Easing musicians' spasms

Vibrations that alter the brain region responsible for controlling the hands could be used to treat musician's dystonia, a movement disorder in which the muscles contract involuntarily, UK researchers suggest.

Musician's dystonia occurs in musicians who have practiced specific complicated movements for years. The muscle spasms are usually painless and generally occur only when playing the instrument.

Dr Karin Rosenkranz of the Royal College of Music in London and colleagues previously demonstrated that musicians with hand dystonia have a response to vibratory stimulation that is less differentiated than that seen in healthy non-musicians. Vibrating a single muscle increases the brain's messages to all of the muscles of the hand. In musicians without dystonia, the brain's response lies between that of healthy non-musicians and musicians with dystonia.

How the study was conducted
To investigate whether it might be possible to train the brain to restore a more normal response in musician's dystonia, the researchers applied low-amplitude vibration to the hand muscles in 24 people: 6 who had musician's dystonia; 6 professional musicians with no dystonia; 6 healthy non-musicians; and 6 people with writer's cramp, which is another type of dystonia that occurs in people while they write.

When the musicians with dystonia paid attention to shifts in vibration frequency, their brain activation became closer to that of the healthy musicians. But people with writer's cramp who did the same exercise showed no changes in their sensorimotor organization.

The findings provide evidence that musician's dystonia and writer's cramp stem from different causes, the researchers suggest. Musicians' dystonia may occur when sensation causes excessive movement, they explain, while writer's cramp may be due to a blunting of movement in response to sensory signals.

Rosenkranz and her team plan to conduct further investigations to determine if using this type of brain training for a more extended period of time can help improve hand movement in people with dystonia. "Our hope is that stimulation can retrain how the brain responds," she said in a statement.

SOURCE: Neurology, online December 26, 2007. – (Reuters Health)

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