In general, two parameters are commonly used to assess and evaluate tremor:
the tremor frequency and the tremor amplitude.
The tremor frequency is an important parameter to analyse the possible underlying pathological processes behind tremor; this parameter is measured in Hertz or Hz. The frequency range of tremor lies between 3 and 20 Hz. Different diseases cause tremors in different frequency bands; these frequencies are shown in the table on the right side.
The tremor frequency can be a supporting parameter for diagnostic purposes to receive a first evaluation of which disease could be the origin of the tremor.
Figure adapted from Table 3 in Deuschl, G., Bain, P. and Brin, M. (1998), Consensus Statement of the Movement Disorder Society on Tremor. Mov. Disord., 13: 2–23. doi:10.1002/mds.870131303
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The tremor amplitude is a relevant parameter to define how strong and intense a tremor manifests.
The tremor amplitude was historically measured in milli-Volt or mV, but the physically more accurate unit for this purpose is milli-g or mG. 1G equals the acceleration or gravity of earth and since the accelerometer measures accelerations, mG is currently used more often than mV (Nevertheless it is possible to convert the values)
In a large scale scientific investigation, it was figured out that the average tremor amplitude of a healthy person lies at approximately 3 mG.
To better understand the relations between the mG unit and the tremor amplitude, the Tremitas GmbH has used the available clinical data from own clinical trials to create a comparison between the amplitudes defined in the “Unified Parkinson’s Disease Rating Scale” (UPDRS) and the “The Essential Tremor Rating Assessment Scale” (TETRAS).
These scales are only for information purposes and are not to be used as exact scales:
You can download the tables for the tremor amplitude and the tremor frequency here
² Raethjen, F Pawlas, M Lindemann, R Wenzelburger, G Deuschl, Determinants of physiologic tremor in a large normal population, In Clinical Neurophysiology, Volume 111, Issue 10, 2000, Pages 1825-1837, ISSN 1388-2457, doi.org/10.1016/S1388-2457(00)00384-9.