Transition from cortical slow oscillations of sleep to spike-wave seizures

Abstract

In cats, spike-wave (SW) seizures have been observed to emerge from cortical slow oscillations (CSOs) and spindles in sleep. We examined a patient's generalized SW seizures that appeared to emerge from CSOs in sleep. Dense array (256-channel) electroencephalographic (dEEG) data were recorded during long-term monitoring for localizing seizure onset for neurosurgical planning. CSOs were identified on the basis of topographic criteria from dEEG studies of normal human sleep. SW discharges were identified in the surface dEEG and examined with distributed linear inverse neural source estimation. This patient's SW discharges appeared to emerge from a series of CSOs that engaged the left frontal pole. Furthermore, 12Hz sleep spindles in this patient were often synchronized in time with the CSOs, and in some instances they shared a similar localization over the left frontal pole at the point of seizure onset. The initial discharges of each seizure engaged both the left frontal pole, which was the primary neural source of this patient's CSOs, and the left temporal lobe, which seemed critical for the evolution of this patient's seizures. The correlation of SW seizures with CSOs in animal studies may be observed in humans as well, providing clues to the pathology of arousal regulation in some cases of nocturnal epilepsy.