Heart rate variability to differentiate essential tremor from early-stage tremor-dominant Parkinson's disease

Essential tremor (ET) and Parkinson's disease (PD) are the most common movement disorders in the elderly, but it is difficult to differentiate ET from early-stage tremor-dominant Parkinson's disease (TDPD).

We investigated heart rate variability (HRV) in 23 patients with ET, 27 patients with TDPD, and 23 healthy controls. HRV was determined using the RR intervals of a 5-min electrocardiogram recording. Measurements of beat-to-beat RR variability, including time domains [(standard deviation of the normal-to-normal RR interval (SDNN), and the root mean square difference of successive RR intervals (RMSSD)] and frequency domains [low-frequency (LF) and high-frequency (HF) components and total spectral power (TP)], were assessed retrospectively.x

In the TDPD group, SDNN, LF, HF, and TP were significantly lower than those in the ET group. In a receiver operating characteristic area under the curve (AUC) analysis, LF was the best potential diagnostic marker (AUC=0.87).

Non-invasive and routine electrocardiography may be helpful in differentiating ET from TDPD during the early disease stage.