Rajan, Roopa;
Anandapadmanabhan, R;
Vishnoi, Aayushi;
Latorre, Anna;
Thirugnanasambandam, Nivethida;
Dipani, Alish;
Biswas, Deblina;
... Bhatia, Kailash; + view all
(2023)
Essential tremor and essential tremor plus are essentially similar electrophysiologically.
Movement Disorders Clinical Practice
10.1002/mdc3.13941.
(In press).
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Essential tremor and essential tremor plus.pdf - Accepted Version Access restricted to UCL open access staff until 28 November 2024. Download (1MB) |
Abstract
BACKGROUND: The merits of classifying the heterogeneous group of essential tremors into essential tremor (ET) and essential tremor plus (ETP) is debated. OBJECTIVES: We studied the electrophysiological and spiral characteristics of tremor in ET and ETP. METHODS: We 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‐ peak frequency, total power, peak power, full width half maximum, tremor stability index and EMG‐coherence. We analysed hand‐drawn spirals to derive mean deviation, tremor variability, inter‐ and intra‐loop widths. We compared these variables among the groups. RESULTS: We recruited 72 participants (81.9% male) with mean age 47.7±16.1years and Fahn‐Tolosa‐Marin Tremor Rating Scale (FTM‐TRS) 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. CONCLUSION: Electrophysiological evaluation revealed postural tremor of frequency 6‐7 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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