Writer's Cramp May Be Tied to Brain Abnormalities

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But there are effective treatments. They include injections of Botox, or Botulinum toxin, a protein complex produced by the bacterium Clostridium botulinum that contains the same toxin that causes food poisoning. Sterile, purified botulin toxin in small doses blocks the release of acetylcholine, a chemical produced by nerve cells that signals muscles to contract.

For the new study, published in the July 24 issue of Neurology, the researchers produced brain images of 30 people who had had writer's cramp for an average of seven years. The images were then compared with brain images of healthy people.

The participants with writer's cramp had less grey matter in three areas of the brain: the cerebellum, the thalamus and the sensorimotor cortex -- areas that control the affected hand.

The researchers now face a chicken-and-egg situation, because it's not clear whether the abnormalities are a cause or effect of writer's cramp.

According to Swift, the work also needs to be confirmed by independent researchers.

The study's author agreed that more research is needed.

"It is reassuring to know that physicians and researchers can identify the brain abnormalities underlying the trouble, even though yet there is no therapeutic consequences," said Dr. Stephane Lehericy, senior author of the study and head of the Center for Neuroimaging Research at Groupe Hospitalier Pitie-Salpetriere in Paris, France.

"Our findings show that several brain structures are abnormal in writer's cramp, including the cerebellum, suggesting that the cerebellum plays a role in the disease," Lehericy said. "The role of this structure in the disease will probably be investigated in more detail in animal models (some animal models have abnormalities in the cerebellum) and also in humans. Moreover, cerebellum is involved in motor control and scaling of fine movements and this may influence the way rehabilitation will be performed," he said.

More information

The Dystonia Society has more on writer's cramp.