Types Of Tremor Research Articles

Effect of a Wrist Harmonic Liquid Tremor Absorber-Damping on the Upper Extremity Essential Tremor.

Essential tremor (ET) is a common type of tremor. Previous research has shown that wearable orthoses and biomechanical loading methods can suppress tremors. This study aims to investigate the effect of a harmonic liquid dampener on upper extremity ET. The study involved 9 women and 5 men from a neurology outpatient clinic. A 285-g liquid-based harmonic dampening wristband was used. Tremors were recorded from the wrist along the x-y-z axes using a vibrometer, and the Bain-Findley Rating Scale (BFRS) was employed for assessment. BFRS scores significantly improved after the wristband was used (mean difference 35.64, P = 0.001, Cohen's d effect size =2.979). The tremor amplitude decreased significantly along the x-axis (Cohen's d: 1.35, P = 0.001), y-axis (Cohen's d: 3.232, P = 0.001), and z-axis (Cohen's d: 3.321, P = 0.001). The liquid-filled harmonic dampening wristband shows promise as a new, effective treatment option for ET patients. © 2025 International Parkinson and Movement Disorder Society.

Tremors in cats: 105 cases (2004-2023).

Although tremors are common neurological presentations, there is little known about their clinical features and underlying etiologies in cats. The aim of this study was to evaluate the clinical features, and underlying diagnoses in cats with tremors. We hypothesized that the results of this study would provide clinically useful information for clinicians when evaluating cats with tremors. This is a retrospective, single-center, study of cats with tremors between 2004-2023. Inclusion criteria included complete medical records, presence or report of tremor or twitch, and a final or presumptive diagnosis. One hundred five cats met the inclusion criteria. The most common diagnoses associated with tremors were degenerative encephalopathy (19/105; 18.1%), feline infectious peritonitis (FIP) (17/105; 16.2%), congenital portosystemic shunt (17/105; 16.2%), intoxication (16/105 15.2%) and polyneuropathy (8/105; 7.6%). Most common degenerative encephalopathies were suspected cerebellar cortical degeneration (7/19; 50%) and lysosomal storage diseases (7/19; 50%) and manifested intention head tremors. Intention head tremors were also seen in cats with FIP and thiamine deficiency encephalopathy. Portosystemic shunt tremors were of variable features, focal or generalised, intentional, nonintentional or both. The most common intoxication was permethrin ingestion and was most commonly associated with generalized tremors as the main presenting complaint. The most common type of tremor in cats with a polyneuropathy was a generalised tremor or limb tremor. Different tremor phenotypes occur and are associated with specific underlying diagnoses in cats. This information can aid clinicians on the best way to approach cats with a variety of tremor phenotypes.

Serum Alpha Synuclein Autoantibodies in patients with Essential Tremor

Abstract Essential tremor (ET) is one of the most common neurological disorders. However, there’s no definite ET biomarker and the diagnosis depends on its clinical presentation. Therefore, ET can be easily misdiagnosed with other diseases especially parkinson’s disease (PD). PD, being one of a group of neurodegenerative diseases calked synucleinopathies, can be difficult to differentiate from ET both in the early stages of these diseases and as they progress, since various types of tremors (such as rest, postural, kinetic, and intention tremors) can be observed in both conditions. We aimed to investigate the relation between ET and alpha synuclein (aSyn) protein in patients with ET and healthy controls. We enrolled 32 patients with ET and 32 age and sex matched controls, aiming to investigate serum level of aSyn protein and its autoantibodies. Additionally, we also investigated neuropsychiatric, non-motor symptoms (NMS), and quality of life (QoL) among two groups. The study found that serum aSyn levels in healthy controls are significantly higher than those in ET cases, in the other hand, serum aSyn autoantibodies shows no significant difference between the two groups. Furthermore, we found that patients with ET had more cognitive impairment, higher depression and anxiety, higher frequency of NMS, and lower quality of life than healthy controls. Conclusion: serum aSyn level can differentiate between patients with ET and healthy controls while serum aSyn autoantibodies cannot differentiate between the two groups.

Magma fizz: Tremor during the Kīlauea summit reservoir decompression

Typical eruptions at Kīlauea volcano involve the evacuation of magma from the summit and/or south caldera reservoirs towards the East or Southwest rift zones. The reservoir drainage provokes the summit deflation, and on extreme occasions, such as in 2018, the summit caldera collapse. Systematically, seismic tremor, often with a particular multichromatic spectral signature characterized by frequency gliding, accompanies summit deflation episodes. In 2018, this type of continuous tremor accompanied the steady subsidence stage, whereas discrete earthquakes dominated the collapse stage. In this work, we aim to understand the source mechanism of the syn-deflation tremor of 2018. To locate the seismic source, we develop a novel machine-learning-based algorithm as an alternative to the amplitude source location technique. We use a large high-resolution catalog to resolve a composite amplitude decay function. Under these conditions, our method outperforms the traditional technique. We locate the tremor source 1 km below the eastern perimeter of the Halema‘uma‘u crater, which coincides with the position of the summit magma reservoir, as determined in many other studies. Furthermore, we model the seismic source as pressure oscillations driven by gas porous flow at the roof of the reservoir. In this model, gas accumulates temporarily in many gas pockets between the magma and the roof. Our modeling shows that the gas flux is responsible for the tremor amplitude modulations, whereas the gas pocket thickness controls the frequency variations. Beyond a critical point of depressurization, the magma cannot contribute further to the tremor oscillations via decompression-driven degassing, nor support the roof above it, resulting in rock failure. This work advances our understanding of magma-degassing dynamics and tremor generation at Kilauea volcano, and provides novel seismological techniques for volcano seismology monitoring and research.

What Should be the Anatomical Target in Deep Brain Stimulatıon in an Essential Tremor Plus Rest Tremor Case? Technical Case Report of Deep Brain Stimulation

While Deep Brain Stimulation (DBS) of Subthalamic Nucleus (STN) is effective on resting tremors, but its effectiveness on postural and kinetic tremors is limited. DBS of the Ventral Intermediate Nucleus (VIM) is effective on many types of tremors, especially postural and kinetic tremors, but its effect is weak on motor symptoms in Parkinson’s disease (PD). Although there is a consensus in the literature about where the anatomical target should be in essential tremor (ET) and PD, there are only case reports about where the anatomical target should be in Essential Tremor Plus Rest Tremor (ET+RT) cases.In this article, we aimed to reveal the effectiveness of STN DBS in a case-diagnosed with ET+RT. The patient had action tremors in both upper extremities for 21 years and developed rest tremors in both upper and lower extremities for the last six years. Rest tremor was effectively controlled with bilateral STN DBS. Postural tremor in the right upper extremity was continued, although it decreased.STN may be an appropriate choice when choosing an anatomical target in DBS in cases of resting, postural, and kinetic tremor.

Enhancing the understanding of coinfection outcomes: Impact of natural atypical porcine pestivirus infection on porcine reproductive and respiratory syndrome in pigs

Atypical porcine pestivirus (APPV) is a novel member of the Pestivirus genus detected in association with congenital tremor (CT) type A-II outbreaks and from apparently healthy pigs, both as singular infection and as part of multi-pathogen infections. 'Classical' pestiviruses are known to cause immunosuppression of their host, which can increase susceptibility to secondary infections, severely impacting health, welfare, and production. To investigate APPV's effect on the host's immune system and characterise disease outcomes, 12 piglets from a natural APPV CT type A-II outbreak were experimentally infected with porcine reproductive and respiratory syndrome virus (PRRSV), a significant porcine pathogen. Rectal temperatures indicating febrile responses, viremia and viral-specific humoral and cellular responses were assessed throughout the study. Pathological assessment of the lungs and APPV-PRRSV co-localisation within the lungs was performed at necropsy. Viral co-localisation and pathological assessment of the lungs (Immunohistochemistry, BaseScope in situ hybridisation) were performed post-mortem. APPV status did not impact virological or immunological differences in PRRSV-infected groups. However, significantly higher rectal temperatures were observed in the APPV+ve/PRRSV+ve group over four days, indicating APPV increased the febrile response. Significant differences in the lung consolidation of the apical and intermediate lobes were also present, suggesting that APPV co-infection may augment lung pathology.

Network of Interactions between the Mut Domains of the E2 Protein of Atypical Porcine Pestivirus and Host Proteins.

Atypical porcine pestivirus (APPV) can cause congenital tremor type A-II in neonatal piglets, posing a significant threat to swine herd health globally. Our previous study demonstrated that the Mut domains, comprising 112 amino acids at the N-terminus, are the primary functional regions of the E2 protein of APPV. This study identified 14 host cellular proteins that exhibit potential interactions with the Mut domains of the E2 protein using yeast two-hybrid screening. Using bioinformatics analysis, we discovered that the Mut domains of the E2 protein might exert regulatory effects on apoptosis by modulating energy metabolism within the mitochondria. We also conducted co-immunoprecipitation, glutathione S-transferase pull-down, and immunofluorescence assays to confirm the interaction between the Mut domains of the E2 protein and cathepsin H and signal sequence receptor subunit 4 (SSR4). Ultimately, SSR4 enhanced APPV replication in vitro. In summary, our study successfully elucidated the interactions between the Mut domains of the E2 protein and host cell protein, predicted the potential pathways implicated in these interactions, and demonstrated SSR4 involvement in APPV infection. These significant findings contribute valuable knowledge toward a deeper understanding of APPV pathogenesis and the role of the Mut domains of the E2 protein in this intricate process.

Functional Neurological Disorders Among Patients With Tremor.

Functional neurological disorders (FNDs) are increasingly recognized in the general population and neurology clinics, and there is evidence that patients with neurological disorders are more likely to have a FND. This study was designed to identify the clinical features of FNDs among patients with movement disorders when the two disorders coexist. The clinical histories and video recordings of 150 consecutive patients with tremors were examined: the types of tremor included essential tremor; essential tremor plus; dystonic tremor; tremor associated with dystonia; and drug-induced, myoclonic, orthostatic, task-specific, parkinsonian, Holmes, and unclassified tremor. Using criteria for "possible" and "probable" coexistent FND, clinical features that helped differentiate between functional and other neurological tremors were identified. There were 27 (18%) patients with functional manifestations, and 17 (11% of full sample) of these patients had signs suggestive of comorbid functional tremor. Patients with comorbid functional manifestations were younger at presentation, and these patients had greater severity of tremor, particularly upper limb postural tremor. Functional manifestations were not more commonly observed among patients with any particular type of tremor, except for patients with Holmes tremor, who were more likely to have comorbid functional neurological manifestations. About 18% of patients with diverse types of tremors also had comorbid functional neurological manifestations. Of the coexistent FNDs, functional tremor was the most common. Patients with co-occurring functional and other neurological tremors presented for evaluation at a younger age and had greater severity of arm tremor than those without comorbid functional neurological manifestations.

ПОЗИЦИОНИРОВАНИЯ РАБОЧЕГО ОРГАНА МАНИПУЛЯЦИОННОЙ РЕАБИЛИТАЦИОННОЙ СИСТЕМЫ ПРИ НАЛИЧИИ ТРЕМОРА КУЛЬТИ ЧЕЛОВЕКА

The problem of accurate positioning of objects using an active prosthesis hand is not widely investigated, where many factors can play a significant role in degrading of the prosthesis accuracy. An unorthodox rehabilitation system equipped with manipulator with elastic links aimed to help people without brushes in performing fine tool movements has been developed. In this system, a force/torque sensor is securing a physical hard connection between the stump and the prosthesis. In such human-prosthesis systems many factors contribute to tool positioning error, but when high accuracy is required, the human tremor in the residual stump becomes a key factor affecting the accuracy of the tool fine movements. Mathematical model of this system is developed and the error resulted by stump tremor is isolated. Depending of the force/torque sensor, two control strategies are presented in order to perform high accuracy working organ movement between two points. The first is to use the sensor to collect involuntary stump movements caused by the tremor. The second is to use the sensor as an input for the control system by recording all stump movements. In computer simulation, the effect of three main types of human tremor on the manipulation accuracy of the rehabilitation system is observed. As a result, a positioning accuracy of 0.1 mm is achievable by meeting some design criteria that would element the resonance effect in the system

Detection and Characterization of Seismic and Acoustic Signals at Pavlof Volcano, Alaska, Using Deep Learning

AbstractVolcanic tremor is a semi‐continuous seismic and/or acoustic signal that occurs at time scales ranging from seconds to years, with variable amplitudes and spectral features. Tremor sources have often been related to fluid movement and degassing processes, and are recognized as a potential geophysical precursor and co‐eruptive geophysical signal. Eruption forecasting and monitoring efforts need a fast, robust method to automatically detect, characterize, and catalog volcanic tremor. Here we develop VOlcano Infrasound and Seismic Spectrogram Network (VOISS‐Net), a pair of convolutional neural networks (one for seismic, one for acoustic) that can detect tremor in near real‐time and classify it according to its spectral signature. Specifically, we construct an extensive data set of labeled seismic and low‐frequency acoustic (infrasound) spectrograms from the 2021–2022 eruption of Pavlof Volcano, Alaska, and use it to train VOISS‐Net to differentiate between different tremor types, explosions, earthquakes and noise. We use VOISS‐Net to classify continuous data from past Pavlof Volcano eruptions (2007, 2013, 2014, 2016, and 2021–2022). VOISS‐Net achieves an 81.2% and 90.0% accuracy on the seismic and infrasound test sets respectively, and successfully characterizes tremor sequences for each eruption. By comparing the derived seismoacoustic timelines of each eruption with the corresponding eruption chronologies compiled by the Alaska Volcano Observatory, our model identifies changes in tremor regimes that coincide with observed volcanic activity. VOISS‐Net can aid tremor‐related monitoring and research by making consistent tremor catalogs more accessible.

Do Hand Exercises Influence Physiological Hand Tremor? An Observational Cohort Study on Healthy Young Adults

Physiological hand tremors appear to be one of the most common types of tremors that occur during the lifespan. Activities most prominently affected by hand tremors are those involving the movement of small muscles, such as fine motor skills, which in turn could be influenced by several factors, including lateral dominance. The difference in skills due to lateral dominance is defined as inter-limb imbalance or inter-limb asymmetry. When this asymmetry is attributed to the tremor and the difference in tremor between the limbs, it could be defined as the inter-limb asymmetry of tremors. This study aimed to evaluate the acute effects of wobble-board hand exercise training on the inter-limb asymmetry of tremors. Thirty-two (eighteen males and fourteen females) participants (age: 25.2 ± 2.6 years, weight: 63.9 ± 10.5 kg, height: 1.66 ± 0.8 m, and BMI: 22.8 ± 2.3 kg/m2) were involved in the study. Before (PRE) and after (POST) the wobble-board hand exercises, postural hand tremor was evaluated using a tri-axial accelerometer fixed under the palm. Recordings were taken for 15 s. One-way Analysis of Variance (ANOVA) was used to examine the effects of hand exercises on inter-limb (dominant vs. non-dominant) asymmetry of tremor in testing time (PRE vs. POST) in relation to sex (male vs. female). The statistical significance was set at p < 0.05. Significant differences were found in physiological hand tremors between limbs (dominant vs. non-dominant) in the PRE evaluation (p = 0.03) independently from sex while no differences were found in the POST evaluation. A significant difference emerged in the PRE evaluation for males (p = 0.04) and females (p = 0.03) in relation to the testing time and preferred hand. This difference was no longer present in the POST evaluation. In conclusion, wobble-board hand exercises could represent an effective strategy to reduce inter-limb asymmetry. These results emphasize the importance of task-specific training to maximize the reduction in inter-limb asymmetry of tremors following wobble-board hand exercises.

Development of a New and Mechanically Intelligent Anti-Tremor Utensil

People living with Parkinson’s disease or with essential tremors face many obstacles in their everyday lives. Being able to eat independently is one of them. Many technologies already exist to help people who have difficulty eating independently. However, following a review of existing devices with a team of occupational therapists, it was found that many commercially available solutions were either unhelpful or too expensive. The need for better adapted solutions was obvious so an iterative design methodology based on the user's needs was followed to create a new anti-tremor utensil. The starting point of the design was to analyze the existing utensils to understand better the pros and cons of the available solutions. During the iterative design methodology, several prototypes emerged and led to the creation of the final spoon prototype presented in this paper. A total of 5 different adaptative spoons were designed and are presented in this paper. A sensor-based frequential analysis combined with an occupational therapist review indicates that the proposed prototype is effective against certain types of tremors and that it could potentially help people living with tremor while they eat. The next step of the development will be to test the new prototype with potential users.

Bedside clinical assessment of patients with common upper limb tremor and algorithmic approach.

The diagnostic approach for patients with tremor is challenging due to the complex and overlapping phenotypes among tremor syndromes. The first step in the evaluation of tremor is to identify the tremulous movement and exclude the tremor mimics. The second step is to classify the tremor syndrome based on the characteristics of tremor from historical clues and focused examination (Axis 1). Comprehensive tremor examinations involve the assessment of tremor in different conditions (rest, action or mixed, position or task-specific), distribution of tremor (upper limb, lower limb, head, jaw), positive signs for functional tremor (FT) if suspected (distractibility, entrainment, co-contraction), and associated neurological signs including parkinsonism, dystonic posture, cerebellar/brainstem signs, neuropathy, and cognitive impairment. A pivotal feature in this step is to determine any distinct feature of a specific isolated or combined tremor syndrome. In this review, we propose an algorithm to assess upper limb tremors. Ancillary testing should be performed if clinical evaluation is unclear. The choice of investigation depends on the types of tremors considered to narrow down the spectrum of etiology (Axis 2). Laboratory blood tests are considered for acute onset and acute worsening of tremors, while structural neuroimaging is indicated in unilateral tremors with acute onset, nonclassical presentations, and a combination of neurological symptoms. Neurophysiological study is an important tool that aids in distinguishing between tremor and myoclonus, etiology of tremor and document specific signs of FT. Treatment is mainly symptomatic based depending on the etiology of the tremor and the patient's disabilities.

Quantitative susceptibility mapping and a nonlinearly transformed atlas for targeting the ventral intermediate nucleus of the thalamus in a patient with tremor and thalamic hypertrophy: illustrative case.

The ventral intermediate nucleus (Vim) of the thalamus is a surgical target for treating various types of tremor. Because it is difficult to visualize the Vim using standard magnetic resonance imaging, the structure is usually targeted based on the anterior and posterior commissures. This standard targeting method is practical in most patients but not in those with thalamic asymmetry. The authors examined the usefulness of quantitative susceptibility mapping (QSM) and transformed Vim atlas images to estimate the Vim localization in a patient with tremor and significant thalamic hypertrophy. A 51-year-old right-handed female had experienced a predominant left-hand action tremor for 6 years. Magnetic resonance imaging showed significant hypertrophy of the right thalamus and caudal shift of the thalamic ventral border. The authors referred to the QSM images to localize the decreased susceptibility area within the lateral ventral thalamic nuclei to target the Vim. In addition, the nonlinearly transformed Vim atlas images complemented the imaging-based targeting. The radiofrequency thalamotomy at the modified Vim target relieved the tremor completely. A combination of QSM and nonlinear transformation of the thalamic atlas can be helpful in the targeting method of the Vim for tremor patients with thalamic asymmetry.

The Effect of Oropharyngeal Resting Tremor on Swallowing Function in a Clinical Cohort of People with Parkinson's Disease.

Parkinson's Disease (PD) is a progressive neurodegenerative disease, with hallmark symptomology typically consisting of tremor, bradykinesia, and rigidity. Though the classic "pill-rolling" rest tremor in the hand or upper limb are often the most salient, it can occur throughout the body including the lower limbs, jaw, face, or tongue. There have been investigations into other motor related phenomena potentially affecting swallow function in PwPD previously. However, there have been no investigations of how oropharyngeal resting tremor in structures such as the tongue or larynx explicitly affects swallowing physiology. A retrospective analysis of previously conducted VFSS on 34 patients diagnosed with idiopathic PD (IPD) was performed to examine how individuals that displayed resting tremor during VFSS (Tremor +) and those who did not (Tremor-) differ in swallowing function. Measures of swallowing function including timing intervals of key swallow events, post-swallow residue, and penetration-aspiration scale (PAS) scores were recorded, and key demographic information including time since diagnosis and medication status were extracted from the medical records available. Multivariate models were used to identify differences between tremor groups for timing intervals and post-swallow residue, and chi-squares were computed for differences in PAS score distribution by group and bolus. Sixty-eight percent (23/34) of this sample displayed oropharyngeal resting tremor in at least one structure during VFSS. There were no instances of other tremor types observed in this sample. All participants were taking medication to manage PD symptomology. Significant effects of tremor group were observed for swallow timing intervals related to airway closure (p < 0.001), post-swallow residue (p < 0.05), and swallow safety at the bolus level in the Tremor + group (p < 0.001). These results suggest that PwPD who present with resting tremor in oropharyngeal structures may manifest with different variations in swallowing physiology, including altered timings of swallow events, increased pharyngeal residue, and greater associations of airway invasion with thinner and larger volume boluses. This study highlights the need for substantially more research into how motor fluctuations and phenotypes of PwPD contribute to alterations in swallowing function.

Expression of human Ras-related protein Rab39B variant T168K in Caenorhabditis elegans leads to motor dysfunction and dopaminergic neuron degeneration

Human RAB39B gene is related to familial early-onset Parkinson disease. In early adulthood, men with the RAB39B c.503C > A (Thr168Lys, p. T168K) mutation develop typical tremor, bradykinesia, and alpha-synuclein accumulation. We investigated the pathological mechanism of RAB39B T168K in a Caenorhabditis elegans model. In early adult C. elegans, RAB39B T168K led to dopaminergic neuron degeneration that presented as disrupted dendrites and blunt neuronal cells. Abnormal dopamine secretion was inferred from a decline in motor function and a positive basal slowing phenotype. Dopamine-associated tests confirmed that synthesis and recycling of dopamine were normal. The RAB39B T168K mutation might impair dopamine vesicular transmission from the presynaptic membrane to the synaptic gap in dopaminergic neurons. The release-dependent feedback mechanism in neurotransmitters regulates the balance of receptor activities. Protein-protein interactions network analysis revealed that RAB39B may also function in lysosomal degradation and autophagy. Impaired disposal of misfolded α-synuclein eventually leads to protein aggregation. Thus, like other members of the Rab family, RAB39B may be involved in vesicular transport associated with dopamine secretion and α-synuclein clearance.

Tremor: A systematic approach.

Tremor is a common but complex involuntary movement disorder often first assessed by general practitioners (GPs). Due to its diverse causes and manifestations, an accurate assessment of a patient's tremor helps guide initial investigations and treatments. The purpose of this paper is to equip GPs with a framework for the identification, diagnosis and management of different types of tremors. This paper offers a comprehensive, current overview of tremor assessment in general practice. It particularly focuses on Parkinson's disease, essential tremor syndrome and dystonic tremor, while highlighting diagnostic masquerades and red flags for urgent neurological evaluation.

Pose-based tremor type and level analysis for Parkinson's disease from video.

Current methods for diagnosis of PD rely on clinical examination. The accuracy of diagnosis ranges between 73 and 84%, and is influenced by the experience of the clinical assessor. Hence, an automatic, effective and interpretable supporting system for PD symptom identification would support clinicians in making more robust PD diagnostic decisions. We propose to analyze Parkinson's tremor (PT) to support the analysis of PD, since PT is one of the most typical symptoms of PD with broad generalizability. To realize the idea, we present SPA-PTA, a deep learning-based PT classification and severity estimation system that takes consumer-grade videos of front-facing humans as input. The core of the system is a novel attention module with a lightweight pyramidal channel-squeezing-fusion architecture that effectively extracts relevant PT information and filters noise. It enhances modeling performance while improving system interpretability. We validate our system via individual-based leave-one-out cross-validation on two tasks: the PT classification task and the tremor severity rating estimation task. Our system presents a 91.3% accuracy and 80.0% F1-score in classifying PT with non-PT class, while providing a 76.4% accuracy and 76.7% F1-score in more complex multiclass tremor rating classification task. Our system offers a cost-effective PT classification and tremor severity estimation results as warning signs of PD for undiagnosed patients with PT symptoms. In addition, it provides a potential solution for supporting PD diagnosis in regions with limited clinical resources.

Tremor in Spinocerebellar Ataxia: A Scoping Review.

Spinocerebellar ataxia (SCA) denotes an expanding list of autosomal dominant cerebellar ataxias. Although tremor is an important aspect of the clinical spectrum of the SCAs, its prevalence, phenomenology, and pathophysiology are unknown. This review aims to describe the various types of tremors seen in the different SCAs, with a discussion on the pathophysiology of the tremors, and the possible treatment modalities. The authors conducted a literature search on PubMed using search terms including tremor and the various SCAs. Relevant articles were included in the review after excluding duplicate publications. While action (postural and intention) tremors are most frequently associated with SCA, rest and other rare tremors have also been documented. The prevalence and types of tremors vary among the different SCAs. SCA12, common in certain ethnic populations, presents a unique situation, where the tremor is typically the principal manifestation. Clinical manifestations of SCAs may be confused with essential tremor or Parkinson's disease. The pathophysiology of tremors in SCAs predominantly involves the cerebellum and its networks, especially the cerebello-thalamo-cortical circuit. Additionally, connections with the basal ganglia, and striatal dopaminergic dysfunction may have a role. Medical management of tremor is usually guided by the phenomenology and associated clinical features. Deep brain stimulation surgery may be helpful in treatment-resistant tremors. Tremor is an elemental component of SCAs, with diverse phenomenology, and emphasizes the role of the cerebellum in tremor. Further studies will be useful to delineate the clinical, pathophysiological, and therapeutic aspects of tremor in SCAs.

Wearable Accelerometer and Gyroscope Sensors for Estimating the Severity of Essential Tremor.

Several validated clinical scales measure the severity of essential tremor (ET). Their assessments are subjective and can depend on familiarity and training with scoring systems. We propose a multi-modal sensing using a wearable inertial measurement unit for estimating scores on the Fahn-Tolosa-Marin tremor rating scale (FTM) and determine the classification accuracy within the tremor type. 17 ET participants and 18 healthy controls were recruited for the study. Two movement disorder neurologists who were blinded to prior clinical information viewed video recordings and scored the FTM. Participants drew a guided Archimedes spiral while wearing an inertial measurement unit placed at the mid-point between the lateral epicondyle of the humerus and the anatomical snuff box. Acceleration and gyroscope recordings were analyzed. The ratio of the power spectral density between frequency bands 0.5-4 Hz and 4-12 Hz, and the sum of power spectrum density over the entire spectrum of 2-74 Hz, for both accelerometer and gyroscope data, were computed. FTM was estimated using regression model and classification using SVM was validated using the leave-one-out method. Regression analysis showed a moderate to good correlation when individual features were used, while correlation was high ([Formula: see text] = 0.818) when suitable features of the gyro and accelerometer were combined. The accuracy for two-class classification of the combined features using SVM was 91.42% while for four-class it was 68.57%. Potential applications of this novel wearable sensing method using a wearable Inertial Measurement Unit (IMU) include monitoring of ET and clinical trials of new treatments for the disorder.