<p>Focal cerebral ischemia, resulting from reduced oxygenated blood flow to specific brain areas, leads to localized brain tissue damage. Non-linear electroencephalogram (EEG) methods for assessing ischemic injury are underexplored, prompting this study to examine chaotic alterations in EEG activity across the frontoparietal, occipital, and temporal lobes in three groups: healthy rats, rats with induced ischemia, and ischemic rats treated with the piroxicam drug. Chaotic variations across the delta, theta, alpha, beta, and gamma EEG sub-bands were assessed at three experimental stages. Piroxicam was found to provide greater protection against ischemic damage in the occipital lobe compared to other regions. The theta EEG band exhibited the highest sensitivity to ischemic injury. Approximate entropy and the largest Lyapunov exponent proved to be more reliable indicators of EEG sub-band chaos than the correlation dimension for evaluating cerebral ischemic damage. These findings suggest the potential of applying chaos theory in EEG analysis to aid neurosurgeons in detecting ischemic brain damage.</p>