Withdrawal seizures vs on-medication seizures: an intracranial EEG recording case report

Abstract

BackgroundIt has long been an interesting question of whether withdrawal seizures in epileptic patients differ from habitual seizures in terms of semiology and electrophysiology.Case presentationHere, we addressed this issue in a 40 year-old woman with drug-resistant focal epilepsy monitored by presurgical intracranial EEG. As a part of this routine pre-operative investigation, anti-seizure medications (ASMs) were halted; as a result, multiple withdrawal seizures were recorded before ASM readministration. During 4 days of invasive monitoring, we noticed three different phases in seizure organization: Acute withdrawal seizure (AWS): The first recorded seizure 10h after the implantation; the stabilized withdrawal seizures (SWS): seven habitual seizures recorded from 24h post implantation to readministration of ASMs; and the Non-withdrawal seizures (NWS): ten seizures recorded 24h after readministration of ASMs. AWS and SWS had the same semiology and same epileptic network, but the propagation time from the temporal pole to the para-hippocampal gyrus (PHG) and hippocampus ranged from no latency in AWS to up to 50 s in SWS. NWS were electrographic seizures, without any apparent clinical manifestation. Seizure onset in this type of seizure, as in the first two types, was in the temporal pole. However, NWS could last up to 3 min without involving the PHG or hippocampus.ConclusionsWe concluded that in acute withdrawal seizures the propagation time of epileptic activity is significantly reduced without affecting ictal organization network or semiology. Furthermore, ASM in this case had a remarkable influence on propagation rather than initiation of epileptic activity.