A North-East town has the world's highest concentration of a little-known but fairly common disease.

Dystonia is a neurological condition - caused by a chemical imbalance - that causes involuntary body movements, including sometimes painful muscle spasms, and often abnormal postures, including a twisted neck.

Epidemiologist Dr Anthony Butler said: "In this country, Darlington, which has a population of just over 100,000 people, has the highest concentration of dystonia anywhere in the world, with 53 sufferers within the postal codes DL1, DL2, and DL3.

"This means that dystonia affects up to one in 2,000 people throughout the area."

Dr Butler wrote to every household in Darlington as part of a study into the extent of the disease, the first comprehensive study of its kind in the world.

"It's not that Darlington has a higher incidence of the disease, it's just that it has been detected," he said.

When the study started, there were only 147 people known to have dystonia in the North-East, but that figure has risen to 1,340 and is continuing to rise at a rate of two new sufferers a week.

Dystonia is the next most common movement disorder after Parkinson's disease.

The disease can lead to sufferers being unable to work.

However, unlike most other movement disorders, such as Parkinson's, multiple sclerosis and motor neurone disease, it is not fatal.

Dr Butler said the disease was often not diagnosed because sufferers were referred to consultants who specialised in conditions of the party of the body where the disease appeared.

Work, including gene research, is under way to find a cure although a treatment, that can provide temporary respite, is available through botulinum toxin - the most prevalent poison known to man, and better known as the Botox beauty treatment.

Today is European Dystonia Day and the North-East-based group Adder (Action for Dystonia, Diagnosis, Education and Research) is taking part to raise awareness.

For further information about dystonia, call Dr Butler on (01325) 332723.