Electrocorticographic characterization of chronic iron-induced epilepsy in rats.

Electrocorticograms were recorded from rats which were unilaterally injected with ferrous chloride solution into the sensorimotor cortex to induce chronic epileptic activity. All of the iron-injected rats showed isolated spikes near the injection site and in the contralateral cortex immediately after the injection. The injection produced 3 kinds of responses in the rats according to the frequency of the isolated spikes. Spike and wave complexes appeared bilaterally approximately 30 days or more after the injection in the rats in which the frequency of the isolated spikes was dominant on the side ipsilateral to the injection site or nearly equal on the two sides. These results suggest that there are at least 2 stages in the development of chronic iron-induced epilepsy.