Studies on quantitative beta activity in EEG background changes produced by intravenous diazepam in epilepsy.

This article deals with the further systematic investigation of the effects of diazepam on quantitative beta activity in EEG background activity, and the determination of the affecting factors concerned. Diazepam (0.1-0.03 mg/kg) was injected intravenously, the percentage of diazepam-induced changes in beta activity (PDICB) over the 8 sites of scalp EEG recordings was quantitatively analyzed using spectral analysis. The affecting factors concerned were also explored by univariate and multivariate statistical analysis in 84 cases of epilepsy. The results showed that the mean PDICB value in epileptic patients (4.49 +/- 4.51) was significantly lower than that in normal controls (8.03 +/- 5.55). In patients with slowing of EEG background pre-diazepam, AED treatment, long duration of receiving AEDs, refractory epilepsy and brain structural damage, the PDICB value was statistically significantly reduced. The mean PDICB values were lower in the patients with CPS, GTCS, etiologic factors, or paroxysmal discharges on the pre-drug EEG recordings, and the PDICB tended toward decrease with advancing disease duration and seizure frequency; however, these trends did not reach statistical significance. Besides the PDICB values also did not statistically correlate with sex, age and age at seizure onset. In multi-variate analysis with a stepwise regression model, it was found that slowing of EEG background and AED treatment were independently and negatively associated with the decreased PDICB. These results suggest that a reduction of beta activity induced by diazepam, which may involve the whole brain besides the epileptogenic lesion, is significantly related not only to cerebral function impairment of structural changes due to the epileptic process, but also to AED interactions or synergistic effects.