Factors influencing seizure induction in patients with intracranial EEG recording

To shorten inpatient epilepsy monitoring unit (EMU) stays during epilepsy surgery evaluation, physicians utilize techniques to induce seizures including antiseizure medication (ASM) reduction, sleep deprivation, and chemical stimulation. We assessed the relative efficacy of these techniques.

We reviewed data from patients admitted for intracranial video-EEG (electroencephalography) evaluation at a single center. Demographics, baseline seizure frequency, seizure type, sleep deprivation, reduction in ASM, chemical stimulation method, and seizures were recorded. Statistical analyses were performed in R with survival analyses.

A total of 209 patients were evaluated. We observed an increase in the risk of seizure occurrence of 1% for every increase of one seizure per week of baseline seizure frequency (confidence interval [CI] = 1.00-1.02, p = .009). Complete cessation of both sodium channel and non-sodium channel ASMs increase the rate of seizure occurrence (CI = 1.46-2.08, p < .0001 and CI = 1.28-1.80, p < .0001, respectively). A partial reduction in sodium channel drugs within 24 h of admission or previous seizure in the EMU increased seizure risk by 40% (CI = 1.18-1.72, p = .0002). For each seizure occurring during admission, the risk of seizure recurrence increased by 5% (CI = 1.03-1.08, p < .0001). Patients with temporal lobe epilepsy exhibited a 19% lower risk of seizures within the initial 24 h of admission than patients with extratemporal seizures (CI = .68-.97, p = .02). Neither chemical stimulation nor sleep deprivation impacted seizure risk.

We found that ASM reduction was the only method that effectively induced seizures in hospitalized patients; sleep deprivation and chemical induction failed to do so. Prospective studies are needed to further understand these induction methods.