Botulinum Toxin A [BTA]
Content by Scope
How does it work?
Skeletal muscles tighten, or contract, in response to the release
from nerve endings of a chemical called acetylcholine [also known as a
neurotransmitter]. The production of too much acetylcholine leads to increased
muscle tone, which results in spasticity.
When BTA is injected into the muscle[s] the release of
acetylcholine is blocked, resulting in a relaxation of overactive muscles. The
injection[s] take effect within a few days and last until new nerve endings grow
back and the affected muscle[s] recover, which usually takes around 12-16 weeks.
Functional benefits, however, usually last longer than this.
Suitability for treatment
Usually a full assessment will be carried out by a hospital
medical team, comprising a consultant [either a paediatrician or orthopaedic
surgeon] and a physiotherapist. An orthotist or occupational therapist may also
be present. This assessment will involve a detailed movement study, which is
often videoed, probably lasting around an hour. A decision will then be made as
to whether the treatment is appropriate and which muscle, or range of muscles
will be injected. A clear indication should also be given as to what the end
result is likely to be.
What does the treatment involve?
BTA is diluted in a saline solution and injected directly into
the muscle[s]. An anaesthetic cream may be applied to the skin to reduce any
discomfort from the injection. Oral sedation is frequently used, or sometimes a
local or general anaesthetic, especially if the individual is very young and/or
anxious, or where the area to be injected is difficult to access. The muscles to
be injected are identified by manual palpation, ultrasound, EMG
[electromyography] or stimulation of the nerve.
The amount of BTA used is determined by the size and number of
muscle[s] to be treated, the degree of spasticity and the weight of the patient,
up to a maximum recommended dose. Multi-level injections, where a number of
sites are injected during the one treatment, are now becoming commonplace.
Following the injection[s], advice and direction should be given
as to how to maximise the effects of BTA. This may involve more intensive
physiotherapy, increased use of walking aids or splinting or some discreet
changes to the daily routine to incorporate greater involvement of the treated
muscles. Sometimes BTA may be used in conjunction with casting to maximise
muscle stretch.
A follow-up appointment will be made to assess how successful the
injection[s] have been and the treatment repeated as necessary. On average the
interval between injections varies from between three to six months:
re-injection will usually be recommended when muscle tone begins to interfere
with function rather than when it returns to pre-injection levels. There is no
absolute limit to the number of re-injections.
Side-effects
In the main, reported side-effects are mild and short-lived.
These include:
·
Post-injection pain requiring simple analgesia
·
Increased frequency of falls within first two 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/irritability
·
Fatigue
·
Anaphylaxis [severe allergic reaction], but this is
rare
No cases of generalised botulism have been recorded. On occasions
a reduced response has been reported to follow-on injections. As yet, no
research is available on the possibility of adverse long-term side- effects from
this treatment.
Access to BTA treatment
Although this treatment is now becoming more common, not all NHS
Trusts will fund BTA. As with all medical treatments, referral should be made
via your GP or consultant.
Conclusion
BTA injections are not suitable for all people with cerebral
palsy and patient selection is very important. For this reason, Scope recommends
that prospective patients ensure that the medical team involved has considerable
experience, both in the management of cerebral palsy and in the administering of
BTA. It is also important to have clear, realistic expectations as to what the
end results of the treatment are likely to be. Any follow-on or associated
interventions, such as physiotherapy, splinting or casting should be discussed
fully with the medical team involved.
At the time of writing there exists a considerable body of
medical research that shows BTA to be a safe and effective treatment for
spasticity in selected patients. While reported side-effects appear to be mild
and short-lived, it will be some time yet before evidence relating to long-term
use of BTA for children with cerebral palsy will be available.
As with any other therapy or treatment, we advise people with
cerebral palsy, their carers or parents to consult their GP, consultant or
health professional before starting or paying for any treatment.
Due to the individual nature of cerebral palsy, some children
will benefit from specific treatments and therapies, others will not. Assessment
of your child's individual needs if very important.
This factsheet is for information
purposes only and is not intended to be a recommendation.
For more information on Botulinum Toxin A, see
SCOPE
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