filmed.

After a full examination, the team will decide whether the treatment is right for you or your child and which muscles to inject. You should get a clear idea of the treatment's expected outcome.

Access to BTA treatment

Although BTA is becoming more common, not all NHS Trusts will fund it. As with all medical treatments, you should ask your GP or consultant to refer you.

An anaesthetic cream may reduce any discomfort from the injection.

If the individual is very young or anxious, a local or general anaesthetic can be used.

The amount of Botox depends on:

  • the size and number of muscles treated
  • the degree of tightness in the muscle
  • the weight of the patient

There is a maximum recommended dose. Injections in several muscles during a single treatment are common.

National Institute for Health and Care Excellence (NICE) guidelines on use of Botox

After treatment

Following the injection, there are various ways to maximise the effects of Botox. These include:

  • more intensive physiotherapy
  • increased use of walking aids or splinting
  • greater use of the treated muscles
  • casting to maximise muscle stretch

A follow-up appointment will assess the success of the injections. On average the interval between injections varies from between 6 to 9 months. Doctors may recommend re-injection when muscle tone begins to interfere with function rather than when it returns to pre-injection levels. There is no limit to the number of re-injections.

Side effects of Botox

In the main, reported side effects of Botulinum Toxin A (BTA) are mild and short-lived. They include:

  • post-injection pain requiring simple pain relief
  • increased frequency of falls within first 2 weeks of injection
  • mild cold or flu-like symptoms
  • temporary incontinence
  • positive effect on constipation
  • difficulty with swallowing, especially where upper limb or neck injected
  • mood swings and irritability
  • fatigue
  • anaphylaxis (severe allergic reaction) but this is rare

The Medicines and Healthcare Products Regulatory Industry advises you to be alert to reactions from the spread of the toxin.

These include:

Cerebral palsy (CP) and fatigue

Seek immediate medical attention if any of these problems develop, from soon after treatment to several weeks afterwards.

Last reviewed by Scope on: 29/08/2023

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