HELEN Cadden's life changed in an instant. She was a student nurse, helping a colleague to assist a 22-stone patient. Suddenly the patient's knees buckled, the other nurse let go and Ms Cadden bore all the woman's weight.

Although she did not know it at the time, the accident caused one of her spinal discs to rupture into seven pieces. The extent of her injury went undetected for months, the debris pressed on to her spinal cord and the damage could not be repaired.

Sixteen years and three operations later, Ms Cadden, 37, says: "I have no recollection of what it is like not to live with pain. It dominates everything you do. The pain relief literally just takes the edge off it."

She says her back hurts constantly and, when she least expects it, searing agony will shoot through her spine into her feet. She compares it to being filleted.

Now, under the care of Glasgow pain clinic, she can, with determination, manage her life and her injury - but she spent eight years writhing between different parts of the NHS before she reached this service.

There was a time when she was trapped at home on the edge of despair and she fears there are still people hidden today, who are enduring the same nightmare. With an official report, just published in Scotland, warning chronic pain services are patchy and inadequate despite repeated attempts to improve them, it seems unfortunately likely that this is the case.

People with chronic pain who do not fall into neat disease categories can become what doctors sometimes call "heart sink" patients because they do not know how to help them.

Many have suffered some form of damage to the nervous system. There are people with sciatica, which is caused by compression or irritation of the sciatic nerve, people with back injuries such as Ms Cadden and even amputees who experience phantom limb pain around the missing joint.

Dr Pete Mackenzie, a consultant in anaesthesia and pain management for Glasgow chronic pain service, says: "Once you have suffered damage to the nervous system, chronic pain can remain persistent for a lifetime."

Yet the condition is not recognised in its own right.

Ms Cadden says when her pain did not stop, she was sent to specialists in other medical fields who already had busy clinics and did not know how to help.

The NHS is brilliant at dealing with emergencies, she says, but when problems will not go away people are made to feel a nuisance.

The new report, pulled together by standards watchdog NHS Quality Improvement Scotland, similarly describes people being "bounced from pillar to post".

Sufferers interviewed for the study recalled encounters with GPs who did not believe in chronic pain or did not know it was possible to get specialist treatment.

But there are, at least in some parts of Scotland, dedicated clinics where patients can have access to radical forms of pain relief such as implanted morphine pumps and psychological support to help them cope.

Ms Cadden was finally referred to Glasgow chronic pain service in 1999 when she had to give up her regular pain killers because they were harming her liver.

"Eight months' wait, it was, for an emergency appointment," she remembers. "Those were the worst eight months of my life."

When she reached the clinic, however, she finally turned a corner. To this day, she calls the consultant she saw her "guardian angel".

"He explained why I was in so much pain," she says. "No-one had explained to me why my body was still telling me my back was broken."

The way she describes it, kinks have been left in her spinal cord which repeatedly alert her brain that something is very wrong with her lower body.

Just understanding this, she says, made a massive difference, along with the morphine-based drugs the consultant prescribed for her.

"It was like the walls that were closing in on me started very slowly to move back a bit," she explains.

Although repeated attempts to return to work have left her unwell, Ms Cadden has been able to find some quality of life.

She is a volunteer who campaigns to prevent other patients waiting eight years for pain clinic services - a challenge which, given that three reports in a decade have made little difference - has its frustrations. Even the clinics that do exist are struggling.

Dr Mackenzie says: "There is a fundamental difference between Scottish pain services, even those known to be good, and services in other parts of the world.

"We still lack resources to be able to work effectively as multi- disciplinary teams."

For example, at the Southern General pain clinic, he says, the various professionals would like to assess patients as a group, but because their psychologist is paid to work only limited hours they can do this only every two months. The wait to see the clinic psychologist, he says, can stretch to a year.

However, Dr Mackenzie finds his work satisfying because he can help people who feel they have been hammering brick walls to no avail.

With the fifth report on chronic pain services since 1994 now in the public domain, he and his patients can only hope this frustrating wait for change is also at and end.