Typical absence seizures (TAS) occur in idiopathic generalized epilepsy (IGE) syndromes and are a common presentation to paediatric neurologists. Considerable overlap in clinical features of IGE syndromes comprising TAS often complicates prognostication. Clinical and EEG diagnostic features in TAS are well known. However, knowledge of prognostic features for each syndrome, whether clinical or EEG-related, is less clear. Perpetuated impressions in clinical practice regarding the role of EEG when used for prognostication in TAS are known. Assumed prognostic features, particularly those relating to EEG have been rarely studied systematically. Despite rapid expansion in epilepsy genetics, the complex and presumed polygenic inheritance of IGE, means that clinical and EEG features are likely to remain the main guide to management and prognostication of TAS for the foreseeable future. We comprehensively reviewed available literature and hereby summarize current knowledge of clinical and EEG characteristics (ictal and interictal) in children with TAS. The literature focuses predominantly on ictal EEG. Where studied, interictal findings reported relate to focal discharges, polyspike discharges, and occipital intermittent rhythmic delta activity, with generalized interictal discharges not thoroughly studied. Furthermore, reported prognostic implications of EEG findings are often conflicting. Limitations of available literature include inconsistent clinical syndrome and EEG finding definitions, and variable EEG analysis methods, particularly lack of raw EEG data analysis. These conflicting findings coupled with varying study methodologies cause lack of clear information or evidence on features which may influence treatment response, outcome, or natural history of TAS.
Keywords: Ictal EEG, Idiopathic generalised epilepsy; Interictal EEG; Typical absence seizures.
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