Tremor Parameters Research Articles

Effect of Partial Deafness on Voice in Children

Elevated hearing thresholds cause disturbances in auditory control of voice. This leads to voice disorders that are described by changes in acoustic parameters of voice measured objectively. Voice changes can also be detected by perceptive assessment with GRBAS scale.This article presents the results of the study performed to analyze voice characteristics in a group of children with prelingual partial deafness (PD), a condition with normal hearing at low frequencies and deep hypoacusis (near deafness) at high frequencies. Voice disorders accompanying partial deafness were not a subject of the intensive study before, therefore our study provides valuable data and help to understand more complex clinical aspects of PD.The study showed that voice characteristics in children with PD differs from children with normal hearing and shows some differences compared to voice of children with other types of hearing impairment. Major changes in PD are seen in frequency (F0, vF0), amplitude (vAm, sAPQ), noise (NHR), and tremor (FTRI) parameters. The changes were present in all groups of objective measures, which makes a difference versus normal hearing; however the most significant changes were seen in a narrower range of parameters compared to children in other types of hearing impairment.Objective parameters correlate with the subjective features of voice of children with partial deafness. With use of GRBAS scale, subjective voice assessment showed elevated indices of grade, roughness, breathy, asthenic and strained voice, which described slightly harsh, breathy, dull, and a little tensed voice.

Akustičke karakteristike glasa kod odraslih osoba sa depresivnim poremećajem

In order to examine the differences in people suffering from depression (EG, N=18) compared to the healthy controls (CG1, N=24) and people with the diagnosed psychogenic voice disorder (CG2, N=9), nine acoustic features of voice were assessed among the total of 51 participants using the MDVP software programme ("Kay Elemetrics" Corp., model 4300). Nine acoustic parameters were analysed on the basis of the sustained phonation of the vowel /a/. The results revealed that the mean values of all acoustic parameters differed in the EG compared to both the CG1 and CG2 as follows: the parameters which indicate frequency variability (Jitt, PPQ), amplitude variability (Shim, vAm, APQ) and noise and tremor parameters (NHR, VTI) were higher; only the parameters of fundamental frequency (F0) and soft index phonation (SPI) were lower (F0 compared to CG1, and SPI compared to CG1 and CG2). Only the PPQ parameter was not significant. vAm and APQ had the highest discriminant value for depression. The acoustic features of voice, analysed in this study with regard to the sustained phonation of a vowel, were different and discriminant in the EG compared to CG1 and CG2. In voice analysis, the parameters vAm and APQ could potentially be the markers indicative of depression. The results of this research point to the importance of the voice, that is, its acoustic indicators, in recognizing depression. Important parameters that could help create a programme for the automatic recognition of depression are those from the domain of voice intensity variation.

Phonatory Characteristics of Male Patients with Classic Essential Tremor.

Voice tremor (VT) is one of the characteristics of essential tremor (ET). This study was designed to describe the group and phonatory characteristics of classic ET patients with VT. This retrospective case-control study compared classic ET patients with age and sex-matched controls. The ET population was subgrouped based on auditory perceptual voice analysis. Electroglottography and acoustic voice samples obtained from both groups were analyzed for contact quotient (CQ) and multidimensional voice program parameters, i.e., fundamental frequency (F0), perturbation, noise, and tremor parameters. The CQ, F0, perturbation, noise, and tremor characteristics significantly increased from the moderate VT group to the severe VT group. The CQ, F0, and noise characteristics reflected the vocal folds' functionality. The perturbation and tremor parameters variation were reasoned considering the tremor-related changes occurring in the laryngeal, vocal tract, and expiratory muscles in patients with ET. Thus, phonatory analysis may help in monitoring the progression of ET.

Using Machine Learning for Predicting the Best Outcomes With Electrical Muscle Stimulation for Tremors in Parkinson's Disease.

Recent studies have identified that peripheral stimulation in Parkinson’s disease (PD) is effective in tremor reduction, indicating that a peripheral feedback loop plays an important role in the tremor reset mechanism. This was an open-label, quasi-experimental, pre- and post-test design, single-blind, single-group study involving 20 tremor-dominant PD patients. The objective of this study is to explore the effect of electrical muscle stimulation (EMS) as an adjunctive treatment for resting tremor during “on” period and to identify the best machine learning model to predict the suitable stimulation level that will yield the longest period of tremor reduction or tremor reset time. In this study, we used a Parkinson’s glove to evaluate, stimulate, and quantify the tremors of PD patients. This adjustable glove incorporates a 3-axis gyroscope to measure tremor signals and an EMS to provide an on-demand muscle stimulation to suppress tremors. Machine learning models were applied to identify the suitable pulse amplitude (stimulation level) in five classes that led to the longest tremor reset time. The study was registered at the www.clinicaltrials.gov under the name “The Study of Rest Tremor Suppression by Using Electrical Muscle Stimulation” (NCT02370108). Twenty tremor-dominant PD patients were recruited. After applying an average pulse amplitude of 6.25 (SD 2.84) mA and stimulation period of 440.7 (SD 560.82) seconds, the total time of tremor reduction, or tremor reset time, was 329.90 (SD 340.91) seconds. A significant reduction in tremor parameters during stimulation was demonstrated by a reduction of Unified Parkinson’s Disease Rating Scale (UPDRS) scores, and objectively, with a reduction of gyroscopic data (p < 0.05, each). None of the subjects reported any serious adverse events. We also compared gyroscopic data with five machine learning techniques: Logistic Regression, Random Forest, Support Vector Machine (SVM), Neural Network (NN), and Long-Short-Term-Memory (LSTM). The machine learning model that gave the highest accuracy was LSTM, which obtained: accuracy = 0.865 and macro-F1 = 0.736. This study confirms the efficacy of EMS in the reduction of resting tremors in PD. LSTM was identified as the most effective model for predicting pulse amplitude that would elicit the longest tremor reset time. Our study provides further insight on the tremor reset mechanism in PD.

Automated complex for remote medical examination

Elements of telemedicine are increasingly being introduced into all spheres of medical services for the population. One promising example is automated systems for remote pre-trip medical examination of drivers. However, most of the telemedicine systems used only control the basic parameters of the body provided for by law. An urgent task is to create methods and tools for a comprehensive assessment of the driver's health based on processing of a set of biomedical signals and data that allow tracking the dynamics of the functional and psychoemotional status. Purpose – development of an automated system for remote medical examination of drivers, which allows not only to monitor basic health indicators for admission to a flight, but also to track indirect signs of fatigue, stress and exposure to psychoactive substances that can provoke inappropriate behavior on the road. A microprocessor-based system for collecting and preliminary processing of information received from a set of biomedical sensors has been developed. The original modules for measuring blood pressure and pulse, non-contact temperature measurement and tremor parameters evaluating have been implemented. The set of diagnostic procedures for the pre-trip examination is implemented in a unified cycle, which ensures the complexity of the interpretation of the results. The developed automated complex and the hardware and software tools included in it can be used to conduct pre-trip examinations of drivers of public and special transport, providing an increase in the diagnostic efficiency of identifying signs that are risk factors when the driver is allowed to work.

A Smart Ink Pen for the Ecological Assessment of Age-Related Changes in Writing and Tremor Features

We present the development of a novel smart ink pen instrumented with force and motion sensors designed for the quantitative and ecological assessment of daily-life handwriting. This work aims at testing the pen’s sensors and algorithms and the use of the smartpen to detect age-related changes in writing and tremor parameters during daily-life handwriting. A comparison against reference instruments was carried out to validate the pen tip force during static and dynamic conditions, the pen’s tilt angle, and the algorithm for the segmentation of the force signal into strokes. The smartpen was tested on 43 healthy adults divided into three age groups (young, middle-old, and old) during unconstrained handwriting on paper. The validation of the pen’s sensors and algorithms reported excellent results. A solid test–retest reliability was found in the writing and tremor indicators extracted from both young and old adults. As for the age-related analysis, the older age groups were characterized by an increase of temporal writing measures, a more uniform writing pressure, and more repetitive and predictable tremor oscillation components. The greatest accomplishment of our smart ink pen is the ability to combine the advantages of the digitizing tablet technology with the natural “feel,” the ease of use, and the ecological validity of the traditional pen-and-paper approach. The proposed solution represents an important step toward a simple, ecologically valid, reliable quantitative assessment of daily-life handwriting. Our smartpen is particularly suitable for daily-life telemonitoring applications in a number of important health-related fields.

The Pathophysiology of Dystonic Tremors and Comparison With Essential Tremor

There are two types of dystonic tremor syndromes (DTS), dystonic tremor (DT) and tremor associated with dystonia (TAWD), and neither is understood. DTS likely share some mechanisms with nontremulous dystonia, and there may also be overlaps with essential tremor (ET). We studied 21 ET (8 females, 13 males) and 22 DTS human patients (10 females, 12 males), including 13 human patients with DT (writer's cramp with writing tremor) and 9 human patients with tremor associated with dystonia (TAWD; cervical dystonia with hand tremor). Tremors were analyzed using accelerometry and surface EMG of the antagonist pairs of arm muscles during posture, simple kinetic movement, and writing. Cerebellar inhibition was performed to assess cerebello-thalamo-cortical involvement. DT exhibited higher variability of peak frequency and greater instability of tremor burst intervals over time (higher tremor stability index) than ET or TAWD regardless of tasks. Intermuscular coherence magnitude between the antagonist pairs increased during the writing task in DT, but not ET or TAWD. ET and TAWD exhibited different phase relationships of the temporal fluctuations of voluntary movement and tremor in the kinetic condition. A linear discriminant classifier based on these tremor parameters was able to distinguish the three groups with a classification accuracy of 95.1%. Cerebellar inhibition was significantly reduced in DT, but not in TAWD, compared with ET and healthy controls. Our study shows that the two DTS are distinct entities with DT closer to nontremorous dystonia and TAWD closer to ET.SIGNIFICANCE STATEMENT This study provides novel findings about characteristics and pathophysiology of the two different types of dystonic tremor syndromes compared with essential tremor. Patients with DTS are classified into DT who have dystonia and tremor in the same area, and tremor associated with dystonia (TAWD) who have dystonia and tremor elsewhere. Our results showed that DT exhibits increased tremor variability, instability, and intermuscular coherence, and decreased cerebello-thalamo-cortical inhibition compared with TAWD. Our study shows that DT and TAWD are distinct phenotypes, and that the physiological characteristics of DT are more similar to nontremorous dystonia, and TAWD is closer to ET.

Transition from passive to pre-extrusion degassing of ascending andesitic magma before the lava dome-building eruption as derived from the seismic signals and tilt changes: Volcán de Colima, México, August–September 2004

Volcanoes emit volcanic gas during various types of activity. In the case of andesitic and dacitic volcanoes the high viscosity of silicic magma inhibits the release of volatiles. This increases the possibility that gas escape will occur explosively. The explosive emission of volatile constituents, presented in magmas, generates the seismic signals which may give information about the process of degassing at different stages of eruption. Transition between the eruptive episodes of lava dome-building at andesitic volcanoes represents the transition from passive degassing of the final stage of one episode to pre-extrusion degassing of the next episode. In this article we use the seismic parameters of volcanic explosions, volcanic tremor and micro-explosions, recorded at Volcán de Colima during August–September 2004, to describe the process of transition from passive to pre-extrusion degassing from episode 2 (May 2001–September 2004) to episode 3 (30 September 2004–January 2007). Variations in the tilt changes allowed us to identify three periods in development of this transition: period of passive degassing at the final stage of episode 2 (until 6 September) and two periods of pre-extrusive degassing at the initial stage of episode 3 defined by processes of inflation and deflation of volcanic structure from 6 to 30 September. Intensity of degassing of magma, expressed in the energy of volcanic explosions, decreased during transition from passive to pre-extrusive stages. During pre-extrusion periods of inflation and deflation of volcanic structure the depths of explosive events became shallower. Period of deflation was characterized also by a dominance of degassing processes occurring within the permeable cap of ascending magma and generating volcanic tremors and swarms of micro-earthquakes. Comparison of degassing of magma during pre-extrusive period and co-extrusive and post-extrusive periods showed the similarity in intensity of degassing of magma during the pre-extrusive and co-extrusive periods but a sharp increase in degassing intensity during the post-extrusive period of lava dome destruction with large explosions. It was shown also minor intensity of degassing processes just preceding the beginning of the lava dome building comparing with intensity of degassing processes just preceding the beginning of the lava dome destruction with great explosions.

Tremorography in the clinical practice

Tremor is the most common type of movement disorders. In practice this differential diagnosis of hyperkinesis is diagnosed clinically and the use of additional methods of objective assessment of tremor increases the accuracy of diagnosis. The use of paraclinical methods of objective assessment of tremor improves the accuracy of diagnosis. Comparison of the neurophysiological parameters of tremor with clinical characteristics has a high diagnostic value, which justifies its use in the routine practice of neurologists. The purpose of the review is to analysis basic electrophysiological characteristics of pathological tremor, as well as the presentation of the material of its own observation.

A novel approach to differential diagnosis of Parkinson's disease and essential tremor

To study tremor and olfactory dysfunction in patients with Parkinson's disease (PD), patients with essential tremor and healthy people for the differential diagnosis and to verify the hypothesis on the inverse dependence between tremor and olfactory dysfunction. Olfactory dysfunction was studied in 45 patients with PD, 40 patients with essential tremor and 64 healthy controls. Tremor was studied in 90 people, including 30 controls and 30 patients with PD and essential tremor. The olfactory function was tested with Sniffin' Sticks test. Tremor parameters were studied with wireless monitoring instrument for electrophysiological signals record, where three essential data flows have been recorded: electromyogram, gyroscope and acceleration. The instrument recorded the frequency and amplitude of each parameter. The data were analyzed with IBM SPSS Statistica 2.3 software using standard methods. Besides, non-linear statistics using ViDaExpert software with elastic map technique was utilized. The elastic map perfectly separated the patients with PD and essential tremor, as well as healthy controls. Three clusters were observed. The analysis of composition of the clusters proved the better quality of olfactory function of the patients with essential tremor compared to the patients with PD. This bias confirms the hypothesis on the inverse dependence between the tremor level and olfactory dysfunction.

Digital medicine technologies for pre-trip medical examination of drivers

The technologies of automation of pre-trip integrated examination of the drivers’ conditions are considered, which make it possible to significantly improve the quality of control while reducing the time for its passage. A comparative analysis of known analogues is carried out, problems are formulated, the solution of which will increase the diagnostic efficiency of telemedicine examination. The configuration of the developed computer control system and the hardware-software structure of the subject’s control panel are described. The ways of increasing the reliability of user identification are considered. Technical means have been developed for non-contact thermometry and assessment of tremor parameters. Algorithms for assessing the physiological and psychoemotional state of drivers have been implemented.

Impact of seismic-type shock parameters on the soil-structure interaction effect in the USC mining region

The paper deals with seismic-type surface and building vibrations randomly occurring as a result of rockbursts in mining regions (random events as with earthquakes). The focus is on the problem of ground vibrations transmission to building foundation – it is one of very important phenomenon associated with soil-structure interaction effect. One of the ways of estimation of possible differences between simultaneously developing free-field vibrations next to a building and building foundation vibrations, i.e. using a ratio of response spectra (RRS), is applied to this study. Analysis concerns the ratio of dimensionless and dimensional acceleration response spectra (β and Sa) – denoted as RRS(β) and RRS(Sa), respectively. Horizontal vibrations parallel to the transverse (x) and longitudinal (y) axis of the representative (typical) two-storey, masonry office building are discussed. Calculations are based on the results of in situ surface vibration measurements performed in the seismically active Upper Silesian Coalfield (USC) mining area in Poland (long-term, full-scale monitoring). Evaluation of the dependence of the curves of ratio of response spectra on some parameters corresponding to mine-induced vibrations (i.e. epicentral distance, mining shock energy, peak value of free-field vibrations) is executed. From the obtained results, it can be definitely concluded that the influence of the most important mining tremor parameters (i.e. epicentral distance, mining shock energy, peak value of free-field vibrations) on the ratio of response spectra calculated in the successive ranges of these parameters, is clearly observed.

Tensometric tremorography in high-precision medical diagnostic systems.

BackgroundThe objective of the study was to develop a system for the precision diagnostics of pathologies of motor brain regions based on tensometric measurement and to explore its diagnostic capabilities.Materials and methodsTremor is a syndrome that indicates the abnormal state of the central nervous system, primarily in the motor brain regions. Analysis of tremor parameters provides significant information about the changes in the body motion control and can be used as an objective index of the central nervous system state. Existing methods are aimed at the analysis of visible tremor based on the use of different sensors. We suggest an alternative approach based on the use of a tensometric system performing tremor measurements when the tremor appears on the background of voluntary isometric efforts. The key advantage of our approach is that it allows to determine the tremor before its visible manifestation. In the article, we describe hardware implementation of our tremor analysis system.ResultsIn the article, we represent the new methodology and the original equipment based on the control of isometric effort. Isometric effort formed by a patient is controlled with the use of a feedback system on the patient’s monitor. We evaluated the performance of our equipment with more than 400 healthy volunteers and patients with various pathologies of the central nervous system motor regions, and the results of the investigations, allowing to identify tremor parameters typical for parkinsonism, are represented in our article.ConclusionTesting of the system confirmed its high diagnostic validity and reliability, high sensitivity, simplicity and high speed of information processing. The approach based on tensometric measurements is very promising for the diagnostics of Parkinson disease and dysfunctions of a central nervous system.

Quantitative Analysis of Parkinsonian Tremor in a Clinical Setting Using Inertial Measurement Units.

Background Parkinson's disease (PD) is a neurodegenerative disorder that affects human voluntary movements. Tremor is one of the most common symptoms of PD and is expressed as involuntary oscillation of the body. Tremors can be analysed in the frequency domain. Objective The aim of the current study was to examine selected tremor parameters (frequency, root mean square, and approximated entropy) in order to quantify the characteristics of patients diagnosed with PD, compared to a healthy control group, and to compare the parameters by dividing the subjects according to UPDRS assessment. Methods The subjects were divided into two groups: a group of people diagnosed with PD (n = 19) and a control group consisting of healthy volunteers (CO = 12). Each subject performed motor tasks specific to certain tremors: the finger-to-nose test. Each subject performed a motor task three times. A nine degree of freedom (DOF) wireless inertial measurement unit was used for the measurement of upper limb motor tasks. For the quantitative estimation of kinetic and postural tremors, dominant frequency, root means square, and approximation entropy were selected and calculated from the measured angular velocity and linear acceleration signals. A one-way ANOVA with a significance level of α = 0.05 was used to test the null hypothesis that the means of the tremor metrics were the same between the PD and CO groups. Results Statistically significant differences between PD patients and control groups were observed in ApEn acceleration signal of kinetic tremor, ApEn angular velocity signal of kinetic tremor, ApEn angular velocity of postural tremor, frequency acceleration signal of postural tremor, and RMS angular speed kinetic tremor. Conclusion Application of inertial measurement units for clinical research of patients and PD tremor evaluation allows providing quantitative information for diagnostic purposes, during screening in a clinical setting that differentiates between PD patients and controls.

Clinical, electrophysiological, and imaging study in essential tremor-Parkinson's disease syndrome

IntroductionEssential tremor-Parkinson's disease (ET-PD) syndrome is a clinical condition in which individuals with a long-lasting history of Essential tremor (ET) eventually develop Parkinson's disease (PD). The aim of the study was to investigate the accuracy performances of clinical, neurophysiological, and imaging biomarkers in differentiating patients affected by ET-PD syndrome from patients with ET or PD. MethodsNineteen patients affected by ET-PD syndrome, 48 ET patients, and 37 tremor-dominant PD (t-PD) patients were included. Electrophysiological studies, including blink-reflex recovery cycle and tremor parameters analyses, were performed in all groups. Nigro-striatal and cardiac sympathetic denervation were also investigated. Sensitivity, specificity and accuracy of clinical, electrophysiological, and radiological features in differentiating ET-PD syndrome from ET and PD were calculated. ResultsET-PD patients had significantly lower rigidity (p = 0.007) and higher postural/kinetic tremor (p = 0.007) scores, in comparison to t-PD patients. ET-PD patients, differently from PD patients, had a synchronous pattern of resting tremor and, differently from ET patients, had abnormal blink-reflex recovery cycle. ET-PD patients also showed reduced nigro-striatal and cardiac sympathetic uptakes, albeit to a lesser extent than in PD patients. The highest accuracy values were found for the synchronous pattern of resting tremor (97.1%) in distinguishing ET-PD from PD, and for presence of abnormal blink-recovery cycle (100%) in distinguishing ET-PD syndrome from ET. ConclusionOur study demonstrates that some electrophysiological parameters, such as a synchronous resting tremor pattern and the abnormal blink-recovery cycle were the most accurate biomarkers in distinguishing patient with ET-PD syndrome from those with ET or those with PD.

The Effect of Deep Brain Stimulation (DBS) for Voice Tremor in a Case of Essential Tremor

Patients with voice tremor present with shaking voice which has a frequency of 4-5 Hz in their vocal tract. In most of cases, voice tremor is refractory to conservative treatment such as medication or voice therapy and the symptoms may affect a patient’s quality of life. We experienced a case of voice tremor accompanied by essential tremor of the upper extremities who was treated with bilateral thalamic deep brain stimulation (DBS). The results of an acoustic analysis and laryngeal endoscopic findings showed a partial improvement following unilateral DBS and complete improvement following bilateral DBS. FTRI, Fatr, ATRI, Jitter, Shimmer, vF0, vAm, NHR, sPPQ and sAPQ seemed to be useful parameters of voice tremor. The results suggest that the indication of DBS should be discussed for patients severely affected by voice tremor after considering the patient’s age, accompanying symptoms, backgrounds, occupation and needs.

Tremor's glove-an innovative electrical muscle stimulation therapy for intractable tremor in Parkinson's disease: A randomized sham-controlled trial

BackgroundMedically refractory resting tremor is a debilitating symptom of Parkinson's disease (PD) patients. In our pilot study, modulation of peripheral reflex mechanism by electrical muscle stimulation (EMS) temporarily suppressed tremor. ObjectivesTo investigate the efficacy of EMS, delivered using Tremor's glove, as a treatment of resting hand tremor. Patients and methodsThirty PD patients with medically refractory resting tremor were randomly allocated to a Tremor's glove group (n=15) or a sham glove group (n=15). Gloves were placed on the most tremulous hand for 30min per testing session. Demographics, clinical rating scales, and tremor parameters (RMS of angular velocity and angular displacement, peak magnitude, and frequency) were assessed before and during stimulation. Correlations with validated clinical rating scales were performed. ResultsThere were no statistically significant differences between groups in demographics, rating scales, or tremor parameters. During stimulation, significant reduction in RMS angular velocity (as percentage) in every axis and peak magnitude in axis (x-, y-) and UPDRS tremor score, were found with Tremor's glove compared to the sham groups (p<0.05, each). Significant moderate correlations were observed between a percentage reduction of RMS angular velocity in every axis and UPDRS tremor scores. Mean duration of tremor reduction after stimulation was 107.78±104.15s. No serious adverse events were observed. ConclusionIn this study, EMS-based Tremor's glove was effective in suppressing resting hand tremor in PD patients. Tremor's glove is light-weight with a good safety profile, making it a future potential therapeutic option for PD patients with medically refractory tremor.

S193 The role of the cerebellum in tremor genesis

Objective The role of the cerebellum in tremor genesis is poorly understood. We measured the quantitative parameters of tremor caused by cerebellar/brainstem lesions to determine the relationship between the localisation of the lesion and the tremor characteristics. Methods We recorded the hand tremor of 77 patients using biaxial accelerometry in resting, postural and intentional position. Center frequency, frequency dispersion, proportional power of 0.9–3 Hz range and intensity were determined. Lesions on MRI/CT scans in inferior olive, cerebellar peduncles, dentate nuclei, cerebellar cortex, red nuclei, substantia nigra were investigated. Results Only 30% of patients with cerebellar/brainstem lesions had pathologic tremor. Tremor was present in postural and intentional position and was characterized by narrow frequency dispersion, a center frequency of 2.4 Hz, and normal intensity. Medulla oblongata lesions caused low intensity tremor, whereas mesencephalon lesions enhanced tremor intensity. In most cases tremor recovered within 4–6 weeks. Discussion Cerebellar/brainstem lesions cause pathologic tremor in 1/3 of the cases. Due to its low intensity and low frequency quantitative measurement is necessary to detect this kind of tremor. Tremor induced by acute lesions in the cerebellum/brainstem tends to recover. Conclusions Tremor evoked by structural lesion of the cerebellum/brainstem is related to a widespread network dysfunction rather than a deficit of a well characterised tremor generator. Significance Our study is the first which provides systematic study on the quantitative parameters of tremor caused by cerebellar/brainstem lesion, and on the relationship between tremor characteristics and the localisation of the lesion.

Research of hand tremor vibrations and interference with external me-chanical oscillations source

This paper presents the research of hand tremor vibrations and interference with external mechanical vibrations source. Photogrammetry were used to capture and analyze hand tremor parameters from 8 patient with essential and Parkinson tremors. Blood perfusion device, that creates mechanical vibrations, was used as an external source of mechanical vibrations and was tested with patients. Device interference with hand tremor showed promising results of hand tremor reduction. The minimum points had 16.5 % lower amplitude of hand tremor. The maximum amplitudes were about 50 % greater and these results show the compatibility of the method but the control algorithm needs to be improved. DOI: http://dx.doi.org/10.5755/j01.mech.22.5.16351

Evaluating the electrophysiological features of tremor in Parkinson's disease and essential tremor using accelerometry

Objective: To investigate the electrophysiological features of tremor intensity, frequency and frequency dispersion of Parkinsonian (PT group) and essential (ET group) tremors using accelerometry. Methods: The amplitude, frequency and frequency dispersion of rest tremor, postural tremor and the influence of weight on tremor of 35 PT patients and 40 ET patients in Department of Neurology, the Second Affiliated Hospital Zhejiang University School of Medicine from May 2015 to April 2016 were retrospectively analyzed and compared. Data of the more and less trembling hands were statistically elaborated. Results: In resting, postural and loading states, PT amplitudes of the less affected hand were smaller than the more affected one. The less affected hand were (147±32), (142±36), (157±40)μV, the more affected hand were (185±41), (164±29), (190±33)μV, respectively; ET amplitudes of the less affected hand were also smaller than the more affected one, and the less affected hand were (149±33), (157±33), (169±43)μV, the more affected hand were (176±39), (189±39), (213±36)μV, respectively; PT frequencies of the less affected hand were faster than the more affected one, with the less affected hand (6.1±1.1), (6.4±1.7), (6.5±2.0)Hz, the more affected hand (5.4±1.3), (5.5±1.1), (5.7±1.1)Hz, respectively, but ET frequencies of the less affected hand were similar to the more affected one, with the less affected hand (6.5±1.3), (7.0±1.2), (7.2±1.5)Hz, the more affected hand (7.0±1.0), (7.3±1.0), (7.6±1.1)Hz, respectively; in resting and postural states, PT frequency dispersions of the less affected hand were broader than the more affected one, the less affected hand were (2.1±0.6), (2.4±1.1)Hz, respectively; the more affected hand were (1.6±0.8), (1.7±0.9)Hz, respectively. But in loading state, PT frequency dispersions were similar in both sides (2.3±1.2, 2.2±1.1)Hz; In resting, postural and loading states, ET frequency dispersions were also similar in both two sides, the less affected hand were (2.0±1.1), (2.2±0.9), (1.9±1.0)Hz, the more affected hand were (1.8±0.6), (1.9±0.8), (2.1±0.7)Hz. Conclusions: Tremor intensity is significantly asymmetric both in PT and ET, while frequency and frequency dispersion are symmetric in ET but asymmetric in PT. Bilateral assessment of frequency related tremor parameters may be useful for differentiating ET from PT.