Yet that is exactly what surgeons in the United States are doing in a bid to find a cure for Parkinson's disease - drilling two holes on either side of the patients' skulls and inserting foetal cells to promote the growth of new brain cells.

In an article in the New England Journal of Medicine, the team of seven researchers outlined the use of placebo surgery in their trials - surgery that has been slammed by the UK's medical community.

A control group of patients underwent the hole-drilling alone to test whether the surgical procedure made them believe they had beaten the disease - a similar effect to patients getting better after taking sugar pills they think are powerful drugs.

A team of US surgeons researching Parkinson's Disease drilled holes in patients' heads

Reports on the success of the procedure are mixed - some studies show there appears to be some benefits for Parkinson's suffers, while others dispute the team's findings.

Drilling a hole in the skull down to the brain tissue - trepanation - has not been widely embraced by the medical community.

All but a few surgeons in Mexico refuse to carry out the procedure.

There is a risk of brain haemorrhage, meningitis, or brain abscess due to infection. And there is no scientific evidence that it works.

Unsafe procedure

Professor Barry Jackson, of the Royal College of Surgeons, is appalled that the researchers are drilling holes in patients' heads.

"The vast majority of surgeons in this country would agree with me, that the risks to a patient of having a hole bored in their skull under a general anaesthetic - twice, one on one side, and one on the other side of the skull - really goes beyond what is allowable under research protocols today."

Dr Michael Wilks, chairman of the British Medical Association's ethics committee, is concerned that the placebo group were offered the foetal cell implanation free of charge at the end of the trial.

"That suggests that the researchers always knew that the implanation was superiour to the placebo surgery - so why do the placebo in the first place?"

What is trepanation?

Shut out of mainstream medicine and regarded as drug-fuelled New Age quacks, trepanation advocates - most of whom have drilled through their own skull - spread the word via the Internet.

They claim that freeing the brain of the all-encompassing barrier of the skull increases blood flow, improving concentration and bringing about a state likened to being "permanently high".

Trepan.com tells the history of trepanation

The website of the International Trepanation Advocacy Group - nominated as weirdest site in the annual Webby awards - includes the history of trepanning, advice on how to ask your doctor to drill a hole in your head (tragically unavailable because it is still under construction), and the Trepan Mall, in which cybersurfers can order books, T-shirts and the director's cut of the documentary A Hole In The Head.

Self-trepanned Peter Halvorson, who runs a diamond-setting business in Pennsylvania, set the website up two years ago.

"Trepanning is one of the earliest surgical operations known, and there is ample evidence to show that it was practised by primitive man in prehistoric times," he says on the website.

"The scraping of a hole in the cranium at that remote period was probably carried out with the object of relieving pains in the head or epilepsy, and at the same time providing an exit for the disease demon or evil spirit and to allow its escape."

Pictured is the skull of a 50-year-old man, thought to have been trepanned in 5100 BC. He had two partially healed holes in his head, suggesting he survived for several years after they were gouged out.

Until the 16th century, a similar procedure was carried out on the insane, to allow light into the brain and evil spirits to escape.

NHS-funded blowholes

Amanda Feilding, of Oxfordshire, who set up the Trepanation Trust in 1998 to campaign for scientific research into the procedure, is profiled on the site.

Self-trepanned with an electric drill, Ms Feilding stood in the 1979 and 1983 general elections advocating NHS-funded trepanation.

She received 49 and 139 votes respectively.

Hugo Bart Huges advocated trepanation in the 1960s

Hugo Bart Huges, a medical student from the Netherlands, introduced her to trepanation in the 1960s.

He had hit upon the idea while trying to come up with a way to prevent hallucinating when taking LSD.

He claimed that increasing the volume of blood in the brain - whether by standing on your head or taking a drill bit to your cranium - expanded consciousness.

Because young children's skulls had yet to harden, he thought they were blessed with greater energy and creativity than adults because their brain had space to pulsate as blood was pumped up from the heart.

Therefore, he theorised, a blowhole in an adult's skull would act like a pressure mechanism in which cerebral spinal fluid would be shunted out and more blood pumped in.