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Predictive Importance Of Index Of Asymmetry In Recovery Following Stroke

Biljana Stojanovic, Ljubomir Djurasic

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Quantitative electroencephalography (QEEG) has been proved as a powerfully tool for prediction of the stage of residual functional disable. For predictive value of QEEG, individual profile of every patient is most important. It has been demonstrated that Index of brain symmetry (BSI) present specific asymmetry of power spectra between two brain hemispheres and it has been normalized from 0 (perfect symmetry) and 1 (maximal asymmetry). Method: We included in our analysis 86 normal subjects in EEG recording. We did frequency analysis using Fast Fourier transformation (FFT) in power spectra for 16 derivations and 20 frequency bands, from 0 to 20Hz, with step of 1. On the base of that data, we got normal distribution with coefficient of variation less than 30%. We determined grades of frontier of allowance in all derivations and in all frequency bands, in the conditions with closed eyes and with eyes open in normal control. Maximal grade for each condition was 320. In this way we appointed the standard. We recorded the EEG in patient on admission and after two months of neurorehabilitation. We did the same procedure in every patients and on the base of the standard we calculated grades. On the base of calculated grades, we determine index of asymmetry using formula (l-d)/(l+d) x 100, and make the curves. Curvilinear of this curve and extent of its declination from 0 suggest on electrophysiological stage of brain. Results: Index of asymmetry in patients with poor long-lasting recovery is more, equal and little bit smaller on control, after two months of rehabilitation in relation to first EEG recording on admission. On the other hand in patients with good long-lasting recovery. Index of assymmetry is reduced.