A method for characterizing essential tremor from the shoulder to the wrist

Geiger, Daniel W; Eggett, Dennis L.; Charles, Steven K.

doi:10.1016/j.clinbiomech.2017.12.003

Cited by 7 publications

(9 citation statements)

References 36 publications

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“…On average, we found the distribution of the amount of postural tremor (WFE > SIER, FPS, WRUD > EFE, SAA and SFE > SAA) and kinetic tremor (FPS, WFE > WRUD, SIER > EFE, SFE > SAA) to be similar except that tremor in FPS played a larger role in kinetic tremor than in postural tremor (Figure 3C-D). The distribution of postural tremor, which we measured in 23 patients covering a broad spectrum of ET severity (Table 1), is similar to our prior, preliminary investigation of postural tremor distribution in 10 patients with mild ET, in which we defined tremor amount in terms of angular displacement instead of acceleration (Geiger et al, 2018). In that study, WFE showed by far the most tremor, then four DOF (FPS, SIER, WRUD, and SFE) exhibited similar amounts of tremor, and EFE and SAA had the lowest tremor.…”

Section: Distribution Of Tremor Amountsupporting

confidence: 65%

“…We followed some of the methodology presented in (Geiger et al, 2018) but also made several important improvements, so we present our methods in detail here. To measure tremor in the 7 main DOF of the upper limb (Figure 1A), we placed electromagnetic motion capture sensors (trakSTAR 3DGuidance by Ascension Technologies, Shelburne, VT) on the trunk and right arm of subjects in the following locations: sternum, inferior to the suprasternal notch; dorsal aspect of the distal upper arm, proximal to the elbow; dorsal aspect of the distal forearm, a few centimeters proximal to the wrist joint center; dorsum of the hand, bridging the third and fourth metacarpals (Figure 1B-C).…”

Section: Experimental Set-upmentioning

confidence: 99%

“…However, since the goal of their study was to demonstrate how to target tremor-generating muscles at individual joints and in individual patients, they did not compare tremor across joints or patients, so their results did not compare tremor magnitude across more than 3 DOF or include the variability across patients or the effect of subject characteristics. We recently presented a method to characterize tremor in the 7 DOF from the shoulder to the wrist (Geiger et al, 2018) but only included preliminary results from a relatively small number of patients (all with mild ET), and without characterizing the variability across patients or the effect of task or subject characteristics. In summary, although subsets of DOF and settings have been studied, the distribution of tremor throughout the upper limb is unknown, as is the variability in this distribution across patients and time, and the effect of conditions and subject characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…In(Geiger et al 2018), shoulder tremor was characterized in the glenohumeral joint, not the thoracohumeral joint as in this paper; however, to enable comparison, we approximated the DOF as equivalent.…”

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confidence: 99%

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Distribution of tremor among the major degrees of freedom of the upper limb in subjects with Essential Tremor

Pigg

Thompson-Westra

Mente

et al. 2020

Clinical Neurophysiology

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Section: Distribution Of Tremor Amountsupporting

confidence: 65%

Section: Experimental Set-upmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Distribution of tremor among the major degrees of freedom of the upper limb in subjects with Essential Tremor

Pigg

Thompson-Westra

Mente

et al. 2020

Clinical Neurophysiology

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“…The methods presented here have been tested and successfully implemented in whole-arm studies of tremor [25,26]. We are currently working on a quantitative comparison of postural vs landmark calibration methods to allow for more informed comparison between studies.…”

Section: Methodsmentioning

confidence: 99%

Tracking Joint Angles During Whole-Arm Movements Using Electromagnetic Sensors

Clark

Dickinson

Loaiza

et al. 2020

Journal of Biomechanical Engineering

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Electromagnetic (EM) motion tracking systems are suitable for many research and clinical applications, including in vivo measurements of whole-arm movements. Unfortunately, the methodology for in vivo measurements of whole-arm movements using EM sensors is not well described in the literature, making it difficult to perform new measurements and all but impossible to make meaningful comparisons between studies. The recommendations of the International Society of Biomechanics (ISB) have provided a great service, but by necessity they do not provide clear guidance or standardization on all required steps. The goal of this paper was to provide a comprehensive methodology for using EM sensors to measure whole-arm movements in vivo. We selected methodological details from past studies that were compatible with the ISB recommendations and suitable for measuring whole-arm movements using EM sensors, filling in gaps with recommendations from our own past experiments. The presented methodology includes recommendations for defining coordinate systems (CSs) and joint angles, placing sensors, performing sensor-to-body calibration, calculating rotation matrices from sensor data, and extracting unique joint angles from rotation matrices. We present this process, including all equations, for both the right and left upper limbs, models with nine or seven degrees-of-freedom (DOF), and two different calibration methods. Providing a detailed methodology for the entire process in one location promotes replicability of studies by allowing researchers to clearly define their experimental methods. It is hoped that this paper will simplify new investigations of whole-arm movement using EM sensors and facilitate comparison between studies.

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Quantitative Separation of Tremor and Ataxia in Essential Tremor

Casamento‐Moran

Yacoubi

Wilkes

et al. 2020

Annals of Neurology

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Objective This study addresses an important problem in neurology, distinguishing tremor and ataxia using quantitative methods. Specifically, we aimed to quantitatively separate dysmetria, a cardinal sign of ataxia, from tremor in essential tremor (ET). Methods In Experiment 1, we compared 19 participants diagnosed with ET undergoing thalamic deep brain stimulation (DBS; ETDBS) to 19 healthy controls (HC). We quantified tremor during postural tasks using accelerometry and dysmetria with fast, reverse‐at‐target goal‐directed movements. To ensure that endpoint accuracy was unaffected by tremor, we quantified dysmetria in selected trials manifesting a smooth trajectory to the endpoint. Finally, we manipulated tremor amplitude by switching DBS ON and OFF to examine its effect on dysmetria. In Experiment 2, we compared 10 ET participants with 10 HC to determine whether we could identify and distinguish dysmetria from tremor in non‐DBS ET. Results Three findings suggest that we can quantify dysmetria independently of tremor in ET. First, ETDBS and ET exhibited greater dysmetria than HC and dysmetria did not correlate with tremor (R2 < 0.01). Second, even for trials with tremor‐free trajectories to the target, ET exhibited greater dysmetria than HC (p < 0.01). Third, activating DBS reduced tremor (p < 0.01) but had no effect on dysmetria (p > 0.2). Interpretation We demonstrate that dysmetria can be quantified independently of tremor using fast, reverse‐at‐target goal‐directed movements. These results have important implications for the understanding of ET and other cerebellar and tremor disorders. Future research should examine the neurophysiological mechanisms underlying each symptom and characterize their independent contribution to disability. ANN NEUROL 2020;88:375–387.

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A method for characterizing essential tremor from the shoulder to the wrist

Abstract: This method can be used to characterize the distribution of tremor throughout the upper limb. Our preliminary characterization suggests that the amount of tremor increases in a proximal-distal manner.

Cited by 7 publications

References 36 publications

Distribution of tremor among the major degrees of freedom of the upper limb in subjects with Essential Tremor

Distribution of tremor among the major degrees of freedom of the upper limb in subjects with Essential Tremor

Tracking Joint Angles During Whole-Arm Movements Using Electromagnetic Sensors

Quantitative Separation of Tremor and Ataxia in Essential Tremor

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