Radiologists have devised a way of doing a brain operation without resorting to the surgeon's knife, using instead just local anaesthetic and sedation. The operation works by feeding a wire up through the groin to an artery in the brain.

The operation was described at the Rontgen Congress, marking 100 years of X-rays, by Andy Adam, consultant at Guy's Hospital, London.

It treats intracerebral aneurysm, which happens when part of the artery wall gets weaker and the force of the blood pumping through it causes the vessel to balloon on one side. The high-blood pressure in the artery means that the bulge could explode, causing catastrophe in the brain.

"A surgeon would take the top of your head off like opening a breakfast egg, find the aneurysm, put a tie across and exclude it from the circulation," said John Reidy, consultant radiologist at Guy's Hospital in London, who has been working with the new technique for aneurysms elsewhere in the body.

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The new method harnesses the latest developments in radiology, which allow the operator to watch and control with great accuracy as the wire moves up through blood vessels to the brain.

The patient lies on an X-ray table and a needle is inserted into an artery in the groin. A catheter is passed through the network of vessels under X-ray control. The radiologist can watch its progress on an X-ray television.

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"It's a tiny catheter," said Dr Reidy, "When you are happy that you are in the right place you can put something into the aneurysm to block it off."

The radiologist eases some very fine platinum wire into the aneurysm: "We can see it all coil up like a ball," he said.

When the space is full the platinum is pushed from the end of the catheter: a clot forms in the aneurysm and it becomes blocked off from the main artery.

The technique, known as percutaneous transcatheter embolisation, is much lower-key than a surgical technique, which would take place in intensive care, says Dr Reidy. "The patient doesn't realise that much is going on."

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