Spectral analysis of Lapine EEG: neurotoxicologic evaluation of new nonionic contrast media.

Effects of the injection of 0.25 ml of nonionic radiocontrast media (280 mg I/ml) and/or istonic and/or hypertonic mannitol into the subarachnoid space on the low frequencies (2--5 Hz) of the EEG were studied in nonanesthetized, curarized rabbits. Compared to the noninjected controls, mannitol did not cause any significant EEG spectrum shifts. P-297 and iopamidol caused a slight decrease in the energy content of the 2--5-Hz band, while DS-1-132 and the nonionic dimer ZK 32347 caused a moderate increase. Since an increase in the slow-wave component of the EEG indicates a pacemaking activity, while a decrease indicates stimulation or irritation, none of the tested nonionic media appear to be biological inert. In this test P-297, iopamidol, and DS-1-132 caused fewer disturbances than metrizamide.