Spike-and-wave

Spike-and-wave is the term that describes a particular pattern of the electroencephalogram (EEG) typically observed during epileptic seizures. A spike-and-wave discharge is a regular, symmetrical, generalized EEG pattern seen particularly during absence epilepsy, also known as ‘petit mal’ epilepsy. The basic mechanisms underlying these patterns are complex and involve part of the cerebral cortex, the thalamocortical network, and intrinsic neuronal mechanisms. The first spike-and-wave pattern was recorded in the early twentieth century by Hans Berger. Many aspects of the pattern are still being researched and discovered, and still many aspects are uncertain. The spike-and-wave pattern is most commonly researched in absence epilepsy, but is common in several epilepsies such as Lennox-Gastaut syndrome (LGS) and Ohtahara syndrome. Anti-epileptic drugs (AEDs) are commonly prescribed to treat epileptic seizures, and new ones are being discovered with less adverse effects. Today, most of the research is focused on the origin of the generalized bilateral spike-and-wave discharge. One proposal suggests that a thalamocortical (TC) loop is involved in the initiation spike-and-wave oscillations. Although there are several theories, the use of animal models has provided new insight on spike-and-wave discharge in humans.

History of generalized epilepsy with absence seizures are dated to the eighteenth century, however the inventor of the electroencephalogram (EEG), Hans Berger, recorded the first EEG of an absence seizure in the 1920s, which led the way for the general notion of spike-and-wave electrophysiology. His first recording of a human EEG was made in 1924 using a galvanometer, but his results were very crude and showed small, undefined oscillations. He continued to refine his technique and increase the sensitivity to the galvanometer, in which he accumulated many EEGs of individuals with and without a brain malfunction or disorder. Among those tested were patients with epilepsy, dementia, and brain tumors. Hans Berger published his findings in 1933, however his results did not give a definitive characterization of the general EEG pattern seen during an epileptic seizure. In 1935, F.A. Gibbs, H. Davis, and W.G. Lennox provided a clear description of EEG spike-and-wave patterns during a petit mal epileptic seizure. An intracellular recording performed by DA Pollen in 1964 revealed that the "spike" aspect of the phenomenon was associated with neuronal firing and the "wave" aspect was associated with hyperpolarization.

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