Also, synchronous afferent stimulation of peripheral muscles induces organizational changes in motor representations, characterized both by an increase in map size of stimulated muscles and a reduction in map separation, as assessed using transcranial magnetic stimulation.The cross-connectivity between areas that are normally segregated in the sensory cortex may prevent normal sensorimotor feedback and so contribute to the observed co-contraction of antagonist muscle groups, and inappropriately timed and sequenced movements that underlie the symptoms of focal dystonia. It is hypothesized that a deficit in inhibition caused by a genetically mediated loss of inhibitory interneurons may be the underlying cause of the deficits observed in dystonia.While usually painless, in some instances the sustained contraction and abnormal posturing in dystonia cause pain. Focal dystonia most typically affects people who rely on fine motor skills—musicians, writers, surgeons, etc. It is thought that the excessive motor training those skills require may contribute to the development of dystonia as their cortical maps become enlarged and begin to overlap. Focal dystonia is generally "task-specific," meaning that it is only problematic during certain activities. Diagnosis
The diagnosis of focal dystonia is highly dependent on the history of the patient, as physical exam is typically normal, and ruling out other causes of movement disorder. The main types of are blepharospasm, oromandibular dystonia, spasmodic dysphonia, spasmodic torticollis, and limb dystonia, all affecting a different region of the body. Labs and imaging may be ordered as workup to evaluate for other causes of dystonia.
David Leisner, classical guitarist, has recovered the full use of his hand after a decade of disability. Billy McLaughlin, guitarist, switched to playing left-handed when affected by dystonia. Christian Münzner, lead guitarist of progressive extreme metal band Obscura
Apostolos Paraskevas, Greek-American classical guitarist-composer, was struck by focal dystonia to his right hand in 2009. He fully recovered in 2013. Charlie Parr, American country blues musician from Minnesota
Alex Webster, bassist
Victor Wooten, bassist, has it on both hands

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