Category: Tremor
Objective: To compare the electrophysiological characteristics of tremor in subjects with Essential Tremor (ET) and Essential Tremor Plus (ET Plus).
Background: Patients with neurological signs in addition to postural tremor are now classified as having ET Plus. There is an ongoing debate about the merits of classifying the heterogeneous group of essential tremor patients into these distinct classes. We sought to study whether the tremor electrophysiological characteristics are distinct in ET and ET Plus.
Method: We recruited 24 subjects (12 ET and 12 ET Plus). Subjects underwent tremor analysis using combined tri-axial accelerometry- surface electromyography as per standard technique. From power spectral density data, we computed Peak Frequency (PF), Peak Power (PP) and Total Power (TP) of spectrum (1-30Hz) in the following conditions: rest, posture 1(arms stretched forward against gravity) and posture 2 (arms abducted with elbows flexed), with and without mental arithmetic and after loading weight in Posture 1. PF, PP, TP at each condition and change in frequency with mental activation and loading (Frequency difference, FD) were compared between the 2 groups ET and ET plus.
Results: PF at rest (ET=6.3± 1.9 Hz, ET Plus=6.3±1.5 Hz, p=.988)), posture 1 (ET=6.6±2.3 Hz, ET Plus=6.1±0.9 Hz, p=.496)), and posture 2 (ET=6.946500±1.9 Hz, ET Plus=6.122500±1.3 Hz, p=.581)), were similar between ET and ET plus. PP and TP were also similar. There was no significant change in tremor frequency with mental arithmetic (P1 Freq difference ET=.3630±1.6 Hz, ET Plus=.3389±1.2 Hz, p=.968)), or loading weight (ET=-.0268±1.6 Hz, ET Plus=-.2341±0.8 Hz, p=.702)), in either group.
Conclusion: Electrophysiological evaluation reveals a predominant postural tremor of frequency 6.3±1.7Hz in both ET and ET Plus. Inspite of the presence of additional clinical features, electrophysiological tremor characteristics are essentially similar between the two groups.
To cite this abstract in AMA style:
R. Anandapadmanabhan, R. Rajan, A. Saini, A. Srivastava. Essential tremor and essential tremor plus are essentially similar on electrophysiological tremor analysis [abstract]. Mov Disord. 2020; 35 (suppl 1). https://www.mdsabstracts.org/abstract/essential-tremor-and-essential-tremor-plus-are-essentially-similar-on-electrophysiological-tremor-analysis/. Accessed June 15, 2025.« Back to MDS Virtual Congress 2020
MDS Abstracts - https://www.mdsabstracts.org/abstract/essential-tremor-and-essential-tremor-plus-are-essentially-similar-on-electrophysiological-tremor-analysis/