Benign Rolandic epilepsy: widespread increases in connectivity in a focal epilepsy syndrome

Benign Rolandic epilepsy (benign epilepsy with centrotemporal spikes; recently renamed self-limited epilepsy with centrotemporal spikes) is associated with widespread deficits in cognition and behavior, suggesting abnormalities in networks that extend beyond the centrotemporal region. To assess functional connectivity in children with benign Rolandic epilepsy, we assessed EEG spectral power and coherence during awake and sleep records in 27 children with centrotemporal spikes. Coherence represents the consistency of the phase difference between two EEG signals when compared over time and serves as a measure of synchronization between two EEG signals based mainly on phase consistency. Epochs of EEG with and without centrotemporal spikes were compared during both waking and sleep. During the spike epochs, there was an increase in spectral power at all frequencies, although statistical significance was seen primarily in the delta, theta and alpha bandwidths. This increase in absolute power was seen at all electrode sites and was similar in left and right-sided electrodes. During centrotemporal spikes, there were significant changes in coherence compared to the EEG segments without spikes. In the theta, alpha and beta bandwidths, there were significant increases in coherence. The increases in coherences were widespread and bilateral, and involved electrode pairs outside the central and temporal regions. To determine if there was a relationship between location of the spikes and coherence values, right-sided, left-sided and bilateral centrotemporal spikes were compared. There was no relationship between location of the centrotemporal spikes and power or coherence values. These findings indicate that benign Rolandic epilepsy results in generalized changes in spectral power and connectivity and raises the suggestion that from a functional standpoint, benign Rolandic epilepsy resembles a generalized rather than focal seizure disorder.