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

BACKGROUND: 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).

METHODS: 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

RESULTS: 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).

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