Generalized Spike and Wave Discharges: A Consideration of Cortical and Subcortical Mechanisms of Their Genesis and Synchronization

Abstract

Generalized spike and wave discharge is one of the most characteristic features of the clinical electroencephalogram. In its classical, regular 3 c/sec form it represents the concomitant of a common form of generalized seizures, the absence attack, which is characterized by a very variable degree of clouding of consciousness and sometimes by minor bilateral motor and autonomic phenomena. No one looking at the electroencephalographic record of such a seizure, be he an expert or a novice, can fail to be impressed by the suddenness with which virtually simultaneously the resting pattern of the electroencephalogram is replaced by high voltage generalized, bilaterally synchronous, rhythmic spike and wave discharge. The cessation of this pattern is equally impressive and so is, often, the symmetry of the waveforms in homologous areas of the hemispheres. Even though the finer analysis of time sequences reveals some lack of perfect synchronization between various areas of the cortex (Petsche 1962), one cannot fail to be impressed by the relative synchronicity of the electrical events. This must imply that a system is being activated which is capable of phase-locking within a relatively narrow range of time-dispersion the discharges of a great number of neurons in widely disparate areas of the brain.