Focal Task-specific Dystonia among Professional Musicians in Latin America.

In Response To: Frucht SJ. Focal task-specific dystonia-from early descriptions to a new, modern formulation. Tremor Other Hyperkinet Mov. 2014; 4. doi: 10.7916/D8VD6WHP.

To the Editor:

We read with great interest the article “Focal Task-specific Dystonia—From Early Descriptions to a New, Modern Formulation” by Frucht.1

The author presented a new working conceptual model of focal task-specific dystonia (FTSD) attempting to integrate phenomenology, physiology, and treatment. Nevertheless, several aspects of FTSD remain unresolved, and the author suggests that international working groups focusing on musician's dystonia (MD) could contribute to better understanding in the field.

The estimated prevalence of FTSD is 0.5–1% for all professional musicians, although there is wide variation in different populations and in the type of instrument played.2–5

To investigate the data available from our region, we conducted a systematic search of MD in Latin America. The Medline, EMBASE, and LILACS databases were explored using the subject terms musician's dystonia Latin America, focal dystonia Latin America, and prevalence studies of FTSD in highly skilled musicians from Latin America. We searched for articles in English and in Spanish. Data from Latin American countries about MD are scarce, and only isolated reports or small series of cases were found in the English literature.6–10

Recently, Aranguiz et al.,6 from Chile, described clinical and demographic characteristics of 12 musicians who developed dystonia. According to the literature, the authors found male predominance (83.3%): eight patients were classical musicians; the hand was the most affected segment (91.7%); and interestingly they described a positive family history of neurological diseases in first-degree relatives in 50% of their patients.

In our country, Argentina, we failed to find extensive epidemiological information concerning MD affecting professional musicians. In previous years, we had conducted a survey in an attempt to estimate the prevalence of FTSD among professional musicians in a community-based study from Argentina.11 Professional musicians from different orchestras in Buenos Aires were invited to complete a confidential and anonymous self-assessment questionnaire that included demographic, epidemiological, and clinical data, and specific questions about FTSD. A total of 190 questionnaires were distributed: 82 (43.15%) were returned, but only 65 were acceptable for the study.

In our series, 16.92% of participants (11/65 individuals) reported suggestive symptoms of FTSD with a mean age of 45.82±14.96 years; European ancestry was reported in 72.23% of the cases. As in other international series, in our survey, men were more affected than women (poner números: 8 men, 3 women ), and we observed a trend towards a positive correlation between FTSD occurrence and longer practice time or longer period playing musical instruments. In agreement with international series, musicians from the Philharmonic Orchestra showed the highest prevalence of FTSD when compared with the City Hall Orchestra. The Philharmonic Orchestra repertoire most likely requires more complex performances and a greater number of hours for practice.

The prevalence of dystonia in our series appears to be higher than others, but we cannot exclude two relevant factors for overestimation of prevalence: the first is related to the screening tool employed for assessment, as we had used a non-validated questionnaire performed ad hoc. The second factor is the absence of clinical examination, especially if we take into account that several of a number of “mimic” conditions, such as pain, overuse, or nerve compression syndrome, could be present.12

The assessment of dystonia in these communities of artists represents a great challenge in Latin America. The lower rate of participation in this survey probably reflects that in Latin America work and economic conditions are different from Europe or North America.4,5 Moreover, the major concern to participate the survey was the fear of losing their job was a major concern that had to be overcome before subjects took part in the survey. Extensive and comprehensive epidemiological studies, including neurological examination, are required to improve health and work conditions of this population in our region.