Anti-seizure medication tapering correlates with daytime delta band power reduction in the cortex

TL;DR

This study shows that tapering anti-seizure medications leads to a significant reduction in daytime delta band power in the cortex, with effects depending on medication levels and independent of epilepsy type or brain region.

Contribution

It provides the first detailed, dose-dependent analysis of how ASM tapering affects cortical delta activity using intracranial EEG data.

Findings

Delta power decreases during medication withdrawal

Degree of withdrawal correlates with delta power reduction

Effects are specific to daytime cortical regions

Abstract

Anti-seizure medications (ASMs) are the primary treatment for epilepsy, yet medication tapering effects have not been investigated in a dose, region, and time-dependent manner, despite their potential impact on research and clinical practice. We examined over 3000 hours of intracranial EEG recordings in 32 subjects during long-term monitoring, of which 22 underwent concurrent ASM tapering. We estimated ASM plasma levels based on known pharmaco-kinetics of all the major ASM types. We found an overall decrease in the power of delta band activity around the period of maximum medication withdrawal in most (80%) subjects, independent of their epilepsy type or medication combination. The degree of withdrawal correlated positively with the magnitude of delta power decrease. This dose-dependent effect was evident across all recorded cortical regions during daytime; but not in sub-cortical regions, or during night time. We found no evidence of a differential effect in seizure onset, spiking, or pathological brain regions. The finding of decreased delta band power during ASM tapering agrees with previous literature. Our observed dose-dependent effect indicates that monitoring ASM levels in cortical regions may be feasible for applications such as medication reminder systems, or closed-loop ASM delivery systems. ASMs are also used in other neurological and psychiatric conditions, making our findings relevant to a general neuroscience and neurology audience.