Musician's Dystonia: Family History as a Predictor for Onset and Course of the Disease

Gender Differences in Task Specific Dystonia: What Can we Learn from Musician's Dystonia?

BACKGROUND

Musician's Dystonia (MD) is a task specific, focal dystonia which usually occurs only at the instrument. The pathophysiology is not fully understood, but several risk factors like over-practice and genetic predisposition are known. Interestingly, 80% of those affected are men, which stands in contrast to the gender distribution in other focal dystonias, such as cervical dystonia.

OBJECTIVES

Our aim was to evaluate the difference in women and men with regard to risk factors leading to MD.

METHODS

We investigated known risk factors for MD in a large cohort of 364 MD patients by retrospectively collecting data on practice behavior and family history.

RESULTS

In line with previous studies, we found a ratio of ~4:1 men to women. Age at onset of MD was significantly lower in women; however, subsequent analysis revealed that it was a positive family history (FH+) and not gender that was associated with a lower age at onset. Furthermore, we found that those with negative family history had accumulated more practice time until onset of MD.

CONCLUSIONS

These results imply that the earlier age at onset in women did not depend on gender but was due to the higher proportion of a positive family history. In contrast, men were less likely to have a positive family history, suggesting that genetic factors may not be the primary reason for the higher prevalence of MD in men. Instead, differences in practice behaviors between men and women may contribute to this gender disparity.

Practice behaviors as trigger factor for the onset of Musicians' Dystonia

Musician's Dystonia (MD) is a task-specific movement disorder that results in an involuntary cramping of muscles involved in playing an instrument such as the upper limbs or the embouchure. It is usually painless and occurs in general only at the instrument. The pathophysiology of MD is not completely understood. The present study aimed at assessing differences in practice behaviors between pianists affected by MD and Healthy Controls (HC) in the years preceding the onset of the disease. Thus, we investigated to what extent practice quantity can be considered a trigger of Musicians' Dystonia. The results showed that despite comparable practice behaviors in childhood, MD pianists incremented the amount of daily practice to a greater extent than their healthy colleagues, especially in the second and in the third decade of life. Thus, subsequent logistic regression analysis showed that high amounts of daily practice might significantly increase the risk of developing MD. Furthermore, gender-related differences in practice behaviors across groups were identified, indicating that male pianists from the MD group might not have practiced significantly more than HC male pianists before the onset of the disease. To the authors' knowledge, these are the first empirical evidence of the role of dysfunctional practice behaviors in triggering MD, which has clinical and educational implications.