Action Tremor Research Articles

Clinicopathologic Correlations of Jaw Tremor in a Longitudinal Aging Study.

The aim of this study is to assess clinical and pathologic correlations of jaw tremor in 3 cohorts enrolled in a long-term aging study. Jaw/lip tremor has been described in various movement disorders but the impact of seeing a jaw tremor on clinician diagnosis and whether the presence of isolated jaw tremor is correlated with subsequent phenoconversion to a different movement disorder are unclear. Data from the Arizona Study of Aging and Neurodegenerative Disease, a longitudinal clinicopathologic study, were used. Control subjects (n = 708) did not have any tremor or parkinsonism. At initial evaluation, 276 subjects who had jaw tremor were categorized as isolated jaw tremor (jaw tremor without limb action tremor or parkinsonism), suspect/possible PD (1 or 2 cardinal features of PD without a history of dopaminergic treatment), parkinsonism (probable PD and other parkinsonian disorders), or nonparkinsonian tremor (e.g., essential tremor). Initial clinical diagnosis was compared with "final diagnosis" based on longitudinal assessments and with clinicopathologic diagnosis when available. In subjects with jaw tremor, we identified 45 isolated jaw tremor, 92 nonparkinsonian tremor, 56 suspect/possible PD, and 83 parkinsonism cases at baseline and followed longitudinally. Neuropathologic diagnosis was available for 137 cases. The mean time from initial to final assessment or autopsy was 6.8 years (SD 4.4). Of the subjects with follow-up data, only 15.4% of those with isolated jaw tremor (6/39) and 8.8% of those with nonparkinsonian tremor (6/68) evolved into a clinical parkinsonian disorder. Neither of these groups was associated with clinicopathologic PD: isolated jaw tremor (1/18) and nonparkinsonian tremor (1/43). Those with jaw tremor initially classified into a parkinsonian group were more highly associated with clinicopathologic PD: 27 of 51 subjects with parkinsonism other and 4 of 25 possible PD. The presence of either jaw tremor in isolation or associated with nonparkinsonian tremor does not portend a neurodegenerative diagnosis.

A Second Case With the V374A KCND3 Pathogenic Variant in an Italian Patient With Early-Onset Spinocerebellar Ataxia.

Background and ObjectivesTo date, approximately 20 heterozygous mainly loss-of-function variants in KCND3 have been associated with spinocerebellar ataxia (SCA) type 19 and 22, a clinically heterogeneous group of neurodegenerative disorders. We aimed at reporting the second patients with the V374A KCND3 mutation from an independent family, confirming its pathogenic role.MethodsWe describe the clinical history of a patient with SCA and conducted genetic investigations including mitochondrial DNA analysis and exome sequencing.ResultsThis male patient was reported to have unstable gait with tremors at the lower limbs and dysarthric speech since childhood. A neurologic examination also showed dysarthria, nystagmus, action tremor, dysmetria, and weak deep tendon reflexes. He had marked cerebellar atrophy at brain MRI, more evident at vermis. Molecular analysis, including exome sequencing and an in silico panel analysis of genes associated with SCA, revealed the c.1121T>C [p.V374A] mutation in KCND3.DiscussionThis report consolidates the pathogenicity of the V374A KCND3 mutation and suggests that the ataxic paroxysmal exacerbations are not a key phenotypic feature of this mutation.

A standardized accelerometry method for characterizing tremor: Application and validation in an ageing population with postural and action tremor.

BackgroundOrdinal scales based on qualitative observation are the mainstay in the clinical assessment of tremor, but are limited by inter-rater reliability, measurement precision, range, and ceiling effects. Quantitative tremor evaluation is well-developed in research, but clinical application has lagged, in part due to cumbersome mathematical application and lack of established standards.ObjectivesTo develop a novel method for evaluating tremor that integrates a standardized clinical exam, wrist-watch accelerometers, and a software framework for data analysis that does not require advanced mathematical or computing skills. The utility of the method was tested in a sequential cohort of patients with predominant postural and action tremor presenting to a specialized surgical clinic with the presumptive diagnosis of Essential Tremor (ET).MethodsWristwatch accelerometry was integrated with a standardized clinical exam. A MATLAB application was developed for automated data analysis and graphical representation of tremor. Measures from the power spectrum of acceleration of tremor in different upper limb postures were derived in 25 consecutive patients. The linear results from accelerometry were correlated with the commonly used non-linear Clinical Rating Scale for Tremor (CRST).ResultsThe acceleration power spectrum was reliably produced in all consecutive patients. Tremor frequency was stable in different postures and across patients. Both total and peak power of acceleration during postural conditions correlated well with the CRST. The standardized clinical examination with integrated accelerometry measures was therefore effective at characterizing tremor in a population with predominant postural and action tremor. The protocol is also illustrated on repeated measures in an ET patient who underwent Magnetic Resonance-Guided Focused Ultrasound thalamotomy.ConclusionQuantitative assessment of tremor as a continuous variable using wristwatch accelerometry is readily applicable as a clinical tool when integrated with a standardized clinical exam and a user-friendly software framework for analysis. The method is validated for patients with predominant postural and action tremor, and can be adopted for characterizing tremor of different etiologies with dissemination in a wide variety of clinical and research contexts in ageing populations.

Distribution of rest tremor in patients with Essential Tremor: Does it lateralize with simple kinetic, postural, or intention tremors?

BackgroundEssential tremor (ET) is characterized by action tremor, although rest tremor may also occur. Despite this, rest tremor has not been studied extensively. A dearth of studies compare the relationship of rest tremor to other types of tremors in ET. MethodsTwo-hundred-and-thirteen ET cases underwent detailed neurological examination, including evaluations of rest, simple kinetic, postural, and intention tremors. A movement disorders neurologist assessed the prevalence of each type of tremor. Each instance of tremor was classified as either symmetrical (present and equally severe on both sides of the body) or asymmetrical (only present on or more severe on one side of the body). Asymmetrical rest tremor that co-occurred with other types of asymmetrical tremors in a given case was further classified as either concordant (i.e., asymmetry on the same side of the body) or discordant (i.e., asymmetry on opposite sides of the body). Chi-square analyses examined the prevalence of concordant versus discordant pairings. ResultsSixty-two cases (29.2%) had rest tremor while seated. Fifteen (7.4%) had rest tremor while standing. Among asymmetric tremor pairings, concordant pairings occurred 2–2.7 times more frequently than discordant pairings – for pairings involving rest tremor while seated, 73.2% were concordant and 26.8% discordant (p < 0.001); for pairings involving rest tremor while standing, 66.7% were concordant and 33.3% were discordant (p = 0.25). ConclusionsRest tremor often lateralized with other tremor types. These data add to our knowledge of the phenotypic manifestations of ET.

No exaggerated tremor severity perception in functional tremor

Symptoms of functional neurological disorder tend to be variable, yet patients often report them being present constantly and of permanently severe intensity. Furthermore, they typically worsen when they are mentioned or during clinical examination. Such phenomena are sometimes interpreted as indicating symptom exaggeration or even fabrication. To test the notion of inaccurate symptom perception or reporting, we directly compared subjective to objective tremulousness of reaching movements in people with a functional action tremor, people with an organic action tremor and healthy controls. Identical subjective and objective measures were used, thus eliminating any potential metacognitive confounders. Furthermore, we assessed both immediate perceptual experience with a real-time perceptual task, offering the most direct comparison; and near-time retrospective reports as the latter contribute to peoples' overall judgement of their condition. There was no significant difference in subjective compared to objective tremor severity between the three groups for either the real-time or retrospective conditions. People with functional tremor do not perceive or report their tremor in an exaggerated manner, compared to people with an organic tremor or healthy controls. We propose that symptom exacerbation through attentional mechanisms provides an alternative explanation for findings that are frequently attributed to 'exaggeration'.

Clinical and Preclinical Neuroimaging Changes in Spinocerebellar Ataxia Type 12: A Study of Three Chinese Pedigrees

Background: Spinocerebellar ataxia type 12 (SCA12) is a rare SCA subtype with unclear clinical and imaging features. Also, the radiological changes in prodromal and early stages remain unknown. Methods: Ten symptomatic and two pre­symptomatic cases from three Chinese pedigrees received clinical assessments and imaging studies including routine magnetic resonance imaging (MRI), diffusion kurtosis imaging (DKI), and positron emission tomography (PET) using ¹⁸F-flurodeoxyglucose (FDG) to investigate glucose metabolism in brain and ¹⁸F-vesicle monoamine transporter 2 (VMAT2) to inspect the integrity of the dopaminergic neuron. Seventy-two healthy individuals were recruited as controls in the quantitative FDG-PET analysis. Imaging parameters were compared between symptomatic and presymptomatic cases with different disease durations. Results: Patients displayed prominent action tremor, moderate ataxia, and subtle parkinsonism with poor levodopa-response. MRI showed extensive but heterogeneous cerebral atrophy, which was most evident in the frontoparietal lobes. Cerebellar atrophy was apparent in later stages. DKI detected impaired fibers in the cerebellar peduncles. In both symptomatic and pre­symptomatic cases, PET-CT showed an earlier FDG decline than atrophic changes in multiple regions, and the frontoparietal lobes were the earliest and most severe. However, the VMAT2 density were normal in the putamen and caudate nucleus of most cases (7/8). Conclusions: We first found that hypometabolism in the cerebral cortex, but not cerebellum, is an early and prominent change in SCA12. The integrity of presynaptic dopaminergic neurons remains largely spared during the whole disease process.

Connecting tremors - a circuits perspective.

Tremor is one of the most prevalent movement disorders in clinical practice. Here, we review new insights in the pathophysiology of tremor. We focus on the three most common tremor disorders: essential tremor (ET), dystonic tremor syndrome (DTS), and Parkinson's disease (PD) tremor. Converging evidence suggests that ET, DTS, and PD tremor are all associated with (partly) overlapping cerebral networks involving the basal ganglia and cerebello-thalamo-cortical circuit. Recent studies have assessed the role of these networks in tremor by measuring tremor-related activity and connectivity with electrophysiology and neuroimaging, and by perturbing network components using invasive and noninvasive brain stimulation. The cerebellum plays a more dominant and causal role in action tremors than in rest tremor, as exemplified by recent findings in ET, DTS, and re-emergent tremor in PD. Furthermore, the role of the cerebellum in DTS is related to clinical differences between patients, for example, whether or not the tremor occurs in a dystonic limb, and whether the tremor is jerky or sinusoidal. Insight into the pathophysiological mechanisms of tremor may provide a more direct window into mechanism-based treatment options than either the etiology or the clinical phenotype of a tremor syndrome.

Difference in the effectiveness of subthalamic nucleus and globus pallidus deep brain stimulation in Parkinson’s disease

Deep brain stimulation (DBS) is regarded as a feasible Parkinson’s disease (PD) treatment option. The subthalamic nucleus (STN) and globus pallidus (GPi) are the two most common sites for DBS. The following criteria were used to select studies that examined the Unified PD Rating Scale (UPDRS) III: (1) had at least three months of follow-up; (2) compared both GPi and STN-DBS; (3) each group included at least five individuals; (4) were conducted after 2010. The majority of studies found no statistically significant difference in UPDRS score improvements between groups. Although there were some encouraging findings in terms of action tremor, rigidity, and urinary symptoms, indicating that STN-DBS would be a better alternative, GPi appeared to be better in terms of side effects; nonetheless, it cannot be said that it is superior. Other larger randomized clinical trials with longer follow-up periods and control groups are required to determine which target is more effective for stimulation and has fewer negative side effects on patients. Keywords: Deep brain stimulation, globus pallidus, Parkinson’s disease, subthalamic nucleus, UPDRS

What could posturography tell us about balance in essential tremor?

BackgroundEssential tremor (ET) is a neurological disorder characterized primarily by action tremor. Balance impairments in ET patients were formerly considered to be uncommon and simply age-related. However quantitative assessment with posturography has revealed impairments in control of both static and dynamic balance. Research questionThe aim of the present study is to assess postural stability with different posturographic techniques in ET patients. MethodsA prospective cross-sectional study conducted in two University Hospitals. Eleven patients diagnosed with essential tremor and twelve healthy controls were included. Balance assessment were performed with: sensory organization test (SOT) and limits of stability (LOS) of the computer dynamic posturography (CDP), results of free-field body sway analysis with mobile posturography (Vertiguard®), modified timed up and go test (TUG), Dizziness handicap inventory (DHI) and activities-specific balance confidence scale (ABC). ResultsPatients with ET showed poorer scores in the SOT than controls for composite balance and somatosensory input. They also performed worse in LOS tests and Vertiguard® device indicated a higher risk of falling. There were no differences in the modified TUG. The mean score of DHI was 15.64 and 85.16 for ABC. SignificancePosturography assessment (CDP and Vertiguard®) is more accurate in showing balance impairment in ET patients than clinical evaluation (modified TUG). Balance impairment involves deteriorated processing of somatosensory input which could be explained by cerebellar dysfunction. Balance deficits could be included into future diagnostic criteria.

EPH108 CO-Morbidities and Mechanistic Similarities of Essential Tremor and Parkinson's Disease and Resulting Diagnostic Challenges

Chronic stimulation of the ventral intermediate nucleus of the thalamus with deep brain stimulation has been a mode of treatment for tremor in both Parkinson’s Disease (PD) and Essential Tremor (ET) (Koller 2000). This mechanistic hypothesis suggests ET and PD action tremor may have similar central origins. There are also similar comorbid conditions that emerge within the first 2 years of diagnosis of the respective diseases. This study analyzed comorbidities among patients diagnosed with ET and PD using claims data from Truven Health Analytics MarketScan® Commercial, and Medicare Supplemental databases (2013-2019).

Motor features associated with cognition in non-demented individuals with essential tremor

IntroductionEssential tremor (ET) is a clinically heterogeneous disease characterized by motor and non-motor features, including cognitive impairment. In a cross-sectional analysis, we determined whether the presence and severity of motor features of ET are associated with cognitive performance. MethodsParticipants enrolled in a study that used motor and neuropsychological measures to characterize a cohort of ET subjects. Action tremor severity and additional motor features (rest tremor, intention tremor, cranial tremor, dystonia, tandem gait missteps) were assessed in non-demented participants. Participants completed a cognitive test protocol assessing domains of memory, executive function, attention, visuospatial ability, and language. An average z-score was calculated to represent global cognition. ResultsThere were 204 ET participants (mean age 78.6, range 55–95). Participants with 10 missteps were more likely to have MCI than those with 0 or 1 misstep (p < 0.001). In unadjusted linear regression models, action tremor severity (p = 0.010), rest tremor (p < 0.001), and tandem gait missteps (p < 0.001) were negatively associated with global cognition. In adjusted models, only tandem gait missteps were negatively associated with global cognition (p < 0.001). Missteps were also negatively associated with memory (p < 0.001), executive function (p < 0.001), attention (p = 0.011), and visuospatial function (p = 0.043). No other motor features were associated with global cognition in adjusted models (p > 0.05). ConclusionAmong non-demented participants with ET, there is an association between cognitive performance and tandem gait missteps, but no other motor features of ET. This is a first step in establishing impaired tandem gait as a possible indicator of cognitive impairment in patients with ET.

Diagnosis and treatment of tremor in psychiatric patients

IntroductionTremor is the most common movement disorder in adults. Due to the visibility, feelings of shame are often present. Many (psycho)pharmacological drugs can induce tremor or increase its severity as a side effect. Sometimes the burden of this side effect is greater than the burden of the psychiatric problem.ObjectivesKnowledge of the different kinds of tremor in psychiatry, and the drugs that may be responsible. Differential diagnosis Treatment of tremor in psychiatry.MethodsA literature search on the most recent insights into classification, diagnosis, differentiation and treatment was carried out with emphasis on drug-induced tremor and its treatment.ResultsThe basic classification is resting, action and intention tremor. Tremors may be due to neurological and metabolic syndromes. Differentiation can often be made according to the time of onset, relation with starting or increasing the dosage of the medication and the course. Rest tremor is often related to antipsychotics and antiemetics and action tremor to lithium, antidepressants, valproic acid, and other anticonvulsants, but also to many drugs used in somatic conditions. The development of intention tremor should alarm the doctor because it could be an intoxication. Treatment of drug-induced tremor consists of reducing the dose or discontinuing the drug in question or switching to another drug with less risk of tremor. If this is not effective, adding a tremor suppressant may help (propranolol, primidone in action tremor and anticholinergics or amantadine in resting tremor.ConclusionsTremor is a common side effect of many (psycho)pharmacological agents and treatment is often possible.DisclosureNo significant relationships.

258 A case of two brothers: should we look beyond a diagnosis of cerebral palsy?

BackgroundPelizaeus-Merzbacher Disease (PMD) is an X-linked leukodystrophy with variable phenotypes often overlapping with cerebral palsy (CP).Case DescriptionsWe describe 2 brothers, presenting at the same time.Case1: 34 years old with a 2-year history of hand tremor, cognitive decline and deteriorating mobility. He required neonatal ICU following a prolonged delivery, was slow to walk and subsequently misdiagnosed at age 4. Examination revealed a left torticollis, intention tremor and spastic paraparesis.Case 2: 29 years old with progressive hand tremor and cognitive decline. He had nystagmus, titubation and late crawling and was diagnosed with CP within his first year of life; becoming wheelchair-bound by age 9. Examination revealed titubation, action tremor, nystagmus and spastic quadriparesis.There were no other family history of similar symptoms or genetic disorder prior to their births.Results of InvestigationsMRI Brain suggested leukodystrophy in both cases. Genetic analysis revealed pathogenic mutation in the PLP1 gene(c454–322G&gt;A;P?) confiriming a diagnosis of Pelizaeus Merzbacher Disease.ConclusionThe phenotypic similarities between PMD and CP especially in early childhood and the delayed progression of symptoms contributed to their misdiagnosis. We should look beyond Cerebral Palsy and consider PLP-related diseases in males with cerebral-palsy-like features regardless of a lack of family history.ihedinachindukwe@gmail.com

Evolving Concepts in Our Understanding and Treatment of Holmes Tremor, Over 100 Years in the Making.

Holmes Tremor (HT) is an irregular, slow-frequency (<4.5 Hz) tremor characterized by a combination of resting, postural, and action tremors mostly of the upper extremities. Symptoms of HT typically emerge 4 weeks to 2 years after a brain injury caused by a spectrum of etiologies. HT pathophysiology is thought to result from aberrant collateral axonal sprouting and synaptic dysfunction following neuronal damage. To date, the dopaminergic nigrostriatal system, cerebello-thalamo-cortical pathway, and dentate-rubro-olivary pathway have all been implicated in the clinical manifestations of HT. The diversity of HT etiologies usually requires a personalized treatment plan. Current treatment options include carbidopa-levodopa, levetiracetam, and trihexyphenidyl, and surgical management such as deep brain stimulation in selected medication-refractory patients. In this review we discuss the pathophysiology, etiology, neuroimaging, and the latest clinical guidelines for care and management of HT.

Familial Brain Calcifications With Leukoencephalopathy: A Novel PDGFB Variant.

ObjectiveTo describe a family with primary familial brain calcifications (PFBCs) and leukoencephalopathy associated with a novel variant in PDGFB.MethodsWe present 3 generations of a family with PFBC associated with a previously unreported variant in PDGFB.ResultsA 24-year-old woman with migraine, bipolar disorder, and functional neurologic disorder was found to have bilateral calcifications of the basal ganglia and frontally predominant periventricular white matter disease. Her father had mild cognitive impairment and action tremor of the hands with basal ganglia and cerebellar calcifications found incidentally on head CT. Her paternal grandmother had severe parkinsonism and dementia with calcifications of the basal ganglia and cerebellum and diffuse, confluent periventricular white matter disease. Genetic testing in both the proband and her father revealed a PDGFB variant (NM_002608.3:c.298C>T:p.Arg100Cys) not reported in publicly available databases. Multiple in silico analysis tools support pathogenicity.DiscussionOur report identifies a novel PDGFB variant associated with PFBC and highlights the rare association of leukoencephalopathy with PDGFB-associated PFBC.

Essential tremor impairs the ability to suppress involuntary action impulses.

Essential tremor (ET) is a movement disorder characterized primarily by action tremor which affects the regulation of movements. Disruptions in cerebello-thalamocortical networks could interfere with cognitive control over actions in ET, for example, the ability to suppress a strong automatic impulse over a more appropriate action (conflict control). The current study investigated whether ET impacts conflict control proficiency. Forty-one ET patients and 29 age-matched healthy controls (HCs) performed a conflict control task (Simon task). Participants were instructed to give a left or right response to a spatially lateralized arrow (direction of the arrow). When the action signaled by the spatial location and direction of the arrow were non-corresponding (induced conflict), the inappropriate action impulse required suppression. Overall, ET patients responded slower and less accurately compared to HCs. ET patients were especially less accurate on non-corresponding conflict (Nc) versus corresponding (Cs) trials. A focused analysis on fast impulsive response rates (based on the accuracy rate at the fastest reaction times on Nc trials) showed that ET patients made more fast errors compared to HCs. Results suggest impaired conflict control in ET compared to HCs. The increased impulsive errors seen in the ET population may be a symptom of deficiencies in the cerebello-thalamocortical networks, or, be caused by indirect effects on the cortico-striatal pathways. Future studies into the functional networks impacted by ET (cortico-striatal and cerebello-thalamocortical pathways) could advance our understanding of inhibitory control in general and the cognitive deficits in ET.

Shaky hands are a part of motor neuron disease phenotype: clinical and electrophysiological study of 77 patients.

In the sharp contrast with the existing literature, we frequently observe minipolymyoclonus, tremor and pseudodystonic thumb posturing in patients with motor neuron disease. We conducted a clinical and electrophysiological study to describe phenomenology, prevalence and pathophysiology of involuntary movements in motor neuron disease. We included 77 consecutive patients. Involuntary movements were assessed at rest and on action. Patients were videotaped. Arm muscle tone, power and deep tendon reflexes were evaluated. Accelerometry with electromyography was recorded in a subset of patients. Involuntary movements were observed in 68.9% of patients and could be separated into rest minipolymyoclonus, thumb tremor, pseudodystonic thumb posture, action minipolymyoclonus, and action tremor. One-third of patients reported negative impact of involuntary movements on hand use. Logistic regression showed that rest minipolymyoclonus and thumb tremor were more likely to occur in patients with more prominent distal muscle weakness and less spasticity. Similarly, action involuntary movements were more likely to appear in weaker patients. Patients with brisk tendon reflexes were more likely to display action tremor than action minipolymyoclonus. Action tremor was characterized by accelerometer and corresponding electromyography peak frequency, which decreased with mass loading, suggesting a mechanical-reflex tremor. Involuntary movements are common, but poorly recognized feature of motor neuron disease that may add to functional impairment. Results of our study suggest that involuntary movements are likely of peripheral origin, with a non-fused contraction of enlarged motor units being a common driving mechanism. Minipolymyoclonus appears if no synchronization of motor units occurs. When synchronization occurs via stretch reflex, mechanical-reflex tremor is generated.

P 22 Effects of multisensory feedback on tremor severity in essential tremor

Introduction : Essential tremor (ET) amplitude is modulated by visual feedback during target-driven movements: In a grip force task, tremor amplitude increases during large-scale visual feedback compared to low-scale visual feedback. It has not been examined whether visual feedback exclusively modulates action tremor severity or if an increase of other afferent input like auditory information has a modulatory effect on tremor amplitude as well. Also, it is unknown whether the sensory signal itself directly affects the tremor generating network or if the effect is rather indirect: enhanced sensory feedback during targeted driven movements might cause arousal/psychological stress. We hypothesized that (1) amplitude of ET is modulated by variation of auditory feedback in the absence of visual feedback in a force tremor paradigm; (2) increase of tremor amplitude coincides with pupillary dilation as a measure of arousal / psychological stress, independently of the quality of sensory feedback Patients & Methods : 14 ET patients conducted a computer-based experiment in which they were asked to match a target force in a force sensor using their thumb and index finger. The quality of them matching the target force was fed back to the participant visually, auditory or a combination of both. For the visual feedback, 2 bars were displayed on a screen, with the distance between these bars decreasing with approximation of the target force. In auditory feedback, a target tone of 440Hz was asked to match by a second tone which changed pitch when approximating the target force. The amplitude of feedback was manipulated via a scaling factor resulting in a large scale and a small scale feedback condition. To characterize the performance (RMSE to target force) and the tremor severity (Power 4-12 Hz) a 3x2 ANOVA was conducted. To control for arousal / psychological stress-induced via the task, pupillometry was recorded. Results : First results showed a comparable deviation from the target force (RMSE) during the experiment in all three sensory feedback modalities. Additionally, tremor severity did not differ between sensory feedback modalities. The ANOVA revealed an effect of the scaling factor on the tremor severity (Power 4-12Hz) for the visual and also for the auditory feedback condition. Pupillometry consistently showed a significantly increased pupil diameter during the large-scale visual- and auditory feedback conditions compared to the small-scale feedback conditions. Conclusion : Our preliminary findings suggest that action tremor in ET is firstly modulated not only by visual but also auditory feedback in a comparable manner and seems to be modality independent. Secondly, arousal / cognitive stress, as measured here by the pupil size, could mediate the increase of tremor amplitude. Further work is required better understand the role of these two possible mechanisms underlying target-related tremor.

Deep Brain Stimulation for Arm Tremor: A Randomized Trial Comparing Two Targets.

ObjectiveDeep brain stimulation (DBS) of the thalamic ventral intermediate nucleus (VIM) effectively suppresses arm tremor. Uncontrolled studies suggest the posterior subthalamic area (PSA) may be superior. We compared the intra‐individual efficacy of VIM‐ versus PSA‐DBS on tremor suppression and arm function.MethodsWe performed a randomized, double‐blind, crossover trial at Oslo University Hospital in patients (18–80 years) with isolated or combined action tremor affecting at least one arm. Four‐contact DBS leads were implanted (bi‐ or unilaterally) with a trajectory to cover the VIM (upper two contacts) and PSA (lower two contacts). Patients were randomized (1:1 ratio) post‐surgery to: Group 1, VIM‐stimulation months 0–3 (period 1), then PSA‐stimulation months 4–6 (period 2); Group 2, PSA‐stimulation first, then VIM‐stimulation. Primary endpoint was the difference in improvement from baseline to the end of the VIM‐ versus PSA‐period in the sum of the dominant arm tremor scores of the Fahn‐Tolosa‐Marin Tremor Rating Scale (FTMTRS), items 5/6 + 10−14.ResultsForty‐five patients were randomized to Group 1 (n = 23) or 2 (n = 22). In the primary endpoint per‐protocol analysis (mixed model, n = 40), mean difference in the sum FTMTRS score improvement for the dominant arm was −2.65 points (95% CI −4.33 to −0.97; p = 0.002). The difference in favour of PSA stimulation was highly significant in period 2, but not period 1.InterpretationOur randomized trial demonstrated that PSA stimulation provided superior tremor suppression compared with VIM stimulation. A period effect reducing tremor for up to three months in both groups was most likely attributed to a post‐surgery stun effect. ANN NEUROL 2022;91:585–601

Tremor in Writer’s Cramp Patients: A Retrospective Study

Background: Tremor is one of the important motor phenotypes of dystonia, however, there is a lacuna in the literature regarding the occurrence of tremor in task-specific dystonia such as writer’s cramp (WC).Aims: To delineate the demographic and clinical characteristics of tremor in WC patients.Methods: This is a detailed chart review of 105 patients of WC who were classified as WC with dystonic action tremor (WCT+) (n = 39; 37.1%) and WC without tremor (WCT-) (n = 66; 53.9%).Results: The mean age of patients was 41.10 ± 14.02 years in the WCT + group and 36.40 ± 14.66 years in the WCT-group. Males were more commonly affected (94.9% in WCT+ and 84.8% in WCT-). The mean duration of disease was significantly higher in WCT + as compared to WCT- (4.16 ± 4.48 years vs. 2.57 ± 2.81 years, p = 0.024). One-third of our patients (29.52%; n = 31) were students but, and the majority of them were classified as WCT- (80.64%, n = 25, p = 0.01). However, tremor was present in all the three doctors in our cohort with WC (p = 0.03). The motor overflow to the elbow and shoulder was significantly associated with the presence of tremor (46.1% of WCT + vs. 15.2% of WCT-patients, p = 0.001). Statistically, there were no significant differences between WCT+ and WCT-patients regarding the presence of complex WC (dystonia during other activities as well) (p = 0.976), mirror dystonia (p = 0.211), and finger flexion/extension abnormalities (p = 0.111).Conclusion: The presence of tremor in WC was associated with a longer duration of disease and the presence of motor overflow.