A radical treatment could halt the condition in at least some of the people suffering from it, writes Dick Ahlstrom, Science Editor.
It is the simplest aspects of life that seem most precious when a disease takes them away. So it was for a long-term Parkinson's disease patient who almost magically had his life restored after receiving a radical new treatment. When Dr Brendan Colgan, from Rathfarnham in Dublin, travelled to France three months ago, he was ferried into surgery in a wheelchair. After treatment he was able to walk back to his hospital bed, eat lunch, then enjoy a long walk with his wife, another simple pleasure Colgan feared he had lost. "I can bring my children to school now, participate in their birthdays and help them with their homework," he says. "I always liked to cook Sunday dinner, peeling spuds, small simple things, doing the garden. It is a whole new world out there."
Colgan's surgery, known as deep brain stimulation, was carried out by the medical research group in Grenoble that developed the treatment. It involves inserting metal probes deep into the brain to pass a weak electric current through tissues associated with Parkinson's disease. Pulses of electricity block the aberrant messages from the brain that cause a range of symptoms, including tremors and muscle stiffness.
Colgan couldn't have the surgery here, as it isn't available. This may soon change, however, as a result of an application for funding that Beaumont Hospital in Dublin intends to make to the Department of Health and Children. "Beaumont has looked at the new treatment and is interested in introducing it," says a hospital spokesman. Beaumont already has much of the equipment for the procedure, but it lacks the money to train a surgeon, buy the probe-positioning software or install the stimulation device in patients.
The cost of treating someone with Parkinson's using the deep brain stimulation system is likely to be about €30,000 a patient - surprisingly, much cheaper than the medication required by many people with Parkinson's. Colgan's drug costs had reached €161,000 a year before his surgery. The deep brain stimulation, including travel, cost about €40,000, and now he only occasionally needs to take medication, so the treatment will have paid for itself in three months.
These are only numbers, however, when compared with the change in his quality of life. "My voice was about gone to nothing and I had all the classical features of severe Parkinson's. My quality of life was desperate and my family's quality of life was desperate," he says.
"I was taking very high doses of apomorphine [an anti-Parkinson's drug\] every one to two hours," as well as levodopa and other drugs, says Colgan. "The dose requirement was increasing, but the control of symptoms was decreasing. For the last two to three years I was going rapidly downhill."
His first symptom, unexplained tiredness, arrived more than 10 years ago, but the diagnosis when it eventually came was a shock. As a doctor he knew the disease usually didn't arise until a person passed 60, but he was only in his 40s, with three young children (now 16, 13 and 12). He also knew the uncompromisingly negative long-term prognosis for the disease.
He was aware of a number of surgical procedures involving the destruction of brain cells, but while he was considering what to do, "deep brain stimulation was coming into the picture", says Colgan.
"It was last December that Donal Costigan [his doctor at Mater Misericordiae University Hospital, in Dublin\] discussed the pros and cons of going for it. Donal said I was in such rag order he suggested I go for it."
Colgan travelled to Grenoble in March for an initial assessment, a doctor's visit that cost just €34. Having been found to be a highly suitable candidate, he was admitted for surgery on September 11th last year, with the operation coming on September 23rd.
It was done under local anaesthetic - brain tissue has no pain sensors - and lasted 29 hours.
It took that long because Pierre Pollak, the neurologist involved, likes to chat with his patients as he fine-tunes the probes. He varies the electricity levels, checking with the patient to gauge the physical response and the benefit delivered. It allows him to "dial up" limb movement, reduce tremors and return normal speech - as well as to avoid producing any new symptoms.
"It was the longest day of my life but the best day of my life," Colgan says. He describes his condition now as "magnificent", and as he walks around Dublin he surprises many friends who had got used to seeing him in a wheelchair. He quotes his local priest, who said: "I never thought I would see a miracle walk in."
Deep brain stimulation can transform the lives of some people with Parkinson's disease, but Colgan warns that many others are unsuitable candidates for the treatment.
"There are probably 7,000 to 8,000 Parkinson's patients here," he says. "I think that there are probably 100 to 300 patients who could benefit from this per year."
Colgan is now back to work part time as a GP. He also plans to make up for lost walking time with an ambitious fund-raising attack on the highest mountain in the Alps, something he promised both to himself and to Pollak.
"I promised I would climb Mont Blanc, and I hope to undertake that next summer," he says. "I will be fit enough to do it - and the proceeds will go to the Parkinson's Association of Ireland."Deep brain stimulation is a radical treatment for Parkinson's disease developed 10 years ago by a medical research group in the French city of Grenoble. Approved by the powerful US Food and Drug Administration only about two years ago, it can profoundly reduce tremors and other symptoms more cheaply than drug therapy.
Parkinson's is an incurable progressive disease in which patients gradually lose control of their movement. Muscles become stiff and severe tremors are common, with a slow but relentless loss of quality of life. Up to 7,000 people in the Republic have the condition. Elsewhere, well-known sufferers include the Pope, Muhammad Ali and Michael J. Fox.
The disease arises due to the loss of brain cells that produce an essential brain-signalling chemical called dopamine. The "gold standard" treatment uses levodopa, a drug that replaces missing dopamine, but long-term use can produce side effects.
Parkinson's physical symptoms are thought to arise due to the overactivity of a tiny part of the brain called the subthalamic nucleus, just below the thalamus. The research group found that electrical stimulation of the subthalamic nucleus blocked its over- activity, causing symptoms to subside.
The new treatment involves inserting two metal probes deep into the brain, each of which carries four separate electrodes. These are connected to a power pack that can be implanted under the skin. The electrodes deliver pulses of very low-power electricity, blocking disruptive signals from the subthalamic nucleus.
A five-year follow-up published last month in the New England Journal of Medicine concluded that it delivered "marked improvements" to motor function without medication.