P25-F The physiologic complexity of hand tremor motion identifies the Parkinsonian tremor and essential tremor

Background Tremor is a common movement disorder, including the parkinsonian tremor (PT) and essential tremor (ET). The tremor motion is dependent upon the numerous underlying physiologic interactions over multiple tempo-spatial scales. The dynamics of the tremor motion is thus “complex”. The characteristics of such physiologic complexity in PT and ET still remain unknown. Here we hypothesize that the complexity of the hand tremor motion would be sensitive to the PT and ET. Methods Forty-eight participants with clinically-diagnosed PT and 48 age-matched participants with ET completed this study. The 30-s tremor motion (i.e., the acceleration) of left and right hands at resting state (i.e., resting tremor) and when the arms were outstretched horizontally (i.e., postural tremor) were measured. The multiscale entropy (MSE) was then used to quantify the complexity of the tremor acceleration. Greater MSE means greater complexity. Results Participants with ET had significantly lower complexity of both resting and postural tremor motion in left and right hands compared to those with PT (F > 9.7, p 0.19, p 0.18, p 0.20, p Conclusions We here demonstrate first-of-its-kind evidence that the PT and ET induced different pathological changes in the physiologic complexity of hand tremor motion. Such complexity metric is sensitive to the disease duration and severity, which may thus serve as a novel marker to help the identification of these pathological conditions in clinical practice.