Detection of tremor bursts by a running second order moment function and analysis using interburst histograms
✍ Scribed by Henricus Louis Journée; Alida Annechien Postma; Mingui Sun; Michiel J. Staal
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 698 KB
- Volume
- 30
- Category
- Article
- ISSN
- 1350-4533
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✦ Synopsis
Introduction:
Conventional linear signal processing techniques are not always suitable for the detection of tremor bursts in clinical practice due to inevitable noise from electromyographic (emg) bursts. this study introduces (1) a non-linear analysis technique based on a running second order moment function (somf) and (2) auto- and cross-interburst interval histograms (ibih) showing distributions of interburst interval emg bursts of pathological tremors illustrating an application of the somf.
Materials and methods:
Emg recordings from extensors and flexors of two patients with parkinson's disease with a rest tremor and from a healthy subject during sustained muscular contraction were preliminary analyzed in a pilot study. the somf was obtained by repeated second order moment calculations within a window of fixed width w (time scale parameter) plotted as a function of time. minimum somf values indicate local "moments of inertia" of each emg burst. bursts were detected and located when minimum somf values were below level l (decision parameter). optimal settings of parameters w and l were calculated empirically for pathological tremor emgs. auto- and cross-ibihs were obtained from minimum somf values of detected bursts.
Results:
Tremor frequency and phase relation between emg bursts from auto- and cross-ibihs agreed with those derived from spectral analysis. burst detection by somf has a high sensitivity and selectivity even with noisy background.
Conclusion:
The somf is appropriate for detection of individual emg bursts of pathological tremors. the technique is sensitive to non-stationary changes of tremor bursts regardless of their amplitude. ibihs provide a measure of tremor frequency and phase difference between emg bursts.