Analysis of spatio‐temporal propagation of occipito‐frontal spikes in childhood epilepsies by 3D sequential voltage mapping and dipole localization

Abstract

AbstractObjectiveWe sought to study the spatio‐temporal propagation of occipito‐frontal spikes in childhood epilepsies by voltage mapping and dipole localization and identify types of occipito‐frontal spikes based on onset, propagation, and stability of their dipoles.MethodsSleep EEG data of children, aged 1–14 years, with a minimum 1 h of recording from June 2018 to June 2021, were analyzed to identify occipito‐frontal spikes. In total, 150 successive occipito‐frontal spikes were manually selected from each EEG and using a source localization software were averaged using automated pattern matching with a threshold of 80%, and sequential 3D voltage maps of averaged spike were analyzed. Stability quotient (SQ) was calculated as the total number of averages/150. Stable dipole was defined as SQ ≥ .8. Dipole analysis was performed with principal component analysis using an age‐appropriate template head model.ResultsTen children with occipito‐frontal spikes were identified; five with self‐limited epilepsy with autonomic seizures (SeLEAS) and five with non‐SeLEAS epilepsies. Three types of occipito‐frontal spikes were identified: (1) narrow occipito‐frontal spikes with stable dipoles seen in all five children with SeLEAS which were “apparently” synchronous and bilateral clone‐like with an occipito‐frontal interval of 10–30 ms and a homogeneous propagation pattern from a unilateral medial parieto‐occipital region to an ipsilateral mesial frontal region; (2) wide occipito‐frontal spikes with stable dipoles seen in one child with non‐SeLEAS and developmental and/or epileptic encephalopathy with spike–wave activation in sleep (D/EE‐SWAS) with an occipito‐frontal interval of 45 ms, caused by focal spike propagation from a deeper temporal focus to ipsilateral peri‐rolandic cortex; and (3) wide occipito‐frontal spikes with unstable dipoles seen in four children with non‐SeLEAS lesional epilepsies with an occipito‐frontal latency of >50 ms and heterogeneous propagation patterns with poor intra‐individual dipole stability.SignificanceWe successfully identified different types of occipito‐frontal spikes in childhood epilepsies. Although the term “occipito‐frontal” is used to describe these spikes on the 10–20 EEG system, true propagation from occipital to frontal regions is not necessary. It is possible to differentiate idiopathic from symptomatic cases by analyzing the stability quotient and the occipito‐frontal interval of occipito‐frontal spikes.