Non-motor features in essential tremor

'Am I fixed, am I better now?': undergoing MR-guided focused ultrasound for essential tremor: an interpretative phenomenological analysis

Introduction

Essential tremor (ET) is characterised by postural and intentional tremor typically affecting the upper limbs, which can negatively impact functionality and quality of life. Magnetic Resonance-guided Focused Ultrasound (MRgFUS) is a novel and promising non-invasive treatment for ET which offers instantaneous results.

Methods

Using interpretative phenomenological analysis we explored the experience of undergoing MRgFUS in six ET patients as well as their experiences pre- and post-procedure.

Results

One-time, retrospective semi-structured interviews were conducted and six themes emerged: Life pre-treatment: "It's everyday tasks that get you down" and "Most people who understand, they are okay. Some people aren't"; MRgFUS: Treatment day: "Going into the unknown" and "There's no way I was going to press that button"; and Life post-treatment: "One is good. Two is better" and "Am I fixed, am I better now?."

Discussion

The findings point to a significant period of adjustment associated with living with ET and the effects of undergoing ET MRgFUS treatment. As ET progressed, participants struggled to cope with increasing symptoms and had to develop coping strategies to manage life with ET. The procedure itself was perceived as strange and extraordinary and despite some immediate adverse effects participants were determined to go through with it. Post procedure, all participants reported tremor suppression which was life changing. While some participants still felt burdened by ET, others expressed it took them a while to psychologically adjust to what essentially was their new body. This study has highlighted the need for patients to be supported at all stages of their ET journey.

Visuomotor Adaptation Deficits in Patients with Essential Tremor

Essential tremor (ET) is a progressive movement disorder whose pathophysiology is not fully understood. Current evidence supports the view that the cerebellum is critically involved in the genesis of the tremor in ET. However, it is still unknown whether cerebellar dysfunction affects not only the control of current movements but also the prediction of future movements through dynamic adaptation toward a changed environment. Here, we tested the capacity of 28 patients with ET to adapt in a visuomotor adaptation task known to depend on intact cerebellar function. We found specific impairments in that task compared to age-matched healthy controls. Adaptation to the visual perturbation was disrupted in ET patients, while de-adaptation, the phase after abrupt removal of the perturbation, developed similarly to control subjects. Baseline tremor-independent motor performance was as well similar to healthy controls, indicating that adaptation deficits in ET patients were not rooted in an inability to perform goal-directed movements. There was no association between clinical severity scores of ET and early visuomotor adaptation abilities. These results provide further evidence that the cerebellum is dysfunctional in ET.

Risk of neurodegenerative diseases in patients with sleep disorders: A nationwide population-based case-control study

OBJECTIVE

Our study aimed to explore the associative relationship between neurodegenerative diseases and sleep disorders.

PATIENTS

This 15-year retrospective longitudinal nationwide population-based matched case-control study used data extracted from the National Health Insurance Research Database. We evaluated 25,589 patients diagnosed with neurodegenerative diseases between 2000 and 2015 and a matched control of 102,356 patients without neurodegenerative diseases.

RESULTS

Sleep disorders were an independent risk factor for the development of neurodegenerative diseases (adjusted odds ratio (OR): 1.794, 95% confidence interval (CI): 1.235-2.268, P < 0.001), with a positive dose-effect relationship (adjusted OR (95% CI): <1 year: 1.638 (1.093-2.872), P < 0.001; 1-5 years: 1.897 (1.260-3.135), P < 0.001; >5 years: 2.381 (1.467-3.681), P < 0.001. Moreover, patients with sleep disorder and comorbid depression had a significantly higher risk of neurodegenerative disorders (adjusted OR: 5.874). Subgroup analysis showed that insomnia was associated with Alzheimer's disease, Pick's disease and essential tremor (adjusted OR (95% CI): 1.555 (1.069-1.965), 1.934 (1.331-2.445) and 2.089 (1.439-2.648), respectively). Obstructive sleep apnea was associated with Parkinson's disease, essential tremor, and primary dystonia (adjusted OR (95% CI): 1.801 (1.239-2.275), 5.523 (3.802-6.977), and 4.892 (3.365-6.178), respectively). Other specific sleep disorders were associated with Pick's disease, Parkinson's disease, essential tremor, and primary dystonia (adjusted OR (95% CI): 8.901 (6.101-11.010), 1.549 (1.075-1.986), 2.791 (1.924-3.531), and 9.114 (6.283-10.506), respectively).

CONCLUSION

Sleep disorders are associated with the subsequent development of neurodegenerative disorders. Moreover, sleep disorder patients with comorbid depression have a higher risk of neurodegenerative diseases.

Odds of Medical Comorbidities in Essential Tremor: Retrospective Analysis of a Large Claims Database in the United States

INTRODUCTION

Essential tremor (ET) is the most common tremor disorder, estimated to affect 7 million individuals in the USA. There is little empirical evidence on comorbidities among this population beyond higher prevalence of brain-related and stress-related disorders. This study aims to examine differences in the prevalence of the 31 Elixhauser comorbidities among ET patients compared to statistically similar control patients.

METHODS

An extract from Optum's de-identified Clinformatics® Data Mart Database (CDM) from 2018 to 2019 of adults aged 40-80 years with at least one claim with an ET diagnosis was propensity score matched to controls. Logistic regression was used to generate doubly robust adjusted odds ratios for each of the 31 Elixhauser comorbidities.

RESULTS

In these analyses, ET patients had significantly greater adjusted odds of depression, alcohol abuse, and other neurological disorders, as well as chronic pulmonary disease, renal failure, hyperthyroidism, and cardiac arrhythmias relative to controls. They also had lower odds of uncomplicated diabetes, congestive heart failure, metastatic cancer, paralysis, peripheral vascular disease, and fluid and electrolyte disorders.

CONCLUSION

A number of recent studies, including our own, suggest that psychiatric, neurologic, and stress-related disorders may be more prevalent among ET patients than controls. Additional differences in the prevalence of a range of medical comorbidities have also been variably reported across studies, suggesting that some combination of these might be more prevalent. Further studies would be of value in sorting through these associations.

Differential contributions of depression, apathy, and anxiety to neuropsychological performance in Parkinson's disease versus essential tremor

INTRODUCTION

Mood symptoms are common features of Parkinson's disease (PD) and essential tremor (ET) and have been linked to worse cognition. The goals of the present study were to compare the severity of anxiety, apathy, and depressive symptoms in PD, ET, and healthy controls (HC) and to examine differential relationships between mood and cognition.

METHOD

Older adults with idiopathic PD (N = 448), ET (N = 128), or HC (N = 136) completed a multi-domain neuropsychological assessment consisting of memory, executive function, and attention/working memory domains. Participants also completed self-reported mood measures. Between-group differences in mood and cognition were assessed, and hierarchical regression models were conducted to examine relationships between mood and cognition in each group.

RESULTS

Relative to the HC group, the PD and ET groups reported more mood symptoms and scored lower across all cognitive measures. There were no differences between the two movement disorder groups. Mood variables explained 3.9-13.7% of the total variance in cognitive domains, varying by disease group. For PD, apathy was the only unique predictor of executive function (β = -.114, p = .05), and trait anxiety was the only unique predictor of attention/working memory (β = -.188, p < .05). For ET, there were no unique predictors, though the overall models significantly predicted performance in the executive function and attention/working memory domains.

CONCLUSIONS

In a large cohort of ET and PD, we observed that the two groups had similar self-reported mood symptoms. Mood symptoms were differentially associated with cognition in PD versus ET. In PD, increased apathy was associated with worse executive function and higher trait anxiety predicted worse attention/working memory. For ET, there were no unique predictors, though the overall mood symptom severity was related to cognition. Our study highlights the importance of considering the relationship between mood and neuropsychological performance in individuals with movement disorders.

Essential tremor patients experience significant burden beyond tremor: A systematic literature review

Background

Essential tremor (ET) is among the most common movement disorders in adults. While ET is diagnosed and primarily characterized by the presence of tremor, it also can impact cognition, sleep, mood, and motor functioning more broadly. The manifestations of ET can have various consequences, including difficulty with activities of daily living (ADL), embarrassment, and overall decline in health-related quality of life, which have not been fully explored in prior studies.

Objective

We performed a systematic literature review to comprehensively characterize the burden experienced by patients with ET from the clinical and humanistic perspectives, focusing on outcomes beyond tremor.

Methods

This systematic literature review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Searches in PubMed, Embase, and Cochrane Library identified original, observational studies of the clinical and humanistic burden in adult patients with ET published in English between 2010 and 2020. Studies assessing epidemiology, treatment patterns, or disease management were excluded. Search results were screened according to pre-determined eligibility criteria. Data from included studies were collected, independently verified, and qualitatively synthesized.

Results

Following the screening of 2,303 records and 145 full-text articles, 39 studies were identified. There was significant heterogeneity in study designs, statistical approaches, and patient cohorts across the included studies. Patients with ET in these studies exhibited more severe disabilities and reduced independence compared to healthy individuals, and they often struggled to perform ADL and relied on caregivers for physical and emotional support. Patients also experienced various issues with movement and balance, increased risk of falls, depression, anxiety, poor sleep quality, and psychosocial consequences including embarrassment, apathy, and enfeeblement.

Conclusion

A systematic literature review of non-tremor manifestations and/or consequences of ET identified far-reaching negative impacts on patients' ability to function independently and revealed accompanying psychosocial effects, including social fear and embarrassment. The reduced function and psychosocial deficits observed in patients with ET result in significant clinical and humanistic burdens, decreasing quality of life. Future studies should evaluate this condition beyond the tremor itself to provide an improved understanding of the multi-dimensional burden of the disease, thereby highlighting the need to diagnose and appropriately manage patients with ET.

Transcranial high-intensity Magnetic Resonance-guided focused ultrasound (tcMRgFUS) - safety and impacts on tremor severity and quality of life

INTRODUCTION

Transcranial high-intensity Magnetic Resonance-guided Focused Ultrasound (tcMRgFUS) is a technique for treatment of severe, medication-refractory Essential Tremor (ET). We summarize 1-year follow-up results focusing on clinical and safety parameters and impacts on quality of life.

METHODS

A total of 45 patients with severe, medication-refractory ET were treated with tcMRgFUS thalamotomy. 37 patients completed the clinical follow-up of 12 months. Tremor severity, disability and quality of life were measured using the Clinical Rating Scale for Tremor (CRST), surface electromyography, the Quality of Life in Essential Tremor Questionnaire (QUEST) and the Short-Form-36 questionnaire (SF-36). Depressive symptoms and cognitive function were assessed using standardized questionnaires. Electrophysiological measurements were conducted to evaluate possible effects on central motor and sensory pathways.

RESULTS

1 year after tcMRgFUS the mean tremor improvement on a hand-specific subscore of the CRST was 82%. The QUEST and SF-36 revealed an improvement of mental quality of life, especially in activities of daily living and psychosocial function; depressive symptoms decreased significantly. There was no worsening of cognitive function overt within the self-rating questionnaire; no prolongation of sensory evoked potentials or central motor conduction time occurred. Side effects were mostly classified as mild (78%) and transient (62%).

CONCLUSIONS

TcMRgFUS for severe tremor has a distinct impact on quality of life and neuropsychological symptoms. Self-assessments of cognitive function revealed stable outcomes 1 year after tcMRgFUS. No prolongation of sensory or motor conduction time were found in neurophysiology measures. Side effects occurred in 78% of treated patients but were mostly transient and mild.

Depressive symptoms predict memory decline in Essential Tremor

INTRODUCTION

Essential tremor (ET), a common movement disorder, is characterized by motor, cognitive and psychiatric symptoms. Depressed mood, a symptom of ET, has historically been viewed as a psychological response to disability. However, depressive symptoms are emerging as a predictor of cognitive decline across several clinical populations. We examined if depressive symptoms predict decline in global cognition, memory, and executive functioning among older adults with ET.

METHODS

125 cognitively normal participants with ET completed three in-person assessments of cognition, mood, and motor symptoms at baseline, 18 months, and 36 months; baseline data were collected from July 2014-July 2016. Depressive symptoms were measured with the Geriatric Depression Scale. Cognitive functioning was measured via a 3-4 hour neuropsychological evaluation. Generalized linear regression models examined depressive symptoms as a predictor of decline in global cognition, executive functioning (EF), and memory.

RESULTS

Participants were grouped according to a median split (GDS <5 versus ≥ 5) due to the bimodal distribution of the data. In unadjusted models, depressive symptoms did not predict change in global cognition (b = -0.002, p = .502) or EF (b = 0.000, p = .931), however individuals with GDS ≥ 5 demonstrated faster memory decline in unadjusted (b = -0.008, p = .039) and adjusted models (b = -0.009, p = .019).

CONCLUSION

The presence of 5 or more depressive symptoms predicted mildly faster memory decline in cognitively normal older adults with ET over 36 months. We discuss potential mechanisms and clinical implications.

Epidemiology of pediatric essential tremor in the United States: a systematic literature review from 2010 to 2020

Background:

Methods:

Results:

Discussion:

Association of Essential Tremor With Dementia and Affective Disorders: A Meta-Analysis

Background

The dementia and affective disorders are common non-motor features in patients with essential tremor (ET). However, the relationship of ET with cognitive impairments and affective disorders remains controversial. This meta-analysis aimed to analyze the association of ET with dementia and affective disorders.

Methods

Original studies published from January 1999 to October 2019 were systematically searched from the database of Medline (OvidSP), EMBASE (OvidSP), and the Cochrane Central Register of Controlled Trials. Pooled standard mean difference (SMD, random effect model), odds ratios (ORs), relative risk (RR), and 95% CI were calculated.

Results

Compared with the Non-ET group, patients with ET had significantly lower Mini-Mental State Examination (MMSE) score (SMD, −1.16; 95% CI, −1.75 to −0.58; p = 0.0001) and had significantly higher depressive and anxiety symptoms scale score (SMD, 0.55; 95% CI, 0.22–0.87; p = 0.0009). The OR for dementia and affective disorders in individuals with ET compared with individuals without ET was 2.49 (95% CI, 2.17–2.85, p &lt; 0.00001). While there was no significant difference in Montreal Cognitive Assessment (MoCA) score between ET and Non-ET groups (SMD, −0.52; 95% CI, −0.16 to 0.13; p = 0.23), there was a significant difference in the risk of mortality between ET and Non-ET groups (RR = 4.69, 95% CI, 2.18–10.07).

Conclusion

The non-motor symptoms should not be neglected among patients with ET. However, the causal relationship between ET and dementia, depression, and anxiety is unclear.

Primidone Intolerance in Essential tremor: Is it More than Just Age?

Background:

There are few medications for the treatment of essential tremor (ET). One of these, primidone, which is one of only two front-line agents, is associated with considerable adverse drug reactions (ADRs). It is unclear why some primidone-treated ET patients develop ADRs whereas others do not, and why these ADRs seem to be more prevalent in ET patients than primidone-treated patients with epilepsy.

Objective:

To review several possible explanations underlying the above-referenced differences.

Methods:

A literature search was conducted in PubMed in October 2021. Studies reporting the ADRs of primidone in different neurological conditions were comprehensively reviewed.

Discussion:

Although there were no head-to-head data, a review of the previous studies on ET and epilepsy patients indicates that the former is relatively more intolerant to primidone. Moreover, not all ET patients develop ADR of similar nature or severity. We discuss several potential mechanisms for this variability in the intolerance to primidone. These include: (i) older age (ET vs. epilepsy patients), (ii) cross-tolerance to primidone in patients with epilepsy, (iii) neurobiological (GABA-related) abnormalities associated with ET.

Conclusion:

We speculate that there are several possible explanations for primidone intolerance in ET. These possibilities should be tested in future studies, and we propose the roadmap for designing these studies. It is of value to obtain detailed insight into these complex issues because primidone remains one of the few frontline anti-tremor medications in ET. Answers to issues we have raised in this article could facilitate more customized formulation of primidone in ET patients.

The Pathophysiology and Treatment of Essential Tremor: The Role of Adenosine and Dopamine Receptors in Animal Models

Essential tremor (ET) is one of the most common neurological disorders that often affects people in the prime of their lives, leading to a significant reduction in their quality of life, gradually making them unable to independently perform the simplest activities. Here we show that current ET pharmacotherapy often does not sufficiently alleviate disease symptoms and is completely ineffective in more than 30% of patients. At present, deep brain stimulation of the motor thalamus is the most effective ET treatment. However, like any brain surgery, it can cause many undesirable side effects; thus, it is only performed in patients with an advanced disease who are not responsive to drugs. Therefore, it seems extremely important to look for new strategies for treating ET. The purpose of this review is to summarize the current knowledge on the pathomechanism of ET based on studies in animal models of the disease, as well as to present and discuss the results of research available to date on various substances affecting dopamine (mainly D3) or adenosine A1 receptors, which, due to their ability to modulate harmaline-induced tremor, may provide the basis for the development of new potential therapies for ET in the future.

Identifying Depressed Essential Tremor Using Resting-State Voxel-Wise Global Brain Connectivity: A Multivariate Pattern Analysis

Background and Objective: Although depression is one of the most common non-motor symptoms in essential tremor (ET), its pathogenesis and diagnosis biomarker are still unknown. Recently, machine learning multivariate pattern analysis (MVPA) combined with connectivity mapping of resting-state fMRI has provided a promising way to identify patients with depressed ET at the individual level and help to reveal the brain network pathogenesis of depression in patients with ET.

Methods: Based on global brain connectivity (GBC) mapping from 41 depressed ET, 49 non-depressed ET, 45 primary depression, and 43 healthy controls (HCs), multiclass Gaussian process classification (GPC) and binary support vector machine (SVM) algorithms were used to identify patients with depressed ET from non-depressed ET, primary depression, and HCs, and the accuracy and permutation tests were used to assess the classification performance.

Results: While the total accuracy (40.45%) of four-class GPC was poor, the four-class GPC could discriminate depressed ET from non-depressed ET, primary depression, and HCs with a sensitivity of 70.73% (P < 0.001). At the same time, the sensitivity of using binary SVM to discriminate depressed ET from non-depressed ET, primary depression, and HCs was 73.17, 80.49, and 75.61%, respectively (P < 0.001). The significant discriminative features were mainly located in cerebellar-motor-prefrontal cortex circuits (P < 0.001), and a further correlation analysis showed that the GBC values of significant discriminative features in the right middle prefrontal gyrus, bilateral cerebellum VI, and Crus 1 were correlated with clinical depression severity in patients with depressed ET.

Conclusion: Our findings demonstrated that GBC mapping combined with machine learning MVPA could be used to identify patients with depressed ET, and the GBC changes in cerebellar-prefrontal cortex circuits not only posed as the significant discriminative features but also helped to understand the network pathogenesis underlying depression in patients with ET.

Genomic Markers for Essential Tremor

There are many reports suggesting an important role of genetic factors in the etiopathogenesis of essential tremor (ET), encouraging continuing the research for possible genetic markers. Linkage studies in families with ET have identified 4 genes/loci for familial ET, although the responsible gene(s) have not been identified. Genome-wide association studies (GWAS) described several variants in LINGO1, SLC1A2, STK32B, PPARGC1A, and CTNNA3, related with ET, but none of them have been confirmed in replication studies. In addition, the case-control association studies performed for candidate variants have not convincingly linked any gene with the risk for ET. Exome studies described the association of several genes with familial ET (FUS, HTRA2, TENM4, SORT1, SCN11A, NOTCH2NLC, NOS3, KCNS2, HAPLN4, USP46, CACNA1G, SLIT3, CCDC183, MMP10, and GPR151), but they were found only in singular families and, again, not found in other families or other populations, suggesting that some can be private polymorphisms. The search for responsible genes for ET is still ongoing.

Head tremor and pain in cervical dystonia

BACKGROUND

Although head tremor (HT) and pain are prevalent in cervical dystonia (CD), their joint relationship to phenotypic features of focal dystonia remains unclear.

OBJECTIVES

We examined how severity of HT and pain are associated with age of CD onset and duration, and whether HT subtypes ("jerky" or "regular") exhibit distinct relationships between severity of HT and pain.

METHODS

The severity of HT and pain were assessed with the Toronto Western Spasmodic Torticollis Rating Scale in retrospective review of 188 CD patients recruited through the Dystonia Coalition.

RESULTS

HT severity was associated with longer CD duration (p < 0.0005), whereas pain severity was associated with younger age at onset (p = 0.043). HT severity and pain severity were not correlated for jerky HT (p = 0.996), but positively correlated for regular HT (p = 0.01).

CONCLUSIONS

The distinct associations of HT and pain with age at onset, disease duration, and HT subtype further characterize the heterogeneity of CD's clinical presentation and suggest similarly heterogeneous underlying mechanisms.

Sleep disorders in essential tremor: systematic review and meta-analysis

Sleep disorders are frequent in patients diagnosed with essential tremor (ET). The present review focuses on sleep disorders and the results of polysomnographic studies performed in patients with ET. For this purpose we performed a systematic review crossing the search term "essential tremor" with "sleep," "sleep disorders," "sleep disturbances" and "polysomnography," and with specific sleep disorders, according to the International Classification of the Sleep Disorders-Third Edition, using the PubMed, EMBASE, MEDLINE, and Web of Science Databases. The most frequent sleep problems reported by patients with ET were the bad quality of sleep and excessive daytime somnolence (the latter could be related to drugs commonly used for the treatment of ET). Probable rapid eye movement sleep behavior disorder, coexistent restless legs syndrome, insomnia, and nocturia were not infrequent complaints, while the presence of other sleep disorders in patients with ET was restricted to anecdotal reports or not described. Meta-analyses of previous reports showed that patients with ET (according to the PRISMA and MOOSE guidelines) showed higher scores in the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale than controls and lower scores than those of patients diagnosed with Parkinson's disease. Studies using polysomnography in patients with ET are scarce and do not permit to establish valid conclusions regarding polysomnographic features in this disorder.

Fatigue in hypokinetic, hyperkinetic, and functional movement disorders

The emerging science of fatigue has soundly endorsed the need for its unified definition, shared terminology and increased recognition in neurological illnesses. Nevertheless, the real impact of fatigue remains under-recognized. Fatigue describes a sense of tiredness, lack of energy or need for increased effort often perceived as overwhelming, pervasive, and disabling. It is a common feature of chronic medical conditions and neurological diseases, including Parkinson's disease (PD) and other hypokinetic, hyperkinetic, and functional movement disorders (FMD). While there is solid evidence for the burden of fatigue in PD, knowledge of fatigue in other movement disorders (MDS) is still limited. Lack of consensus definition, rigorous measures and the high prevalence of potential confounders such as apathy, depression and sleepiness are the main obstacles in studying fatigue in MDS. This review of the prevalence, impact, and clinical correlates of fatigue in common MDS summarizes current hypotheses for the pathophysiological mechanisms underlying fatigue and gives a brief overview of treatment options. Fatigue is a prevalent, disabling, primary non-motor symptom (NMS) in MDS, including atypical and secondary parkinsonisms, dystonia, essential tremor (ET) and a hallmark feature of FMD. We report the hypothesis that fatigue is a perceptual disorder of the sensorimotor system. Given the relevance of this burdensome symptom, fatigue deserves greater clinical and research attention to better understand its manifestation and pathophysiology and to improve diagnosis and treatment.

A Phase 2 Proof-of-Concept, Randomized, Placebo-Controlled Trial of CX-8998 in Essential Tremor

Background

Available essential tremor (ET) therapies have limitations.

Objectives

The objective of this study was to evaluate CX‐8998, a selective T‐type calcium channel modulator, in essential tremor.

Methods

Patients 18–75 years old with moderate to severe essential tremor were randomized 1:1 to receive CX‐8998 (titrated to 10 mg twice daily) or placebo. The primary end point was change from baseline to day 28 in The Essential Tremor Rating Assessment Scale performance subscale scored by independent blinded video raters. Secondary outcomes included in‐person blinded investigator rating of The Essential Tremor Rating Assessment Scale performance subscale, The Essential Tremor Rating Assessment Scale activities of daily living subscale, and Kinesia ONE accelerometry.

Results

The video‐rated The Essential Tremor Rating Assessment Scale performance subscale was not different for CX‐8998 (n = 39) versus placebo (n = 44; P = 0.696). CX‐8998 improved investigator‐rated The Essential Tremor Rating Assessment Scale performance subscale (P = 0.017) and The Essential Tremor Rating Assessment Scale activities of daily living (P = 0.049) but not Kinesia ONE (P = 0.421). Adverse events with CX‐8998 included dizziness (21%), headache (8%), euphoric mood (6%), and insomnia (6%).

Conclusions

The primary efficacy end point was not met; however, CX‐8998 improved some assessments of essential tremor, supporting further clinical investigation. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Sleep Disorders in Patients with Essential Tremor

PURPOSE OF THE REVIEW

Patients diagnosed with essential tremor (ET) report frequent sleep complaints. This review focuses on the main findings of studies addressing sleep features in patients diagnosed with ET, updating previously reported information. Bad quality of sleep and excessive daytime somnolence are very frequent in patients with ET, although the effects of the drugs used for the therapy of ET could contribute to these complaints. REM sleep behavior disorder, restless legs, insomnia, and nocturia are frequent complaints as well. There is a lack of studies addressing polysomnographic features of ET.

Disrupted Brain Network Topology in Drug-naïve Essential Tremor Patients with and Without Depression : A Resting State Functional Magnetic Resonance Imaging Study

PURPOSE

This study was carried out to investigate brain functional connectome and its potential relationships with the disease severity and emotion function in patients with essential tremor with and without depressive symptoms by using resting-state functional magnetic resonance imaging and graph theory approaches.

METHODS

In this study 33 essential tremor patients with depression, 45 essential tremor patients without depression and 79 age and gender-matched healthy controls were recruited to undergo a 3.0‑T imaging scan. The whole brain functional connectome was constructed by thresholding the partial correlation matrices of 116 brain regions, and the topologic properties were analyzed by using graph theory approaches and network-based statistic approaches. Nonparametric permutation test was also used for group comparisons of topological metrics. Correlation analyses between topographic features and the clinical characteristics were performed.

RESULTS

The functional connectome in both essential tremor patients with and without depression showed abnormalities at the global level (decrease in clustering coefficient, global efficiency, and local efficiency but increase in characteristic path length) and at the nodal level (decrease nodal centralities in the cerebellum, motor cortex, prefrontal-limbic regions, default mode network) (p < 0.05, false discovery rate corrected). Moreover, essential tremor patients with depression showed higher node efficiency in superior frontal gyrus and posterior cingulate gyrus compared to essential tremor without depression.

CONCLUSION

Our results may provide insights into the underlying pathophysiology of essential tremor patients with and without depression and aid the development of some potential biomarkers of the depressive symptoms in patients with essential tremor.

Altered local and matrix functional connectivity in depressed essential tremor patients

BACKGROUND

Depression in essential tremor (ET) has been constantly studied and reported, while the associated brain activity changes remain unclear. Recently, regional homogeneity (ReHo), a voxel-wise local functional connectivity (FC) analysis of resting-state functional magnetic resonance imaging, has provided a promising way to observe spontaneous brain activity.

METHODS

Local FC analyses were performed in forty-one depressed ET patients, 49 non-depressed ET patients and 43 healthy controls (HCs), and then matrix FC and clinical depression severity correlation analyses were further performed to reveal spontaneous neural activity changes in depressed ET patients.

RESULTS

Compared with the non-depressed ET patients, the depressed ET patients showed decreased ReHo in the bilateral cerebellum lobules IX, and increased ReHo in the bilateral anterior cingulate cortices and middle prefrontal cortices. Twenty-five significant changes of ReHo clusters were observed in the depressed ET patients compared with the HCs, and matrix FC analysis further revealed that inter-ROI FC differences were also observed in the frontal-cerebellar-anterior cingulate cortex pathway. Correlation analyses showed that clinical depression severity was positively correlated with the inter-ROI FC values between the anterior cingulate cortex and bilateral middle prefrontal cortices and was negatively correlated with the inter-ROI FC values of the anterior cingulate cortex and bilateral cerebellum lobules IX.

CONCLUSION

Our findings revealed local and inter-ROI FC differences in frontal-cerebellar-anterior cingulate cortex circuits in depressed ET patients, and among these regions, the cerebellum lobules IX, middle prefrontal cortices and anterior cingulate cortices could function as pathogenic structures underlying depression in ET patients.

Mood and emotional disorders associated with parkinsonism, Huntington disease, and other movement disorders

This chapter provides a review of mood, emotional disorders, and emotion processing deficits associated with diseases that cause movement disorders, including Parkinson's disease, Lewy body dementia, multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, frontotemporal dementia with parkinsonism, Huntington's disease, essential tremor, dystonia, and tardive dyskinesia. For each disorder, a clinical description of the common signs and symptoms, disease progression, and epidemiology is provided. Then the mood and emotional disorders associated with each of these diseases are described and discussed in terms of clinical presentation, incidence, prevalence, and alterations in quality of life. Alterations of emotion communication, such as affective speech prosody and facial emotional expression, associated with these disorders are also discussed. In addition, if applicable, deficits in gestural and lexical/verbal emotion are reviewed. Throughout the chapter, the relationships among mood and emotional disorders, alterations of emotional experiences, social communication, and quality of life, as well as treatment, are emphasized.

Managing Essential Tremor

Essential tremor is one of the most common tremor syndromes. According to the recent tremor classification, tremor as a symptom is defined as an involuntary, rhythmic, oscillatory movement of a body part and is classified along two axes: axis 1-defining syndromes based on the clinical features such as historical features, tremor characteristics, associated signs, and laboratory tests; and axis 2-classifying the etiology (Bhatia et al., Mov Disord 33:75-87, 2018). The management of this condition has two major approaches. The first is to exclude treatable etiologies, as particularly during the onset of this condition the presentation of a variety of etiologies can be with monosymptomatic tremor. Once the few etiologies with causal treatments are excluded, all further treatment is symptomatic. Shared decision-making with enabling the patient to knowledgeably choose treatment options is needed to customize the management. Mild to moderate tremor severity can sometimes be controlled with occupational treatment, speech therapy of psychotherapy, or adaptation of coping strategy. First-line pharmacological treatments include symptomatic treatment with propranolol, primidone, and topiramate. Botulinum toxin is for selected cases. Invasive treatments for essential tremor should be considered for severe tremors. They are generally accepted as the most powerful interventions and provide not only improvement of tremor but also a significant improvement of life quality. The current standard is deep brain stimulation (DBS) of the thalamic and subthalamic region. Focused ultrasound thalamotomy is a new therapy attracting increasing interest. Radiofrequency lesioning is only rarely done if DBS or focused ultrasound is not possible. Radiosurgery is not well established. We present our treatment algorithm.

Neuropsychiatric Symptoms and Quality of Life in Patients With Adult-Onset Idiopathic Focal Dystonia and Essential Tremor

Background: While idiopathic focal dystonia (IFD) and essential tremor (ET) have been considered pure movement disorders, they reportedly induce neuropsychiatric manifestations and may thus be more accurately described as network disorders.

Methods: The present multi-center, cross-sectional, case-control study evaluated the severity of depression and anxiety with the Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI), respectively; the frequency of neuropsychiatric disorders with the Korean-Mini International Neuropsychiatry Interview; and QoL with the Short-Form 36 (SF-36).

Results: Seventy-four subjects participated in this study (IFD, 27; ET, 24; controls, 23). The BDI and BAI scores were higher in the IFD and ET groups than in the control group. Although the frequency of neuropsychiatric disorders diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition Axis I was comparable among the groups, the prevalence of major depressive disorder tended to be high among patients with IFD. QoL was correlated with the severity of depression and anxiety across the groups.

Conclusions: Depression and anxiety are more severe in patients with IFD and ET compared to healthy controls, while their severity is similar among patients with IFD and ET. Axis I major depressive disorder is relatively more prevalent in patients with IFD. Neuropsychiatric symptoms affect QoL regardless of the affected individual's condition, addressing neuropsychiatric symptoms in patients with movement disorders may be crucial to improving their QoL.

Distinct non-motor features of essential tremor with head tremor patients

BACKGROUND

There have been few comprehensive scale studies on the non-motor symptoms (NMS) of patients with essential tremor (ET) with head tremor (ETh) and those with ET without head tremor (ETol). We aimed to explore the motor symptoms and NMS of these two subgroups.

METHODS

We enrolled 199 patients with ET (125, ETol; 74 ETh) and 132 healthy controls. We evaluated motor symptoms using the Fahn-Tolosa-Marin Tremor Rating Scale (TRS) and NMS using the Non-Motor Symptom Scale (NMSS). We compared NMSS scores and the prevalence of each NMS between the patient subgroups. Finally, we conducted a logistic regression analysis of the correlation between head tremor and NMS severity, as well as other determinants.

RESULTS

There were no significant between-subgroup differences in demographic characteristics. Further, they presented similar tremor clinical manifestation; however, the ETh subgroup showed a higher prevalence of rest tremor, feeling of sadness, forgetting things or events, and swallowing difficulty, as well as TRS scores, compared with the ETol subgroup. Both patient subgroups showed high scores and prevalence (>50%) in difficulty falling asleep. Logistic regression analysis indicated age as a tremor severity determinant; further, head tremor and tremor severity were NMS determinants.

CONCLUSION

Both patient subgroups presented various NMS including sleep disturbances, cognitive deficits, and affective disorders. The ETh subgroup showed a high prevalence of certain NMS aspects including memory and affective disorder; further, they had aggravated NMS. ET with both upper limb tremor and head tremor may be regarded as a more severe clinical subtype.

REM sleep behaviour disorder in essential tremor: A polysomnographic study

Our objectives were to assess the prevalence of REM sleep behaviour disorder in patients with Essential Tremor, using video-polysomnography and to compare REM sleep behaviour disorder features in essential tremor with those of patients with alpha-synucleinopathies. Forty-nine patients with essential tremor were screened with the REM Sleep Behaviour Disorder Screening Questionnaire. Patients scoring positive and those with spontaneous complaints of REM sleep behaviour disorder (n = 6) underwent video-polysomnography. The clinical features of essential tremor were compared between patients with and without REM sleep behaviour disorder. Video-polysomnography data were compared between patients who had essential tremor and Parkinson's disease with REM sleep behaviour disorder and those with idiopathic REM sleep behaviour disorder. Fourteen patients (23.5%) screened positive for REM sleep behaviour disorder, confirmed by video-polysomnography in five (11.6%). All patients with essential tremor and REM sleep behaviour disorder had rest tremor, compared with 13 (34.2%) in the group with essential tremor but without REM sleep behaviour disorder (p = .009). In video-polysomnography, patients with essential tremor and REM sleep behaviour disorder were similar to patients with Parkinson's disease with REM sleep behaviour disorder and presented worse sleep dysfunction and lower severity of REM sleep behaviour disorder compared to those with idiopathic REM sleep behaviour disorder. We found a high prevalence of REM sleep behaviour disorder in patients with essential tremor, associated with a predominance of rest tremor. Polysomnography data from patients with essential tremor and REM sleep behaviour disorder were similar to those in patients with Parkinson's disease. This suggests a relation between this subgroup of patients with essential tremor and the alpha-synucleinopathies.

Demoralization in essential tremor: prevalence, clinical correlates, and dissociation from tremor severity

OBJECTIVE

Essential tremor (ET) is associated with psychological difficulties, including anxiety and depression. Demoralization (feelings of helplessness, hopelessness, inability to cope), another manifestation of psychological distress, has yet to be investigated in ET. Our objectives are to (1) estimate the prevalence of demoralization in ET, (2) assess its clinical correlates, and (3) determine whether demoralization correlates with tremor severity.

METHODS

We administered the Kissane Demoralization Scale (KDS-II) and several psychosocial evaluations (ie, scales assessing subjective incompetence, resilience, and depression [eg, Geriatric Depression Scale]) to 60 ET subjects. Tremor was assessed with a disability score and total tremor score. KDS-II >8 indicated demoralization.

RESULTS

Among 60 ET subjects (mean age = 70.2 ± 6.8 years), the prevalence of demoralization was 13.3%, 95% confidence interval = 6.9-24.2%. Although there was overlap between demoralization and depression (10% of the sample meeting criteria for both), 54% of depressed subjects were not demoralized, and 25% of demoralized subjects were not depressed. Demoralization correlated with psychological factors, but demoralized subjects did not have significantly higher total tremor scores, tremor disability scores, or years with tremor.

CONCLUSIONS

Demoralization has a prevalence of 13.3% in ET, similar to that in other chronic or terminal illnesses (eg, cancer 13-18%, Parkinson's disease 18.1%, coronary heart disease 20%). Demoralization was not a function of increased tremor severity, suggesting that it is a separable construct, which could dictate how a patient copes with his/her disease. These data further our understanding of the psychological and psychosocial correlates of ET.

Essential tremor pathology: neurodegeneration and reorganization of neuronal connections

Essential tremor (ET) is the most common tremor disorder globally and is characterized by kinetic tremor of the upper limbs, although other clinical features can also occur. Postmortem studies are a particularly important avenue for advancing our understanding of the pathogenesis of ET; however, until recently, the number of such studies has been limited. Several recent postmortem studies have made important contributions to our understanding of the pathological changes that take place in ET. These studies identified abnormalities in the cerebellum, which primarily affected Purkinje cells (PCs), basket cells and climbing fibres, in individuals with ET. We suggest that some of these pathological changes (for example, focal PC axonal swellings, swellings in and regression of the PC dendritic arbor and PC death) are likely to be primary and degenerative. By contrast, other changes, such as an increase in PC recurrent axonal collateral formation and hypertrophy of GABAergic basket cell axonal processes, could be compensatory responses to restore cerebellar GABAergic tone and cerebellar cortical inhibitory efficacy. Such compensatory responses are likely to be insufficient, enabling the disease to progress. Here, we review the results of recent postmortem studies of ET and attempt to place these findings into an anatomical-physiological disease model.

Clinical Profile of Non-Motor Symptoms in Patients with Essential Tremor: Impact on Quality of Life and Age-Related Differences

Background

Identifying the clinical phenotypes of non-motor symptoms (NMSs) of essential tremor (ET) among different populations is necessary due to their impact on the quality of life (QoL). This study aimed to investigate the clinical phenotype and impact of NMSs on QoL in Egyptian patients with ET.

Methods

Thirty ET patients were compared to 30 matched controls. Subjects were evaluated by the Fahn-Tolosa-Marin Tremor Rating Scale, Non-Motor Symptoms Scale (NMSS), Montreal Cognitive Assessment, Hamilton Anxiety Rating Scale, Beck Depression Inventory, Pittsburgh Sleep quality Index, and the Short Form 36 Health Survey Questionnaire. Both groups were divided into two subgroups of younger (<45 years, 14 patients) and older age (>45 years, 16 patients) groups, to investigate age-related differences.

Results

ET patients showed significantly worse cognition, depression, anxiety, sleep and NMSS domains (p < 0.001), compared to controls, that negatively affected and predicted QoL. Older patients had more cognitive impairment (p = 0.003) and worse sleep/fatigue (p = 0.032) and sexual functions (p = 0.006), compared to younger group.

Discussion

The study supports that NMSs are integral part of ET, negatively affect QoL, and similarly affect younger and older patients. Therefore, NMSs should be explored for proper care of ET patients.

Prevalence and Risk Factors of Depression and Anxiety in Essential Tremor Patients: A Cross-Sectional Study in Southwest China

Background: Essential tremor (ET) is one of the most common movement disorders, and it has been associated with anxiety and depression, but risk factors for these mental symptoms are unclear. This study aimed to evaluate the prevalence and potential risk factors of depression and anxiety in ET patients in China. Methods: This cross-sectional study involved 245 Han Chinese patients with ET. Depression was assessed using the Hamilton Depression Rating Scale-24 Items, and anxiety was assessed using the Hamilton Anxiety Rating Scale. Clinico-demographic characteristics were compared between patients with or without depression or anxiety. Results: We revealed that 63.3% of patients had at least mild anxiety and 54.3% had at least mild depression. Severity of anxiety or depression was correlated with lower Mini-Mental State Exam score (P = 0.028 and P = 0.002, respectively), higher self-report functional disability score (P = 0.027 and P = 0.003, respectively), as well as the presence of tremor in the neck (both P < 0.001), face (P = 0.025 and P < 0.001, respectively), or voice (both P < 0.001). Binary logistic regression identified female sex, presence with cranial tremor, and greater functional disability score as risk factors of anxiety; the last two factors were also the determinants of depression. Neither anxiety nor depression correlated with physician-assessed severity of arm or leg tremor. Conclusion: Chinese ET patients show high prevalence of depression and anxiety. ET patients should be screened for these mental symptoms, especially women and those with cranial tremor and self-reported functional disability.

Enfeeblement in Elders with Essential Tremor: Characterizing the Phenomenon and Its Role in Caregiver Burden

Background

Individuals with essential tremor (ET), a common movement disorder, experience functional impairment, which contributes to burden experienced by their loved ones and caregivers. Some burdened caregivers report their loved ones as seeming debilitated or prematurely old, a concept that we have called enfeeblement. Using the Essential Tremor Enfeeblement Survey (ETES), we seek to characterize enfeeblement in elders with ET and assess its contribution to caregiver burden.

Methods

We administered the ETES (range = 8–40, higher scores indicating more enfeeblement) and other scales to 98 caregivers of individuals with ET. Individuals with ET were also queried regarding tremors, cognitive abilities, and overall health. We then identified demographic and clinical correlates of ETES and modeled the contribution of ETES to caregiver burden (assessed using the Zarit 12-item Burden Interview [ZBI-12]).

Results

Mean ETES score was 14.2 ± 6.2 (median = 12.0, range = 8.0–32.0); 26.5% of respondents endorsed at least one of the eight ETES items. Older age, greater tremor severity and disability, more functional and gait disability, more cognitive difficulty, and more depressive symptoms were associated with higher ETES scores. ETES was the strongest contributor to caregiver burden (ZBI-12) and substantially increased the variance explained in models of caregiver burden.

Discussion

Enfeeblement seems to describe a previously unexplained component of caregiver burden in elders with ET. The presence of enfeeblement may contribute to greater burden and should be factored into assessments of patient and caregiver needs.

Essential tremor: diagnosis and management

Essential tremor is one of the most common movement disorders in adults and can affect both children and adults. An updated consensus statement in 2018 redefined essential tremor as an isolated action tremor present in bilateral upper extremities for at least three years. Tremor may also be present in other locations, commonly the neck or the vocal cords. Patients with additional neurologic symptoms are now categorized as "essential tremor plus." Additional clinical features associated with the condition include but are not limited to cognitive impairment, psychiatric disorders, and hearing loss. When treatment is needed, propranolol and primidone are considered first line treatments. Patients who are severely affected are often offered deep brain stimulation. Although the ventral intermediate nucleus of the thalamus is the traditional surgical target, the caudal zona incerta is also being studied as a possible superior alternative. Magnetic resonance imaging guided high intensity focused ultrasound is a newer surgical alternative that may be ideal for patients with substantial medical comorbidities. Current research explores novel oral treatments, chemodenervation, and noninvasive neuromodulation for treatment of essential tremor.

Neuroimaging depression and anxiety in essential tremor: A diffusion tensor imaging study

OBJECTIVE

Patients with essential tremor (ET) may exhibit non-motor features, including those that are neuropsychiatric. Depression and anxiety are the most common among these. This study aims to investigate the possible relationship between microstructural brain changes and symptoms of depression and anxiety in ET.

METHODS

We assessed 62 ET patients (40 women and 22 men, mean age 46.0 ± 20.4) for symptoms of depression and anxiety using the Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI). Thirty-two patients had severe or moderate symptoms of anxiety, and 15 patients had severe or moderate depressive symptoms. Microstructural brain changes were evaluated using diffusion tensor imaging (DTI), which was reported using fractional anisotropy (FA), mean diffusivity (MD), apparent diffusion coefficient (ADC), radial diffusivity (RD), and axial diffusivity (AD) values calculated for 17 regions of interest including the prefrontal cortex, paralimbic and limbic structures and cerebellar peduncles. We evaluated the relationship between observed changes in brain regions and symptoms of depression and anxiety.

RESULTS

Decreased left amygdala FA (p = 0.003) and increased left amygdala RD (p = 0.04) were detected in depressed vs. non-depressed ET patients. Left ventrolateral prefrontal cortex (VLPFC) FA (p = 0.02) and left precuneus FA (p = 0.02) values differed between anxious patients vs. non-anxious ET patients. BDI scores were correlated with left amygdala FA and left RD, while BAI scores were correlated with left VLPFC FA and left precuneus FA.

DISCUSSION

Our results provide evidence that symptoms of depression and anxiety could be based in structural brain changes observed in patients with ET.

A Phase 2, Randomized, Double-Blind, Placebo-Controlled Trial of CX-8998, a Selective Modulator of the T-Type Calcium Channel in Inadequately Treated Moderate to Severe Essential Tremor: T-CALM Study Design and Methodology for Efficacy Endpoint and Digital Biomarker Selection

Background: Essential tremor (ET) is a common, progressive neurological syndrome with bilateral upper-limb dysfunction of at least 3-year duration, with or without tremor in other body locations. This disorder has a negative impact on daily function and quality of life. A single oral therapy has been approved by FDA for ET. Off-label pharmacotherapies have inadequate efficacy and poor tolerability with high rates of patient dissatisfaction and discontinuation. Safe and efficacious pharmacotherapies are urgently needed to decrease tremor and improve daily living. T-CALM (Tremor-CAv3 modulation) protocol is designed to assess safety and efficacy of CX-8998, a selective modulator of the T-type calcium channel, for ET therapy.

Methods/Design: T-CALM is a phase 2, proof of concept, randomized, double-blind, placebo-controlled trial. Titrated doses of CX-8998 to 10 mg BID or placebo will be administered for 28 days to moderate to severe ET patients who are inadequately treated with existing therapies. The primary endpoint will be change from baseline to day 28 of The Essential Tremor Rating Assessment Performance Subscale (TETRAS-PS). Secondary efficacy endpoints for clinician and patient perception of daily function will include TETRAS Activity of Daily Living (ADL), Quality of Life in Essential Tremor Questionnaire (QUEST), Clinical Global Impression-Improvement (CGI-I), Patient Global Impression of Change (PGIC), and Goal Attainment Scale (GAS). Kinesia One, Kinesia 360, and iMotor will biometrically evaluate motor function and tremor amplitude. Safety will be assessed by adverse events, physical and neurological exams and laboratory tests. Sample size of 43 patients per group is estimated to have 90% power to detect a 5.5-point difference between CX-8998 and placebo for TETRAS-PS. Efficacy analyses will be performed with covariance (ANCOVA) and 2-sided test at 0.05 significance level.

Discussion: T-CALM has a unique design with physician rating scales, patient-focused questionnaires and scales and objective motor measurements to assess clinically meaningful and congruent efficacy. Patient perception of ET debilitation and therapy with CX-8998 will be key findings. Overall goal of T-CALM is generation of safety and efficacy data to support a go, no-go decision to further develop CX-8998 for ET. Design of T-CALM may guide future clinical studies of ET pharmacotherapies.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT03101241

Clinical Characteristics of Essential Tremor in South India: A Hospital-Based Cohort Study

Introduction

Essential tremor (ET) is the most common adult movement disorder. Classic ET is characterized by action tremor of hands (95% cases), and tremor involving other regions is less common. Recent studies have revealed a few patients exhibiting nontremor features that include cognitive disorders, tandem gait abnormality, mood fluctuations, olfactory abnormality, hearing impairment, and sleep disorders. Very few studies on ET have so far been conducted in India, and the present study is a pioneering attempt to evaluate the clinical characteristics of patients diagnosed with ET.

Materials and Methods

A standardized assessment protocol was used to collect data. Diagnosis of ET was established using consensus criteria established by the Movement Disorder Society. Tremor Research Group Essential Tremor Rating Assessment Scale was used to evaluate tremor impact. The severity of hand tremor was assessed by Glass Scale, and cognitive function was assessed by Mini-Mental Status Examination.

Results

Out of the 45 patients enrolled, 73.3% were male and 26.6% were female, with a mean age of 44 ± 15 years. Postural tremor was observed in all, followed by intention tremor in 9 and rest tremor in 6 patients. Tremor of the hand was identified to be most predominant (100%). Voice tremor was observed in 15 (33.3%) patients and head tremor in 12 patients (26.6%) who were all females. Leg tremor was observed in 12 patients (26.6% of patients) and tongue tremor in 6 (13%) patients. Baseline asymmetry of tremor was observed in 60% of patients and positive family history in 35% of patients. The most common nontremor feature was tandem gait abnormality (40%). Moreover, most of the patients had Glass Scale II.

Conclusion

Baseline asymmetry of tremor and male predominance were observed in the study. While hand tremor was the most common form of tremor, tandem gait abnormality was the most common nontremor feature as observed in patients with ET.

Post-diagnostic lived experiences of individuals with essential tremor

Purpose: This research study aimed to explore the lived experience of individuals with essential tremor.Method: This study was qualitative in nature and informed by interpretative phenomenological analysis methodology. Semi-structured interviews were conducted with a relatively homogenous sample of nine individuals with a diagnosis of essential tremor.Results: Three major themes were constructed: "But they often look at you like you're some drug addict or smackhead": Social attitudes to difference; "I just couldn't do it anymore": The restrictive nature of essential tremor; and "You've got to cope; you've got to learn to fight different ways": Rescuing some normality amid physical deterioration.Conclusion: This study offers much needed experiential understanding and interpretation of one of the most prevalent neurological conditions with regard to the emotions associated with specific day-to-day experiences, the restrictions placed upon everyday practicalities and the coping strategies employed. This study has highlighted the need for health care professionals to provide individuals with information regarding psychological support, and a need for more public awareness campaigns centred around essential tremor.Implications for rehabilitationJudgements of others and being unable to conform to social norms results in social embarrassment and anxiety for people with essential tremor.Public awareness campaigns could help reduce the stigma experienced by people with essential tremor.The emotional response to the physical limitations of essential tremor can also be complex and particular to the individual and signposting to psychological support may be helpful.

Essential Tremor and Parkinson's Disease: Exploring the Relationship

Background

There is longstanding controversy surrounding the possible link between essential tremor (ET) and Parkinson's disease (PD). Inconsistent and unreliable diagnostic criteria may in part account for some of the difficulties in defining the relationship between these two common movement disorders.

Methods

References for this systematic review were identified using PubMed with the search terms "essential tremor" AND "Parkinson's disease" with articles published in English between 1960 and September 2018 included.

Results

In this review we provide evidence that some patients diagnosed with ET have an increased risk of developing PD years or decades after onset of action tremor. There are several still unresolved questions about the link between the two disorders including lack of verifiable diagnostic criteria for the two disorders and marked overlap in phenomenology. Here we review clinical, epidemiologic, imaging, pathologic, and genetic studies that address the ET-PD relationship. Several lines of evidence support the association between ET and PD, including overlapping motor and non-motor features, relatively high prevalence of rapid eye movement sleep behavior disorder (26-43%) in ET patients, increased prevalence of PD in patients with longstanding antecedent ET, increased prevalence of ET in family members of patients with PD, and the presence of Lewy bodies in the brains of some ET patients (15-24%).

Discussion

There is a substantial body of evidence supporting the association between ET and PD within at least a subset of patients, although the nature and possible pathogenic mechanisms of the relationship are not well understood.

Prediction of depression and anxiety via patient-assessed tremor severity, not physician-reported motor symptom severity, in patients with Parkinson’s disease or essential tremor who have undergone deep brain stimulation

OBJECTIVE

Deep brain stimulation (DBS) is an effective therapy for movement disorders such as idiopathic Parkinson’s disease (PD) and essential tremor (ET). However, some patients who demonstrate benefit on objective motor function tests do not experience postoperative improvement in depression or anxiety, 2 important components of quality of life (QOL). Thus, to examine other possible explanations for the lack of a post-DBS correlation between improved objective motor function and decreased depression or anxiety, the authors investigated whether patient perceptions of motor symptom severity might contribute to disease-associated depression and anxiety.

METHODS

The authors performed a retrospective chart review of PD and ET patients who had undergone DBS at the Cleveland Clinic in the period from 2009 to 2013. Patient demographics, diagnosis (PD, ET), motor symptom severity, and QOL measures (Primary Care Evaluation of Mental Disorders 9-item Patient Health Questionnaire [PHQ-9] for depression, Generalized Anxiety Disorder 7-item Scale [GAD-7], and patient-assessed tremor scores) were collected at 4 time points: preoperatively, postoperatively, 1-year follow-up, and 2-year follow-up. Multivariable prediction models with solutions for fixed effects were constructed to assess the correlation of predictor variables with PHQ-9 and GAD-7 scores. Predictor variables included age, sex, visit time, diagnosis (PD vs ET), patient-assessed tremor, physician-reported tremor, Unified Parkinson’s Disease Rating Scale part III (UPDRS-III) score, and patient-assessed tremor over time.

RESULTS

Seventy PD patients and 17 ET patients were included in this analysis. Mean postoperative and 1-year follow-up UPDRS-III and physician-reported tremor scores were significantly decreased compared with preoperative scores (p < 0.0001). Two-year follow-up physician-reported tremor was also significantly decreased from preoperative scores (p < 0.0001). Only a diagnosis of PD (p = 0.0047) and the patient-assessed tremor rating (p < 0.0001) were significantly predictive of depression. A greater time since surgery, in general, significantly decreased anxiety scores (p < 0.0001) except when a worsening of patient-assessed tremor was reported over the same time period (p < 0.0013).

CONCLUSIONS

Patient-assessed tremor severity alone was predictive of depression in PD and ET following DBS. This finding suggests that a patient’s perception of illness plays a greater role in depression than objective physical disability regardless of the time since surgical intervention. In addition, while anxiety may be attenuated by DBS, patient-assessed return of tremor over time can increase anxiety, highlighting the importance of long-term follow-up for behavioral health features in chronic neurological disorders. Together, these data suggest that the patient experience of motor symptoms plays a role in depression and anxiety—a finding that warrants consideration when evaluating, treating, and following movement disorder patients who are candidates for DBS.

Essential Tremor is not Only a Movement Disorder; Its Relationship with Sleep and Anxiety

Introduction

Essential tremor (ET) is the most common movement disorder, and some studies suggest that there are non-motor symptoms as well as motor symptoms. This study aims to investigate the relationship between ET and anxiety and sleep disorder.

Methods

The study was conducted with 38 healthy individuals in the control group and 40 patients who admitted to the neurology clinic of our hospital and had definite ET according to the Consensus statement of the Movement Disorder Society on Tremor. Pittsburgh Sleep Quality Index (PSQI) and Hamilton Anxiety Rating Scale (HAM-A) were applied to both groups. Statistical analysis was carried out with SPSS 22.0 for Windows.

Results

The patient and control groups were similar in terms of age, gender and educational status. The PSQI and HAM-A scores in the patient group were significantly higher than the control group (p<0.000, p<0.000, respectively). Both scores were higher in female patients compared to male patients (p<0.05, p<0.05, respectively), and in married patients compared to single patients (p<0.05, p<0.05, respectively).

Conclusion

Sleep disorder and anxiety are more common in patients with ET than in healthy individuals. We believe that more severe sleep disorders and anxiety in female and/or married patients are indicative of the psychosocial component of the disorder, and that this condition should not be overlooked and should be studied more comprehensively in this regard.

A Review of Scales to Evaluate Sleep Disturbances in Movement Disorders

Patients with movement disorders have a high prevalence of sleep disturbances that can be classified as (1) nocturnal sleep symptoms, such as insomnia, nocturia, restless legs syndrome (RLS), periodic limb movements (PLM), obstructive sleep apnea (OSA), and REM sleep behavior disorder; and (2) diurnal problems that include excessive daytime sleepiness (EDS) and sleep attacks. The objective of this review is to provide a practical overview of the most relevant scales that assess these disturbances to guide the choice of the most useful instrument/s depending on the line of research or clinical focus. For each scale, the reader will find a brief description of practicalities and psychometric properties, use in movement disorder cohorts and analyzed strengths and limitations. To assess insomnia, the Pittsburgh Sleep Quality Index, a generic scale, and three disease-specific scales: the Parkinson Disease Sleep Scale (PDSS), the PDSS-2, and Scales for outcomes in Parkinson's disease (PD)-Sleep-Nocturnal Sleep subscale are discussed. To evaluate nocturia, there are no specific tools, but some extensively validated generic urinary symptom scales (the Overall Bladder Questionnaire and the Overactive Bladder Symptom Score) and some PD-specific scales that include a nocturia item are available. To measure RLS severity, there are currently four domain-specific generic scales: The International Restless Legs Scale, the Johns Hopkins Restless Legs Severity Scale, the Restless Legs Syndrome-6 measure, a Pediatric RLS Severity Scale, and the Augmentation Severity Rating Scale (a scale to evaluate augmentation under treatment) and several instruments that assess impact on quality of sleep and health-related quality of life. To evaluate the presence of PLM, no clinical scales have been developed to date. As far as OSA, commonly used instruments such as the Sleep Apnea Scale of the Sleep Disorders Questionnaire, the STOP-Bang questionnaire, and the Berlin Questionnaire are reviewed. Three scales have been extensively used to assess EDS: the generic Epworth Sleepiness Scale, the Stanford Sleepiness Scale, and the PD-specific Scales for outcomes in PD-Sleep-Daytime sleepiness subscale. To date, only the Inappropriate Sleep Composite Score specifically evaluates propensity to sleep attacks.

Could Wearable and Mobile Technology Improve the Management of Essential Tremor?

Essential tremor (ET) is the most common movement disorder. Individuals exhibit postural and kinetic tremor that worsens over time and patients may also exhibit other motor and non-motor symptoms. While millions of people are affected by this disorder worldwide, several barriers impede an optimal clinical management of symptoms. In this paper, we discuss the impact of ET on patients and review major issues to the optimal management of ET; from the side-effects and limited efficacy of current medical treatments to the limited number of people who seek treatment for their tremor. Then, we propose seven different areas within which mobile and wearable technology may improve the clinical management of ET and review the current state of research in these areas.

Self-report depressive symptoms are dissociated from tremor severity in essential tremor

BACKGROUND

Depressive symptoms are associated with essential tremor (ET). However, the relationship between cognitive, functional, and motor measures with depressive symptoms in ET is not yet understood.

METHODS

The following measures were cross-sectionally assessed in a group of 223 subjects with ET: the Montreal Cognitive Assessment (MoCA) Scale, the Lawton Independent Activities of Daily Living (IADL) Scale, a neurologist assessment of tremor severity, and the Geriatric Depression Scale (GDS).

RESULTS

20% (44) of the subjects met GDS criteria for depression (GDS ≥ 10). 43% (94) of the subjects showed at least some cognitive impairment (≤24 on the MoCA), and 15.3% (34) reported significant functional impairment (IADL score < 7). There was no significant association between GDS score and tremor scale score. The total GDS was negatively associated with the total MoCA score (Spearman's r = -0.15, p = 0.03). The total GDS was also negatively associated with the IADL score (Spearman's r = -0.19, p = 0.02), (logistic model odds ratio, OR = 4.91, p < 0.01). Over 60% of subjects who were depressed, per GDS cut-off score (≥10), were not receiving medical treatment for depression.

CONCLUSIONS

There was a high point prevalence of depressive symptoms in subjects with ET. Self-report depressive symptoms are dissociated from tremor severity. Hence, these data do not support the hypothesis that depression in ET represents a psychological reaction to the tremor. There appears to be a clustering of cognitive, functional, and depressive symptoms in ET. Screening of depression in ET can improve our understanding and treatment of this disorder.

Psychological Suffering in Essential Tremor: A Study of Patients and Those Who Are Close to Them

Background

Although the motor and non-motor features of essential tremor (ET) have been characterized in detail, it is not known whether ET patients suffer psychologically and whether those who are close to them consider them to be suffering in this way.

Methods

Fifty ET patients and 50 “close others” (COs), identified by patients “as someone who knows you well and sees you often” and who can “provide a different perspective on your well-being”, reported their own depressive symptoms, daily stress, and perceptions of patient psychological suffering and patient overall suffering with validated scales. ET patients’ tremor severity, duration, disability, cognition, and number of medications were also assessed.

Results

ET patients reported levels of psychological suffering within the range documented in arthritis and dementia patients from previous studies, and COs perceived significantly more psychological suffering in patients than patients reported themselves. Regression models, controlling for tremor severity, duration, and disability revealed that patients’ greater psychological suffering was associated with greater patient depression. The greater perceptions of COs of patient psychological and overall suffering were associated with greater CO depression and daily stress. Sensitivity analysis showed that patients’ cognitive status or number of medications did not affect the results.

Discussion

Multidisciplinary teams caring for ET patients should look beyond simple clinical ET indicators. They should be aware of patient experiences and perceptions of COs of psychological and overall suffering. This will help guide the development of evidence-based, supportive interventions that improve communication about the needs of ET patients and those who are close to them.

Is there a Premotor Phase of Essential Tremor?

BACKGROUND

Essential tremor (ET) is the most common tremor disorder. In addition to its hallmark feature, kinetic tremor of the upper limbs, patients may have a number of non-motor symptoms and signs (NMS). Several lines of evidence suggest that ET is a neurodegenerative disorder and certain NMS may antedate the onset of tremor. This article comprehensively reviews the evidence for the existence of a "premotor phase" of ET, and discusses plausible biological explanations and implications.

METHODS

A PubMed search in May 2017 identified articles for this review.

RESULTS

The existence of a premotor phase of ET gains support primarily from longitudinal data. In individuals who develop incident ET, baseline (i.e., premotor) evaluations reveal greater cognitive dysfunction, a faster rate of cognitive decline, and the presence of a protective effect of education against dementia. In addition, baseline evaluations also reveal more self-reported depression, antidepressant medication use, and shorter sleep duration in individuals who eventually develop incident ET. In cross-sectional studies, certain personality traits and NMS (e.g., olfactory dysfunction) also suggest the existence of a premotor phase.

DISCUSSION

There is preliminary evidence supporting the existence of a premotor phase of ET. The mechanisms are unclear; however, the presence of Lewy bodies in some ET brains in autopsy studies and involvement of multiple neural networks in ET as evident from the neuroimaging studies, are possible contributors. Most evidence is from a longitudinal cohort (Neurological Disorders of Central Spain: NEDICES); additional longitudinal studies are warranted to gain better insights into the premotor phase of ET.

Psychiatric comorbidities in movement disorders

Psychiatric comorbidities are common in movement disorders. This review provides a practical approach to help clinicians to recognize psychiatric disorders in the most frequent movement disorders. However, the extent of neurodegeneration, as well as the impact of medications with considerable CNS effects, influences the diverse psychiatric presentations that, in turn, are influenced by the stress of living with a movement disorder. Depression, anxiety, and psychosis are the most common psychiatric comorbidities in movement disorders and of the medications used to treat the motor disturbances. These psychiatric problems impair patients' functioning throughout the course of the chronic neurodegenerative diseases. Due to the direct connection between brain dysfunction and psychiatric symptoms, there is hope that understanding the psychiatric comorbidities in movement disorders will lead to a better quality-of-life.

The Experience of Essential Tremor Caregivers: Burden and Its Correlates

Background

Essential tremor (ET) is associated with physical and cognitive impairments, as well as embarrassment, avoidance of social settings, and related difficulties that negatively impact the lives of patients. In similar disease contexts, burden on friends and relatives acting as caregivers has been noted and has well-documented implications. There has been no study examining caregiver burden related to ET.

Methods

Data were gathered from 55 ET participants enrolled in a clinical study and their caregivers. The Zarit Burden Interview was used to assess caregiver burden. To assess clinical features that may be associated with burden, we collected several variables including the Montreal Cognitive Assessment, self-reported tremor disability, a videotaped neurological examination, questionnaires assessing ET participants’ suffering, caregivers’ perceptions of that suffering, and both caregiver and ET participant depressive symptoms. Spearman’s correlations were performed between caregiver burden and clinical features, and we created a multivariate linear regression model predicting caregiver burden.

Results

Many ET caregivers provide little to no care and experience little to no burden. However, some caregivers (11%) provide over 25 h of care/week, and 13% experience high levels of burden. Caregivers most commonly provided assistance with writing and cooking. Increased burden was associated with the ET participants’ decreased cognition, more caregiving tasks, more hours/week of caregiving activities, a longer duration of care, more ET participant falls/year, more medications taken by the ET participant, and more depressive symptoms in both the ET participant and the caregiver (all p < 0.05). ET participants’ suffering and their caregivers’ perceptions of suffering were both associated with increased burden. Neither tremor severity score nor self-reported tremor disability score was associated with increased caregiver burden. Using a multivariate linear regression model, we found that caregivers’ increased perception of their partners’ suffering was the best predictor of caregiver burden.

Conclusion

While not all relatives and friends of ET patients provide extensive care or experience high burden, there is a group reporting high levels of caregiver burden that requires the attention and counseling of clinicians. This burden is associated with primarily non-tremor symptoms of ET and with caregivers’ perception that their partners are suffering.

Essential tremor and depression

Introduction

Depression and neuropsychiatric disorders in individuals with essential tremor (ET) are not well characterized in the literature.

Methods

We compared 104 ET subjects with 481 non-ET controls involved in the Arizona Study of Aging and Neurodegenerative Disorders. An analysis of baseline depression scales and neuropsychiatric inventory (NPI) was done between the two groups. Comparisons were made additionally within the ET group based on tremor severity, duration of tremor and age of onset.

Results

There were no significant differences among each of the scales between the ET and non-ET groups. There were no significant differences in the ET group above and below the median tremor duration. Additionally, no differences were found in the ET group based on objective measures of tremor severity, age of onset, or those with subjectively distressing tremor compared with those without.

Conclusion

There were no significant differences in depressive symptoms between ET and non-ET groups. Furthermore, no correlation was found between depressive symptoms in ET groups based on tremor severity, duration, or age of onset.

The Olivary Hypothesis of Essential Tremor: Time to Lay this Model to Rest?

BACKGROUND

Although essential tremor (ET) is the most common tremor disorder, its pathogenesis is not fully understood. The traditional model of ET, proposed in the early 1970s, posited that the inferior olivary nucleus (ION) was the prime generator of tremor in ET and that ET is a disorder of electrophysiological derangement, much like epilepsy. This article comprehensively reviews the origin and basis of this model, its merits and problems, and discusses whether it is time to lay this model to rest.

METHODS

A PubMed search was performed in March 2017 to identify articles for this review.

RESULTS

The olivary model gains support from the recognition of neurons with pacemaker property in the ION and the harmaline-induced tremor models (as the ION is the prime target of harmaline). However, the olivary model is problematic, as neurons with pacemaker property are not specific to the ION and the harmaline model does not completely represent the human disease ET. In addition, a large number of neuroimaging studies in ET have not detected structural or functional changes in the ION; rather, abnormalities have been reported in structures related to the cerebello-thalamo-cortical network. Moreover, a post-mortem study of microscopic changes in the ION did not detect any differences between ET cases and controls.

DISCUSSION

The olivary model largely remains a physiological construct. Numerous observations have cast considerable doubt as to the validity of this model in ET. Given the limitations of the model, we conclude that it is time now to lay this model to rest.

Current concepts of essential tremor

Essential tremor is clinically defined but there is increasing evidence that it is not a unique entity. Its pathophysiology has been studied with many methods but may also vary between subtypes. Neurophysiologically, there is strong evidence that a specific cerebello-thalamo-cortical loop is abnormally oscillating. The cause of its uncontrolled oscillation is not yet understood. The clear proof of a degenerative cause is still lacking and abnormal receptors or other causes of altered non-progressive functional disturbance cannot be excluded. Strong evidence supports the major involvement of the cerebellum and there is ample evidence that GABA is the main neurotransmitter involved in the pathophysiology in ET. Genetics have provided so far only a few rare subtypes which are due to specific mutations but there is no doubt that it is mostly a hereditary condition. There is evidence that the large subgroup of late onset tremor is a separate condition and this tremor is an independent risk factor for earlier mortality and comes with signs of premature aging (aging-related tremor). It will be important to improve phenotyping of patients in more detail possibly to include not only features of the tremor itself but also other clinical assessments like force measurements or cognitive testing. Based on these variables, we may be able to better understand the presumably different mechanisms underlying different variants of the disease.