Co-occurrence of childhood absence epilepsy and self-limited focal epilepsy interictal discharges: Differences from childhood absence epilepsy alone.

Objective: Some children with Childhood Absence Epilepsy (CAE) exhibit focal abnormalities similar to those observed in Self-Limited Focal Epilepsies of Childhood (SeLFEs). It remains unclear whether this subgroup of patients may present distinct clinical characteristics or prognoses compared to those with CAE and generalized discharges alone. In this study, we retrospectively evaluated the electroclinical features of patients with CAE plus focal abnormalities and compared them with those with CAE lacking focal abnormalities.

Methods: We included children diagnosed with absence epilepsy with onset before the age of 10 years and normal neuropsychomotor development prior to seizure onset. These patients were evaluated and followed up at our Institute between January 2013 and January 2023.

Results: Fifteen out of 100 patients with CAE (15%) exhibited focal epileptiform abnormalities characteristic of SeLFEs. In 6 cases (40%), focal interictal epileptiform discharges (IEDs) emerged only after the resolution of absences during routine electroencephalograms (EEGs), while in 9 cases (60%), they occurred concurrently with generalized discharges in the same EEG. Three patients experienced clinical seizures associated with both syndromes, and one of them displayed during the same recording a focal seizure immediately followed by an absence seizure. Patients with both generalized and focal epileptiform abnormalities (CAE plus SeLFE-IEDs/SeLFEs) showed similar outcomes compared to those with generalized abnormalities alone, but they had an earlier age at absence onset (4.3 years vs. 5.7 years, p = 0.03), an increased occurrence of automatisms during absence seizures (50% vs. 17.5%, p = 0.02), and required a higher number of antiepileptic drugs to control absences (average 2.1 vs. 1.4, p = 0.002).

Conclusions: CAE and SeLFEs share several features, and their coexistence or sequential evolution in clinical practice is not uncommon. This overlap may suggest common pathophysiological mechanisms involving cortico-thalamo-cortical circuits.