Scientists have found strong evidence that botox injections can help children with cerebral palsy.
Botox is used to smooth out wrinkles
Botox is more commonly used by cosmetic surgeons to smooth out wrinkles.
The botulinum toxin can be deadly, paralysing muscles needed for breathing, but only very small doses are given in medical or cosmetic treatments.
US researchers have shown children who received the treatment demonstrated a significant improvement in their symptoms.
In the UK, experts have long called for the treatment using the botulinum toxin to be universally available.
They welcomed the new findings, and said they provided even more support for their call.
Some were able to hold a pen and write for the first time, or use a computer touch screen to communicate
Dr Marc DiFazio, Walter Reed Army Medical Center
It is estimated one in 400 people in the UK have cerebral palsy, where a part of the brain, usually the part that controls the muscles and movement, is affected.
The Botulism toxin is thought to relieve cerebral palsy symptoms by reducing tightness in muscles, which allows better control of movement, and increasing the stretch of muscles, reducing the risk of permanent muscle contractions.
It works by blocking the signal that nerves are trying to pass to the muscle.
US researchers studied 250 children aged one to 16, who were given botulinum toxin to treat cerebral palsy.
Two hundred had repeated treatments and just under 150 were followed, on average, for more than two years.
Researchers looked at evidence from videos of the children, assessments by doctors and reports from families.
They found 86% of all the children studied demonstrated noticeable improvements in symptoms of muscle spasticity after the injections.
Of those who were followed for more than two years, more than 80% continued to show improvement over their initial symptoms before beginning treatment.
The benefits were often seen for more than four months after an injection.
Improvements seen ranged from making voluntary movements for the first time to improved stance and walking.
'Safe and effective'
Dr Marc DiFazio, a neurologist at Walter Reed Army Medical Center in Washington DC, who led the research, said: "It's very exciting to see the progress these kids can make.
"Some of them are able to do more for themselves, like feeding themselves or turning on a faucet (tap).
"Some were able to hold a pen and write for the first time, or use a computer touch screen to communicate.
"These may not seem like big changes, but they can be life-changing for these kids and their families."
He added: "These results confirm that botulinum toxin in appropriate dosing is safe and effective for long-term use for children with cerebral palsy."
He said only a few children had mild side effects after being given the treatment, such as a flu-like reaction and mild weakness in the legs.
A spokesman for the charity Scope told BBC News Online: "Botulism toxin treatment does have benefits for some children, but it may not be the solution for all.
"This new research reinforces what we know already. It is obviously encouraging."
But he said access to the treatment depended on where people lived, whether there was local support for it and if there were the resources to fund it.
"It is still a postcode lottery," he said.
The research was presented to the annual meeting of the American Academy of Neurology.