Present
Etiology
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Although the pathophysiology of musicians' focal dystonia (MD) has become clearer in recent years, the exact etiology of the condition remains elusive. Dystonia is a clinically and genetically heterogeneous syndrome and as with other forms of adult-onset focal dystonias, many possible contributing factors have been identified, both organic and non-organic. Altenmüller and colleagues confirm that “while there may be a family history, neurophysiological, physical, and environmental factors, trauma and stress contribute to the phenotypic development of MD” (Altenmuller & Jabusch, 2009).
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Genetic predisposition to MD has been postulated through several studies looking into familial history and gene mutation (Altenmüller, 1998; Jankovic & Ashoori, 2008; Schmidt et al., 2009). An earlier, pre-2000 study looking at multiple types of focal dystonia confirmed that a quarter of participants had a family member with dystonia (Waddy et al., 1991). Results were confirmed in similar research, suggesting the presence of an autosomal gene or genes with reduced penetrance as a common cause of focal dystonias (Stojanović et al., 1995). Although genetic markers, including the DYT1 gene series, have been established as being involved in early-onset forms of generalized or focal dystonias, genetic involvement in musicians’ focal dystonia, which is generally late onset, remains inconclusive. To date, there has also been no specific genetical study on larger samples of musicians with hand dystonia (Butler & Rosenkranz, 2006).
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As the search for a definitive etiology remains inconclusive, MD research has increasingly surrounded the role of extrinsic triggers such as overuse, chronic pain, perfectionism, and anxiety disorders (Schneider et al., 2021). MD sufferers frequently report psychological disturbances that they associate with their condition which validates research showing that areas of the brain associated with dystonia are also involved in the mediation of cognitive and emotional processes (Butler et al., 2007). In 1982, Sheeny and Marsden found no evidence of psychiatric disorder comorbidity in their study of 22 patients with focal dystonias (FDs) (Sheehy & Marsden, 1982). The question of whether the psychological traits of FDs were in fact secondary psycho-reactive responses to FDs was debated in a further study (Ludolph & Windgassen, 1992). Contrastingly, Frommer and colleagues have demonstrated primary psychological and psychosocial connections to FDs, reporting high levels of pre-existing obsessive-compulsive disorders (OCD) and anxiety among patients (Frommer, 1992; Windgassen & Ludolph, 1991). Related pathological findings have revealed that over-activity of the direct striatopallidal structures of the basal ganglia, which are associated with dystonia, are also involved in the mediation of cognitive and emotional processes (Butler et al., 2007; Ioannou et al., 2016). Dysfunctional basal ganglia circuity, identified as playing a fundamental role in the physical symptomology of FDs may also extend to limbic loops involving the amygdala and orbitofrontal cortex that elicit or suppress motor activity in response to emotion (Ron, 2009).
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