Measurement Of Tremor Research Articles

P 6 Visuomotor adaptation is impaired in Essential Tremor

Introduction: Evidence has accumulated to support the theory that the cerebellum is crucially involved in the primary pathophysiology of Essential Tremor (ET). The cerebellum is critical for integration of sensorimotor information to create an internal model of movement using prediction errors. Neurological disorders causing cerebellar injury, such as degenerative cerebellar ataxia or cerebellar stroke, disrupt visuomotor integration and impede error-based learning. We hypothesized that cerebellar dysfunction in ET is also associated with impairment of visuomotor integration and error-based learning. Materials & Methods: To test this hypothesis, mildly to moderately affected ET patients (N=34; mean TETRAS score: 32.15 ± 13.78) and age-matched healthy controls performed a visuomotor adaptation task (Fig. 1A). The task was displayed on a PC monitor and movements were captured using a digital tablet. The experiment was divided into 3 phases (Fig. 1C): a baseline phase (BL), including simple center-to-target movements; an adaptation phase (ADP), in which a 30° visuomotor perturbation was introduced and a de-adaptation phase (DA), in which this perturbation was removed. The angle between the hand path and the center-target path, termed angular error, was calculated to assess visuomotor adaptation (Fig. 1B). Adaptation indices (AI; AI1 = ADP1 – BL2; AI2 = ADP8 – BL2; AI3 = DA1 – ADB8) were evaluated to assess the differences in angular error in each phase of the task (Fig. 2B). Covariates recorded were: clinical characteristics of ET patients, such as disease duration, alcohol responsivity, current medication, clinical measures of tremor and ataxia (as indexed by the TETRAS and SARA score), and basic motor performance as assessed by reaction and movement times. Results: AIs were significantly lower in ET patients compared to controls (Fig. 2A). No differences were found between ET patients and controls at BL or at DA, suggesting that the effects were specific to the adaptation phase. No differences in basic motor performance between groups were evident (all p>0.2), indicating that adaptation deficits in ET were not caused by impaired motor functions. In addition, there was no association between clinical parameters of ET and visuomotor adaptation abilities, suggesting that the reduced ability to adapt the motor response to the visual perturbation was unlikely to result from the tremulous movement. Conclusion: We found that visuomotor adaptation was impaired in ET, specifically in the adaptation phase. These results provide further evidence for linking ET to cerebellar dysfunction. Because the impairment was unrelated to clinical measures of tremor or ataxia and to basic motor performance, cerebellar dysfunction underlying visuomotor impairment in ET may be differentiated from the pathophysiological origin of other cerebellar diseases.

Milestones in Tremor Research: 10 Years Later.

Major progress has occurred during the last decade in the field of tremor. From the clinical standpoint, a new classification has completely revised the nosology of tremor syndromes and has re‐conceptualized essential tremor as a syndrome rather than a single disease entity, fueling an ongoing enlightened debate. Significant advances have been obtained in terms of instrumental measurement of tremor, remarking on the possibility of developing novel treatment strategies based on tremor characteristics, namely tremor‐phase. Moreover, a better understanding of the pathophysiological mechanisms has further led to the suggestion of refining the classification of tremor syndromes according to their driving underpinnings. Finally, surgical options such as deep brain stimulation and focused ultrasound thalamotomy are now part of the therapeutic portfolio for tremor, but several oral drugs, including long‐chain alcohols, T‐channel blockers, allosteric modulators of potassium channels, and of GABA‐A receptors, are currently being tested and hold promise. This review will discuss the key milestones in tremor research of the last 10 years, with a focus on the most common tremor syndromes, namely essential tremor, dystonic tremor, and Parkinsonian tremor.

Measurement of Tremor on Arteriovenous Fistulas with a Flexible Capacitive Sensor.

Arteriovenous fistula (AVF) is a widely used vascular access for hemodialysis in clinical. It is a great challenge to monitoring the status of AVF in daily life due to acute AVF stenosis may occur on unnoticeable occasions, such as sleeping. Inspiring tremor is almost always accompanied by a healthy AVF, which can be adopted as an essential physiological sign for AVF monitoring. Hence, a fistula tremor measurement system based on a flexible capacitive pressure sensor is designed in this study. The sensor consists of polydimethylsiloxane(PDMS) dielectric layers, electrode layers, ground layers, and shielding layers. The PDMS layers are fabricated as cross superposition transverse microstructure film to enhance dielectric constant and sensitivity of the sensor. The isolation shielding layers and ground layers guarantee the sensing chain is noise-free. A microcontroller embedded AD7746 measurement circuit is designed for signal acquisition. We test our prototype on the wrists of healthy volunteers and AVF on dialysis patients separately. The pulse signals and AVF tremor signals are clear and distinguishable. The sensor and measurement system have excellent potential in wearable AVF monitoring.

The Effects of Remote Signal Transmission and Recording on Acoustical Measures of Simulated Essential Vocal Tremor: Considerations for Remote Treatment Research and Telepractice

PurposeStudies on medical and behavioral interventions for essential vocal tremor (EVT) have shown inconsistent effects on acoustical and perceptual outcome measures across studies and across participants. Remote acoustical and perceptual assessments might facilitate studies with larger samples of participants and repeated measures that could clarify treatment effects and identify optimal treatment candidates. Furthermore, remote acoustical and perceptual assessment might allow clinicians to monitor clients’ treatment responses and optimize treatment approaches during telepractice. Thus, the purpose of this study was to evaluate the accuracy of remote signal transmission and recording for acoustical and perceptual assessment of EVT. MethodSimulations of EVT were produced using a computational model and were recorded using local and remote procedures to represent client- and clinician-end recordings respectively. Acoustical analyses measured the extent and rate of fundamental frequency (fo) and intensity modulation to represent vocal tremor severity and the cepstral peak prominence (CPPS) to represent voice quality. The data were analyzed using repeated measures analysis of variance (ANOVA) with recording as the within-subjects factor and sex of the computational model as the between-subjects factor. ResultsThere was a significant main effect of recording on the rate of fo modulation and significant interactions of recording and sex for the extent of intensity modulation, rate of intensity modulation, and CPPS. Posthoc pairwise comparisons and analysis of effect size indicated that recording procedures had the largest effect on the extent of intensity modulation for male simulations, the rate of intensity modulation for male and female simulations, and the CPPS for male and female simulations. Despite having disabled all known software and computer audio enhancing options and having stable ethernet connections, there was inconsistent attenuation of signal amplitude in remote recordings that was most problematic for samples with a breathy voice quality but also affected samples with typical and pressed voice qualities. ConclusionsAcoustical measures that correlate to perception of vocal tremor and voice quality were altered by remote signal transmission and recording. In particular, signal transmission and recording in Zoom altered time-based estimates of intensity modulation and CPPS with male and female simulations of EVT and magnitude-based estimates of intensity modulation with male simulations of EVT. In contrast, signal transmission and recording in Zoom minimally altered time- and magnitude-based estimates of fo modulation with male and female simulations of EVT. Therefore, acoustical and perceptual assessments of EVT should be performed using audio recordings that are collected locally on the participant- or client-end, particularly when measuring modulation of intensity and CPP or estimating vocal tremor severity and voice quality. Development of procedures for collecting local audio recordings in remote settings may expand data collection for treatment research and enhance telepractice.

Isolated Cavities Dominate Greenland Ice Sheet Dynamic Response to Lake Drainage

AbstractSeasonal variability in the Greenland Ice Sheet's (GrIS) sliding speed is regulated by the response of the subglacial drainage system to meltwater inputs. However, the importance of channelization relative to the dewatering of isolated cavities in controlling seasonal ice deceleration remains unsolved. Using ice motion, moulin hydraulic head, and glaciohydraulic tremor measurements, we show the passing of a subglacial floodwave triggered by upglacier supraglacial lake drainages slowed sliding to wintertime background speeds without increasing the hydraulic capacity of the moulin‐connected drainage system. We interpret these results to reflect an increase in basal traction caused by the dewatering of isolated cavities. These results suggest the dewatering of isolated parts of the subglacial drainage system play a key role in driving seasonal slowdowns on the GrIS.

Real-time estimation of phase and amplitude with application to neural data

Computation of the instantaneous phase and amplitude via the Hilbert Transform is a powerful tool of data analysis. This approach finds many applications in various science and engineering branches but is not proper for causal estimation because it requires knowledge of the signal’s past and future. However, several problems require real-time estimation of phase and amplitude; an illustrative example is phase-locked or amplitude-dependent stimulation in neuroscience. In this paper, we discuss and compare three causal algorithms that do not rely on the Hilbert Transform but exploit well-known physical phenomena, the synchronization and the resonance. After testing the algorithms on a synthetic data set, we illustrate their performance computing phase and amplitude for the accelerometer tremor measurements and a Parkinsonian patient’s beta-band brain activity.

Noninvasive Thalamotomy for Refractory Tremor by Frameless Radiosurgery

We sought to determine whether a more widely accessible, noninvasive, frameless approach to radiosurgical thalamotomy would improve objective measures of refractory essential or parkinsonian tremor without added toxicity compared with reports of frame-based radiosurgery. We conducted a single-arm pilot observational prospective trial of adult patients with essential or parkinsonian tremor from 2013 to 2019 and report results at 1-year follow-up. Patients were treated with frameless unilateral radiosurgical ablation of the thalamic ventral intermediate nucleus to a maximum dose of 160 Gy. Treatment response was measured by the Fahn-Tolosa-Marin (FTM) tremor rating scale and the Quality of Life in Essential Tremor or Parkinson's Disease Questionnaire obtained before treatment and at 3, 6, 9, and 12 months. Thirty-three patients, including 23 with essential tremor and 10 with Parkinson's disease, were enrolled. Overall treatment response rate per FTM was 83% (15 of 18) at 6 months. There was a marked improvement in tremor, with an average total FTM reduction of 21% at 3 months (from 46 to 30 points; P = .003) and 41% at 6 months (from 46 to 24 points; P = .001). At 6 months, functional decline had regressed by 54% (from 15 to 7 points; P = .001). Quality of life improved by 57% (P = .001) at 6 months in patients with essential tremor, and patients with Parkinson's disease had unchanged quality of life. At 1-year follow-up, grade 2 neurologic adverse events were observed in 6% (2 of 33) of patients without any grade ≥ 3 events. Noninvasive, frameless radiosurgical thalamotomy may be a feasible treatment for patients with refractory tremor and demonstrates short-term safety at 1-year follow-up. This pilot study provides promising preliminary descriptions of efficacy, and definitive estimates of long-term safety and benefit require further study with longer follow-up.

Discovery of Parkinson's disease states and disease progression modelling: a longitudinal data study using machine learning

Parkinson's disease is heterogeneous in symptom presentation and progression. Increased understanding of both aspects can enable better patient management and improve clinical trial design. Previous approaches to modelling Parkinson's disease progression assumed static progression trajectories within subgroups and have not adequately accounted for complex medication effects. Our objective was to develop a statistical progression model of Parkinson's disease that accounts for intra-individual and inter-individual variability and medication effects. In this longitudinal data study, data were collected for up to 7-years on 423 patients with early Parkinson's disease and 196 healthy controls from the Parkinson's Progression Markers Initiative (PPMI) longitudinal observational study. A contrastive latent variable model was applied followed by a novel personalised input-output hidden Markov model to define disease states. Clinical significance of the states was assessed using statistical tests on seven key motor or cognitive outcomes (mild cognitive impairment, dementia, dyskinesia, presence of motor fluctuations, functional impairment from motor fluctuations, Hoehn and Yahr score, and death) not used in the learning phase. The results were validated in an independent sample of 610 patients with Parkinson's disease from the National Institute of Neurological Disorders and Stroke Parkinson's Disease Biomarker Program (PDBP). PPMI data were download July 25, 2018, medication information was downloaded on Sept 24, 2018, and PDBP data were downloaded between June 15 and June 24, 2020. The model discovered eight disease states, which are primarily differentiated by functional impairment, tremor, bradykinesia, and neuropsychiatric measures. State 8, the terminal state, had the highest prevalence of key clinical outcomes including 18 (95%) of 19 recorded instances of dementia. At study outset 4 (1%) of 333 patients were in state 8 and 138 (41%) of 333 patients reached stage 8 by year 5. However, the ranking of the starting state did not match the ranking of reaching state 8 within 5 years. Overall, patients starting in state 5 had the shortest time to terminal state (median 2·75 [95% CI 1·75-4·25] years). We developed a statistical progression model of early Parkinson's disease that accounts for intra-individual and inter-individual variability and medication effects. Our predictive model discovered non-sequential, overlapping disease progression trajectories, supporting the use of non-deterministic disease progression models, and suggesting static subtype assignment might be ineffective at capturing the full spectrum of Parkinson's disease progression. Michael J Fox Foundation.

Rest tremor correlates with reduced contralateral striatal dopamine transporter binding in Parkinson's disease

IntroductionIn vivo dopamine transporter imaging is a useful tool for distinguishing nigrostriatal pathologies (e.g. Parkinson's disease) from other causes of tremor. However, while many of the motoric features of Parkinson's disease (e.g. bradykinesia, rigidity, hypomimia) correlate well with reduced striatal dopamine transporter binding, the same relationship has not been demonstrated for tremor. We investigated the relationship between striatal dopamine transporter binding and quantitative measures of tremor. Methods23 participants with Parkinson's disease underwent standardised clinical assessment including structured, videotaped clinical examination, tremor neurophysiology study of both upper limbs using accelerometry and surface EMG, and Technitium-99 m TRODAT-1 brain SPECT imaging. Normalised striatal uptake values were calculated. Tremor EMG and accelerometry time series were processed with Fourier transformation to identify peak tremor power within a window of 3–10Hz and to calculate the tremor stability index (TSI). ResultsSpearman correlation analyses revealed an association between tremor power and contralaterally reduced striatal uptake in a number of recording conditions. This association was strongest for rest tremor, followed by postural tremor, with the weakest association observed for kinetic tremor. Lower TSI was also associated with lower contralateral striatal uptake in a number of rest and postural conditions. ConclusionThese data suggest a relationship between Parkinsonian rest tremor and contralateral reduction in striatal dopamine binding. Use of quantitative neurophysiology techniques may allow the demonstration of clinico-pathophysiological relationships in tremor that have remained occult to previous studies.

Tremor measurements in a 22-year cohort study of workers exposed to hand-held vibrating tools

ObjectivesThe objectives of this cohort study were to evaluate possible long-term effects of occupational exposure to hand-arm vibration (HAV) in terms of increased tremor. The aims were to evaluate whether exposure during follow-up, baseline hand-arm vibration syndrome (HAVS), baseline manual dexterity or current medical conditions or life-style habits might be associated with increased tremor. A further aim was to compare two different activation conditions: postural vs rest tremor.MethodsForty men (current age: 60.4 years) who had previously worked as manual workers in a specialized engineering and construction company enrolled in the study. Their hand functions had been examined in 1994. At the baseline examination, 27 had been diagnosed with HAVS, while 13 were not exposed. The follow-up examination in 2016–2017 comprised the CATSYS Tremor Pen® for measuring postural and rest tremor and the Grooved Pegboard Test for assessing manual dexterity. Blood samples were taken for assessing biomarkers that might have impact on tremor.ResultsNeither cumulative exposure to HAV during follow-up nor HAVS at baseline were associated with increased tremor. A test for manual dexterity at baseline was significantly associated with increased tremor (Tremor Intensity) at follow-up. Blood markers of current medical conditions and tobacco consumption were associated with increased tremor. Rest tremor frequency was higher than postural tremor frequency (p < 0.001).ConclusionsThe main findings of this 22-year cohort study were no indications of long-term effects on tremor related to HAV exposure and previous HAVS status. However, baseline manual dexterity was significantly associated with increased tremor at follow-up. Activation conditions (e.g., hand position) are important when testing tremor.

Online Censoring Based Weighted-Frequency Fourier Linear Combiner for Estimation of Pathological Hand Tremors

An online censoring (OC) based weighted-frequency Fourier linear combiner (OC-WFLC) adaptive filtering structure is proposed to reduce data processing costs in the estimation of pathological hand tremor (PHT) measurements. The proposed OC-WFLC is combined with the Fourier linear combiner (FLC) to effectively separate the PHT and voluntary movement from the hand tremor signal. The OC-WFLC is shown to adaptively extract the most informative frequency information, that is readily employed within the FLC to adaptively decompose the measurement signal into its PHT and voluntary movement components. The utilization of the OC strategy in the proposed framework is shown to significantly reduce data processing costs without adverse effects on the performance. Simulation results on real-world PHT data demonstrate the ability of the proposed OC-WFLC to yield a dramatic reduction of the processing time, a prerequisite for real-time rehabilitative, wearable, and assistive technology designed for PHT patients.

Imaging Tremor Quantification for Neurological Disease Diagnosis.

In this paper, we introduce a simple method based on image analysis and deep learning that can be used in the objective assessment and measurement of tremors. A tremor is a neurological disorder that causes involuntary and rhythmic movements in a human body part or parts. There are many types of tremors, depending on their amplitude and frequency type. Appropriate treatment is only possible when there is an accurate diagnosis. Thus, a need exists for a technique to analyze tremors. In this paper, we propose a hybrid approach using imaging technology and machine learning techniques for quantification and extraction of the parameters associated with tremors. These extracted parameters are used to classify the tremor for subsequent identification of the disease. In particular, we focus on essential tremor and cerebellar disorders by monitoring the finger–nose–finger test. First of all, test results obtained from both patients and healthy individuals are analyzed using image processing techniques. Next, data were grouped in order to determine classes of typical responses. A machine learning method using a support vector machine is used to perform an unsupervised clustering. Experimental results showed the highest internal evaluation for distribution into three clusters, which could be used to differentiate the responses of healthy subjects, patients with essential tremor and patients with cerebellar disorders.

Novel smart data analysis technologies to differentiate Parkinson’s disease from essential tremor

Smart approach to study the relation between tremor and olfactory malfunction is studied. It is shown that neither olfactory function measurement, nor tremor measurement solely are able to differentiate Parkinson’s disease from essential tremor. On the contrary, the combination of these two medical examination techniques yields reliable discrimination of these two pathologies. Also, the inverse relation pattern between olfactory and tremor is proven. These results are obtained through the implementation of novel smart technique of non-linear clustering based on elastic map method.

Quantitative measures of postural tremor at the upper limb joints in patients with essential tremor.

BACKGROUND: It is important to quantitatively assess tremor for accurate diagnosis and evaluation of the response to interventions in patients with essential tremor (ET).OBJECTIVE: The purpose of this study was to investigate the relationship between quantitative measures of postural tremor and clinical rating scale in patients with ET.METHODS: 18 ET patients performed a postural tremor task that required them to hold their arms outstretched parallel to the floor while wearing a gyro sensor based measurement system. The time domain variables were derived from the sensor signals. Additionally, the frequency domain variables were derived from the power spectrum of the angular velocity signal. Spearman correlation analysis was employed in the relationship between the variables and clinical score.RESULTS: The RMS angular velocity of roll and yaw directions at the hand joint were strongly correlated with the clinical rating scale ( 0.7, 0.01). Similarly, the peak power of roll and yaw directions at the hand joint were moderately correlated with the clinical rating scale ( 0.61 and 0.67, 0.01). In contrast, no significant correlation coefficients were observed in the peak frequency ( 0.05).CONCLUSION: These results indicate that hand tremor of roll and yaw directions are more associated with assessment of severity of ET compared to other joints. This study suggests that quantitative measurements of postural tremor should be considered as tremor directionality as well as attachment location.

The Effects of Long-Term 40-Hz Physioacoustic Vibrations on Motor Impairments in Parkinson's Disease: A Double-Blinded Randomized Control Trial.

Recent studies have suggested that vibration therapy may have a positive influence in treating motor symptoms of Parkinson’s disease (PD). However, quantitative evidence of the benefits of vibration utilized inconsistent methods of vibration delivery, and to date there have been no studies showing a long-term benefit of 40 Hz vibration in the PD population. The objective of this study was to demonstrate the efficacy of vibration administered via a physioacoustic therapy method (PAT) on motor symptoms of PD over a longer term, completed as a randomized placebo-controlled trial. Overall motor symptom severity measured by the Unified Parkinson’s Disease Rating Scale III showed significant improvements in the treatment group over 12 weeks. Specifically, all aspects of PD, including tremor, rigidity, bradykinesia, and posture and gait measures improved. To our knowledge, this is the first study to quantitatively assess 40-Hz vibration applied using the PAT method for potential long-term therapeutic effects on motor symptoms of PD.

Pose and Optical Flow Fusion (POFF) for accurate tremor detection and quantification

Limb tremor measurements are one factor used to characterize and quantify the severity of neurodegenerative disorders. These tremor measurements can also provide dosage-response feedback to guide medication treatments. Here, we propose a system to automatically measure limb tremors in home or clinic settings. The key feature of proposed method is that it is contactless; not requiring a user to wear or hold a device or marker. Our sensor is a Kinect 2, which measures color and depth and estimates rough limb motion. We show that its pose accuracy is poor for small limb tremors below 10 mm amplitude, and so we propose an additional level of tremor tracking that recovers limb motion at a higher precision. Our method upgrades the sensitivity to achieve detection and analysis for tremors down to 2 mm amplitude. We include empirical experiments and measurements showing improved tremor amplitude and frequency estimation using our proposed Pose and Optical Flow Fusion (POFF) algorithm.

Tremorography in fragile X-associated tremor/ataxia syndrome, Parkinson's disease and essential tremor

BackgroundFragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disease affecting carriers of a 55–200 CGG repeat in the fragile X mental retardation 1 gene, may receive an initial diagnosis of Parkinson's disease (PD) or essential tremor (ET) due to overlapping motor symptoms. Therefore, tremor and bradykinesia were compared in these disorders using quantitative tremorography. MethodsThe inertial sensor based Kinesia ™ system was used to quantify upper extremity tremor and bradykinesia in participants with FXTAS (n = 25), PD (n = 23), ET (n = 18) and controls (n = 20) and regression analysis was performed to determine whether tremorography measures distinguished between the groups. The FXTAS Rating scale (FXTAS-RS) was administered to determine whether sub-score items on the clinician rated scale correlated with tremorography variables. ResultsFXTAS participants had reduced finger tap speed compared to those with ET, and ET had increased kinetic tremor compared to PD. Higher kinetic tremor distinguished FXTAS from PD (p = .02), and lower finger tap speed distinguished FXTAS from ET (p = .004). FXTAS-RS tremor and bradykinesia items correlated with tremorography measures (p = .005 to <0.0001). ConclusionsThis is the first quantitative study to compare tremor and bradykinesia in FXTAS, PD and ET. Kinetic tremor and bradykinesia measures using a quantitative inertial sensor system distinguished FXTAS from PD and ET, respectively. Such technologies may be useful for detecting precise tremor and bradykinesia abnormalities and distinguishing the tremor and bradykinesia profiles in each of these disorders.

Effects of ramped-frequency thalamic deep brain stimulation on tremor and activity of modeled neurons

ObjectiveWe conducted intraoperative measurements of tremor to quantify the effects of temporally patterned ramped-frequency DBS trains on tremor. MethodsSeven patterns of stimulation were tested in nine subjects with thalamic DBS for essential tremor: stimulation ‘off’, three ramped-frequency stimulation (RFS) trains from 130 → 50 Hz, 130 → 60 Hz, and 235 → 90 Hz, and three constant frequency stimulation (CFS) trains at 72, 82, and 130 Hz. The same patterns were applied to a computational model of the thalamic neural network. ResultsTemporally patterned 130 → 60 Hz ramped-frequency trains suppressed tremor relative to stimulation ‘off,’ but 130 → 50 Hz, 130 → 60 Hz, and 235 → 90 Hz ramped-frequency trains were no more effective than constant frequency stimulation with the same mean interpulse interval (IPI). Computational modeling revealed that rhythmic burst-driver inputs to thalamus were masked during DBS, but long IPIs, concurrent with pauses in afferent cerebellar and cortical firing, allowed propagation of bursting activity. The mean firing rate of bursting-type model neurons as well as the firing pattern entropy of model neurons were both strongly correlated with tremor power across stimulation conditions. ConclusionFrequency-ramped DBS produced equivalent tremor suppression as constant frequency thalamic DBS. Tremor-related thalamic burst activity may result from burst-driver input, rather than by an intrinsic rebound mechanism. SignificanceRamping stimulation frequency may exacerbate thalamic burst firing by introducing consecutive pauses of increasing duration to the stimulation pattern.

Effects of ventral intermediate nucleus deep brain stimulation across multiple effectors in essential tremor

ObjectiveEssential tremor (ET) prominently affects the upper-limbs during voluntary movements, but can also affect the lower-limbs, head, and chin. Although deep brain stimulation (DBS) of the ventral intermediate nucleus (VIM) of thalamus improves both clinical ratings and quantitative measures of tremor, no study has quantified effects of DBS on tremor across multiple body parts. Our objective was to quantify therapeutic effects of DBS across multiple body parts in ET. MethodsWe performed quantitative assessment of tremor in ET patients who had DBS for at least one year. We assessed tremor on and off VIM-stimulation using triaxial accelerometers on the upper-limbs, lower-limbs, head and chin during seated and standing tasks. ResultsVIM-DBS significantly reduced tremor, but there was no statistical difference in degree of tremor reduction across the measured effectors. Compared to healthy controls, ET patients treated with DBS showed significantly greater tremor power (4–8 Hz) across all effectors during seated and standing tasks. ConclusionsVIM-DBS reduced tremor in ET patients. There was no significant difference in the degree of tremor reduction across the measured effectors. SignificanceThis study provides new quantitative evidence that VIM-DBS is effective at reducing tremor across multiple parts of the body.

How Do I Assess Tremor Using Novel Technology?

Transducers are defined as any sensor that converts a physiological signal of tremor into an electrical signal. Evolving technologies have utilized transducers to develop devices for tremor measurement that are more convenient, accurate, and capable of continuous recording. Transducer-based methods provide valuable diagnostic tools for the clinician that can distinguish between different tremor syndromes and differentiate tremor from other hyperkinetic movement disorders. Transducers are also used to objectively quantify and track tremor symptom severity over time and assess clinical response to intervention (e.g., pharmaceutical treatments or DBS). This video highlights the utility of transducer-based methods in characterizing and quantifying tremor and reviews the available technologies for measuring tremor. We provide case examples that demonstrate how different technology-based measures for tremor direct the approach to diagnosis and management of symptoms.