October 2, 2017Quiz
Focal dystonia is a neurological condition, a type of dystonia, that affects a muscle or group of muscles in a specific part of the body, causing involuntary muscular contractions and abnormal postures. For example, in focal hand dystonia, the 1) ___ either curl into the palm or extend outward without control. In musicians, the condition is called musician's focal dystonia, or simply, musician's dystonia. In sports, it is commonly referred to as the yips.
Current medical science does not precisely describe the causes of dystonia. Misfiring of neurons in the sensorimotor cortex, a thin layer of neural tissue that covers the 2) ___, is thought to cause contractions. This misfiring may result from impaired inhibitory mechanisms during muscle contraction. When the brain tells a given muscle to contract, it simultaneously silences muscles that would oppose the intended movement. It appears that dystonia interferes with the brain's ability to inhibit those surrounding muscles, leading to loss of selectivity. The sensorimotor cortex is organized as discrete maps of the human body. Under normal conditions, each body part (such as individual fingers) occupies a distinct area on these cortical 3) ___. In dystonia, these maps lose their distinct borders and overlap occurs. Exploration of this initially involved over-training particular finger movements, in non-human primates, which resulted in the development of focal hand dystonia.
Examination of the primary somatosensory cortex in the trained animals showed grossly distorted representations of the maps pertaining to the fingers when compared to the untrained animals. Additionally, these maps in the dystonic animals had lost the distinct borders that were noted in the untrained animals. Imaging studies in humans with focal dystonia have confirmed this finding. 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 TMS or 4) ___ ___ ___. 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 5) ___. While usually painless, in some instances the sustained contraction and abnormal posturing in dystonia cause 6) ___. 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.
Dystonia is often treated with injections of Botox, a commercially prepared form of botulinum toxin. Botox reduces the symptoms of the disorder but it is not a cure for dystonia. Since the root of the problem is 7) ___, doctors have explored sensorimotor retraining activities to enable the brain to rewire itself and eliminate dystonic movements. The work of several doctors such as Nancy Byl and Joaquin Farias has shown that sensorimotor retraining activities and proprioceptive stimulation can induce neuroplasticity, making it possible for patients to recover substantial function that was lost to focal dystonia. Bass guitarist and instructor Scott Devine said that he wears a glove while playing bass guitar because of the condition. He finds that the glove stops the involuntary finger movements. He says it works for him but does not suggest that it may work for everyone with the condition.
Performing music at a professional level is probably one of the most complex human accomplishments. Extremely fast and complex, temporo-spatially predefined movement patterns have to be learned, memorized, and retrieved with high reliability in order to meet the expectations of listeners. Performing music requires not only the integration of multimodal sensory and motor information, and its precise monitoring via auditory and kinesthetic feedback, but also emotional communicative skills, which provide a speaking rendition of a musical masterpiece. To acquire these specialized auditory-sensory-motor and emotional 8) ___, musicians must undergo extensive training periods over many years, which start in early childhood and continue on through stages of increasing physical and strategic complexities. Performance anxiety, linked to high societal pressures such as the fear of failure and heightened self-demands, frequently accompanies these learning processes. Motor disturbances in musicians are common and include mild forms, such as temporary motor fatigue with short-term reduction of motor skills, painful overuse injuries following prolonged practice, anxiety-related motor failures during performances (choking under pressure), as well as more persistent losses of motor control, here termed dynamic stereotypes (DSs).
Musician's dystonia (MD), which is characterized by the permanent loss of control of highly skilled movements when playing a musical instrument, is the gravest manifestation of dysfunctional motor programs, frequently linked to a genetic susceptibility to develop such motor disturbances. Motor failures in musicians develop along a continuum, starting with subtle transient degradations due to fatigue, overuse, or performance stress, which transform by and by into more permanent, still fluctuating motor degradations, the DSs, until a more irreversible condition, MD manifests.
Begin slowly and increase gradually any unaccustomed use of the hands. - Michael Charness, MD (The Musician's Way, p. 237)
Violinist Peter Oundjian, guitarist Liona Boyd, pianists Leon Fleischer and Gary Graffman - all are musicians whose careers were upended by musicians dystonia (MD). Among the approximately 1% of musicians who develop MD, the effects are debilitating. Over time, usually decades, the program in the brain that they depend on to control their movements gets corrupted, and they lose command of certain task-specific actions. For instance, violinists with MD might experience curling of the left 3rd and 4th fingers when they play, but those fingers will function normally when they do other activities. Researchers also find that MD appears more often in the more intensely used hand. Hence, violinists are more likely to be affected in the left hand, pianists in the right, although any muscle group could be involved, even arm or shoulder 9) ___. Some musicians diagnosed with MD seem to develop it without any precipitating factor aside from long-term repetitive movement. For others, the condition surfaces months or years following a change of instrument or technique, subsequent to a dramatic increase in playing time, or after they begin doing a new, skillful repetitive activity. In those types of situations, the process via which a musician's brain acquires a new movement program corrupts the pre-existing one and then dystonic contractions result. On top of that, physician Raoul Tubiana reports that the musicians he diagnosed with MD displayed awkward postural and movement habits. It's conceivable, then, that physical misuse contributes to provoking MD in some individuals, maybe because musicians who move awkwardly foster more convoluted and corruption-prone wiring in their brains. Given that MD can run in families, a genetic component seems certain. According to the Dystonia Medical Research Foundation, At present, researchers have recognized multiple forms of inheritable dystonia and have identified at least 13 genes or chromosomal locations responsible for the various manifestations. Note that the forms of dystonia referred to in that quote don't include MD, for which no culpable 10) ___ have yet been discovered. In light of the above information, it's possible that some musicians could be genetically predestined to acquire MD no matter how gracefully they play owing to the way that prolonged repetitive motion affects their brains. The published research also implies that if we emphasize certain behaviors and avoid others, we can probably reduce the chances of MD arising.
Sources: http://www.violinist.com/blog/Klickstein/20119/12705/; nih.gov; Wikipedia
ANSWERS: 1) fingers; 2) brain; 3) maps; 4) transcranial magnetic stimulation. 5) dystonia; 6) pain; 7) neurological; 8) skills; 9) muscles; 10) genes