Interstitial white matter brain oedema does not alter the electroencephalogram.

An experimental study was performed to determine the effects of interstitial white mater oedema on the electroencephalogram (EEG). Using both rodent and feline infusion models of focal brain oedema no difference was found between the EEG waveforms recorded epidurally from the infused and control hemispheres. It is concluded that where focal slow-wave EEG abnormalities overlie oedematous brain the EEG abnormalities are not primarily related to the brain oedema but arise from either local biomechanical or other pathophysiological mechanisms.