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Characterising different types of tremor using combined EMG and kinematic registration in a paradigm based on initiation and inhibition of wrist movement.

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  • Biology
  • Medicine

Abstract

Making a quick and correct distinction between different types of tremor can be a challenge. Because of the overlap in tremor frequency and activation patterns, making an accurate diagnosis can prove to be very hard, but is important because of the different treatment strategies provided for separate types of tremor. To assess whether combined kinematic and EMG registration can help characterise different types of tremor, our explorative pilot study consisted of a set of movement tasks which all depend on muscle agonist and antagonist activation patterns in the lower arm. This paradigm was previously used to establish difference in motor output between Parkinson patients and healthy controls, but was not used in tremor-dominant Parkinson patients, or any other kind of tremor research before. To assess movement initiation, a ballistic movement task was included, characterised by the abrupt initiation of movement and the absence of intentional stops due to the limits of wrist excursion. A circle movement task was used as a means to study smooth movement, evaluating the effectiveness of elaborate agonist and antagonist cooperation. A four-stop movement task consisting of stepwise interrupted movements was added to investigate alternating movement initiation and inhibition. During testing, both kinematics, by means of angular displacement, and muscular activity were recorded. For the statistical analysis, mixed ANOVA’s, t-tests, Mann Whitney U tests and Wilcoxon signed rank tests were used. Twenty-four patients were examined using this paradigm, five of which suffered from Parkinson’s disease, seven from functional tremor, five from enhanced physiological tremor, three from essential tremor and three from Holmes tremor. Results for the ballistic and four-stop movement revealed worse performance the groups of participants with essential or Holmes tremor. Participants with Holmes tremor also performed significantly worse on the circle task, regarding kinematic aspects. We conclude that combined kinematic and EMG registration can be useful in characterising different types of tremor, though kinematic registration proved to be of greater significance. Future research is needed, to affirm kinematic parameters in a larger study population, eventually leading to faster and more accurate diagnosis of tremor.

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