تاریخچه مختصر تشنج غائب معمولی – بازبینی تشنج پتیت مال A brief history of typical absence seizures — Petit mal revisited

1. Introduction In 1981, the ILAE defined absence seizures as impairment of consciousness with mild clonic, atonic, tonic, or autonomic components [1]. The clinical hallmark of absence seizures is a “blank stare”. In the new ILAE classification, absences are defined ad generalized nonmotor seizures [2], which does not take the full spectrum of clinical phenomena into consideration. Typical absences are associated with generalized spike–wave discharges on electroencephalogram (EEG), and develop in childhood, typically between 4 and 10 years of age, but later ages have been reported [3], and are encountered almost exclusively in idiopathic generalized epileptic syndromes [4]. These seizures usually last 9 to 10 s, and often occur tens or hundreds of times per day. They are easily provoked by hyperventilation [5] and less commonly by photic stimulation, and may be associated with eye opening, eyelid movements, and oral automatisms [6,7]. Brain magnetic resonance imaging of patients with typical absence seizures is normal, and may not be required for the diagnosis in cases with typical electroclinical features. The neurophysiological correlate of typical absence seizures is generalized 2.5 to 5 Hertz (Hz) spike–wave discharges (classically, 3 Hz) with abrupt onset and termination [8], sometimes with higher amplitude over frontal regions [9] on the EEG. The interictal EEG has normal background activity although sometimes short bursts of spike– wave discharges may occur. These characteristic electroclinical features permit to differentiate typical absence seizures from atypical absence seizures or other seizures with impaired consciousness. Depending on the epilepsy in the context of which they appear, typical absence seizures may occur as the only seizure type or together with generalized tonic–clonic seizures or myoclonic seizures. In this article, we have traced back the history of typical absence seizures, from their initial clinical description to the more recent nosological positioning. However, one should be extremely cautious when dealing with historic records on epilepsy. The neurophysiological basis of the disease was discovered only toward the end of the 19th Century, and one had to wait until the 1920’s for the possibility of recording the brain electrical activity of patients with epilepsy by means of the EEG. As reported above, absences are seizure types which can be adequately diagnosed only with an EEG recording showing the characteristic 3-Hz generalized pattern. Consequently, it is possible that historical records referring to “petit mal” or “absences” in the pre-EEG era may have actually referred to nonmotor seizures other than true typical absences or even to nonepileptic events. With this caveat in mind, we have searched the extant scientific literature to report any relevant reference to absence seizures with the final aim of sketching out a short, but comprehensive history of this seizure type. Being aware of the importance of analyzing historical documents as directly as possible, we have reported the most relevant excerpts found in the literature in English translation (made by F. Brigo and E. Trinka; the original French and German texts are reported as supplementary material).