Absence seizures (AS) are generalized non-motor seizures characterized by sudden and brief loss of consciousness, without voluntary movements, accompanied by generalized spike-wave discharges (GSWDs) on EEG. According to the ILAE classification, AS are subdivided into typical and atypical, with the addition of absence with eyelid myoclonia and myoclonic absence in the operational classification of 2017 [1], [2], [3].

Dramatic differences in terms of comorbidity and prognosis exist between typical and atypical absences depending on underlying syndromes, with atypical absences, mostly occurring in developmental epileptic encephalopathies (DEEs), generally considered as intractable. On the other hand, typical absence seizures and underlying idiopathic generalized epilepsies (IGE) have long been considered to have a relatively good outcome, although a considerable proportion of patients may continue to experience AS, whether or not associated with other seizure types.

In the context of IGE, except for childhood absence epilepsy (CAE), refractory AS in adolescence/adulthood receive relatively little attention from the epileptology community, with research and improvement efforts focusing more on generalized tonic-clonic seizures (GTCS) and myoclonic seizures causing falls. Besides, epidemiological data on the prognosis of AS and the outcome of IGE may be undermined by possible misdiagnoses due to the indistinct boundaries between IGE syndromes.

In the context of DEEs and notably in Lennox-Gastaut syndrome (LGS) atypical absences may be underestimated compared with other more spectacular seizures, such as atonic, tonic or GTC seizures, because they are sometimes difficult to identify in patients with a varying degree of cognitive impairment.

Between these two extremes of generalized epilepsy represented by EGI and the LGS, some patients exhibit atypical electroclinical features that are on borderline between idiopathic syndromes and more severe conditions, sometimes described as “intermediate” forms of generalized epilepsy [4], [5]. Interestingly, drug resistance in patients with IGE has been associated with EEG features typical of LGS [5], [6], [7], [8]. Consistently, human and animal studies have demonstrated substantial overlap in terms of brain networks generating GSWD associated with typical and atypical AS [9], [10], [11], [12], [13].

Finally, whatever AS are typical or atypical and independent of the underlying syndrome, pharmacological treatment of AS is rather limited, and evidence supporting polytreatment and use of new antiseizure medications (ASMs) as well as neuromodulation therapies is lacking.

Here we aim to review the pathophysiological mechanisms of AS, to provide a concise overview of the electroclinical spectrum of AS in adolescence and adulthood, to describe the electroclinical features associated with drug resistance in IGE, and finally to discuss the therapeutic arsenal, including new ASMs and neurostimulation. Particular emphasis will be placed on discussing the link between pathophysiological mechanisms underlying AS and deep brain stimulation targets.