High prevalence of primary focal dystonia in the Faroe Islands

Abstract

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.

Prevalence of Essential Tremor in the Faroe Islands: A Population-Based Study

“…The prevalence of PD in the Faroe Islands is high [43], as is the prevalence of certain forms of dystonia [13]. However, the current data indicate that the prevalence of ET, another involuntary movement, is comparable to that of other populations.…”

“…Prior epidemiological work has established high prevalence of several movement disorders (i.e., PD [43] and primary focal dystonia [13]) in the Faroe Islands, providing an impetus to study the most common adult-onset movement disorder, ET. Also, given the potential for founder effects in the Islands, and the highly genetic nature of ET, the Faroe Islands provide a particularly interesting setting in which to study the prevalence of ET.…”

“…Due to the isolated geographic location and homogenous population [10], the Faroe Islands have been the focus of epidemiological investigations of a number of neurological disorders. The prevalence of several movement disorders, such as Parkinson's disease (PD) [11,12] and primary focal dystonia [13], is high, while multiple sclerosis [14,15] and amyotrophic lateral sclerosis [16] are comparable to other European countries. Yet curiously, no studies of prevalence of one of the most common neurological disorders, ET, have been undertaken in the Faroe Islands.…”

Blood Harmane (1-Methyl-9H-Pyrido[3,4-b]indole) and Mercury in Essential Tremor: A Population-Based, Environmental Epidemiology Study in the Faroe Islands

“…The Faroe Islands, located in the North Atlantic Ocean, between Norway and Iceland, are inhabited by 49,121 individuals of whom 24,154 are age > 40 (January 1, 2016). Due to the isolated geographic location and homogenous population, they have been the focus of epidemiological investigations of numerous neurological disorders [21][22][23][24]. The Faroese diet is high in marine food [17], and high level of exposure to methyl mercury through diet makes it a valuable location to study the effects of this neurotoxicant [25].…”

Transient, Isolated Head Tremor in “Unaffected” Individuals: Is Essential Tremor an Even More Prevalent Disease Than We Suppose?

“…Indeed, in this manner, we identified three additional FD-ET with isolated head tremor that we attributed to dystonia. Second, while it is still possible that some number of the 26 isolated head tremor cases may have had cervical dystonia/dystonic tremor in the complete absence of (1) dystonic neck postures, (2) neck deviation, (3) jerk-like neck movements, (4) hypertrophy of neck muscles, (5) non-rhythmicity of tremor, and (6) non-oscillatory tremor, the prevalence of dystonia in the population is several orders of magnitude less than that of ET ( 29 ); the prevalence of focal cervical dystonia is generally on the order of 0.002–0.02%, which is 200–2,000 less prevalent than ET among those age 40 and older ( 23 ). Hence, it is far more likely that the head tremor observed (esp.…”