Neurotoxicity of nonionic iodinated water-soluble contrast media in myelography: experimental study

The neurotoxicity of four contrast media--iotrol, iopamidol, metrizamide, and ioglunide--was studied by subarachnoid injection in 14 rabbits implanted with four cerebral electrodes. Thirty-four recordings and quantitative analyses were carried out of spontaneous electrical brain activity, seizure activity, and visual- and somatosensory-evoked potentials. The quantitative study of the electroencephalograms showed differences among the four products. All four of the contrast media induced a general slowing of the electroencephalographic activity and, 30 min after injection, slow waves and a shift of the spectrum energy toward the slow frequencies (0.5-3.5 Hz). The slowing of the recording was the least marked with iotrol and recovery of a normal recording was also quickest with iotrol. The quantitative study of electrical seizures and paroxysms revealed higher seizure activity with ioglunide and iopamidol. The study of the evoked potentials does not permit any distinction among the four contrast agents. Metrizamide induced the fewest seizures, but, considering the slow waves and the seizures, iotrol appears to be the least neurotoxic.