Objective: To determine whether electrophysiological features derived from EMG and accelerometry can distinguish PD tremor from ET.

Background: Clinical differentiation between tremor in Parkinson’s disease (PD) and essential tremor (ET) may be difficult, particularly in patients with overlapping phenomenology. Accurate classification is important to guide management and selection of advanced therapies such as deep brain stimulation (DBS) or high-intensity focused ultrasound (HIFU). Electrophysiological tremor assessment is a simple, non-invasive, low-cost approach that can objectively quantify tremor characteristics.

Method: Tremor recordings will be obtained from 25 patients with PD and 25 patients with ET. Assessments will be performed under three conditions: rest, postural holding, and action (finger-to-nose). Surface EMG will be recorded from wrist flexor and extensor muscles, together with distal and proximal accelerometry in the upper limb. Each condition will be recorded for 30–60 seconds. Extracted metrics will include dominant tremor frequency (distal/proximal), proximal-to-distal amplitude ratio, half-power bandwidth (HPBW 50%), within-epoch frequency variability, number and relative amplitude of harmonics, EMG activation pattern (alternating vs synchronous), and the EMG alternation index. Between-group comparisons will be performed across conditions. We will additionally explore classification performance of individual features and multivariable models combining electrophysiological metrics.

Results: We hypothesize that PD and ET will display distinct electrophysiological signatures, including differences in spectral structure (dominant frequency/harmonics), tremor stability (bandwidth and frequency variability), and EMG coupling (activation pattern and alternation index), with condition-specific discriminatory patterns.

Conclusion: Objective tremor profiling using EMG and accelerometry may support differentiation between PD and ET in routine clinical practice and inform therapeutic decisions, including selection for DBS or HIFU targets.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/objective-profiling-of-parkinsonian-and-essential-tremor-using-emg-and-accelerometry/