An invasive back treatment left Diane Mahood suffering from a little-known but disabling condition.
Twenty-four years ago I had surgery for a slipped disc which had been causing problems. For a while the backache disappeared but gradually returned after I had children. Five years later I had a myelogram, an X-ray of the spinal cord in which dye is injected into the spinal column to show up soft tissue. Nothing was found, but after this procedure my back got progressively worse. Later, I had exploratory surgery on the spine: the surgeon said he found "scarring".

Over the following years my back gradually became more painful but no one seemed able to explain why. I underwent moretreatment, including an epidural and steroid injection.

Finally, 12 years ago, a friendly professor at a pain clinic explained to me what was wrong. He said I had arachnoiditis - inflammation and scarring of the arachnoid membrane that covers and protects the spinal cord.

The membrane is normally like filigree, resembling a spider's web (hence the name) but the scarring makes it look like congealed strands of spaghetti, and squashes the spinal cord and nerve roots, causing permanent pain and sometimes spastic paralysis. The disease can also result in headaches, epilepsy and blindness. It had been caused by the invasive procedures I had undergone - yet I had never once been warned of this horrific side effect.

At 47, I am on morphine for the excruciating pain and am increasingly disabled. I cannot sit for long as any weight on the spine makes the pain worse; neither can I walk far. Sometimes I lose all feeling from the waist down. My bladder has also been affected by nerve damage: sometimes I cannot pass water, sometimes I have to have a catheter. I have been told the condition is inoperable, incurable and probably going to get worse. My husband, a coastguard working 12-hour shifts, is also my carer.

Although arachnoiditis can be caused by disorders such as meningitis, most cases are now thought by specialists to be linked to spinal procedures such as myelography, epidural steroid injections and sometimes back surgery. US researchers think these procedures may trigger chemical changes in some patients which prevent healing. Because the condition so often goes undiagnosed it is difficult to estimate the number of sufferers, although one specialist has put the number at close to a million worldwide.

In the past, oil-based dyes were used for myelograms but these were banned in Britain in 1978: the US and Scandinavia banned their use in the Forties. A court case against Glaxo, manufacturer of the dye, by 432 sufferers ended in an out-of-court settlement last year without Glaxo admitting liability. Some arachnoiditis sufferers are currently suing their health authorities for negligence in the way the dye was used. At the moment, water-based dyes are used in myelography, although US research has found they are also associated with the disease and some doctors believe that any chemical injected into the spine may act as an irritant.

Too few doctors take arachnoiditis seriously: they are all too ready to pass off the symptoms as simple backache. I know of arachnoiditis patients who have been admitted into psychiatric wards because their doctor had thought the problem was all in the head.

Getting disability benefits is a battle: most sufferers just have to hope that an understanding doctor, who has actually heard of arachnoiditis, will examine them, but too often ignorance is the name of the game. On application forms for Disability Living Allowance the condition is described as "chronic backache". Yet this is a "backache" which can stop the inner organs from functioning correctly, which can cause blindness and which can stop you getting to the bathroom on time.

Although they are less widespread than in the past, invasive spinal procedures are still carried out without patients being given warning of their possible side effects. What can you do if you need tests done on your spine? Insist on a scan, whether it is a CT scan or a more detailed MRI (Magnetic Resonance Imaging) scan, both of which are readily available. They give the surgeon deeper detail of all soft tissues, more than any of the invasive procedures mentioned above, without any risk to the patient.

For more information send an SAE to the Arachnoiditis Trust, PO Box 27, Stoneycroft, Liverpool L13 5RS.