WRIST TREMOR - INVESTIGATION OF AGONIST-ANTAGONIST INTERACTION BY MEANS OF LONG-TERM EMG RECORDING AND CROSS-SPECTRAL ANALYSIS

We have developed a method to observe and quantify the phasic relation ship between the burst patterns of antagonistic muscles in any roughly periodic movement, such as tremor, for up to 24 h. This paper describ es our approach, in which long-term EMG recordings are evaluated by a procedure based on cross-spectral analysis. The method is then illustr ated by data from 6 patients with essential tremor. Our data confirm e arlier observations that a particular patient may show different burst patterns at different times. However, as opposed to tremor analysis b ased on short-term recording, our method allows quantitative statement s on the relative frequency of the burst patterns, as they occur under everyday conditions. In addition, our data suggest that in ET (a) alt ernating tremor activity in one hand may occur simultaneously with syn chronous activity in the other hand; (b) along with the classical alte rnating and co-contracting patterns there may be significant 'non-clas sical' activity, that cannot be called alternating or synchronous.