A study at University College London suggests that RSI symptoms may be caused by damage to nerves in the hand and arm.

In the past it has been thought to be a muscular problem caused by fatigue.

Jane Greening: patients have clear signs of sensory loss

Underlying cause

The research could also lead to a simple test to show if people are developing RSI symptoms before they even feel them.

Jane Greening, the report's co-author, said if muscles are used in a prolonged way, they become sore. But the research suggests the underlying cause for RSI symptoms is the nerves themselves.

Upper limb disorders

The term RSI is often used to describe work-related upper limb disorders. Its exact causes remain unknown, and the lack of objective symptoms has led many doctors and lawyers to claim it is all in patients' minds.

Dr Bruce Lynn discovered strong indications that sufferers have a neural problem

But co-author Dr Bruce Lynn says the new study should make those people take a second look.

"There's plenty of evidence that RSI is not all in the mind, but there have been employers, lawyers and doctors who have taken that view," he said.

Tim Gopsill, spokesman for the National Union of Journalists, which picked up the bill after a union member lost a high-profile RSI case against Reuters Ltd in 1993, welcomed the study.

'Better late than never'

"It's better late than never," Mr Gopsill said. "We've known all along that RSI wasn't all in the mind, but the legal and medical professions have taken a long time to face reality.

"Our hope now is that this report will be accepted by everybody and that doctors, lawyers and employers understand that it is a serious condition."

A vibrating probe used in the study which detects damage to nerves in the hand and arm

Low point

The result of the court case against Reuters was seen as a low point for sufferers of RSI.

Judge John Prosser, ruling against the journalist Rafiq Mughal, said that keyboard operators who gave up their jobs because of aching muscles were "eggshell personalities who need to get a grip on themselves. RSI is meaningless and has no place in the medical books".

Since then, however, there have been several compensation claims won by employees. Last year former machine operator Muriel Simpson won �186,000 against her former employer Bowater Scott.

• See Relevant Stories for tips to work out how well you are using your computer, and a personal tale of the impact RSI had on one woman.