Objective: To comprehensively evaluate the effects of loading, tapping performance, and ballistic movements on major tremor features in patients with essential tremor (ET).

Background: In recent years, a comprehensive set of neurophysiological tests, including the loading test, tapping performance analysis, and the evaluation of response to ballistic movements, has been proposed to formulate laboratory-supported criteria for diagnosing functional tremor. These criteria are intended for use in both clinical practice and experimental research [1], [2].

Method: The enrolled ET patients were evaluated using a standardized clinical scale, the Fahn-Tolosa-Marin Tremor Rating Scale (FTM-TRS).  A comprehensive tremor evaluation at baseline and during loading, finger tapping (at 1, 3, and 5 Hz), and ballistic movements was conducted using an optoelectronic system. Data were analyzed through non-parametric Friedman Analysis of Variance (ANOVA).

Results: Thirteen ET patients were included (6 females, 64.9±17.6 years), with a mean disease duration of 15.6±10.9 years and an FTM-TRS score of 20.6±10.1. At baseline, postural tremor had a mean frequency of 5.98±1.42 Hz and a mean amplitude of 0.053±0.036 GRMS^2. ANOVA unveiled a difference in amplitude (Chi-square=12.24; p=0.03), with lower values during 1 Hz finger-tapping movements (0.045 GRMS^2), compared to the other conditions. Moreover, we found an inverse correlation between baseline tremor amplitude and the reduction in tremor amplitude during 1 Hz tapping (r=-0.62, p=0.021). Finally, the analysis did not reveal variations in tremor frequency across different manoeuvres (Chi-square=3.48; p=0.62).

Conclusion: Gaining insights into the impact of loading, tapping performance, and ballistic movements on postural tremor features in patients with tremor holds relevance for clinical applications, especially within the diagnostic process. Expanding the analysis to larger patient samples could contribute to a deeper understanding of how clinical factors influence the observed effects.

References: [1] P. Schwingenschuh et al., “Moving toward ‘laboratory‐supported’ criteria for psychogenic tremor,” Movement Disorders, vol. 26, no. 14, pp. 2509–2515, Dec. 2011, doi: 10.1002/mds.23922.
[2] P. Schwingenschuh et al., “Validation of ‘laboratory‐supported’ criteria for functional (psychogenic) tremor,” Movement Disorders, vol. 31, no. 4, pp. 555–562, Apr. 2016, doi: 10.1002/mds.26525.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/effects-of-loading-tapping-performance-and-ballistic-movements-on-postural-tremor-features-in-patients-with-essential-tremor/