Tremor Study Group

About

The Tremor Study Group (TSG) evolved from the Task Force on Tremor, which completed its work in June 2017. The Task Force reviewed published rating scales.¹  and transducers² for measuring tremor and developed a revised classification scheme for tremor.³ An evidence-based review of published treatments for essential tremor was conducted.⁴ Based on this work, the following objectives for the TSG were identified.

Bylaws 

1. Deep tremor phenotyping

A systematic, deep phenotyping of patients with monosymptomatic tremor disorders (e.g., essential tremor) is needed. The TSG is therefore developing an ordinal assessment tool that will guide clinicians in deep tremor phenotyping, so as to distinguish essential tremor from essential tremor plus and other forms of tremor that are commonly mistaken as essential tremor. The assessment tool will capture subtle or questionable features of dystonia, myoclonus, parkinsonism and ataxia. A video protocol is being developed in conjunction with this tool. To validate this assessment and video protocol, each member of the TSG will produce a video assessment of three patients: essential tremor, essential tremor plus and a combined tremor syndrome that presented with the sole complaint of tremor (monosymptomatic tremor disorder). The ultimate goal is to incorporate this assessment tool and video protocol into a web-based REDCap database that can be used in conjunction with clinical research studies.
 

2. Tremor scales development

Othostatic tremor severity scale

In our previous review of available tremor assessment scales, it was found that there is no validated scale for orthostatic tremor.¹ Treatment of this relatively rare condition is being approached pharmacologically and surgically, and a validated scale for orthostatic tremor has been developed.⁵

Unified Tremor Rating Scale

A scale is needed that captures typical (action tremor) and atypical (e.g., rest tremor, prominent lower limb tremor) tremor in patients with essential tremor and essential tremor plus. We are developing a new scale that builds upon the strengths of the Fahn-Tolosa-Marín scale and the Essential Tremor Rating Assessment Scale (TETRAS). This scale will become one of a battery of scales for the clinical assessment of tremor.

3. Instrumented measures of tremor

Certain aspects of tremor are believed to be useful in distinguishing essential tremor from other tremors (e.g., dystonic tremor and rhythmic cortical myoclonus). However, these tremor characteristics (e.g., irregularity in amplitude and rhythm, fluctuating axis of rotation, posturing of the head or limb) are very difficult to assess by clinical inspection. We believe there is a role for motion transducers, computerized video analysis, and other electrophysiologic methods in the characterization of tremor. We envision such methods being used in a deep phenotyping of tremor patients.

4. Web-based tremor database

The TSG has the overall goal of promoting greater depth and standardization in the phenotyping of patients with tremor disorders, particularly monosymptomatic tremor disorders such as essential tremor. The scales developed by the TSG will be incorporated into a web-based tremor database that will have data elements in common with the Dystonia Coalition database. This database will be linked to an archive of patient videos and to repositories of DNA samples for research.