Agreement among movement disorder specialists on the clinical diagnosis of essential tremor

Diagnostic Uncertainties in Tremor

The approach and diagnosis of patients with tremor may be challenging for clinicians. According to the most recent consensus statement by the Task Force on Tremor of the International Parkinson Movement Disorder Society, the differentiation between action (i.e., kinetic, postural, intention), resting, and other task- and position-specific tremors is crucial to this goal. In addition, patients with tremor must be carefully examined for other relevant features, including the topography of the tremor, since it can involve different body areas and possibly associate with neurological signs of uncertain significance. Following the characterization of major clinical features, it may be useful to define, whenever possible, a particular tremor syndrome and to narrow down the spectrum of possible etiologies. First, it is important to distinguish between physiological and pathological tremor, and, in the latter case, to differentiate between the underlying pathological conditions. A correct approach to tremor is particularly relevant for appropriate referral, counseling, prognosis definition, and therapeutic management of patients. The purpose of this review is to outline the possible diagnostic uncertainties that may be encountered in clinical practice in the approach to patients with tremor. In addition to an emphasis on a clinical approach, this review discusses the important ancillary role of neurophysiology and innovative technologies, neuroimaging, and genetics in the diagnostic process.

Topologically Disrupted Gray Matter Networks in Drug-Naïve Essential Tremor Patients With Poor Sleep Quality

Background

Sleep disturbances are widespread among patients with essential tremor (ET) and may have adverse effects on patients' quality of life. However, the pathophysiology underlying poor quality of sleep (QoS) in patients with ET remains unclear. Our study aimed to identify gray matter (GM) network alterations in the topological properties of structural MRI related to QoS in patients with ET.

Method

We enrolled 45 ET patients with poor QoS (SleET), 59 ET patients with normal QoS (NorET), and 66 healthy controls (HC), and they all underwent a three-dimensional T1-weighted MRI scan. We used a graph-theoretical approach to investigate the topological organization of GM morphological networks, and individual morphological brain networks were constructed according to the interregional similarity of GM volume distributions. Furthermore, we performed network-based statistics, and partial correlation analyses between topographic features and clinical characteristics were conducted.

Results

Global network organization was disrupted in patients with ET. Compared with the NorET group, the SleET group exhibited disrupted topological GM network organization with a shift toward randomization. Moreover, they showed altered nodal centralities in mainly the frontal, temporal, parietal, and cerebellar lobes. Morphological connection alterations within the default mode network (DMN), salience, and basal ganglia networks were observed in the SleET group and were generally more extensive than those in the NorET and HC groups. Alterations within the cerebello-thalamo-(cortical) network were only detected in the SleET group. The nodal degree of the left thalamus was negatively correlated with the Fahn-Tolosa-Marin Tremor Rating Scale score (r = −0.354, p =0.027).

Conclusion

Our findings suggest that potential complex interactions underlie tremor and sleep disruptions in patients with ET. Disruptions within the DMN and the cerebello-thalamo-(cortical) network may have a broader impact on sleep quality in patients with ET. Our results offer valuable insight into the neural mechanisms underlying poor QoS in patients with ET.

Gamma Knife® stereotactic radiosurgery as a treatment for essential and parkinsonian tremor: long-term experience

INTRODUCTION

Unilateral Gamma Knife™ stereotactic radiosurgery on the ventral-intermediate nucleus of the thalamus is a minimally invasive neurosurgical option for refractory tremor. We describe the experience of Gamma Knife™ thalamotomy (GKT) in patients with essential tremor (ET) and tremor-dominant Parkinson's disease (PD) at our specialised stereotactic neurosurgery unit.

METHODS

We reviewed the cases of patients treated with GKT between January 2014 and February 2018 with a minimum of 12 months' follow-up. We analysed clinical and demographic variables, indication, radiation dose, effectiveness (based on subscales of the Fahn-Tolosa-Marin [FTM] scale and the Movement Disorders Society-Unified Parkinson's Disease Rating Scale [MDS-UPDRS] motor score), and adverse events.

RESULTS

Thirteen patients were registered, 6 with a diagnosis of tremor-dominant PD, four with refractory ET, and three with ET and PD. Median age was 78 years (range, 62-83), with seven patients aged over 75 years. Four patients were receiving anticoagulants and two had history of stroke. The maximum radiation dose administered was 130 Gy. Mean (standard deviation) follow-up duration was 30.0 (14.5) months. Significant tremor improvement was observed on the FTM subscales: 63.6% at 12 months and 63.5% at the end of follow-up; MDS-UPDRS tremor items showed improvements of 71.3% at 12 months and 60.3% at the end of follow up. Eleven patients reported significant improvements in quality of life, and 3 reported mild and transient adverse effects.

CONCLUSIONS

This is the largest series of patients with essential and parkinsonian tremor treated with GKT and followed up in the long term in Spain. GKT can be safe and effective in the long term in patients with refractory tremor, including in elderly patients and those receiving anticoagulants.

Disrupted Brain Functional Network Topology in Essential Tremor Patients With Poor Sleep Quality

Sleep disturbances, especially poor quality of sleep (QoS), are common among essential tremor (ET) patients and may have adverse effects on their quality of life, but the etiology driving the poor QoS in these individuals remains inadequately understood. Few data are available on the neuroimaging alterations of ET with poor QoS. Thirty-eight ET patients with poor QoS (SleET), 48 ET patients with normal QoS (NorET), and 80 healthy controls (HCs) participated in this study. All subjects underwent a 3.0-T magnetic resonance imaging (MRI) scan for resting-state functional MRI data collection. Then, the whole-brain functional connectome was constructed by thresholding the partial correlation matrices of 116 brain regions. Graph theory and network-based statistical analyses were performed. We used a non-parametric permutation test for group comparisons of topological metrics. Partial correlation analyses between the topographical features and clinical characteristics were conducted. The SleET and NorET groups exhibited decreased clustering coefficients, global efficiency, and local efficiency and increased the characteristic path length. Both of these groups also showed reduced nodal degree and nodal efficiency in the left superior dorsolateral frontal gyrus, superior frontal medial gyrus (SFGmed), posterior cingulate gyrus (PCG), lingual gyrus, superior occipital gyrus, right middle occipital gyrus, and right fusiform gyrus. The SleET group additionally presented reduced nodal degrees and nodal efficiency in the right SFGmed relative to the NorET and HC groups, and nodal efficiency in the right SFGmed was negatively correlated with the Pittsburgh Sleep Quality Index score. The observed impaired topographical organizations of functional brain networks within the central executive network (CEN), default mode network (DMN), and visual network serve to further our knowledge of the complex interactions between tremor and sleep, adding to our understanding of the underlying neural mechanisms of ET with poor QoS.

Computerised analysis of writing and drawing by essential tremor phenotype

We investigated whether computerised analysis of writing and drawing could discriminate essential tremor (ET) phenotypes according to the 2018 Consensus Statement on the Classification of Tremors. The Consensus scheme emphasises soft additional findings, mainly motor, that do not suffice to diagnose another tremor syndrome. Ten men and nine women were classified by blinded assessors according to Consensus Axis 1 definitions of ET and ET plus. Blinded scoring of tremor severity and alternating limb movement was also conducted. Twenty healthy participants acted as controls. Four writing and three drawing tasks were performed on a Wacom Intuos Pro Large digital tablet with a pressure-sensor mounted ink pen. Sixty-seven computerised measurements were obtained, comprising static (dimensional and temporal), kinematic and pen pressure features. The mean age of ET participants was 67.2±13.0 years and mean tremor duration was 21.7±19.0 years. Six were classified as ET, five had one plus feature and eight had two plus features. The computerised analysis could predict the presence and number of ET plus features. Measures of acceleration and variation of pen pressure performed strongly to separate ET phenotypes (p<0.05). Plus features were associated with higher scores on the Fahn-Tolosa-Marin Tremor Rating Scale (p=0.001) and it appeared that ET groups were mainly being separated according to severity of tremor and by compensatory manoeuvres used by participants with more severe tremor. There were, in addition, a small number of negative kinematic correlations suggesting some slowness with ET plus. Abnormal repetitive limb movement was also correlated with tremor severity (R=0.57) by clinical grading. Critics of the Consensus Statement have drawn attention to weaknesses of the ET plus concept in relation to duration and severity of ET. This classification of ET may be too biased towards tremor severity to assist in distinguishing underlying biological differences by clinical measurement.

Bayesian Interpretation of Essential Tremor Plus

Essential tremor (ET) plus is a new tremor classification that was introduced in 2018 by a task force of the International Parkinson and Movement Disorder Society. Patients with ET plus meet the criteria for ET but have one or more additional systemic or neurologic signs of uncertain significance or relevance to tremor (“soft signs”). Soft signs are not sufficient to diagnose another tremor syndrome or movement disorder, and soft signs in ET plus are known to have poor interrater reliability and low diagnostic sensitivity and specificity. Therefore, the clinical significance of ET plus must be interpreted probabilistically when judging whether a patient is more likely to have ET or a combined tremor syndrome, such as dystonic tremor. Such a probabilistic interpretation is possible with Bayesian analysis. This review presents a Bayesian analysis of ET plus in patients suspected of having ET versus a dystonic tremor syndrome, which is the most common differential diagnosis in patients referred for ET. Bayesian analysis of soft signs provides an estimate of the probability that a patient with possible ET is more likely to have an alternative diagnosis. ET plus is a distinct tremor classification and should not be viewed as a subtype of ET. ET plus covers a more-comprehensive phenotyping of people with possible ET, and the clinical interpretation of ET plus is enhanced with Bayesian analysis of associated soft signs.

Essential tremor

Essential tremor (ET) is one of the most common movement disorders, with a reported >60 million affected individuals worldwide. The definition and underlying pathophysiology of ET are contentious. Patients present primarily with motor features such as postural and action tremors, but may also have other non-motor features, including cognitive impairment and neuropsychiatric symptoms. Genetics account for most of the ET risk but environmental factors may also be involved. However, the variable penetrance and challenges in validating data make gene-environment analysis difficult. Structural changes in cerebellar Purkinje cells and neighbouring neuronal populations have been observed in post-mortem studies, and other studies have found GABAergic dysfunction and dysregulation of the cerebellar-thalamic-cortical circuitry. Commonly prescribed medications include propranolol and primidone. Deep brain stimulation and ultrasound thalamotomy are surgical options in patients with medically intractable ET. Further research in post-mortem studies, and animal and cell-based models may help identify new pathophysiological clues and therapeutic targets and, together with advances in omics and machine learning, may facilitate the development of precision medicine for patients with ET.

Exploring Interrater Disagreement on Essential Tremor Using a Standardized Tremor Elements Assessment

Background

Patients with upper limb action tremor frequently exhibit additional neurological signs of uncertain significance. Clinicians vary in their interpretation, and interrater agreement on the final diagnosis is poor.

Objectives

A new clinical tool for assessing the presence or absence of clinical signs that are important in axis‐1 classification of tremor patients is introduced: the Standardized Tremor Elements Assessment (STEA). Interrater agreement is determined, and signs leading to disagreement in the final diagnosis are identified.

Methods

Three tremor‐focussed and one dystonia‐focussed movement disorder specialists rated 59 videos of patients with upper limb action tremor syndromes using STEA. Interrater agreements for final diagnosis and STEA items were calculated.

Results

Interrater agreement regarding the final diagnosis was higher within the group of tremor specialists and poor between dystonia and tremor specialists. Greater agreement was found for items characterizing tremor than for signs of dystonia.

Conclusions

Clinical signs leading to diagnostic disagreement were identified with STEA, and STEA should therefore be useful in future studies of diagnostic disagreement. The thresholds for considering neurological signs as soft versus significant for ataxia, parkinsonism, dystonia, etc. are critically important in tremor classification and must be studied across movement disorder subspecialties, not simply within a pool of tremor specialists.

Do We Belittle Essential Tremor by Calling It a Syndrome Rather Than a Disease? No

A task force of the International Parkinson and Movement Disorder Society (MDS) recently published a tremor classification scheme that is based on the nosologic principle of two primary axes for classifying an illness: clinical manifestations (Axis 1) and etiology (Axis 2). An Axis 1 clinical syndrome is a recurring group of clinical symptoms, signs (physical findings), and possibly laboratory results that suggests the presence of at least one underlying Axis 2 etiology. Syndromes must be defined and used consistently to be of value in finding specific etiologies and effective treatments. The MDS task force concluded that essential tremor is a common neurological syndrome that has never been defined consistently by clinicians and researchers. The MDS task force defined essential tremor as a syndrome of bilateral upper limb action tremor of at least 3 years duration, with or without tremor in other locations (e.g., head, voice, or lower limbs), in the absence of other neurological signs (e.g., dystonia, parkinsonism, myoclonus, ataxia, peripheral neuropathy, and cognitive impairment). Deviations from this definition should not be labeled as essential tremor. Patients with additional questionably-abnormal signs or with signs of uncertain relevance to tremor are classified as essential tremor plus. The MDS classification scheme encourages a thorough unbiased phenotyping of patients with tremor, with no assumptions of etiology, pathology, pathophysiology, or relationship to other neurological disorders. The etiologies, pathology, and clinical course of essential tremor are too heterogeneous for this syndrome to be viewed as a disease or a family of diseases.

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.

Gamma Knife® stereotactic radiosurgery as a treatment for essential and parkinsonian tremor: long-term experience

INTRODUCTION

Unilateral Gamma Knife™ stereotactic radiosurgery on the ventral-intermediate nucleus of the thalamus is a minimally invasive neurosurgical option for refractory tremor. We describe the experience of Gamma Knife™ thalamotomy (GKT) in patients with essential tremor (ET) and tremor-dominant Parkinson's disease (PD) at our specialised stereotactic neurosurgery unit.

METHODS

We reviewed the cases of patients treated with GKT between January 2014 and February 2018 with a minimum of 12 months' follow-up. We analysed clinical and demographic variables, indication, radiation dose, effectiveness (based on subscales of the Fahn-Tolosa-Marin [FTM] scale and the Movement Disorders Society-Unified Parkinson's Disease Rating Scale [MDS-UPDRS] motor score), and adverse events.

RESULTS

Thirteen patients were registered, 6 with a diagnosis of tremor-dominant PD, four with refractory ET, and three with ET and PD. Median age was 78 years (range, 62-83), with seven patients aged over 75 years. Four patients were receiving anticoagulants and two had history of stroke. The maximum radiation dose administered was 130 Gy. Mean (standard deviation) follow-up duration was 30.0 (14.5) months. Significant tremor improvement was observed on the FTM subscales: 63.6% at 12 months and 63.5% at the end of follow-up; MDS-UPDRS tremor items showed improvements of 71.3% at 12 months and 60.3% at the end of follow up. Eleven patients reported significant improvements in quality of life, and 3 reported mild and transient adverse effects.

CONCLUSIONS

This is the largest series of patients with essential and parkinsonian tremor treated with GKT and followed up in the long term in Spain. GKT can be safe and effective in the long term in patients with refractory tremor, including in elderly patients and those receiving anticoagulants.

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.

Distinct cortical activity patterns in Parkinson's disease and essential tremor during a bimanual tapping task

Background

Parkinson’s disease (PD) and essential tremor (ET) are neurodegenerative diseases characterized by movement deficits. Especially in PD, maintaining cyclic movement can be significantly disturbed due to pathological changes in the basal ganglia and the cerebellum. Providing external cues improves timing of these movements in PD and also affects ET. The aim of this study is to determine differences in cortical activation patterns in PD and ET patients during externally and internally cued movements.

Methods

Eleven PD patients, twelve ET patients, OFF tremor suppressing medication, and nineteen age-matched healthy controls (HC) were included and asked to perform a bimanual tapping task at two predefined cue frequencies. The auditory cue, a metronome sound presented at 2 or 4 Hz, was alternately switched on and off every 30 s. Tapping at two different frequencies were used since it is expected that different brain networks are involved at different frequencies as has been shown in previous studies. Cortical activity was recorded using a 64-channel EEG cap. To establish the cortical activation pattern in each group, the task related power (TRP) was calculated for each subject. For inter-groups analysis, EEG electrodes for divided into 5 different areas.

Results

Inter-group analysis revealed significant differences in areas responsible for motor planning, organization and regulation and involved in initiation, maintenance, coordination and planning of complex sequences of movements. Within the area of the primary motor cortex the ET group showed a significantly lower TRP than the HC group. In the area responsible for combining somatosensory, auditory and visual information both patient groups had a higher TRP than the HC group.

Conclusions

Different neurological networks are involved during cued and non-cued movements in ET, PD and HC. Distinct cortical activation patterns were revealed using task related power calculations. Different activation patterns were revealed during the 2 and 4 Hz tapping task indicating different strategies to execute movements at these rates. The results suggest that a including a cued/non-cued tapping task during clinical decision making could be a valuable tool in an objective diagnostic protocol.

A Power Spectral Density-Based Method to Detect Tremor and Tremor Intermittency in Movement Disorders

There is no objective gold standard to detect tremors. This concerns not only the choice of the algorithm and sensors, but methods are often designed to detect tremors in one specific group of patients during the performance of a specific task. Therefore, the aim of this study is twofold. First, an objective quantitative method to detect tremor windows (TWs) in accelerometer and electromyography recordings is introduced. Second, the tremor stability index (TSI) is determined to indicate the advantage of detecting TWs prior to analysis. Ten Parkinson's disease (PD) patients, ten essential tremor (ET) patients, and ten healthy controls (HC) performed a resting, postural and movement task. Data was split into 3-s windows, and the power spectral density was calculated for each window. The relative power around the peak frequency with respect to the power in the tremor band was used to classify the windows as either tremor or non-tremor. The method yielded a specificity of 96.45%, sensitivity of 84.84%, and accuracy of 90.80% of tremor detection. During tremors, significant differences were found between groups in all three parameters. The results suggest that the introduced method could be used to determine under which conditions and to which extent undiagnosed patients exhibit tremors.

The Top 50 Most-Cited Articles in Orthostatic Tremor: A Bibliometric Review

Background

Article-level citation count is a hallmark indicating scientific impact. We aimed to pinpoint and evaluate the top 50 most-cited articles in orthostatic tremor (OT).

Methods

The ISI Web of Knowledge database and 2017 Journal Citation Report Science Edition were used to retrieve the 50 top-cited OT articles published from 1984 to April 2019. Information was collected by the Analyze Tool on the Web of Science, including number of citations, publication title, journal name, publication year, and country and institution of origin. Supplementary analyses were undertaken to clarify authorship, study design, level of evidence, and category.

Results

Up to 66% of manuscripts were recovered from five journals: Movement Disorders (n = 18), Brain (n = 4), Journal of Clinical Neurophysiology (n = 4), Neurology (n = 4), and Clinical Neurophysiology (n = 3). Articles were published between 1984 and 2018, with expert opinion as the predominant design (n = 22) and review as category (n = 17). Most articles had level 5 evidence (n = 26). According to their countries of origin, 34% of articles belonged to the United States (n = 17) leading the list, followed by United Kingdom (n = 15). University College London yielded the greater number of articles (n = 12), followed by the University of Kiel (n = 9). Most popular authors were G. Deuschl (n = 10), C.D. Marsden (n = 6), J. Jankovic (n = 5), P.D. Thompson (n = 5), J.C. Rothwell (n = 5), L.J. Findley (n = 4), and P. Brown (n = 4), who together accounted for 48% of them. All papers were in English.

Discussion

Publishing high-cited OT articles could be facilitated by source journal, study design, category, publication language, and country and institution of origin.

No reliable gray matter changes in essential tremor

BACKGROUND

Voxel-based morphometry (VBM) has been used to study human brain gray matter (GM) alterations in essential tremor (ET) for over one decade. However, the literature revealed heterogeneous findings.

METHODS

We therefore conducted a coordinate-based meta-analysis to synthesize the VBM studies to examine which brain regions show the most reliable GM alterations in patients with ET relative to healthy controls.

RESULTS

A total of 16 original VBM studies, comprising 387 patients with ET and 355 healthy controls, were included in this meta-analysis. This quantitative meta-analysis revealed no evidence of robust and reliable alterations in regional brain GM structures in ET. Meta-regression analyses indicate that many moderators (e.g., MR field strength, statistical methodology, age, onset age, gender, illness severity, illness duration, and family history) account for some of the heterogeneity in GM across studies.

CONCLUSIONS

High heterogeneity in GM alterations across studies may reflect true heterogeneity in ET regarding the clinic, etiology, and pathology, as well as possibly the VBM methodological variations. Currently, this heterogeneity limits the use of VBM as a reliable tool to distinguish ET from healthy controls. In order to improve reproducibility of VBM results in ET, future research may benefit from increasing the sample size, comprehensively subtyping ET phenotypes, and using well-designed and standardized imaging acquisition and analytical protocols. Furthermore, data sharing should be considered as a high priority.

Deficits in tapping accuracy and variability in tremor patients

Background

The basal ganglia and cerebellum are brain structures involved in movement initiation, execution and termination. They are thought to be involved in the tremor generation and movement deficits in Parkinson’s disease (PD) and essential tremor (ET). Especially in PD, maintaining cyclic movement, such as walking or tapping can be significantly disturbed. Providing external cues improves timing of these movements in PD but its effect on ET has not yet been studied in depth. The aim of this study is to evaluate the usefulness of a bimanual tapping task as a tool during clinical decision making.

Method

Hand movements and tremor was recorded using accelerometers and EMG (m. extensor carpi ulnaris) from PD and ET patients and healthy controls during a bimanual tapping task as a way to distinguish PD from ET. All subjects performed the tapping task at two different frequencies, 2 Hz and 4 Hz, with and without the presence of auditory cues.

Results

No significant intra-group differences were found in the patient groups. Acceleration data revealed significantly less accurate tapping and more variable tapping in PD than in ET and healthy controls. ET subjects tapped less accurate and with a greater variability than healthy controls during the 4 Hz tapping task. Most interestingly the tapping accuracy improved in PD patients when kinetic tremor was recorded with EMG during the task.

Conclusion

Providing ET and PD patients with an external cue results in different tapping performances between patient groups and healthy controls. Furthermore, the findings suggest that kinetic tremor in PD enables patients to perform the task with a greater accuracy. So far this has not been shown in other studies.

A method for characterizing essential tremor from the shoulder to the wrist

BACKGROUND

Despite the pervasive and devastating effect of Essential Tremor (ET), the distribution of ET throughout the upper limb is unknown. We developed a method for characterizing the distribution of ET and performed a preliminary characterization in a small number of subjects with ET.

METHODS

Using orientation sensors and inverse kinematics, we measured tremor in each of the seven major degrees of freedom (DOF) from the shoulder to the wrist while ten patients with mild ET assumed 16 different postures. We described the tremor in each DOF in terms of power spectral density measures and investigated how tremor varied between DOF, postures, gravitational torques, and repetitions.

FINDINGS

Our method successfully resulted in tremor measures in each DOF, allowing one to compare tremor between DOF and determine the distribution of tremor throughout the upper limb, including how the distribution changes with posture. In our small number of subjects, we found that the amount of power in the frequency band associated with ET (4-12Hz) was lowest in the shoulder and greatest in the wrist. Similarly, the existence and amplitude of peaks in this band increased from proximal to distal. Although the amount of tremor differed significantly between postures, we did not find any clear patterns with changes in posture or gravitational torque.

INTERPRETATION

This method can be used to characterize the distribution of tremor throughout the upper limb. Our preliminary characterization suggests that the amount of tremor increases in a proximal-distal manner.

Consensus Statement on the classification of tremors. from the task force on tremor of the International Parkinson and Movement Disorder Society

BACKGROUND

Consensus criteria for classifying tremor disorders were published by the International Parkinson and Movement Disorder Society in 1998. Subsequent advances with regard to essential tremor, tremor associated with dystonia, and other monosymptomatic and indeterminate tremors make a significant revision necessary.

OBJECTIVES

Convene an international panel of experienced investigators to review the definition and classification of tremor.

METHODS

Computerized MEDLINE searches in January 2013 and 2015 were conducted using a combination of text words and MeSH terms: "tremor", "tremor disorders", "essential tremor", "dystonic tremor", and "classification" limited to human studies. Agreement was obtained using consensus development methodology during four in-person meetings, two teleconferences, and numerous manuscript reviews.

RESULTS

Tremor is defined as an involuntary, rhythmic, oscillatory movement of a body part and is classified along two axes: Axis 1-clinical characteristics, including historical features (age at onset, family history, and temporal evolution), tremor characteristics (body distribution, activation condition), associated signs (systemic, neurological), and laboratory tests (electrophysiology, imaging); and Axis 2-etiology (acquired, genetic, or idiopathic). Tremor syndromes, consisting of either isolated tremor or tremor combined with other clinical features, are defined within Axis 1. This classification scheme retains the currently accepted tremor syndromes, including essential tremor, and provides a framework for defining new syndromes.

CONCLUSIONS

This approach should be particularly useful in elucidating isolated tremor syndromes and syndromes consisting of tremor and other signs of uncertain significance. Consistently defined Axis 1 syndromes are needed to facilitate the elucidation of specific etiologies in Axis 2. © 2017 International Parkinson and Movement Disorder Society.

Zonisamide for essential tremor

BACKGROUND

Essential tremor (ET) is one of the most common movement disorders. The treatment is primarily based on pharmacological agents. Although primidone and propranolol are well established treatments in clinical practice, they can be ineffective in 25% to 55% of patients, and can produce serious adverse events in a large percentage of them. For these reasons, it may be worthwhile evaluating the treatment alternatives for ET. Zonisamide has been suggested as a potentially useful agent for the treatment of ET but there is uncertainty about its efficacy and safety.

OBJECTIVES

To assess the effect on functional abilities and the safety profile of zonisamide in adults with essential tremor (ET).

SEARCH METHODS

We carried out a systematic search, without language restrictions to identify all relevant trials. We searched CENTRAL, MEDLINE, Embase, NICE, ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform (ICTRP) to January 2017. We searched BIOSIS Citation Index (2000 to January 2017) for conference proceedings. We handsearched grey literature and examined the reference lists of identified studies and reviews.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) of zonisamide versus placebo or any other treatment. We included studies in which the diagnosis of ET was made according to accepted and validated diagnostic criteria. We excluded studies conducted in patients presenting secondary forms of tremor or reporting only neurophysiological parameters to assess outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently collected and extracted data using a data collection form. We assessed the risk of bias and the quality of evidence.We used inverse variance methods for continuous outcomes and measurement scales. We compared differences between treatment groups as mean differences. We combined results for dichotomous outcomes using Mantel-Haenszel methods and obtained risk differences to compare treatment groups. We used Review Manager 5 software for data management and analysis.

MAIN RESULTS

We only considered one study eligible for this review (20 participants). Assessments of risk of bias for most domains were unclear or low. Adverse events were only reported in participants from the zonisamide group, making it possible that they were aware of treatment group assignment. We are uncertain as to the effects of zonisamide on motor tasks (mean difference (MD) -0.00, 95% confidence interval (CI) -1.51 to 1.51, very low-quality evidence) and functional disabilities (MD -0.30, 95% CI -1.23 to 0.63, very low-quality evidence) when compared with placebo. Three participants in the zonisamide group (30%) and two participants in the placebo group (20%) discontinued the treatment and withdrew from the study for any reason (very low-quality evidence), however the increased risk of withdrawal in the zonisamide group was statistically non-significant (risk difference (RD) 0.1, 95% CI -0.28 to 0.48). Six participants in the zonisamide group (60%) and none of the participants in the placebo group (0%) developed adverse events (AEs), with a RD of 0.60 (95% CI 0.28 to 0.92; very low quality evidence). The most common AEs, experienced with zonisamide treatment, were headache, nausea, fatigue, sleepiness, and diarrhoea. Quality of life was not assessed in the study included.

AUTHORS' CONCLUSIONS

Based on currently available data, there is insufficient evidence to assess the efficacy and safety of zonisamide treatment for ET.

Topiramate for essential tremor

BACKGROUND

Essential tremor (ET) is one of the most common movement disorders. The management is primarily based on pharmacological agents and in clinical practice propranolol and primidone are considered the first-line therapy. However, these treatments can be ineffective in 25% to 55% of people and are frequently associated with serious adverse events (AEs). For these reasons, it is worthwhile evaluating other treatments for ET. Topiramate has been suggested as a potentially useful agent for the treatment of ET but there is uncertainty about its efficacy and safety.

OBJECTIVES

To assess the efficacy and safety of topiramate in the treatment of ET.

SEARCH METHODS

We carried out a systematic search without language restrictions to identify all relevant trials in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (January 1966 to January 2017), Embase (January 1988 to January 2017), National Institute for Health and Care Excellence (1999 to January 2017), ClinicalTrials.gov (1997 to January 2017) and World Health Organization International Clinical Trials Registry Platform (ICTRP; 2004 to January 2017). We searched BIOSIS Citation Index (2000 to January 2017) for conference proceedings. We handsearched grey literature and the reference lists of identified studies and reviews.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) of topiramate versus placebo/open control or any other treatments. We included studies in which the diagnosis of ET was made according to accepted and validated diagnostic criteria. We excluded studies conducted in people presenting with secondary forms of tremor or reporting only neurophysiological parameters to assess outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently collected and extracted data using a data collection form. We assessed the risk of bias and the quality of evidence. We used a fixed-effect meta-analysis for data synthesis.

MAIN RESULTS

This review included three trials comparing topiramate to placebo (309 participants). They were all at high overall risk of bias. The quality of evidence ranged from very low to low. Compared to placebo, participants treated with topiramate showed a significant improvement in functional disability and an increased risk of withdrawal (risk ratio (RR) 1.78, 95% confidence interval (CI) 1.23 to 2.60). There were more AEs for topiramate-treated participants, particularly paraesthesia, weight loss, appetite decrease and memory difficulty.

AUTHORS' CONCLUSIONS

This systematic review highlighted the presence of limited data and very low to low quality evidence to support the apparent efficacy and the occurrence of treatment-limiting AEs in people with ET treated with topiramate. Further research to assess topiramate efficacy and safety on ET is needed.

The investigation into the cutaneous silent period in patients with essential tremor pre-treatment and post-treatment

Although essential tremor (ET) is the most common movement disorder, little is known regarding its pathophysiology. Cutaneous silent period (CSP) is a spinal inhibitory reflex that causes suppression of the voluntary muscle contraction that is induced by strong electrical stimulation of the cutaneous nerves. Clinical interest in the CSP stems from its potential usefulness for evaluating segment and components of sensory nerves that are not well assessed by standard electrodiagnostic methods. The aim of this study was to investigate CSP in patients with ET before and after treatment. A total of 30 patients (12 females + 18 males), having ET diagnosis and propranolol treatment initiated, were studied with technique of CSP. Patient group's pre-treatment latency average is found 84.45 ± 18.63, average CSP duration 42.37 ± 11.82, and CSP final latency average 127.10 ± 19.13. According to post-treatment CSP analysis, it is seen that patients' average latency values are found 83.14 ± 20.92 and it is determined that there is no significant statistical difference compared to pre-treatment latency values (p > 0.05). Post-treatment average CSP duration is found 36.64 ± 13.38, and it is seen that there is a significant statistical shortening compared to pre-treatment durations (p < 0.05). Patients' post-treatment CSP final latency averages are found 123.17 ± 13.67, and it is determined that there is no significant statistical difference compared to pre-treatment latency values (p > 0.05). The main finding of this study is that in ET the CSP is prolonged and that treatment with propranolol shortens the CSP and brings it closer to normal values. A small dose of propranolol has the effect of shortening pathologically prolonged CSP in a subset of ET patients (women and without family history), making further investigations with this method interesting. From this point of view in our study, patients with ET treatment give an idea of the effectiveness of propranolol. In recent years, a technique of CSP is interested in the field of electrophysiology and shows the effect of ET that given other pharmacological treatment and also it can be considered a quantitative measure to compare them. The usefulness of CSP should be supported by further studies with more patients.

Pregabalin for essential tremor

BACKGROUND

Essential tremor is one of the most common movement disorders. Treatment primarily consists of pharmacological agents. While primidone and propranolol are well-established treatments in clinical practice, they may be ineffective in 25% to 55% of patients and can produce serious adverse events in a large percentage of them. For these reasons, it is worth evaluating the treatment alternatives for essential tremor. Some specialists have suggested that pregabalin could be a potentially useful agent, but there is uncertainty about its efficacy and safety.

OBJECTIVES

To assess the effects of pregabalin versus placebo or other treatment for essential tremor in adults.

SEARCH METHODS

We performed a systematic search without language restrictions to identify all relevant trials up to December 2015. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, NICE, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform (ICTRP). We handsearched grey literature and examined the reference lists of identified studies and reviews.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) of pregabalin versus placebo or any other treatments. We included studies in which the diagnosis of ET was made according to accepted and validated diagnostic criteria. We excluded studies conducted in patients presenting secondary forms of tremor or reporting only neurophysiological parameters to assess outcomes.

DATA COLLECTION AND ANALYSIS

Two reviewers independently collected and extracted data using a data collection form. We assessed the risk of bias of the body of evidence, and we used inverse variance methods to analyse continuous outcomes and measurement scales. We compared the mean difference between treatment groups, and we combined results for dichotomous outcomes using Mantel-Haenszel methods and risk differences We used Review Manager software for data management and analysis.

MAIN RESULTS

We only found one study eligible for this review (22 participants). We assessed the risk of bias for most domains as unclear. We graded the overall quality of evidence as very low. Compared to placebo, patients treated with pregabalin showed no significant improvement of motor tasks on the 36-point subscale of the Fahn-Tolosa-Marin Tremor Rating Scale (TRS) (MD -2.15 points; 95% CI -9.16 to 4.86) or on the 32-point functional abilities subscale of the TRS (MD -0.66 points; 95% CI -2.90 to 1.58).The limited evidence showed no difference in study withdrawal (Mantel-Haenszel RD -0.09; 95% CI -0.48 to 0.30) and presentation of adverse events between pregabalin and placebo (Mantel-Haenszel RD 0.18; 95% CI -0.13 to 0.50).

AUTHORS' CONCLUSIONS

The effects of pregabalin for treating essential tremor are uncertain because the quality of the evidence is very low. One small study did not highlight any effect of this treatment; however, the high risk of bias and the lack of other studies on this topic limit further conclusion.

Eye movement abnormalities in essential tremor

Essential tremor (ET) is the most prevalent movement disorder, characterized mainly by an action tremor of the arms. Only a few studies published as yet have assessed oculomotor abnormalities in ET and their results are unequivocal. The aim of this study was to assess the oculomotor abnormalities in ET patients compared with the control group and to find the relationship between oculomotor abnormalities and clinical features of ET patients. We studied 50 ET patients and 42 matched by age and gender healthy controls. Saccadometer Advanced (Ober Consulting, Poland) was used to investigate reflexive, pace-induced and cued saccades and conventional electrooculography for evaluation of smooth pursuit and fixation. The severity of the tremor was assessed by the Clinical Rating Scale for Tremor. Significant differences between ET patients and controls were found for the incidence of reflexive saccades dysmetria and deficit of smooth pursuit. Reflexive saccades dysmetria was more frequent in patients in the second and third phase of ET compared to the first phase. The reflexive saccades latency increase was correlated with severity of the tremor. In conclusion, oculomotor abnormalities were significantly more common in ET patients than in healthy subjects. The most common oculomotor disturbances in ET were reflexive saccades dysmetria and slowing of smooth pursuit. The frequency of reflexive saccades dysmetria increased with progression of ET. The reflexive saccades latency increase was related to the severity of tremor.

Alprazolam for essential tremor

BACKGROUND

Essential tremor (ET) is one of the most common movement disorders. Treatment is based primarily on pharmacological agents. On this basis, although primidone and propranolol are well-established treatments in clinical practice, they could be ineffective in 25% to 55% of patients and can produce serious adverse events (AEs) in a large percentage of individuals. For these reasons, evaluating treatment alternatives for ET may be a worthwhile pursuit. Alprazolam has been suggested as a potentially useful agent for treatment of individuals with ET, but its efficacy and safety are uncertain.

OBJECTIVES

PrimaryTo assess the efficacy and safety of alprazolam in the treatment of individuals with ET. SecondaryTo examine effects of alprazolam treatment on the quality of life of people with ET.

SEARCH METHODS

We carried out a systematic search without language restrictions to identify all relevant trials. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (January 1966 to September 2015), EMBASE (January 1988 to September 2015), the National Institute for Health and Care Excellence (NICE) (1999 to September 2015), ClinicalTrials.gov (1997 to September 2015) and the World Health Organiza tion (WHO) International Clinical Trials Registry Platform (ICTRP) (2004 to September 2015). We handsearched grey literature and examined the reference lists of identified studies and reviews.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) of alprazolam versus placebo or any other treatment. We included studies in which ET was diagnosed according to accepted and validated diagnostic criteria. We excluded studies that included patients presenting with secondary forms of tremor or reporting only neurophysiological parameters for the pur p ose of assessing outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently collected and extracted data using a data collection form. We assessed risk of bias and the body of evidence. We used inverse variance methods for continuous outcomes and measurement scales. We compared differences between treatment groups as mean differences. We used Review Manager software for management and analysis of data.

MAIN RESULTS

We included in this review one trial that compared alprazolam versus placebo (24 participants). It was judged to have high overall risk of bias. We graded the overall quality of evidence as very low. Compared with those given placebo, participants treated with alprazolam showed a significant reduction in tremor severity (mean difference (MD) -0.75, 95% confidence interval (CI) -0.83 to -0.67). Nine alprazolam-treated participants (75%) developed AEs, mainly represented by sedation (50%), constipation (17%) and dry mouth (9%). No participants in the alprazolam group and no p articipants in the placebo group discontinued treatment and dropped out of the study.

AUTHORS' CONCLUSIONS

Currently available data reveal evidence insufficient for assessment of the efficacy and safety of alprazolam treatment for individuals with ET.

Tremor and Klinefelter's Syndrome

Background

Klinefelter’s syndrome (KS) has been associated with tremor, but reports on tremor phenomenology and treatment are limited.

Case Reports

Patient 1 is a 17-year-old male with a dystonic tremor treated with deep brain stimulation (DBS). Patient 2 is a 57-year-old male with a predominant left hand resting tremor and dystonic features.

Discussion

Our cases suggest that the tremor in patients with KS may be dystonic in nature. Patient 1 is also the third reported case of successful treatment with DBS. These cases have implications for elucidating the underlying neurobiological mechanism of tremor and identifying treatment options.

Are patients with limb and head tremor a clinically distinct subtype of essential tremor?

BACKGROUND

Essential tremor (ET) is the most common tremor disorder in adults. In addition to upper limbs, the tremor in ET may also involve head, jaw, voice, tongue, and trunk. Though head tremor (HT) is commonly present in patients with ET, large comparative studies of ET patients with HT (HT+) and without HT (HT-) are few.

METHODS

To determine whether ET with HT is a distinct clinical subtype by comparing ET patients with and without HT, a chart review of 234 consecutive patients with ET attending the neurology clinics of the National Institute of Mental Health and Neurosciences, India, was done. A movement disorder specialist confirmed the diagnosis of ET in all patients using the National Institutes of Health collaborative genetic criteria.

RESULTS

HT was present in 44.4% of the patients. Comparison between HT+ and HT- showed that the HT+ group patients: (1) were older, (2) had later onset of tremor, (3) had unimodal distribution of age at onset with a single peak in the fifth decade, (4) had more frequent voice tremor, and (5) were more likely to have mild cervical dystonia. HT was part of presenting symptoms in nearly two thirds of the ET patients and in the rest it was detected during clinical examination.

CONCLUSIONS

Several demographic and clinical variables suggest that ET patients with HT have a distinct clinical phenotype.

Sensorineural Hearing Loss in Non-depressed Essential Tremor Cases and Controls: A Clinical and Audiometric Study

Background

Patients with essential tremor (ET) have an increased prevalence of hearing loss, and depression is a confounding issue for both conditions. We assessed hearing loss in non-depressed ET patients and controls using a questionnaire and audiometric tests.

Methods

The study included 34 patients with ET and 45 volunteers were included. Both groups were asked if they had hearing loss, and pure tone audiometry, speech recognition threshold, tympanogram, short increment sensitivity index (SISI), tone decay, and otoacoustic emission audiological tests were conducted.

Results

Seventeen subjects (50.0%) in the patient group answered “yes” to the question “Do you have hearing loss?” compared to one (2.2%) subject in the control group (p<0.001). The tone decay values of the right ear at 4,000 Hz were higher in the patient group. The number of subjects in which the otoacoustic emissions could not be obtained in the right ear was higher in the ET patients (p = 0.005).

Discussion

The results support the presence of a cochlear pathology in ET and may indicate that ET and sensorineural hearing loss may be components of a common disease process.

White matter correlates of cognitive impairment in essential tremor

BACKGROUND AND PURPOSE

Impairment of cognitive functions occurs in essential tremor, though the mechanism is largely unknown. The aim of this study was to find microstructural correlates of cognitive dysfunction seen in essential tremor by using DTI and neuropsychological assessment.

MATERIALS AND METHODS

Fifty-five patients with essential tremor and 55 matched healthy controls were evaluated. Essential tremor was diagnosed by using the National Institutes of Health criteria. Subjects were assessed by using a structured neuropsychological battery. DTI data were acquired by using 3T MR imaging and were analyzed by using tract-based spatial statistics. Fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity were analyzed.

RESULTS

Patients were considered cognitively impaired when the test score was 1.5 SDs below or above the mean of healthy controls (depending on the type of test) in ≥3 neuropsychological tests. Patients with cognitive impairment had significantly higher mean diffusivity, radial diffusivity, and axial diffusivity values in the bilateral frontoparietal regions. In patients with cognitive impairment, mean diffusivity, radial diffusivity, and axial diffusivity showed correlations with various neuropsychological test scores. Executive function correlated with DTI measures of the frontal white matter, cingulum, inferior superior longitudinal and uncinate fasciculi, anterior thalamic radiations, and posterior lobe of the cerebellum. Visuospatial function correlated with the right parieto-occipital lobe, whereas visual-verbal memories correlated with the anterior thalamic radiations, inferior longitudinal and uncinate fasciculi, and the posterior lobe of the cerebellum. No significant correlations were found between fractional anisotropy and any of the neuropsychological test scores.

CONCLUSIONS

The present study demonstrates a correlation between neuropsychological test scores and DTI measures, suggesting a neuroanatomic basis for cognitive impairment seen in patients with essential tremor.

Increased Prevalence of Non-motor Symptoms in Essential Tremor

Background

Cases with essential tremor (ET) have been described with Lewy body inclusions, the hallmark of Parkinson disease (PD). Patients with PD may suffer from anosmia, depression, constipation, and rapid eye movement sleep behavior disorder (RBD), sometimes years before the appearance of their motor syndrome. The objective of this study was to evaluate the prevalence of these non-motor Parkinson's associated symptoms in patients with ET.

Methods

Fifty ET subjects were contacted by phone and given questionnaires evaluating the presence or absence of anosmia, depression, constipation, and RBD. Frequencies of these symptoms were compared with their published prevalence in the general population.

Results

Of the patients with ET, 4.5% reported having anosmia or hyposmia and 21.7% reported being constipated, similar to what is observed in the general population. Using a screening questionnaire for RBD, 43.5% of ET patients are possibly suffering from RBD, whereas in the general population prevalence is estimated to be 0.5%. Finally, depression was detected in 21.7% of ET patients; in the general population, prevalence is 5%.

Discussion

Patients with ET seem to have more RBD and more depression than found in the general population. Prospective studies with normal control groups are needed to confirm these findings.

Association between cortical volume loss and cognitive impairments in essential tremor

BACKGROUND AND PURPOSE

Impairment of cognitive functions occurs in essential tremor (ET) although the mechanism is largely unknown. A possible association between cognitive performance and brain atrophy in ET patients was examined using neuropsychological tests and voxel-based morphometry (VBM).

METHODS

Twenty-five patients with ET and 25 matched healthy controls were evaluated. ET was diagnosed using the National Institutes of Health collaborative genetic criteria. Severity of tremor was assessed using the Fahn-Tolosa-Marin (FTM) tremor rating scale. Subjects were assessed using a structured neuropsychological battery. Brain images were acquired using a 3T magnetic resonance imaging scanner. VBM analysis was performed using Statistical Parametric Mapping 8.

RESULTS

The age of the patients was 45.0 ± 10.7 years and of controls 45.4 ± 10.7 years. Tremor duration was 9.84 ± 6.63 years and total FTM score was 37.34 ± 17.67. Patients were divided into two groups: ETCI with cognitive impairment (three or more abnormal neuropsychological tests, 1.5 standard deviation criterion) and ETNCI without cognitive impairment. Compared with controls, the ETCI group had significantly impaired performance in neuropsychological tests. One-way analysis of variance was performed between the three groups (ETCI, ETNCI, controls) followed by the two-sample t test. Compared with controls, grey matter volume (GMV) loss was observed in ETCI in the cerebellum (anterior and posterior lobes) and medial frontal gyrus. GMV loss was observed in ETCI compared with ETNCI in the medial frontal gyrus, post central gyrus, anterior cingulate and insula. Impairment in neuropsychological tests significantly correlated with GMV of the medial frontal gyrus, superior parietal lobe, middle temporal gyrus, occipital lobe, lentiform nucleus, insular and cingulate cortices and cerebellum posterior lobe in ETCI.

CONCLUSIONS

A correlation between neurocognitive deficits in ETCI and GMV was observed suggesting that grey matter atrophy appears to be a correlate of cognitive impairment in ET.

What is essential tremor?

Classic essential tremor is a clinical syndrome of action tremor in the upper limbs (at least 95 % of patients) and less commonly the head, face/jaw, voice, tongue, trunk, and lower limbs, in the absence of other neurologic signs. However, the longstanding notion that essential tremor is a monosymptomatic tremor disorder is being challenged by a growing literature describing associated disturbances of tandem walking, personality, mood, hearing, and cognition. There is also epidemiologic, pathologic, and genetic evidence that essential tremor is pathophysiologically heterogeneous. Misdiagnosis of essential tremor is common because clinicians frequently overlook other neurologic signs and because action tremor in the hands is caused by many conditions, including dystonia, Parkinson disease, and drug-induced tremor. Thus, essential tremor is nothing more than a syndrome of idiopathic tremulousness, and the challenge for researchers and clinicians is to find specific etiologies of this syndrome.

Clinical features and nigrostriatal dysfunction in patients with combined postural and resting tremors

BACKGROUND

The characteristics of clinical features and nigrostriatal dopaminergic dysfunction in patients with combined postural and resting tremors have been less clearly reported.

METHODS

The present study examined 43 patients with a visible persistent bilateral postural tremor and a unilateral/bilateral resting tremor involving the hands and forearms. The patients had experienced tremors for more than 3 years, with no evidence of Parkinson's disease or other parkinsonian disorders. Visual and quantitative analyses of [18F] N-(3-fluoropropyl)-2beta-carbon ethoxy-3beta-(4-iodophenyl) nortropane (FP-CIT) PET in 36 patients were performed. Seventeen age-matched normal controls were also studied.

RESULTS

On visual analysis, 28 patients (78%) showed normal [18F] FP-CIT uptake and eight (22%) showed significantly reduced uptake, suggesting nigrostriatal dopaminergic neuronal degeneration. The reduced [18F] FP-CIT uptake was significantly associated with earlier age-at-onset of tremor and asymmetric presentation of resting tremor. On quantitative analysis, there were statistically significant differences in the [18F] FP-CIT uptake ratio in the posterior putamen between patients with reduced uptake (2.37 ± 1.83) and patients with normal uptake (6.39 ± 1.35) (P < 0.001). However, posterior putamen uptake levels in patients with normal [18F] FP-CIT uptake on visual analysis were similar to those in normal controls (7.22 ± 1.29) (P = 0.291).

CONCLUSION

The nigrostriatal dopaminergic dysfunction in patients with combined postural and resting tremors may be associated with earlier age-at-onset of tremor and asymmetric pattern of resting tremor, which might help to correctly diagnose patients with mixed tremors.

Defining dystonic tremor

A strong association between dystonia and tremor has been known for more than a century. Two forms of tremor in dystonia are currently recognized: 1) dystonic tremor, which is tremor produced by dystonic muscle contraction and 2) tremor associated with dystonia, which is tremor in a body part that is not dystonic, but there is dystonia elsewhere. Both forms of tremor in dystonia frequently resemble essential tremor or another pure tremor syndrome (e.g., isolated head and voice tremors and task-specific writing tremor), and relationships among these tremor disorders have long been debated. Misdiagnosis is common because mild dystonia is frequently overlooked in patients with tremor. It is now clear that essential tremor is a syndrome, not a specific disease, and the use of essential tremor as a specific clinical diagnosis is arguably an impediment to elucidating this and other pure tremor syndromes and their relationship to dystonia. A new classification, primary tremor, is proposed and would be used for any disorder in which tremor is the sole or principal abnormality with no identifiable etiology other than possible genetic inheritance. This classification scheme would facilitate tremor research by moving the focus from the narrow question "Is it essential tremor?" to a broader consideration of what genetic and environmental factors cause primary tremor disorders, and how do they relate to dystonia and other neurological disorders.

Methodological issues in clinical drug development for essential tremor

Essential tremor (ET) is one of the most common tremor disorders in the world. Despite this, only two medications have received Level A recommendations from the American Academy of Neurology to treat it (primidone and propranolol). Even though these medications provide relief to a large group of ET patients, up to 50% of patients are non-responders. Additional medications to treat ET are needed. This review discusses some of the methodological issues that should be addressed for quality clinical drug development in ET.

Rates of diagnosis and treatment of neurological disorders within a prevalent population of community-dwelling elderly people in sub-Saharan Africa

Background: The prevalence of neurological disorders in those aged 70 years and over in the Hai district of Tanzania has been previously reported. The following research reports rates of patient’s: treatment seeking, diagnosis and treatment within this prevalent population.

Methods: All people identified as having at least one neurological disorder in the prevalence study were questioned regarding whether they had sought treatment for their disorder, whether they had had a previous correct diagnosis and whether they were being currently treated.

Results: From a background population of 2232 people, 349 people had neurological disorders, of whom 225 (64.5%) had sought treatment for their symptoms. Of the 384 disorders identified in these 349 people, only 14.6% had been diagnosed and only 9.9% were receiving appropriate treatment. Males were significantly more likely to have been diagnosed and were more likely to have been treated appropriately.

Conclusions: Levels of diagnosis and treatment were low, with some gender inequality. Reasons for this may include a lack of recognition of the condition within the local population and lack of access to appropriate services. In the absence of effective primary and secondary preventative measures, and effective treatment, the burden of neurological disorders is likely to increase with further demographic ageing.

Non-motor features in essential tremor

INTRODUCTION

Essential tremor (ET) is increasingly recognized to have several non-motor manifestations. The aim of this study was to determine the prevalence of non-motor manifestations in ET and its impact on the quality of life (QOL).

METHODS

This was a cross-sectional case-control questionnaire-based study. The subjects were 50 patients with ET and 50 matched healthy controls. All subjects were assessed by Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Parkinson Fatigue Scale, Brief Pain Inventory, Hamilton Anxiety Rating Scale, and Hamilton Depression Rating Scale. In addition, QOL in Essential Tremor questionnaire was administered to patients with ET.

RESULTS

Patients with ET, when compared with controls, had significantly higher prevalence and higher mean scores of sleep disturbances (46% vs 8%, P < 0.001; 5.9 ± 4.6 vs 2.6 ± 2.3, P < 0.001), fatigue (30% vs 8%, P = 0.009; 5.8 ± 0.8 vs 2.5 ± 0.4, P < 0.001), anxiety (66% vs 18%, P = 0.009; 7.4 ± 9.0 vs 0.7 ± 2.6, P < 0.001), depression (44% vs 8%, P = 0.009; 7.8 ± 7.9 vs 1.7 ± 3.3, P < 0.001) as well as higher mean score of pain severity (1.9 ± 2.3 vs 0.6 ± 1.2, P = 0.001) and interference owing to pain (2.0 ± 2.9 vs 0.5 ± 1.2, P = 0.001). Following hierarchical regression analysis, depression was the only non-motor feature that affected the QOL.

CONCLUSION

There was a significantly higher prevalence and greater severity of sleep disturbances, fatigue, pain, anxiety, and depression in patients with ET and depression significantly affected the QOL.

Tremor is attenuated during walking in essential tremor with resting tremor but not parkinsonian tremor

We used accelerometry and visual examination by a neurologist to measure the intensity and frequency of hand tremor under resting, postural, writing, and walking conditions among patients with essential tremor with resting tremor (n=11) and Parkinson's disease (n=38). The intensity of essential tremor was markedly attenuated during walking relative to resting. The intensity and frequency of parkinsonian tremors were higher while walking than while resting. We suggest that assessment of the intensity and frequency of tremor during walking is clinically useful for differentiating between essential tremor with resting tremor and parkinsonian tremor, especially in the early stages, when the two conditions are often difficult to distinguish. Parkinsonian tremors are known to be enhanced during walking. Our clinical experience, as well as that of others, suggests that the intensity of essential tremor with resting tremor is markedly attenuated during walking.

Tremor--some controversial aspects

The commonest cause of pathological tremor is essential tremor (ET). However, it has proved difficult to identify genetic mutations causing ET, particularly because other causes of tremor continue to be misdiagnosed as ET. Whether subjects with dystonia or Parkinson's disease (PD) carry an increased genetic risk of developing ET, or vice versa, is controversial. In addition, the notion of a separate disorder of benign tremulous parkinsonism (BTP) has been debated. This article gives a selective viewpoint on some areas of uncertainty and controversy in tremor.

Telemonitoring System of Neurological Signs in a Health Telematique Network

The paper presents a new, experimental, wireless tremor telemonitoring system composed of an optional variable number of portable devices integrating three-axis acceleration mini-sensors which are connected to very small dimensions acquisition systems with Wi-Fi transmission capabilities. The main advantages of the design system consist of the possibilities to monitor simultaneously many body parts of one or multiple subjects on local or more extended areas both for scheduled assessments and in an everyday life environment. Possible applications of the presented experimental system, considered as a part of a health telematic network, consist of delivering supplementary, consistent sets of data to clinicians in order to reliably assess patients’ state in home and community settings, over longer periods of time. This system consists of delivering new data necessary for differential diagnosis of different types of tremors, or to precise different stages of illness in a health telematic network. The multiple simultaneous measuring capabilities and the extended observation time period could cover eventually neglected aspects related to occasional, temporary, or an intermittent tremor. The Wi-Fi DAQ proposed system’s novelty, in contrast with existing Wi-Fi solutions, is its ultra low power Wi-Fi capability, which makes it suitable for sensing applications where battery power management is critical.

Mitochondrial DNA in patients with essential tremor

Essential tremor (ET) is one of the most common of the movement disorders. However, there has been little agreement in the neurological literature regarding diagnostic criteria for ET. It is not clear to what extent ET is associated with defects of mitochondrial DNA. In this study, we analyzed mitochondrial DNA (mtDNA) from the blood cells of the normal and ET patients using the long and accurate polymerase chain reaction (LA-PCR) and PCR. The large deletions were detected within several regions of mtDNA, but were not detected in the D-loop or CO I regions in ET patients. From our study, it is suggested that ET is a disorder showing a deficiency of mtDNA multicomplexes, and it also appears that mitochondrial dysfunction could be one of the causative factors of ET.

HS1-BP3 gene variant is common in familial essential tremor

Essential tremor (ET) is a movement disorder characterized by a postural or kinetic tremor of the hands, head, or voice. It is typically a familial condition and affects 1% to 4% of the general population. The trait is genetically linked to chromosome 2p in some families. A variant (828C-->G) in exon 7 of the hematopoietic-specific protein 1 binding protein 3 gene (HS1-BP3) on chromosome 2p recently has been found to segregate with ET in 2 families. To determine the frequency of this variant in a larger series, we studied patients with ET, Parkinson disease (PD), and controls without tremor. Affected singletons representing 73 families from the United States with dominantly inherited ET, 35 individuals with PD, and 304 healthy controls older than age 60 were tested for the 828C-->G variant in exon 7 of the HS1-BP3 gene by a BseYI restriction enzyme digest of the polymerase chain reaction product. Heterozygous carriers of the mutant allele were identified in 12 individuals with ET (16.4%) and in 1 individual with PD and postural tremor (3%). All of the healthy controls (608 chromosomes) were homozygous for the wild-type allele. The 828C-->G genetic variant in the HS1-BP3 gene occurs relatively frequently in subjects with ET. The variant may also be found in some individuals with PD and postural tremor. The HS1-BP3 gene plays a putative role in regulating catecholamine and serotonin metabolism, but the functional consequences of the amino acid substitution (A265G) caused by this genetic variant is unknown.