Role of inhibitory mechanisms in staring spells

Phenomena of a negative nature--a motionless stare with arrest of mental activity--characterize absence seizures and some complex partial seizures. In agreement with this clinical observation, it has been found that the slow waves of the spike-wave complex are associated with inhibitory postsynaptic potentials and cessation of neuron firing in both humans and experimental animals. Gamma-aminobutyric acid (GABA) concentration is increased in the cerebral cortex in some experimental models of spike-wave discharge, and GABA agonists exacerbate spike-wave discharges in a variety of experimental models. GABAergic neurons and terminals are also increased in the hippocampus of seizure-sensitive gerbils, and kindling of the hippocampus and amygdala appears to enhance GABAergic inhibitory mechanisms. Antiabsence drugs selectively depress inhibitory pathways in the central nervous system, providing further evidence in support of the hypothesis that absences represent inhibitory paroxysms. Antiabsence drugs also appear to be useful adjunctive drugs in the treatment of complex partial seizures associated with spike-wave discharges, suggesting that here too inhibitory mechanisms may play a prominent role. All these clinical, physiological, and pharmacological observations would indicate that staring spells represent inhibitory seizures, occurring primarily in absences and secondarily in some complex partial seizures.