The usefulness of accelerometric registration with assessment of tremor parameters and their symmetry in differential diagnosis of parkinsonian, essential and cerebellar tremor

Background and purpose: The aim of the study was to perform an analysis of the recorded tremor using accelerometry and select those parameters that are the most useful in differentiation of tremor types. Material and methods: We examined 45 patients with parkinsonian tremor (PT), 39 patients with essential tremor (ET) and 35 patients with cerebellar tremor (CT). The control group consisted of 52 healthy persons. The analysis included tremor intensity, frequency of spectral peaks, centre frequency, standard deviation of the centre frequency, and harmonic index. Parameters of tremor were compared between particular groups of patients with pathological tremor and with the control group. The side-to-side symmetry of these parameters was also analysed. Results: Tremor intensity was significantly higher in patients than in controls. There was a significant side-to-side asymmetry of intensity in all patient groups. Significantly lower peak frequency, centre frequency and standard deviation of centre frequency were found in patients compared to the control group. The frequency was symmetric in ET and in controls, but asymmetric in other subjects. The differences between hands regarding the standard deviation of centre frequency were significantly greater in all patient groups than in controls, who revealed no difference of this parameter between sides. Harmonic index was significantly greater and asymmetric in all groups of patients when compared to the control group. Conclusions: Standard deviation of centre frequency and harmonic index are the most valuable variables in differentiation of tremor. The assessment of symmetry of tremor parameters is useful in discrimination of various types of pathological tremor.