Search

Background: Although essential tremor (ET) is associated with cognitive decline, we know little about how specific cognitive changes predict significant events in patients' lives. We examined the relations of attention, executive function, language, memory, and visuospatial performance to the occurrence of near falls, falls, walking aid use, home health aide use, non-independent living and hospitalizations within a prospective, longitudinal study of ET cases. We expected executive function and memory to be most strongly associated with these events., Methods: 131 ET cases (mean age at baseline = 76.4 ± 9.4 years; 109 normal cognition; 17 mild cognitive impairment, 5 demented) completed questionnaires (clinical history and occurrence of life events) and a battery of neuropsychological tests at baseline and at 18, 36, and 54 months. We assessed associations between cognitive functioning and outcomes via regression equations., Results: Cases with lower baseline levels of executive function reported more near falls, p < 0.006, and were more likely to use a walking aid, p < 0.03, odds ratio (OR) = 2.89 during the follow-up period, than were other cases. Decline in executive function was associated with home health aide use during follow-up, p < 0.04, OR = 3.34. Baseline visuospatial performance also bore a marginally significant association with non-independent living arrangements during follow-up, p < 0.06, OR = 2.13. These effects were independent of age and tremor severity., Conclusion: These data establish the important role that cognitive decline, and executive function specifically, play in the experiences of ET patients. Moreover, these associations are of sufficient magnitude to have significant clinical implications., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier B.V. All rights reserved.)

In 2018, the new Consensus Statement on the Classification of Tremors, by the Task Force on Tremor of the International Parkinson Movement Disorder Society, was published. So far, the article has been cited more than 400 times in peer-reviewed international journals and commonly debated in conferences and meetings due to an enthusiastic welcome from the community. Compared to the previous Consensus Statement (1998), the main novelties are: 1) the classification of tremor according to clinical manifestation (Axis 1) and etiology (Axis 2), and therefore the use of a syndromic approach; 2) the definition of essential tremor as a syndrome; 3) the recognition of the new category essential tremor plus, that derives from the uncertain significance of the soft neurological signs often associated with essential tremor. In this paper, we summarise and explain the most important aspects of the new classification of tremors, highlighting the main novelties, their relevance, and application in clinical practice. Moreover, we discuss its possible weakness and reflect on the critical comments made so far. We believe that this new tremor classification is comprehensive, rigorous, and consistent and, considering our current knowledge of tremor syndromes, it is the best we can do at present. This article is part of the Special Issue "Tremor" edited by Daniel D. Truong, Mark Hallett, and Aasef Shaikh., (Copyright © 2022. Published by Elsevier B.V.)

Tremor, the most common movement disorder, may occur in isolation or may co-exist with a variety of other neurologic and movement disorders including parkinsonism, dystonia, and ataxia. When associated with Parkinson's disease, tremor may be present at rest or as an action tremor overlapping in phenomenology with essential tremor. Essential tremor may be associated not only with parkinsonism but other neurological disorders, suggesting the possibility of essential tremor subtypes. Besides Parkinson's disease, tremor can be an important feature of other parkinsonian disorders, such as atypical parkinsonism and drug-induced parkinsonism. In addition, tremor can be a prominent feature in patients with other movement disorders such as fragile X-associated tremor/ataxia syndrome, and Wilson's disease in which parkinsonian features may be present. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna., (Copyright © 2021. Published by Elsevier B.V.)

Background: There is evidence that the risk of mortality is increased in patients with essential tremor (ET), however, there are few longitudinal, prospective data on the predictors of mortality in ET. There is also evidence that ET is associated with cognitive impairment; yet, it is unknown whether this is associated with elevated risk of mortality., Methods: In a longitudinal, prospective study of 194 elders with ET, an extensive neuropsychological test battery was performed at three time points: baseline, 18 months, and 36 months, and cognitive diagnoses (normal, mild cognitive impairment [MCI], and dementia) were assigned during consensus conferences. We used Cox proportional hazards models to estimate hazard ratios (HR) for death., Results: The mean baseline age was 79.1 ± 9.7 years. During follow-up, 52 (26.8%) died. In initial univariate models, a variety of baseline factors were associated with increased risk of mortality, including demographic variables (i.e., older age), cognitive variables and gait and balance variables. In the final multivariate Cox model, baseline dementia (HR = 2.66, p = 0.006), older baseline age (HR = 1.18, p < 0.001), and more reported falls at baseline (HR = 1.10, p < 0.001) were independently associated with increased risk of mortality. Amnestic MCI was marginally associated with increased risk of mortality (HR = 1.93, p = 0.08) in primary analyses and significantly (p < 0.05) in several sensitivity analyses., Conclusions: In this longitudinal, prospective study, baseline dementia resulted in a 2- to 3-times increase in risk of mortality in ET, further highlighting the clinical significance of cognitive impairment, specifically dementia, in this population., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: The spectrum of symptoms exhibited by patients with essential tremor (ET) extends far beyond the classical tremor. This study aims to explore and establish the presence of subtle balance abnormalities in ET using dynamic posturography (DP)., Methods: DP was performed on 18 patients with ET and 26 controls. Diagnosis of ET was based on the Consensus Statement of the Movement Disorder Society on Tremor. Dynamic stability which included the overall balance index, anterior-posterior index and mediolateral index, and limits of stability were measured., Results: Patients with ET had significantly impaired balance indices. Impairment of dynamic stability revealed poor static balance control in all directions. Lower limits of stability scores indicated a smaller range of motion prior to which patients have to shift foot balance. No correlations were observed between age at evaluation, age at onset, duration of illness and the balance indices., Conclusions: Dynamic posturography reveals significant balance impairment in patients with ET which is unrelated to the age at onset, age at evaluation or duration of illness. This finding concurs with pre-existing reports and adds to the growing body evidence of cerebellar involvement in ET., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Objective: The extent to which individuals with ET who have clinically significant cognitive impairment are aware of their cognitive changes is unclear. Reduced awareness has important implications for everyday function and decision-making., Methods: 150 individuals with ET (109 Normal Cognition (ET-NC group), and 30 with MCI and 11 dementia (ET-CI group)) completed self-ratings and objective assessments of memory, language, and executive functioning. Discrepancy scores were calculated to assess awareness of cognitive functioning. One sample t-tests evaluated whether mean discrepancy scores in each group were comparable to zero (i.e., accurate). Analyses of covariance (ANCOVA) compared discrepancy scores across two groups controlling for age and education., Results: In the ET-NC group, discrepancy scores for language (M=-0.08, SD=1.10) and executive functioning (M=-0.01, SD=0.99) were comparable to zero. Memory discrepancy scores (M=0.32, SD=1.22) were greater than zero. In the ET-CI group, memory, (M=0.78, SD=1.01), language, (M=0.46, SD=0.95), and executive (M=0.39, SD=1.14) discrepancy scores were all greater than zero. Discrepancy scores were larger in ET-CI group than in ET-NC group for memory: F(1,148)=4.02, p=0.047, language: F(1,148)=6.16, p=0.014, and executive: F(1,148)=4.51, p=0.035., Conclusions: Individuals with ET and normal cognition accurately assessed their language and executive abilities, demonstrating mild overconfidence in memory function. Individuals with ET and cognitive impairment overestimated their performance in all domains of functioning. Since ET is linked to increased risk for cognitive impairment, and such impairment may not be accurately perceived, cognitive functioning should be proactively and regularly screened in ET., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Surprisingly little has been written about the combined clinical entity, essential tremor-Parkinson's disease (ET-PD), which is the result of a double disease hit. We carefully quantified tremor burden using a wide range of measures (tremor severity, tremor-related disability, tremor-related quality of life) and furthermore, studied additional motor and non-motor features in ET-PD., Methods: In this prospective, clinical-epidemiological study, we performed a standardized, structured clinical evaluation of 27 ET-PD patients, comparing them to age-matched samples of 35 PD and 109 ET patients., Results: The number of hours/day shaking was lowest in PD (median=3.0), intermediate in ET (median=10.0) and highest in ET-PD (median=14.0) (p<0.001). All measures of mobility and balance (Berg Balance test, Activities-specific Balance Confidence Scale, Timed Up and Go test) worsened across groups in a stepwise manner from ET to PD to ET-PD (p<0.05). Mini-mental state test scores worsened (p=0.002) and daytime sleepiness increased (p=0.002) across groups from ET to PD to ET-PD., Conclusions: The ET-PD patient seems to be more than just a PD patient with a little more kinetic tremor. Aside from a significantly greater tremor burden, ET-PD patients exhibited more cognitive and sleep problems and more mobility and balance problems than patients with isolated PD., Competing Interests: None, (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Differential diagnosis of tremor disorders, including essential tremor (ET) and Parkinson's disease-tremor dominant type (PD-TDT), requires further investigation. Therefore, the current study aimed to compare non-motor and tremor features in order to differentiate between ET and PD-TDT., Methods: Twenty-eight patients with classic ET and 24 patients with typical PD-TDT were retrospectively enrolled in a multi-stage investigation process. Tremor features including surface electromyogram (EMG) were analyzed in detail. For non-motor symptom analyses, the global cognition test, frontal function test, and non-motor symptoms scale (NMSS) were administered, in addition to collecting patient history data., Results: Patients with PD-TDT presented with more asymmetric tremor, whereas patients with ET presented with more symmetric tremor. Leg tremor was observed only in patients with PD-TDT. Surface EMG analyses of arm tremor demonstrated considerable overlaps in tremor type, tremor frequency, and contractive patterns. However, patients with PD-TDT were significantly more likely to exhibit resting tremor, and experienced alternative contraction patterns only for kinetic tremor, which was in contrast to patients with ET. For non-motor symptom analyses, patients with PD-TDT had more non-motor symptoms compared to patients with ET (mean=5.0 vs. 2.6; P=0.002). Specifically, patients with PD-TDT exhibited higher frequencies of hyposmia, REM sleep behavior disorder (RBD)-like symptom, urinary frequency, and memory disturbance. Age- and gender- matched analyses for the severity of NMSS scores did not indicate significant differences. However, patients with PD-TDT displayed slightly lower scores of frontal function test compared to patients with ET., Conclusions: Careful and detailed evaluations of both tremor features and non-motor symptoms are required in order to distinguish between ET and PD-TDT., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The traditional view of essential (ET) tremor is as a mono-symptomatic condition characterized by action tremor. Over the past decade, researchers have learned that this picture is an over-simplification. First, it is clear that many patients also have other motor manifestations (e.g., ataxic gait). Second, the presence of a variety of non-motor features, both cognitive and psychiatric, is now appreciated. Mild cognitive changes (esp. executive dysfunction) have been documented in several studies. More recently, two population-based studies have demonstrated an association between ET and dementia. Clinically, while most of these cases developed Alzheimer's disease, the neuropathological underpinnings of this dementia have not been fully explored. Psychiatric manifestations include specific personality traits, anxiety, social phobia, and depressive symptoms. Depression may be a primary manifestation of the illness rather than a secondary response to disability. The emerging view of ET is that it is a disease whose central feature is action tremor but in which both motor and non-motor features occur. As in other neurodegenerative conditions, ET appears to be more than a disease of the motor system. Further study of these non-motor phenomena will advance our understanding of disease mechanisms and enhance the quality of clinical interactions with patients.