[Topographic changes in cerebral electric activity after premedication with flunitrazepam].

AIM

The effects on cerebral function of premedication with the benzodiazepine flunitrazepam and with morphine were studied on the evening of the preoperative day (2 mg flunitrazepam p.o.) and 90 minutes before induction of anaesthesia (2 mg flunitrazepam plus 15 mg morphine i.m.).

DESIGN

The EEG was analysed topographically (17 electrodes) and quantitatively.

RESULTS

As a typical effect of benzodiazepines, increases in electrical activity in the frequency band beta-1 of the power spectrum were observed, and could be demonstrated 10 minutes after oral application, mainly in the frontal and central parts of the cortex. Increases in the powerbands delta and theta indicated induction of sleep approximately 15-20 minutes after application and were not looked upon as an effect of the benzodiazepine exclusively. These increases were noticed first in the central, occipital and temporal areas and after 30 minutes in the frontal parts of the cortex. Flunitrazepam plus morphine showed qualitatively similar but quantitatively less pronounced results. Topographical differences were similar to the results of an application of flunitrazepam alone.

DISCUSSION

The results demonstrate the importance of a topographical as well as quantitative evaluation in studies on complex interactions of sedative or narcotic drugs and their clinical effects on cerebral function.