The Conundrum of Dystonia in Essential Tremor Patients: How does One Classify these Cases?

Du, Wenqin; Bain, Peter G.; Defazio, Giovanni; Jankovic, Joseph; Kim, Christine; Tan, Eng‐King; Vidailhet, Marie; Louis, Elan D.

doi:10.5334/tohm.690

Cited by 10 publications

(10 citation statements)

References 24 publications

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“…Furthermore, we have here shown that patients with ET + DS have some similarities with both ET and TwD and therefore we cannot conclusively claim whether the presence of soft dystonic signs is prodromal to the development of overt dystonia 15,16 or instead represent an unspecific finding that is unrelated to the tremor syndrome. [21][22][23] Importantly, both AAO and disease duration were similar between the groups and therefore these features cannot explain the differences we found between the groups. FH was found to be lower in TwD than in ET/ET + DS.…”

Section: Discussionmentioning

confidence: 67%

Comparing Essential Tremor with and without Soft Dystonic Signs and Tremor Combined with Dystonia: The TITAN Study

Erro,

Lazzeri,

Terranova

et al. 2024

Movement Disord Clin Pract

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BackgroundTremor disorders remain as clinical diagnoses and the rate of misdiagnosis between the commonest non‐parkinsonian tremors is relatively high.ObjectivesTo compare the clinical features of Essential Tremor without other features (pure ET), ET plus soft dystonic signs (ET + DS), and tremor combined with dystonia (TwD).MethodsWe compared the clinical features of patients with pure ET, ET + DS, and TwD enrolled in The ITAlian tremor Network (TITAN). Linear regression models were performed to determine factors associated with health status and quality of life.ResultsThree‐hundred‐eighty‐three patients were included. Sex distribution was significantly different between the groups with males being more represented in pure ET and females in TwD. The initial site of tremor was different between the groups with about 40% of TwD having head tremor and ET + DS unilateral upper limb tremor at onset. This pattern mirrored the distribution of overt dystonia and soft dystonic signs at examination. Sensory trick, task‐specificity, and position‐dependence were more common, but not exclusive, to TwD. Pure ET patients showed the lowest degree of alcohol responsiveness and ET + DS the highest. Midline tremor was more commonly encountered and more severe in TwD than in the other groups. Regression analyses demonstrated that tremor severity, sex, age, and to a lesser degree the variable “group”, independently predicted health status and quality of life, suggesting the existence of other determinants beyond tremor.ConclusionsPure ET and TwD manifest with a phenotypic overlap, which calls for the identification of diagnostic biomarkers. ET + DS shared features with both syndromes, suggesting intra‐group heterogeneity.

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Section: Discussionmentioning

confidence: 67%

Comparing Essential Tremor with and without Soft Dystonic Signs and Tremor Combined with Dystonia: The TITAN Study

Erro,

Lazzeri,

Terranova

et al. 2024

Movement Disord Clin Pract

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“…The phenomenology of these maneuvers is variable, but consistent in each individual patient. A common phenomenon consists of placement of a finger on the chin or hand in the occipital area of the head 12 ; others include touching the lower face or the posterior neck, and, less commonly, the upper face 24 . Another maneuver involves raising the arms without touching the head 29 .…”

Section: Resultsmentioning

confidence: 99%

“…Currently, there is no test to definitively diagnose iCD, and the gold standard is a clinical diagnosis based on history, clinical features, and phenomenology. Studies on iCD have often relied on clinicians’ experience to identify diagnostic features, but differences of opinion have emerged, even among experts, particularly if features are subtle or less severe 11‐13 . The International Parkinson and Movement Disorder Society's Dystonia Study Group convened a consensus panel to characterize the clinical features of iCD, review terminology, and suggest internationally agreed diagnostic criteria.…”

Section: Introductionmentioning

confidence: 99%

Isolated Cervical Dystonia: Diagnosis and Classification

et al. 2023

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This document presents a consensus on the diagnosis and classification of isolated cervical dystonia (iCD) with a review of proposed terminology. The International Parkinson and Movement Disorder Society Dystonia Study Group convened a panel of experts to review the main clinical and diagnostic issues related to iCD and to arrive at a consensus on diagnostic criteria and classification. These criteria are intended for use in clinical research, but also may be used to guide clinical practice. The benchmark is expert clinical observation and evaluation. The criteria aim to systematize the use of terminology as well as the diagnostic process, to make it reproducible across centers and applicable by expert and non‐expert clinicians. Although motor abnormalities remain central, increasing recognition has been given to nonmotor manifestations, which are incorporated into the current criteria. Three iCD presentations are described in some detail: idiopathic (focal or segmental) iCD, genetic iCD, and acquired iCD. The relationship between iCD and isolated head tremor is also reviewed. Recognition of idiopathic iCD has two levels of certainty, definite or probable, supported by specific diagnostic criteria. Although a probable diagnosis is appropriate for clinical practice, a higher diagnostic level may be required for specific research studies. The consensus retains elements proven valuable in previous criteria and omits aspects that are no longer justified, thereby encapsulating diagnosis according to current knowledge. As understanding of iCD expands, these criteria will need continuous revision to accommodate new advances. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

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“…4,5 Developing objective biomarkers for soft signs like dystonia and ataxia is one approach toward more accurate classification. 6 Electrophysiological tremor analysis may offer another approach, as relatively distinct electrophysiological signatures are known to exist in various tremor syndromes. For instance, the frequency and positional features of tremor on combined surface electromyography (EMG)-accelerometric tremor analysis are characteristically different in parkinsonian tremor, ET, and cerebellar tremor.…”

mentioning

confidence: 99%

“…Developing objective biomarkers for soft signs like dystonia and ataxia is one approach toward more accurate classification 6 . Electrophysiological tremor analysis may offer another approach, as relatively distinct electrophysiological signatures are known to exist in various tremor syndromes.…”

mentioning

confidence: 99%

Essential Tremor and Essential Tremor Plus Are Essentially Similar Electrophysiologically

Rajan,

Anandapadmanabhan,

Vishnoi

et al. 2023

Movement Disord Clin Pract

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

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The Conundrum of Dystonia in Essential Tremor Patients: How does One Classify these Cases?

Cited by 10 publications

References 24 publications

Comparing Essential Tremor with and without Soft Dystonic Signs and Tremor Combined with Dystonia: The TITAN Study

Comparing Essential Tremor with and without Soft Dystonic Signs and Tremor Combined with Dystonia: The TITAN Study

Isolated Cervical Dystonia: Diagnosis and Classification

Essential Tremor and Essential Tremor Plus Are Essentially Similar Electrophysiologically

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