Some patients who suffer a burst blood vessel in their head could be suffering from a tissue disorder which could be identified with a skin test, say doctors.

Aneurysms are areas of blood vessel which have become weakened and bulge outwards.

Occasionally, the pressure of the blood flow can burst the vessel, often causing dangerous internal bleeding. If it happens inside the skull - an intracranial aneurysm - this is a type of stroke that can cause brain damage or even death.

It is still hotly debated whether or not a traditional surgical approach should be used when an aneurysm is found

Dr Andy Molyneux

Experts at the University of Heidelberg in Germany say they are a long way from a reliable screening test for the condition, but feel at least some people are vulnerable to aneurysm because of a disorder of "connective tissue".

This is found in the joints and skin as well as the walls of blood vessels, and helps keep all three flexible and strong.

Aneurysm may occur, say the researchers, when the connective tissue in the artery wall somehow loses its strength and stretches outwards.

To test the theory, they looked at skin samples from 21 patients who had already suffered an intracranial aneurysm - most had suffered bleeding on the brain at some point.

Genetic weakness

They found that a third of them did have defects in the structure of the connective tissue in the skin.

A small sample of patients with no aneurysms did not have any such problems - and none were found in a database of 3,000 skin tissue biopsies taken for other medical problems.

Dr Caspar Grond-Ginsbach, who led the study, said: "Our findings suggest that people with multiple aneurysms have a predisposing connective tissue disorder, leading to a weakness of the artery wall.

"This disorder can be diagnosed by a skin test."

Dr Andy Molyneux, a consultant in neuroradiology at the Oxford Radcliffe Hospital, said that it was an interesting finding, but unlikely to change the way doctors looked for aneurysms, or treated them once they found them.

He said: "There is a small group of patients who have an abnormality of their connective tissue, and are at a higher risk of aneurysms.

"However, it is already a relatively uncommon disorder, so screening for it is not necessarily going to be worthwhile.

"It is still hotly debated whether or not a traditional surgical approach should be used when an aneurysm is found. Many small aneurysms will never cause any problems."