Typical Absence Seizures and Related Epilepsy Syndromes

Abstract

Typical absence (TA) seizures are brief generalized seizures of abrupt onset and termination characterized by loss of awareness with subtle motor features. The EEG reveals bilateral, synchronous, symmetrical 3 to 4 Hz spike-wave discharges on a normal background. They usually start in childhood or adolescence, but occur in around 15% of adults with seizures. Four main theories on the pathophysiology of TA seizures have been proposed: centrencephalic theory, thalamic clock theory, cortical theory, and corticoreticular theory. More recently, it has been suggested that the cortical focus theory of TA seziures bridges cortical and thalamic theories. The mechanisms underlying the generalized spike-wave discharges that characterize this seizure appears to involve thalamocortical circuitry which has been studied extensively in the generation of sleep spindles. TA seizures may be seen in a number of genetic generalized epilepsy/idiopathic generalized epilepsy syndromes which have different prognosis and outcomes. Their clinical and EEG manifestations are syndrome-related. For treatment, valproic acid, ethosuximide and lamotrigine are first-line medications.

Keywords

• electroencephalography
• epilepsy
• genetic generalised epilepsy
• idiopathic generalised epilepsies
• typical absence seizures