High prevalence of primary focal dystonia in the Faroe Islands

Objective – There are no previous studies undertaken about primary
focal dystonia in the Faroe Islands. The aim of this study was to
establish the prevalence of these diseases in the Faroese population.
Methods – Patients were ascertained and registered prospectively from
January 1, 1994, through 2013 when they were examined at the
Neurological Clinic of the Faroese National Hospital or at a private
neurological practice, which together constitutes all the available
neurological services in the Faroe Islands. Result – On January 1, 2014,
there were 29 individuals within the entire Faroese population of 48,100
with primary focal dystonia: 23 with torticollis, four with writer’s
cramp, one with oromandibular dystonia, and one with laryngeal
dystonia; no one had blepharospasm. The prevalence of primary focal
dystonia was 602 per million (395–873) (95% confidence limit). The
most common subtype was cervical dystonia with a prevalence of 478
(332–728) per million. Conclusion – The study yielded that (i) the
prevalence of primary focal dystonia of 602 (395–873) per million is far
higher in the Faroe Islands than that revealed in most other regions
studied and (ii) the prevalence of the cervical dystonia subtype is far
more common than elsewhere with the highest prevalence of 478 (332–
728), which is higher than described in any previously published survey.
As the study is serviced-based, the result may underestimate actual
occurrence; thus, prevalence rates may be even higher.