Focal dystonia
From Wikipedia, the free encyclopedia
Focal dystonia is a neurological condition affecting a muscle or group of muscles in a part of the body causing an undesirable muscular contraction or twisting. For example, in focal hand dystonia, the fingers either curl into the palm or extend outward without control.
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[edit] Causes
The misfiring of neurons in the sensorimotor cortex, a thin layer of neural tissue covering the brain is thought to cause contractions. The sensorimotor cortex contains "maps" of the human body. Under normal conditions, discrete body parts (such as the individual fingers) occupy their own distinct areas on these sensorimotor cortex maps. However in dystonia these maps cease to be so distinct. [1]
Research showing this initially involved non-human primates that were over-trained on particular finger movements with the result that they developed focal hand dystonia. Examination of their primary somatosensory cortex showed that the representations of the fingers were grossly distorted with finger representations that were segregated in normal animals having become co-represented in the cortex of dystonic animals. Imaging studies on humans have confirmed this finding with individuals with focal hand dystonia having finger representations in their brains that are abnormal in showing fusion compared to those in normals.[2]
The lack of cross-connectivity between areas that are normally segregated in sensory cortex may prevent normal sensorimotor feedback and so contribute to co-contractions of antagonist muscle groups, and inappropriately timed and sequenced movements that underlie the symptoms of focal dystonia of the hand.
Prior to the works demonstrating sensorimotor cortical deficits, focal hand dystonia was principally treated with BoTox injections which block muscle contractions in the affected muscles. Following these works, multiple groups have now demonstrated that behavioral remediation can ameliorate many symptoms of focal hand dystonia, and restore most of the performance deficit[3].
While usually painless, there are some instances when the condition does indeed cause pain for the patient--usually through sustained contraction and abnormal posturing. Focal dystonia most typically affects those who rely on fine motor skills - musicians, writers, surgeons, etc. It is generally "task specific," meaning that it is only problematic during certain activities.
[edit] Notable cases
Musicians affected by focal dystonia include Leon Fleisher, of the Peabody Conservatory of Music, who had suffered from this affliction in his right hand, as did Alex Klein, formerly the first oboist of the Chicago Symphony, Ernestine Whitman, former member of the Atlanta Symphony and currently a professor of flute at Lawrence University, pianist and keyboard player Keith Emerson, guitarist Dominic Frasca, and the pianist Gary Graffman, who performs exclusively with his left hand. Former principal tuba of the New York Philharmonic, Warren Deck was diagnosed with focal dystonia of the upper lip in 2001, ending his playing career. In 2005, New Age acoustic guitarist Billy McLaughlin announced via his website that he is suffering from focal dystonia, which severely limits his ability to play right-handed (and as a result, he taught himself to play left-handed). Another musician to be afflicted by this condition is shred guitarist Terry Syrek, who recorded his entire album "AUM" with just two fully functioning fingers of his fret hand. A well known bass guitarist, Andy Billups, who plays with British rock act The Hamsters, has also made a partial recovery from this disorder and continued to play by using modified guitar plectrums to make up for the limited function of his right hand. Classical guitarist David Leisner has recovered the full use of his hand and has returned successfully to the concert stage and recording studio in the early 1990s after a decade of disability. British guitarist Jon Berry of Black River Forge developed the condition in his left fretting hand in 2007 and has now switched to playing almost exclusively left handed. Brazilian singer-guitarist Badi Assad was diagnosed with focal dystonia in 1999 (after having been misdiagnosed with carpal tunnel syndrome). She eventually recovered and was able to resume her career.[4] Scott Adams, the writer of the Dilbert comics, is also afflicted with focal dystonia of the hand, which impedes his artwork.[5]
[edit] Treatment
This condition is often treated with injections of botox, a commercially prepared form of botulinum toxin. Botox, however, merely targets the symptoms of the disorder and is not a cure for dystonia. Since the root of the problem is neurological, it is thought that sensorimotor retraining activities can enable the brain to "rewire" itself in a manner that can ultimately eliminate dystonic movements. The work of several doctors, most notably Nancy Byl and Joaquin Farias has shown that sensorimotor retraining activities and proprioceptive stimulation can induce neuroplasticity, making it possible to recover substantial function that was lost from Focal Dystonia. There are successful exercise therapies developed independently by Frank Wilson and Patrick O'Brien[6].
[edit] References
- ^ Byl NN, Merzenich MM, Jenkins WM. (1996). A primate genesis model of focal dystonia and repetitive strain injury: I. Learning-induced dedifferentiation of the representation of the hand in the primary somatosensory cortex in adult monkeys. Byl NN, Merzenich MM, Jenkins WM. Neurology. 47(2):508-20. PMID 8757029
- ^ Bara-Jimenez W, Catalan MJ, Hallett M, Gerloff C. Ann Neurol. (1998). Abnormal somatosensory homunculus in dystonia of the hand. 44(5):828-31. PMID 9818942
- ^ Zeuner KE, Bara-Jimenez W, Noguchi PS, Goldstein SR, Dambrosia JM, Hallett M. (2002). Sensory training for patients with focal hand dystonia. Ann Neurol. 51(5):593-8. PMID 12112105
- ^ Badi Assad's web site
- ^ Scott Adams, Drawing the Line
- ^ http://handoc.com/Documents/Acquisition_Loss_Skilled_Movement_dist.pdf
[edit] Sources
- National Geographic, May 2005: "Poison: 12 Toxic Tales", "Concerto in B for Botox and Piano"
- Rich, Robert F.; Mackin, Evelyn; Callahan, Anne; A. Lee Osterman; Terri M. Skirven; Schneider, Lawrence J. (2002). Hunter, Mackin & Callahan's Rehabilitation of the Hand and Upper Extremity (2 Volume Set). St. Louis: Mosby. pp. 2053–2075 ("Focal Hand Dystonia"). ISBN 0-323-01094-6.
- Farias Martínez J ,Sarti-Martínez MA*.Title. ["Elite musicians treated by specific fingers motion program to stimulate proprioceptive sense."][1] Spanish Society of Anatomy Congress.proceedings pag110. Publication:European Journal of Anatomy.
- Farias, Joaquin. "Rebellion of the body. Understanding musician's Focal dystonia". Galene Editions 2004.
- Farias, Joaquin. "Playing without practice. Exercises for musicians affected by Focal Dystonia". O.F.S. 2002.
- Leisner, David. "Curing Focal Dystonia or How to Play the Guitar with Large Muscles." Guitar Review 133 (2007): 10–15.
- Pascual-Leone A (2001). "The brain that plays music and is changed by it". Ann. N. Y. Acad. Sci. 930: 315–29. PMID 11458838. http://www.annalsnyas.org/cgi/pmidlookup?view=long&pmid=11458838.
- Solomon, Jason W. What Every Guitarist Should Know: A Guide to the Prevention and Rehabilitation of Focal Dystonia. Guitar Review 133 (2007): 2–9.
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