Media playback is unsupported on your device Media caption Sound waves operate on brain to repair man's tremor

Doctors in London have used sound waves to successfully operate deep inside the brain.

They treated a man from Cornwall who suffered from uncontrollable tremors in his right hand.

Selwyn Lucas, who is 52, can now hold his hand steady and said he felt "fantastic".

The team at St Mary's hospital used MRI guided focused ultrasound to destroy tissue causing mistimed electrical signals to be sent to muscles.

The BBC was given exclusive access to the treatment, which was performed in the imaging department rather than operating theatres, and did not involve surgeons.

Dr Peter Bain, consultant neurologist with Imperial College Healthcare NHS Trust, told me ultrasound brain surgery had an "enormous future" and could be used to treat other movement disorders such as Parkinson's disease.

Prof Wladyslaw Gedroyc, consultant radiologist at Imperial College Healthcare NHS Trust, said: "This is a game changer for patients with these movement disorders because we can cure them with a treatment which is completely non-invasive and we don't have to give unpleasant drugs."

Around one million people in the UK suffer from tremors - uncontrollable shaking of the hands, head or body.

It is a neurological condition usually caused by faulty circuits in the thalamus, a small area at the base of the brain.

It can sometimes be treated with drugs, which can have serious side effects, or with brain surgery, but this carries the risk of stroke and infection.

I first met Selwyn Lucas a week before his surgery, at Charing Cross hospital, when he attended his final assessment.

His right hand does not shake when it is at rest, but begins to vibrate uncontrollably when he goes to use it.

Each time he tried to do something with his hand it began to shake.

He was asked to draw a spiral shape and as soon as he put pen to paper his right hand began juddering.

This is typical of the condition known as "essential tremor", which affects one in 25 adults over the age of 40.

It contrasts with the tremors in Parkinson's disease, which occur when the patient's hand or other affected limb is at rest.

Mr Lucas, who is a painter and decorator, said the tremors began nearly 20 years ago and have got progressively worse.

"I have to use my left hand when painting to do all the edging, otherwise I would end up with wiggly lines between the walls and ceiling," he said.

"My concern is that it might spread to my left hand."

Close shave

On the morning of surgery, Mr Lucas arrived at St Mary's Hospital with a shaved head - necessary because hair could trap heat from the ultrasound and cause a burn.

After another shave, to remove any remaining follicles, a metal frame was bolted to his scalp to ensure that his head remained completely still during treatment.

He was then led to the MRI suite and his head inserted in the ultrasound machine.

How it works

Media playback is unsupported on your device Media caption How the ultrasound machine works

The machine uses high-intensity focused ultrasound to destroy the faulty electrical circuits in the brain which are causing the tremor.

Ultrasound is sound waves which are at higher frequencies than those audible to humans.

At low intensity, ultrasound is harmless, and widely used for health imaging, such as in pregnancy.

By contrast, the machine at St Mary's uses 1,024 high-intensity, focused ultrasound beams which target a precise point in the thalamus.

But how can sound waves perform surgery?

At high intensity, ultrasound waves cause molecules to vibrate, which generates energy and heat.

When the beams are focused on a single point, this can ablate, or destroy, tissue by heating cells to near 60C until they die.

Prof Gedroyc said: "One simple way to imagine this is to think of how a magnifying glass can be used to focus the sun's rays on a single point and burn a hole."

Remarkable result

The procedure lasted around five hours and involved more than a dozen "sonications", each lasting several seconds.

These were calculated using the real-time brain scans of the MRI machine, which showed where the temperature hot spot was being targeted.

After each sonication, the patient was asked to raise his right hand to check the tremor.

His neurologist, Dr Bain, also checked that his speech was not slurred, which would be a warning sign that the ultrasound was targeting the wrong part of the brain.

Dr Bain said there was little margin for error: "It's like asking the RAF to blow up 10 Downing Street but leave 11 Downing Street in perfect shape - we have to be very careful because parts of the brain with vital functions are just nearby."

The result was remarkable - the tremors in Mr Lucas's right hand completely disappeared, and doctors hope this will be permanent.

Image caption Steady hand for the first time in years

Mr Lucas was also able to write his name for the first time in years.

His ability to draw a spiral also showed dramatic improvement.

'It's brilliant'

Mr Lucas emerged from the scanner with no apparent ill-effects and a beaming smile.

He told me: "I'm absolutely made-up. It's brilliant. I'm looking forward to being able to carry a tray of drinks without worrying about dropping them."

His wife, Marianna, said she was thrilled for him.

"Selwyn used to get very frustrated and his condition did get him down from time to time, so this is wonderful."

The ultrasound machine, Exablate Neuro, is produced by Insightec, a technology firm based in Israel.

There are 24 of the machines worldwide, in the United States, Japan, Canada, South Korea, Spain, Italy, Israel, Switzerland, but this is the first in the UK.

The £1.1m cost was funded entirely by the Imperial College Healthcare Charity.

Media playback is unsupported on your device Media caption How sound waves operate on the brain

Focused ultrasound was approved for essential tremor by the Food and Drug Administration in the United States earlier this year. It also has a CE mark in Europe.

The treatment at St Mary's is part of an international trial, which is now full, to further assess its safety and effectiveness.

So far, four patients have been treated and there are about 15 more who have been identified for the trial.

The results will form a crucial part of evidence to be submitted to NICE and NHS England on whether the procedure should be made widely available.

The cost of the treatment is £12,500 compared with £35,000 for brain surgery.

Dr Bain said deep brain stimulation, which involves drilling through the skull and implanting an electrode in the thalamus, carried a one-in-100 risk of stroke and one-in-1,000 risk of death. "The balance of gain to risk is hugely altered by this treatment, and the patient can go home the same day," he said.

Next year the same team at Imperial College Healthcare NHS Trust will take part in an international trial to treat motion disorders in Parkinson's disease.

A different part of the brain will be targeted - one which is responsible for causing use bradykinesia, slowness of movement, which is a feature of Parkinson's.

Time-saving benefit

Dr Bain said it could also be used to correct tremors from other neurological disorders, such as multiple sclerosis, and might have wider applications.

"We could also potentially use it for activating chemicals inside the body which remain inert until you focus sound waves on them, and this could be invaluable in treating brain tumours."

If the procedure is approved it will require a significant reorganisation in the way hospitals treat patients with serious tremors.

It would free up time in operating theatres, which would be a major benefit.

But the MRI unit at St Mary's already runs at full capacity, so services would need to be reorganised in order to enable the ultrasound machine to get fully used.

It can take years for medical advances to be picked up by the NHS.

The radiology and neurology teams at Imperial College are hoping this is one innovation that will be rapidly adopted.

Follow Fergus on Twitter