PANCE Neurology Practice Test

Absence seizures are defined by brief lapses of consciousness with abrupt onset and quick recovery. On EEG, they show a generalized, bilaterally synchronous spike-and-wave pattern at about 3 Hz. This 3 Hz generalized spike-and-wave reflects synchronized thalamocortical network activity that momentarily disrupts widespread cortical function, which matches the clinical brief impairment seen during absence spells.

Other patterns don’t fit absence. Focal sharp waves in the temporal lobe point to focal epilepsy and focal onset, not generalized involvement. Theta rhythm without spikes is a slower, non-ictal pattern seen with drowsiness or normal sleep states. Delta waves in occipital regions aren’t the hallmark of absence and can be seen in other conditions or age-related EEG variants.