[Evaluating the electrophysiological features of tremor in Parkinson's disease and essential tremor using...

Objective: To investigate the electrophysiological features of tremor intensity, frequency and frequency dispersion of Parkinsonian (PT group) and essential (ET group) tremors using accelerometry. Methods: The amplitude, frequency and frequency dispersion of rest tremor, postural tremor and the influence of weight on tremor of 35 PT patients and 40 ET patients in Department of Neurology, the Second Affiliated Hospital Zhejiang University School of Medicine from May 2015 to April 2016 were retrospectively analyzed and compared. Data of the more and less trembling hands were statistically elaborated. Results: In resting, postural and loading states, PT amplitudes of the less affected hand were smaller than the more affected one. The less affected hand were (147±32), (142±36), (157±40)μV, the more affected hand were (185±41), (164±29), (190±33)μV, respectively; ET amplitudes of the less affected hand were also smaller than the more affected one, and the less affected hand were (149±33), (157±33), (169±43)μV, the more affected hand were (176±39), (189±39), (213±36)μV, respectively; PT frequencies of the less affected hand were faster than the more affected one, with the less affected hand (6.1±1.1), (6.4±1.7), (6.5±2.0)Hz, the more affected hand (5.4±1.3), (5.5±1.1), (5.7±1.1)Hz, respectively, but ET frequencies of the less affected hand were similar to the more affected one, with the less affected hand (6.5±1.3), (7.0±1.2), (7.2±1.5)Hz, the more affected hand (7.0±1.0), (7.3±1.0), (7.6±1.1)Hz, respectively; in resting and postural states, PT frequency dispersions of the less affected hand were broader than the more affected one, the less affected hand were (2.1±0.6), (2.4±1.1)Hz, respectively; the more affected hand were (1.6±0.8), (1.7±0.9)Hz, respectively. But in loading state, PT frequency dispersions were similar in both sides (2.3±1.2, 2.2±1.1)Hz; In resting, postural and loading states, ET frequency dispersions were also similar in both two sides, the less affected hand were (2.0±1.1), (2.2±0.9), (1.9±1.0)Hz, the more affected hand were (1.8±0.6), (1.9±0.8), (2.1±0.7)Hz. Conclusions: Tremor intensity is significantly asymmetric both in PT and ET, while frequency and frequency dispersion are symmetric in ET but asymmetric in PT. Bilateral assessment of frequency related tremor parameters may be useful for differentiating ET from PT.