By Prof. Alberto Albanese, MD
Professor of Neurology
Istituto Neurologico C. Besta
The clinical features of dystonia were first reported in detail in 1911, when Oppehneim (1) and Flatau and Sterling (2) described some Jewish children affected by a syndrome that was retrospectively considered to represent familial cases of DYT1 dystonia. Some decades later, in 1975, the first international conference on dystonia was held in New York. It was then recognized that, in addition to severe generalized forms, the dystonia phenotype also encompasses poorly-progressive focal and segmental cases with onset in adulthood, such as blepharospasm, torticollis and writer’s cramp (3).
These forms were previously considered independent disorders and were mainly classified among neuroses. A modern definition of dystonia was worded some years later, in 1984 (4). During the following years it became evident that dystonia syndromes are numerous and diversified, new terminological descriptors (e.g., dystonia plus, heredodegenerative dystonias, etc.) and additional classification schemes were introduced. The clinical complexity of dystonia was then fully recognized.
Dystonia is the most common type of movement disorder to be misdiagnosed (5,6) and also a condition difficult to teach, due to the terminological and classificatory conundrum. As for other movement disorders (such as tremor) the term dystonia has historically been used at the same time to refer to the clinical phenomenology and to the numerous dystonia syndromes. The phenomenology of dystonia consist of a collection of objective physical signs that have been recently listed (7).
In 2009 the organizing committee of the Fifth International Dystonia Symposium (held in Barcelona, Spain, in October 2011) was set up. The idea of organizing a consensus conference to revise the classification of dystonia was raised within that committee. The Dystonia Medical Research Foundation, the Dystonia Coalition and the European Dystonia Federation (now called Dystonia Europe) provided the seeding sponsorships for a consensus meeting that was convened in the outskirts of Rome in May 2011. The main items on the agenda were: to discuss the evolution of current classification systems, to find a consensus on terminology, to identify what was not accounted for by current classifications, and to draft a consensus for a new classification.
The meeting was attended by a panel of world-renowned experts in dystonia. Notwithstanding the positive atmosphere and a strong commitment, only the first two items on agenda could be covered during this two-day meeting. Review of inconsistencies in classifications and terminology took most of the meeting time. It became also clear that a new definition of dystonia had to be drafted aside a new classification. The intense work carried out in Rome allowed to focus the most important issues. The panel performed much by e-mail exchange and met again in Barcelona (October 2011) and, with the addition of new members, in Dublin (June 2012).
In Barcelona it was agreed to separate the clinical features of dystonia from the listing of causes, but these two aspects remained intertwined until the last in-person meeting in Dublin. Here new panel members, who had not been involved in previous discussions, were asked to review the work and to propose solutions to stalemates. This approach paid off and consensus was finally reached on an innovative two-axis classification that separated phenomenology (axis I) from etiology (axis II).
The new classification is largely compatible with previous schemes and overcomes earlier terminological inconsistencies. The first axis (clinical features) is a clinical description that supports clinical diagnostic assessment. The second axis is structured as a database of different etiologies. By combining the two axes together each patient can be described in detail, taking into account clinical characteristics and etiological descriptors.
Three in-person meetings and a rich e-mail exchange were necessary to accomplish this task. The teamwork has been intense. I have particularly enjoyed observing how clinical knowledge and intelligence have allowed to resolve a number of apparently unsolvable issues. The structure of this new classification may be valuable beyond dystonia, as several movement disorders share a complex overlap between phenomenology and etiology. A similar structure may in the future apply to the forthcoming classifications of tremor and of other movement disorders.
1. Oppenheim H. Über eine eigenartige Krampfkrankheit des kindlichen und jugendlichen Alters (Dysbasia lordotica progressiva, Dystonia musculorum deformans). Neurologische Centralblatt 1911;30:1090-107.
2. Flatau E, Sterling W. Progressiver Torsionspasm bie Kindern. Z ges Neurol Psychiat 1911;7:586-612.
3. Marsden CD. Dystonia: the spectrum of the disease. Res Publ Assoc Res Nerv Ment Dis 1976;55:351-67.
4. Fahn S, Marsden CD, Calne DB. Classification and investigation of dystonia. In: Marsden CD, Fahn S, editors. Movement disorders 2. London: Butterworths; 1987. p. 332-58.
5. Fahn S. The varied clinical expressions of dystonia. Neurol Clin 1984;2:541-54.
6. Lalli S, Albanese A. The diagnostic challenge of primary dystonia: evidence from misdiagnosis. Mov Disord 2010;25:1619-26.
7. Albanese A, Lalli S. Is this dystonia? Mov Disord 2009;24:1725-31.