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.

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. 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. 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. 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. 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.