Abstract
BackgroundAn objective evaluation of tremor severity is necessary to document the course of disease, the efficacy of treatment, or interventions in clinical trials. Most available objective quantification devices are complex, immobile, or not validated. New methodWe used the TREMITAS-System that comprises a pen-shaped sensor for tremor quantification. The Power of Main Peak and the Total Power were used as surrogate markers for tremor amplitude. Tremor severity was assessed by the TREMITAS-System and relevant subscores of the MDS-UPDRS and TETRAS rating scales in 14 patients with Parkinson's disease (PD) and 16 patients with Essential tremor (ET) off and on therapy. We compared tremor amplitudes assessed during wearable and hand-held constellations. ResultsWe found significant correlations between tremor amplitudes captured by TREM and tremor severity assessed by the MDS-UPDRS in PD (r = 0.638–0.779) and the TETRAS in ET (r = 0.597–0. 704) off and on therapy. The TREMITAS-System captured the L-Dopa-induced improvement of tremor in PD patients (p = 0.027). Tremor amplitudes did not differ between the handheld and wearable constellation (p > 0.05). Comparison with existing methodsWe confirm the results of previous studies using inertial based sensors that tremor severity and drug-induced changes of tremor severity can be quantified using inertial based sensors. The assessment of tremor amplitudes was not influenced by using a handheld or wearable constellation. ConclusionsThe TREMITAS-System can be used to quantify rest tremor in PD and postural tremor in ET and is capable of detecting clinically relevant changes in tremor in clinical and research settings.
Highlights
Tremor is defined as an involuntary, rhythmic, oscillatory movement of a body part and is classified along two main axes – clinical features and etiology [1]
At baseline all Parkinson's disease (PD) patients presented with a rest tremor (MDS-UPDRS 3.17 þ 3.18; more affected hand: mean 1⁄4 4.1, SD 1⁄4 1.2, range 1⁄4 2–6) and no patient developed levodopa induced dyskinesias in the ON state
We showed that TREM can quantify rest tremor in PD and postural tremor in Essential tremor (ET) and is capable of detecting changes in tremor amplitude induced by a L-Dopa challenge test [6] in PD
Summary
Tremor is defined as an involuntary, rhythmic, oscillatory movement of a body part and is classified along two main axes – clinical features and etiology [1]. Various transducer-based methodologies such as accelerometry, electromyography, gyroscopy, electromagnetic tracking, actigraphy, and digitizing tablets are currently used [3] Due to their size, their weight, potential high costs, time consuming measurements and their complexity, most devices are only used in electrophysiological laboratories and are not as yet applicable for daily clinical use or home monitoring. Tremor severity was assessed by the TREMITAS-System and relevant subscores of the MDS-UPDRS and TETRAS rating scales in 14 patients with Parkinson's disease (PD) and 16 patients with Essential tremor (ET) off and on therapy. Conclusions: The TREMITAS-System can be used to quantify rest tremor in PD and postural tremor in ET and is capable of detecting clinically relevant changes in tremor in clinical and research settings
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