Tremor Rating Research Articles

Transcranial focused ultrasound for the treatment of tremor: A preliminary case series

BackgroundEssential tremor (ET) can be debilitating. Treatments for ET include beta-blockers and surgical interventions. Low-intensity focused ultrasound (LIFU) may offer an office-based non-invasive alternative. ObjectiveThis pilot open label clinical trial explores safety, feasibility, and potential efficacy of LIFU in treatment of ET. MethodsWe report outcomes from the first 10 participants in this IRB-approved trial of LIFU for treatment of ET. The ventral intermediate nucleus of the thalamus (Vim) was targeted using structural and functional MRI. Participants underwent eight 10-min sessions of LIFU targeting the contralateral (Vim) to the most affected hand. Safety was closely monitored; Global Rating of Change (GRC) and The Essential Tremor Rating Scale (TETRAS) scores were collected. ResultsNo adverse effects were reported. Eight participants reported a GRC ≥2. TETRAS performance subscale demonstrated clinically significant improvement in all participants. ConclusionPreliminary findings support LIFU's safety and feasibility. The potential efficacy encourages additional sham-controlled studies.

Essential Tremor and Essential Tremor Plus Are Essentially Similar Electrophysiologically.

The merits of classifying the heterogeneous group of essential tremors into essential tremor (ET) and essential tremor plus (ETP) are debated. We studied the electrophysiological and spiral characteristics of tremor in ET and ETP. We reviewed standardized videos from a tremor database and clinically classified patients into ET, ETP, or dystonic tremor (DT). The following variables were derived from combined tri-axial accelerometry-surface electromyography (EMG)-peak frequency, total power, peak power, full width half maximum, tremor stability index and EMG-coherence. We analyzed hand-drawn spirals to derive mean deviation, tremor variability, inter-, and intra-loop widths. We compared these variables among the groups. We recruited 72 participants (81.9% male) with mean age 47.7 ± 16.1 years and Fahn-Tolosa-Marin Tremor Rating Scale total score 31.1 ± 14.1. Patients with ET were younger (P = 0.014) and had less severe tremor (P = 0.020) compared to ETP and DT. In ETP group, 48.6% had subtle dystonia. Peak frequency was greater in ETP (7.3 ± 0.3 Hz) compared to DT (6.1 ± 0.4 Hz; P = 0.024). Peak power was greater in ETP and DT for postural tremor. Rest tremor was recordable on accelerometry in 26.7% of ET. Other variables were similar among the groups. Electrophysiological evaluation revealed postural tremor of frequency 6 to 7 Hz in ET, ETP, and DT with subtle differences more severe tremor in ETP and DT, and higher frequency in ETP compared to DT. Our findings suggest a similar tremor oscillator in these conditions, supporting the view that these entities are part of a spectrum of tremor disorders, rather than distinct etiological entities.

Clinical benefit of transcutaneous afferent patterned stimulation (TAPS) in essential tremor patients with high unmet need: a secondary analysis of TAPS studies

ABSTRACT Background Transcutaneous afferent patterned stimulation (TAPS) is a noninvasive neuromodulation therapy that improves hand tremor in essential tremor (ET) patients. The benefits of TAPS in ET patients with high unmet need (severe tremor, non-responsive to medication, age ≥65 years) and early responders (substantial TAPS tremor improvement in the first month) remains unknown. Research design and methods Literature was surveyed for TAPS studies to assess the response in the high unmet need subgroup and early responders. Analyses were performed using previously collected Tremor Research Group Essential Tremor Rating Scale (TETRAS) scores, Bain & Findley activities of daily living (BF-ADL) scores, and tremor power. Results Significant differences in BF-ADL and TETRAS improvement were observed with TAPS over sham for the high unmet need subgroup in a randomized controlled study (P<0.03). During a 3-month open-label study, the high unmet need subgroup and early responders showed significant improvements in BF-ADL, TETRAS, and tremor power (P<0.001). Analysis of previous real-world evidence demonstrated that early responders maintained effectiveness and usage at 3 and 12 months (P<0.001). Conclusions TAPS showed comparable improvements in ET with high unmet need as reported in the original studies, and greater efficacy in early responders. These findings inform patient selection and the trial process for identifying TAPS responders.

Deep brain stimulation for essential tremor versus essential tremor plus: should we target the same spot in the thalamus?

Although ET is a phenomenologically heterogeneous condition, thalamic DBS appears to be equally effective across subtypes. We hypothesized stimulation sites optimized for individuals with essential tremor (ET) would differ from individuals with essential tremor plus syndrome (ET-plus). We examined group differences in optimal stimulation sites within the ventral thalamus and their overlap of with relevant white matter tracts. By capturing these differences, we sought to determine whether ET subtypes are associated with anatomically distinct neural pathways. A retrospective chart review was conducted on ET patients undergoing VIM DBS at MUSC between 01/2012 and 02/2022. Clinical, demographic, neuroimaging, and DBS stimulation parameter data were collected. Clinical characteristics and pre-DBS videos were reviewed to classify ET and ET-plus cohorts. Patients in ET-plus cohorts were further divided into ET with dystonia, ET with ataxia, and ET with others. DBS leads were reconstructed using Lead-DBS and the volume of tissue activated (VTA) overlap was performed using normative connectomes. Tremor improvement was measured by reduction in a subscore of tremor rating scale (TRS) post-DBS lateralized to the more affected limb. Sixty-eight ET patients were enrolled after initial screening, of these 10 ET and 24 ET-plus patients were included in the final analyses. ET group had an earlier age at onset (p = 0.185) and underwent surgery at a younger age (p = 0.096). Both groups achieved effective tremor control. No significant differences were found in lead placement or VTA overlap within ventral thalamus. The VTA center of gravity (COG) in the ET-plus cohort was located dorsal to that of the ET cohort. No significant differences were found in VTA overlap with the dentato-rubral-thalamic (DRTT) tracts or the ansa lenticularis. Dystonia was more prevalent than ataxia in the ET-plus subgroups (n = 18 and n = 5, respectively). ET-plus with dystonia subgroup had a more medial COG compared to ET-plus with ataxia. VIM DBS therapy is efficacious in patients with ET and ET-plus. There were no significant differences in optimal stimulation site or VTA overlap with white-matter tracts between ET, ET-plus and ET-plus subgroups.

Accelerometric Classification of Resting and Postural Tremor Amplitude.

Clinical rating scales for tremors have significant limitations due to low resolution, high rater dependency, and lack of applicability in outpatient settings. Reliable, quantitative approaches for assessing tremor severity are warranted, especially evaluating treatment effects, e.g., of deep brain stimulation (DBS). We aimed to investigate how different accelerometry metrics can objectively classify tremor amplitude of Essential Tremor (ET) and tremor in Parkinson's Disease (PD). We assessed 860 resting and postural tremor trials in 16 patients with ET and 25 patients with PD under different DBS settings. Clinical ratings were compared to different metrics, based on either spectral components in the tremorband or pure acceleration, derived from simultaneous triaxial accelerometry captured at the index finger and wrist. Nonlinear regression was applied to a training dataset to determine the relationship between accelerometry and clinical ratings, which was then evaluated in a holdout dataset. All of the investigated accelerometry metrics could predict clinical tremor ratings with a high concordance (>70%) and substantial interrater reliability (Cohen's weighted Kappa > 0.7) in out-of-sample data. Finger-worn accelerometry performed slightly better than wrist-worn accelerometry. We conclude that triaxial accelerometry reliably quantifies resting and postural tremor amplitude in ET and PD patients. A full release of our dataset and software allows for implementation, development, training, and validation of novel methods.

Cognitive impairment in essential tremor assessed by the cerebellar cognitive affective syndrome scale.

Essential tremor (ET) is a movement disorder characterized by cerebellar neurodegenerative changes. ET is also associated with non-motor symptoms including cognitive impairment. The neuropsychologic profile of a patient with ET could relate to cerebellar cognitive affective syndrome (CCAS). This study aimed to assess the prevalence of cognitive impairment in patients with ET and identify whether the cognitive impairment in ET corresponds to a CCAS. Cognitive functions were evaluated with the CCAS-Scale (CCAS-S) in 20 patients with ET and 20 controls matched for age, sex, and level of education. The results of the CCAS-S were compared between patients and controls. The underlying determinant of CCAS inpatients with ET was identified through the correlation between the results of the CCAS-S and age at onset of symptoms, disease duration, and the Essential Tremor Rating Assessment Scale (TETRAS). On a group level, ET patients performed significantly worse than matched controls. In total, 13 individuals with ET had a definite CCAS (CCAS-S failed items ≥ 3). ASO and TETRAS scores significantly correlated with CCAS-S performances in ET patients. CCAS is highly prevalent in patients with ET which supports the cerebellar pathophysiology of associated cognitive impairment and supports a more systematic use of the CCAS-S to cognitively assessed patients with ET.

Medication Status and Related Factors in Essential Tremor Patients: A Cross-Sectional Study in China

Introduction: Essential tremor (ET) is one of the most common movement disorders. Oral drugs play a crucial role in treating ET, with various available options such as propranolol, primidone, and topiramate. However, the medication status and related factors among Chinese ET patients are unknown yet. Methods: This study used the baseline data from the National Survey of Essential Tremor Plus in China cohort. ET patients with information related to medication intake were included. Medication patients were defined as patients who were taking medication at the time of the survey. We further defined recommended medication users according to Chinese guideline recommendations and clinical knowledge. We used mean and standard deviation (SD), median and interquartile range (IQR), or frequencies and percentages when appropriate for descriptive analysis. We used multivariate logistic regression analyses to explore factors related to medication intake in all ET patients and in recommended medication users. Results: Of 1,153 included ET participants, 207 (18.0%) took medication. Arotinolol (115, 55.6%) and propranolol (63, 30.4%) were the top 2 used medicines. Patients with middle school education (odds ratio 0.57, 95% confidence interval 0.39–0.83), college or higher level education (0.46, 0.28–0.76), and late-onset ET (LO-ET) (0.38, 0.23–0.63) were less likely to take medication. Patients with intention tremor (1.90, 1.38–2.62), every 10-unit increase in age (1.10, 1.00–1.21), Tremor Research Group Essential Tremor Rating Assessment Scale (TETRAS) Part 1 (1.63, 1.37–1.93), and TETRAS Part 2 (1.81, 1.48–2.22) were more likely to take medication. Among 332 recommended medication users, only 104 (31.3%) took medicine. The associations of LO-ET (0.36, 0.17–0.75), intention tremor (2.27, 1.35–3.81), TETRAS Part 1 (1.52, 1.09–2.13), and TETRAS Part 2 (1.59, 1.15–2.20) with medication were similar to all ET patients. Conclusion: The proportion of medication intake is low among both all ET patients and recommended medication users. The top 2 commonly used medications among all ET patients are arotinolol and propranolol. Influencing factors of medication intake are different between all ET patients and recommended medication users. Clinicians are suggested to provide counseling and education on ET medication to promote medication intake.

Effects of Peripheral Cooling on Upper Limb Tremor Severity and Functional Capacity in Persons with MS.

Upper limb intention tremor in persons with multiple sclerosis (pwMS) affects the ability to perform activities of daily life and is difficult to treat. The study investigated the effect of peripheral upper limb cooling on tremor severity and functional performance in MS patients with intention tremor. In experiment 1, 17 patients underwent two 15 min cooling conditions for the forearm (cold pack and cryomanchet) and one control condition. In experiment 2, 22 patients underwent whole arm cooling for 15 min using multiple cold packs. In both experiments, patients were tested at four time points (pre- and post-0, -25 and -50 min cooling) on unilateral tasks of the Test Evaluant les Membres supérieurs des Personnes Agées (TEMPA), Fahn's tremor rating scale (FTRS), Nine Hole Peg Test (NHPT). In experiment 1, the mean FTRS ranged from 13.2 to 14.1 across conditions. A two-way ANOVA showed mainly time effects, showing that cooling the forearm significantly reduced the FTRS, the performance on the NHPT, and three out of four items of the TEMPA, mostly independent of the cooling modality. In experiment 2, the mean FTRS was 13.1. A repeated measures ANOVA showed that cooling the whole arm reduced the FTRS and time needed to execute two out of four items of the TEMPA. These effects occurred immediately after cooling lasting at least 25 min. Cooling the whole upper limb led to a clinically noticeable effect on tremor severity and improved functional performance, which was pronounced during the first half-hour after cooling.

Neuropathic Tremor in Guillain-Barré Syndrome.

Neuropathic Tremor (NT) is a postural/kinetic tremor of the upper extremity, often encountered in patients with chronic neuropathies such as paraprotein-associated and hereditary neuropathies. To describe the clinical and electrophysiological features of NT in a previously underrecognized setting- during recovery from Guillain-Barré Syndrome (GBS). Patients with a documented diagnosis of GBS in the past, presenting with tremor were identified from review of clinical records. Participants underwent structured, videotaped neurological examination, and electrophysiological analysis using tri-axial accelerometry-surface electromyography. Tremor severity was assessed using the Fahn-Tolosa-Marin Tremor Rating Scale. We describe the clinical and electrophysiological features of 5 patients with GBS associated NT. Our cohort had a fine, fast, and slightly jerky postural tremor of frequency ranging from 8 to 10 Hz. Dystonic posturing and overflow movements were noted in 4/5 patients. Tremor appeared 3 months-5 years after the onset of GBS, when patients had regained near normal muscle strength and deep tendon jerks were well elicitable. Electrophysiological analysis of tremor strongly suggested the presence of a central oscillator in all patients. NT is not limited to chronic inflammatory or hereditary neuropathies and may occur in the recovery phase of GBS. The tremor is characterized by a high frequency, jerky postural tremor with dystonic posturing. Electrophysiological evaluation suggests the presence of a central oscillator, hypothetically the cerebellum driven by impaired sensorimotor feedback.

Tremor in Patients with Relapsing-Remitting Multiple Sclerosis: Clinical Characteristics and Impact on Quality of Life.

Little is known about the prevalence and clinical characteristics of tremors in patients with multiple sclerosis (MS), their associated clinical disability, and their impact on quality of life (QoL). This study aimed to investigate the frequency and types of tremors in patients with relapsing remitting MS (RRMS) in remission, and their impact on patients' QoL. A total of 250 patients with RRMS in remission were examined for tremors. All patients were assessed using the Expanded Disability Status Scale (EDSS). Patients with tremors underwent further assessment using the Fahn-Tolosa-Marin Tremor Rating Scale (FTMTRS), the Beck Depression Inventory (BDI), the Montreal Cognitive Assessment (MoCA) scale, and the Short Form 36 Health Survey Questionnaire (SF-36). Brain MRI was obtained for a subgroup of patients. Tremors were detected in 36 patients (14.4%) and were associated with significantly worse EDSS scores, BDI (P = 0.021), MoCA, most SF-36 domains, higher total and last year relapses (P < 0.001) and longer disease duration (P = 0.027). Patients with tremors showed higher lesion load (P = 0.007), more infratentorial (P ≤ 0.001), cerebellar and diencephalic lesions (P = 0.024), and cortical atrophy (P = 0.012). Total FTMTRS was significantly correlated to age, EDSS, and physical functioning. Dystonia was associated with tremors in 17 patients (6.8% of total RRMS patients and 47.2% of patients with tremors). The current study confirms the common occurrence of tremors and their subtypes among patients with RRMS with mild disability and demonstrates their association with increased disability and impaired QoL.

Conversion Rate of Essential Tremor to Essential Tremor Parkinson Disease: Data From a Prospective Longitudinal Study.

There has been a long-standing dialog as to whether essential tremor (ET) increases the risk of developing Parkinson disease (PD). While there are relevant cross-sectional data, there are almost no longitudinal prospective data. We quantified the conversion rate from ET to ETPD in a prospective longitudinal cohort study of patients with ET. We compared the observed rate with that reported in the epidemiologic literature. We enrolled patients with ET in a prospective, longitudinal study. A senior movement disorders neurologist evaluated standardized neurologic examinations every 18 months. One hundred ninety-three patients with ET (mean age = 78.1 ± 9.6 years, range = 55-96) had a mean follow-up duration of 4.1 years. Seven (3.6%) converted from ET to ETPD. The incidence of PD among patients with ET was 7/792.9 person-years (py; i.e., 882.8/100,000 py). A meta-analysis of the incidence (per 100,000 py) of PD in 14 studies from 13 countries across 4 continents reported an incidence of PD = 61.21 (men, 40 years or older) and 37.55 (women, 40 years or older). The incidence/100,000 py in men peaked in the 80- to 89-year-old age group (258.47) and in women in the 80- to 89-year-old age group (103.48 py). The abovementioned published values are 3.4-23.5 times lower than the value we observed for ET. The incidence of PD in an ET cohort is substantially higher than that reported in historical population-based control groups across numerous countries. Additional prospective longitudinal data are needed to further explore this association.

Acute stimulation with symmetric biphasic pulses induces less ataxia compared to cathodic pulses in DBS for essential tremor

BackgroundSymmetric biphasic pulses have been shown to acutely increase the therapeutic window of ventralis intermedius deep brain stimulation (Vim-DBS) for essential tremor (ET) compared to cathodic pulses. Acute supratherapeutic stimulation can induce ataxic side effects in Vim-DBS. ObjectiveTo investigate the effect on tremor, ataxia and dysarthria of 3 h of biphasic stimulation in patients with DBS for ET. MethodsA randomized, doubled-blind, cross-over design was used to compare standard cathodic pulses with symmetric biphasic pulses (anode-first) during a 3-h period per pulse shape. During each 3-h period, all stimulation parameters were identical, except for the pulse shape. Tremor (Fahn-Tolosa-Marin Tremor Rating Scale), ataxia (International Cooperative Ataxia Rating Scale) and speech (acoustic and perceptual measures) were assessed hourly during the 3-h periods. ResultsTwelve ET patients were included. During the 3-h stimulation period, tremor control was equivalent between the two pulse shapes. Biphasic pulses elicited significantly less ataxia than cathodic pulses (p = 0.006). Diadochokinesis rate of speech was better for the biphasic pulse (p = 0.048), but other measures for dysarthria were not significantly different between the pulses. ConclusionSymmetric biphasic pulses induce less ataxia than conventional pulses after 3 h of stimulation DBS in ET patients.

Effect of Ventral Intermediate Nucleus Deep Brain Stimulation on Vocal Tremor in Essential Tremor.

There is a paucity of literature examining the effect of Ventral Intermediate Nucleus (VIM) deep brain stimulation (DBS) on voice in patients with vocal tremor (VT). Investigate the effect of unilateral and bilateral VIM DBS on voice in patients with Essential Tremor (ET) and VT. All patients receiving VIM DBS surgery underwent voice evaluation pre- and six-months post-operatively. We collected patient-reported quality-of-life outcome measures and acoustic voice measures of sustained phonation and connected speech. Acoustic measures specific to VT included amplitude tremor intensity index (ATRI), frequency tremor intensity index (FTRI), rate and extent of F0 modulation, and rate and extent of intensity modulation. Five patients, age 72.8 ± 2.6 years, 4 female, 1 male with mean disease duration of 29 ± 26.2 years met the inclusion criteria and were included. Two subjects had bilateral procedure and three had unilateral. We observed significant improvements in measures of vocal tremor including ATRI, FTRI, rate of F0 modulation, rate of intensity modulation, and extent of intensity modulation, as well as patient reported voice-related quality of life measured by VHI-10. Bilateral VIM DBS cases showed greater improvement in VT than unilateral cases. Both unilateral and bilateral VIM DBS resulted in significant improvement of VT, with more improvement demonstrated in patients having bilateral as compared to unilateral VIM DBS. In addition, patients also reported significant improvements in voice-related quality of life. If larger studies confirm our results, VIM DBS has the potential to become a treatment specifically for disabling VT.

Conversion Rate of Essential Tremor to Essential Tremor-Parkinson’s Disease: Data from a Prospective, Longitudinal Study (S42.010)

<h3>Objective:</h3> We quantified the conversion rate from essential tremor (ET) to ET with Parkinson’s disease (ETPD) in a prospective, longitudinal cohort study of ET cases. We compared the observed rate to that reported in the epidemiological literature. <h3>Background:</h3> There has been a longstanding dialogue as to whether ET increases the risk of developing PD. While there are relevant cross-sectional data, there are almost no longitudinal, prospective data. <h3>Design/Methods:</h3> We enrolled ET cases in a prospective, longitudinal study. A senior movement disorders neurologist evaluated standardized neurological examinations every 18 months. <h3>Results:</h3> 193 ET cases (mean age = 78.1 ± 9.6 years, range = 55 – 96) had a mean follow-up duration of 4.1 years. Seven (3.6%) converted from ET to ETPD. The incidence of PD among ET cases was 7/792.9 person years [py] (i.e., 882.8/100,000 py). A meta-analysis of the incidence (per 100,000 py) of PD in 14 studies from 13 countries across 4 continents reported an incidence of PD = 61.21 (males, ≥40 years) and 37.55 (females, ≥40 years). The incidence/100,000 py in males peaked in the 80 – 89 year old age group (258.47) and in females in the 80 – 89 year old age group (103.48 py). The above published values are 3.4 – 23.5 times lower than the value we observed for ET. <h3>Conclusions:</h3> The incidence of PD in an ET cohort is substantially higher than that reported in historical, population-based control groups across numerous countries. Additional prospective, longitudinal data are needed to further explore this association. <b>Disclosure:</b> Dr. Louis has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Wolters Kluwer - Merritt’s Textbook of Neurology. The institution of Dr. Louis has received research support from National Institutes of Health. Dr. Berry has nothing to disclose. Dr. Ghanem has nothing to disclose. Dr. Cosentino has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Association for Frontotemporal Dementia. Dr. Cosentino has received personal compensation in the range of $500-$4,999 for serving as a Consultant for SAGE Pharmaceuticals.

The Effects of Thalamic Deep Brain Stimulation on Gait in Essential Tremor: a Kinematic Study. (P7-11.001)

<h3>Objective:</h3> To determine the effect of ventral intermediate thalamic nucleus (VIM) deep brain stimulation (DBS) on gait parameters in patients with essential tremor (ET). <h3>Background:</h3> DBS is an established treatment for medication-refractory ET. ET can be associated with primary gait impairment; additionally, the effect of VIM-DBS on gait is currently debated, with reports ranging from a more frequently observed worsening to an improvement with therapeutic stimulation. Determining VIM-DBS effects on gait is pivotal to determine patient candidacy for this treatment. <h3>Design/Methods:</h3> Database review from our kinematics laboratory identified 27 patients (women, 15; men, 12) with ET who underwent VIM-DBS (bilateral, 5; unilateral, 22) and pre- and post-DBS quantitative gait kinematics analysis with a 3D commercial motion analysis (MA) system. Post-DBS assessments were performed on stimulation. Changes in gait outcomes from pre- to post- were expressed as effect sizes (Cohen’s d) and categorized as “small,” “medium,” or “large” using established cutoff values. Post-DBS Tremor Research Group Essential Tremor Rating Scale motor scores on and off stimulation were retrospectively reviewed and available for 22 patients; percent change of on versus off stimulation was calculated and scores were compared with paired samples t-tests. <h3>Results:</h3> Patients underwent DBS at a mean age of 69.4±8.5 years. The average percent reduction of the contralateral upper limb tremor scores on versus off stimulation was 80.4±13.4 (p&lt;0.001), 10.3±3.7 months after surgery. Postoperative MA was performed 9.6±5.9 months after surgery. Small worsening effects were observed in gait speed (d=−0.32), cadence (d=−0.39), and step length (d=−0.24), which were not statistically significant. No changes were observed in step width. <h3>Conclusions:</h3> Thalamic DBS improved tremor scores, but we observed a small, non-statistically significant, worsening trend of some gait parameters. Further study is required to clarify the observed effect of VIM-DBS on gait and identify pre-DBS gait features predictive of poor gait outcomes. <b>Disclosure:</b> Dr. Testini has nothing to disclose. Dr. McKay has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biocircuit Technologies. The institution of Dr. McKay has received research support from NIH. The institution of Dr. McKay has received research support from the McCamish Foundation. Dr. Tripathi has nothing to disclose. Miss Genias has nothing to disclose. Mr. Skelton has received personal compensation for serving as an employee of AthenaHealth. Douglas Bernhard has nothing to disclose. Dr. Miocinovic has nothing to disclose. Dr. Aia has nothing to disclose. The institution of Dr. Buetefisch has received research support from NIH. The institution of Dr. Higginbotham has received research support from NIH/NINDS . The institution of Dr. Higginbotham has received research support from Bright Focus Foundation. The institution of Dr. Higginbotham has received research support from American Academy of Neurology. Dr. Scorr has received research support from Dystonia Medical Research Foundation. Shirley Triche has nothing to disclose. Dr. Factor has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Acorda. Dr. Factor has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Sunovion. Dr. Factor has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Alterity. Dr. Factor has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Lundbeck. Dr. Factor has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen. The institution of Dr. Factor has received research support from Impax. The institution of Dr. Factor has received research support from Biohaven. The institution of Dr. Factor has received research support from Sunovion. The institution of Dr. Factor has received research support from Vaccinex. The institution of Dr. Factor has received research support from Voyager. The institution of Dr. Factor has received research support from Neurocrine. The institution of Dr. Factor has received research support from US World Meds. The institution of Dr. Factor has received research support from Addex. The institution of Dr. Factor has received research support from Prelinia. The institution of Dr. Factor has received research support from Medtronics. The institution of Dr. Factor has received research support from Boston Scientific. Dr. Factor has received publishing royalties from a publication relating to health care. Dr. Factor has received publishing royalties from a publication relating to health care. Dr. Factor has received publishing royalties from a publication relating to health care. Dr. Factor has received publishing royalties from a publication relating to health care. Dr. Esper has received research support from Centers for Disease Control and Prevention. Dr. Esper has received publishing royalties from a publication relating to health care.

510 Prospective, Multicenter, International Outcomes Study of Deep Brain Stimulation for Essential Tremor

INTRODUCTION: Essential Tremor (ET) treatment is focused on medical management of motor symptoms and includes pharmacotherapy and ventral intermediate nucleus (VIM) thalamotomy, which is being largely replaced by thalamic Deep Brain Stimulation (DBS) as the surgical treatment of choice. DBS of the VIM thalamus is recommended as a therapeutic option for appropriate subjects with ET (Elble RJ., et al. Expert Rev Neurother. 2018). METHODS: This is a prospective, on-label, multi-center, international DBS outcomes study conducted at up to 50 implanting centers. All participants are implanted with a multiple-source, constant-current directional DBS system (Vercise, Boston Scientific). Subjects are followed for up to 3-years post implantation where their overall improvement in quality of life and ET symptoms are evaluated. Clinical endpoints evaluated at baseline and follow-up timepoints include: The Essential Tremor Rating Assessment Scale (TETRAS), Quality of Life in Essential Tremor Questionnaire (QUEST), Fahn-Tolosa-Marin Rating Scale (TRS), and Global Impression of Change. Adverse events also collected. RESULTS: To date, 18-implanted subjects with a mean disease duration of 15.1 ± 14.6-years and a baseline QUEST Summary Index score of 35.0 ± 12.4. At 6-months post-DBS, a clinically significant improvement in quality of life (∆ = 19.5-point change in QUEST SI score) was reported. In addition, a mean 9-hours of tremor reduction was noted (14-hours at Baseline, 6.9-hours at 6-months) in a typical day at 6-months. All subjects (100%) reported mild disability, and no subject reported moderate or marked disability (89% at baseline) as reported by TRS at 6 months. CONCLUSIONS: This work represents the first comprehensive, large scale collection of real-world outcomes and evaluation of safety and effectiveness of a multiple-source, constant-current DBS system capable of providing directionality for use in treatment of Essential Tremor.

The relationship of tremor severity with proximal and distal muscle strength and upper extremity functional skills in older adults with essential tremor

Although it is known that muscle strength training is effective in Essential Tremor (ET), it is not known which muscle groups are more affected. The study was conducted to examine the relationship between tremor severity and proximal and distal muscle strength and upper extremity functional skills in older adults with ET. A total of 40 older adults who were diagnosed with ET (mean age of 74.07 ± 4.83years) and 40 older adults without tremor (mean age of 70.10 ± 4.05years) were included in the study. Tremor severity was evaluated with the Fahn-Tolosa-Marin Tremor Rating Scale (FTMTRS), the proximal muscular strength with digital muscle dynamometer, handgrip strength with hand dynamometer, and pinch grip strength with pinchmeter. The Arm and Shoulder Problems Questionnaire (DASH) was used to determine the functional status of the upper extremities. Fine Manual Dexterity was measured with the Nine-Hole Peg Test (NHPT). All proximal and distal muscle strengths were significantly lower, DASH and NHPT were significantly higher in the group with ET (p < 0.05). A significant negative correlation was detected between tremor severity and all proximal and distal muscular strength and a significant positive correlation between tremor severity and DASH in group with ET (p < 0.05). However, no significant correlations were found between tremor severity and NHPT in the group with ET. It was found that older adults who had tremors had low proximal and distal muscular strength, upper extremity functionality was affected and hand skills was impaired. Furthermore tremor severity is affected by both proximal and distal muscle strength.

Bilateral transcranial direct current stimulation may be a feasible treatment of Parkinsonian tremor.

Parkinsonian tremor is a common pathological tremor that affects over 6 million people worldwide. It lowers patients' quality of life and threatens their career development, especially when patients' occupation requires dexterous manipulation. In spite of current available treatments in clinics, there is a lack of low-cost, low side-effect, effective solutions for Parkinsonian tremor. Transcranial direct current stimulation (tDCS) may be an alternative treatment. In this research, we explored the immediate effect of tDCS with a novel bilateral electrode setup over Parkinsonian tremor. In such a bilateral setup, the cathode was placed over the primary cortex contralateral to the more affected side of Parkinsonian tremor while the anode symmetrically over the other hemisphere. It was designed as a modification to the traditional cathodal setup. The performance of this bilateral setup was compared with three other setups including anodal setup, cathodal setup, and sham (control). A randomized, sham-controlled, double-blind, crossover experiment was carried out over 13 qualified patients diagnosed with idiopathic Parkinson's disease (PD). Before and after the stimulus of each tDCS setup, subjects were tested before and after tDCS with four measures, including the Unified Parkinson's Disease Rating Scale (UPDRS), Fahn-Tolosa-Marin Tremor Rating Scale (FTMTRS), Purdue Pegboard Test (PPT) and a self-design Continuous Tremor Signal Assessment (CTSA). Tremor intensity calculated from CTSA data were regarded as the primary outcome of the experiment. Statistical results of CTSA, FTMTRS and PPT showed both bilateral tDCS and cathodal tDCS effectively suppressed Parkinsonian tremor. A quantitative comparison of the effect in tremor suppression indicated the optimal suppressive effect was obtained with bilateral tDCS. Based on the results of UPDRS, anodal tDCS was found to benefit subjects' overall performance the most, however, it had little effect in improving Parkinsonian tremor, as revealed by the results of other evaluations. Our study suggests a beneficial immediate effect of bilateral tDCS in Parkinsonian tremor suppression. In addition, we assume there may be an underlying interhemispheric unbalance of cortical excitability which contributes to Parkinsonian tremor genesis. Identifier: ChiCTR2100054804.

Essential tremor and the scales: Quality of life in essential tremor, the Fahn-Tolosa-Marin Tremor Rating Scale; and, the Bain and Findley Clinical Tremor Rating Scale

Essential tremor and the scales: Quality of life in essential tremor, the Fahn-Tolosa-Marin Tremor Rating Scale; and, the Bain and Findley Clinical Tremor Rating Scale

Chronic inflammatory demyelinating polyradiculoneuropathy-associated tremor: Phenotype and pathogenesis.

Tremor in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is underrecognized, and the pathophysiology remains incompletely understood. This study evaluated tremor in CIDP and tested the hypothesis, established in other demyelinating neuropathies, that tremor occurs due to mistimed peripheral inputs affecting central motor processing. Additionally, the tremor stability index (TSI) was calculated with the hypothesis that CIDP-related tremor is more variable than other tremor disorders. Consecutive patients with typical CIDP were prospectively recruited from neuromuscular clinics. Alternative causes of neuropathy and tremor were excluded. Cross-sectional clinical assessment and extensive tremor study recordings were undertaken. Pearson correlation coefficient was used to compare nerve conduction studies and tremor characteristics, and t-test was used for comparisons between groups. Twenty-four patients with CIDP were included. Upper limb postural and action tremor was present in 66% and was mild according to the Essential Tremor Rating Assessment Scale. Tremor did not significantly impact disability. Surface electromyography (EMG) found high-frequency spectral peaks in deltoid (13.73 ± 0.66 Hz), biceps brachii (11.82 ± 0.91 Hz), and extensor carpi radialis (11.87 ± 0.91 Hz) muscles, with lower peaks in abductor pollicis brevis EMG (6.07 ± 0.45 Hz) and index finger accelerometry (6.53 ± 0.42 Hz). Tremor was unchanged by weight loading but correlated with ulnar nerve F-wave latency and median nerve sensory amplitude. TSI (2.3± 0.1) was significantly higher than essential tremor. Postural tremor is a common feature in CIDP. Tremor was unaffected by weight loading, typical of centrally generated tremors, although there was a correlation with peripheral nerve abnormalities. The high beat-to-beat variability on TSI and gradation of peak frequencies further suggest a complex pathophysiology. These findings may assist clinicians with the diagnosis of neuropathic tremor.