Utility of wide band EEG (HFO)

Abstract

High-frequency oscillations (HFOs) are defined as electroencephalographic activity at frequencies over 80 Hz. To record HFOs, a sampling frequency at or above 2 kHz and anti-alias filtering at or above 600 Hz is recommended. HFOs can be recorded using clinical macroelectrodes. Visual identification of HFOs can be achieved by high-pass filtering, increasing sensitivity, and temporally expanding the electroencephalogram (EEG). Interictal HFOs in intracranial EEGs suggest the localization of the seizure onset zone and epileptogenic zone. Ictal-onset HFOs in intracranial EEGs may be helpful in improving seizure outcome after epilepsy surgery. Epileptic encephalopathies in children show many interictal HFOs in scalp EEGs, and these HFOs may contribute to the development of cognitive deficits in this condition. Clues for differentiating pathological HFOs from physiological HFOs include the presence or absence of accompanying spikes, a different coupling pattern with slow waves, and different suppression patterns during rapid-eye-movement sleep.