Patterns of intrahemispheric propagation in pediatric photoparoxysmal response

Abstract

A symmetric, bilateral pattern is the most common type of PPR across genders and all ages, regardless of grade of PS and the presence of epilepsy. The results of this study show the current PPR classification in a new light and provide a basis for the concept of PPR lateralization based on objective, quantitative findings.

Symmetry and interhemispheric propagation of paediatric photoparoxysmal response

“…Power spectra and coherence values have been studied in certain neurological entities [9,10], but to date not a single description has concerned PPR. In our previous paper [2], several differences in amplitude values over left and right hemispheres were recorded, but none of the possible associations of that observation could have been matched to the purpose of that work.…”

“…In PS patients, an individual pattern of PPR propagation was established for every patient, according to the protocol described in our previous paper [2]. The PPR propagation pattern was based on amplitudes and characterised dominant tracks in the left and right cerebral hemispheres.…”

“…While our previous paper considered possible pathways of propagation of the PPR within one hemisphere [2], in the present study we have focused on a direct comparison of the response to IPS in both cerebral hemispheres. For the purpose of analysis, we adopted the hypothesis that the discharge begins in occipital areas and usually spreads forwards.…”

“…In this part of the analysis, the PPR group was divided into two subgroups: patients with symmetric dominant tracks (n = 24, 48% of the PPR group), and patients with asymmetric dominant tracks (n = 26; 52% of the PPR group). The dominance of tracks was established using the method described in our previous paper [2]. Every lead at the course of a discharge was analysed and compared to the respective contralateral one.…”

“…Our previous study [2] drew attention to the internal differentiation of the route from the occipital to frontal areas, not disparaging the Waltz classification, but adding a quantitative element to the pattern of the propagation within the hemisphere. The PPR, like other pathological discharges, reveals some predilection for a particular pathway, which probably has an anatomical or functional background [3,4].…”