Differential diagnosis of tremor syndromes is challenging task for neurologists. The need of a new classification scheme arises from recent developments in the clinical definition of specific tremor syndromes such as dystonic tremor, as well from the recent advances in the surgical treatment. That is, a precise diagnostic definition is required. The Task Force on Tremor of the International Parkinson and Movement Disorder Society has recently released a new classification aimed to provide a helpful tool for the clinicians approaching patients with tremor (Bhatia et al, Mov Disord. 2018 Jan;33(1):75-87). The new scheme is based on two main axes: 1) clinical features; 2) etiology. This novel classification encourages the clinicians to first describe the clinical features, including historical features, tremor characteristics (in terms of topography, activation conditions and frequency), associated signs and additional laboratory tests (electrophysiology, functional and structural imaging, serum and tissue biomarkers). Accordingly, axis I allows to distinguish isolated from combined tremor syndrome. Axis II defines three main categories for etiology (acquired, genetically defined or idiopathic, either familial or sporadic). With this scheme, a tremor syndrome may have multiple etiologies, and a certain etiology may lead to multiple syndromes. A major advance of the new classification is that Essential Tremor is recognized as a syndrome with multiple etiologies. The new classification scheme of tremors represents a step forward in the Movement Disorders field to accurately define tremor syndromes and allows recruiting homogenous patient populations for further research studies.
key points
1. The novel classification of tremor syndromes is based on two main axes.
2. Axis I allows to distinguish isolated from combined tremor syndrome.
3. Axis II is an aid to define etiology.
4. In new classification, Essential Tremor is recognized as a syndrome with multiple etiologies.
5. The new classification provides a useful tool for precise diagnostic definition of patients with tremor syndromes
Bhatia KP, Bain P, Bajaj N, Elble RJ, Hallett M, Louis ED, Raethjen J, Stamelou M, Testa CM, Deuschl G, and the Tremor Task Force of the International Parkinson and Movement Disorder Society.
Consensus Statement on the classification of tremors. From the task force on tremor of the International Parkinson and Movement Disorder Society. Mov Disord. 2018 Jan;33(1):75-87. www.ncbi.nlm.nih.gov/pubmed/29193359