Involuntary Thumb Flexion on Neurological Examination: An Unusual Form of Upper Limb Dystonia in the Faroe Islands

• Type of Material: Article
• Authors: Christine Y. Kim, Yale University School of Medicine; Maria Skaalum Petersen, Faroese Hospital System; Eina H. Eliasen, Faroese Hospital System; Giovanni Defazio, Università degli Studi di Cagliari; Paul Greene, Icahn School of Medicine at Mount Sinai; Hyder Jinnah, Emory University; Marina A. J. Tijssen, University Medical Centre Groningen; Elan D. Louis, Yale University School of Medicine
• Language: English
• Date: 2019-01-01
• Publisher: Columbia University Libraries: Creative Commons Attribution Non-Commercial No Derivatives
• Publication Version: Final Published Version
• Copyright Statement: © 2019 Kim et al.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.7916/tohm.v0.686
• Title of Journal or Parent Work: Tremor and Other Hyperkinetic Movements
• ISSN: 2160-8288
• Volume: 9
• Grant/Funding Information: Editor: Julian Benito-Leon, Hospital “12 de Octubre,” Spain
• Keywords: Faroe Islands; thumb flexion; Dystonia; phenomenology; focal dystonia
• Research Categories: Biology, Neuroscience

Abstract

Background: The prevalence of dystonia varies worldwide. A prior report suggested a high prevalence of focal dystonia in the Faroese population, possibly reflecting a founder effect. During standardized neurological examination as part of an ongoing neuroepidemiologic study in the Faroe Islands, we noted an unusual phenomenon of thumb flexion during repetitive hand movements in a subset of subjects and sought to define its phenomenology. Methods: We requested commentary from a panel of dystonia experts regarding the phenomenology of the movements. These experts reviewed the videotaped neurological examination. Results: Among the experts, dystonia was the leading diagnosis. Alternate causes were considered, but deemed less likely. Discussion: Diagnosis of dystonia requires careful clinical assessment and consideration of associated features. We report a novel form of dystonia, not previously described to our knowledge, in this isolated population. Further studies of dystonia prevalence in the Faroe Islands are merited to characterize its burden in this population and its specific clinical characteristics.