The EEG in BRE shows normal background activity with frequent spikes in the centrotemporal regions. See the image below of an EEG showing these typical spikes.

Unlike other forms of partial epilepsies, brief focal slowing in BRE appears only in the region of extremely frequent spiking. Discharges characteristic of epilepsy (spikes, spikes followed by slow waves, and sharp waves) may appear on one side of the brain or both sides. The discharges on the two sides can be either independent or synchronized. They may extend beyond the centrotemporal regions.

Although the spike on the EEG appears in the centrotemporal area, the temporal lobe is not the generator of BRE spikes. Rather, they are generated in the base of the rolandic fissure.

There is no correlation between seizure frequency, spikes between seizures, and treatment response. A child can be seizure-free for a long period despite the presence of extremely frequent spikes. Spikes are usually of high voltage and are most commonly seen during drowsiness and non-REM sleep. They are not activated by hyperventilation (unlike absence epilepsy).