Supplementary Material for: Seizure Burden Before and After Lidocaine as Add-on Therapy in (a)EEG-Confirmed Neonatal Seizures

Introduction
The primary aim of this study was to evaluate the total seizure burden (TSB) and maximum hourly seizure burden (MSB) before and after the administration of lidocaine (LDC) as add-on therapy in neonates with amplitude-integrated electroencephalography (aEEG)-confirmed seizures. Secondary aims were documenting the need for additional ASM at 4, 12, and 24 hours after LDC, and the rate of seizure freedom for at least 24, 48, and 72 hours after LDC.

Methods
This single-center, retrospective cohort study included neonates with persistent seizures after phenobarbital who received add-on LDC therapy. Neonates were monitored with a continuous 2-channel aEEG. The TSB and MSB were calculated using raw EEG data collected 4 hours before and after the administration of LDC.

Results
Sixty-one neonates were included. Seizure etiology consisted of hypoxic-ischemic encephalopathy (n=24), hemorrhagic or ischemic stroke (n=16), central nervous system infection (n=7), genetic (n=8), metabolic disorders (n=4), and unknown etiology (n=2). After LDC administration, median TSB decreased significantly from 31 (interquartile range, IQR 16–68) to 0 minutes (IQR 0–0, p<0.01), and MSB from 10 (IQR 6–41) to 0 min/hour (IQR 0–0, p<0.01). The need for additional ASM was 3% (2/61) within 4h and 41% (25/61) within 24h. Seizure freedom after LDC was achieved in 71% (42/59) for at least 24h and 52% (29/56) for 72h.

Discussion
LDC significantly reduced TSB and MSB in neonates with (a)EEG-confirmed seizures, achieving 100% seizure reduction in the majority, with half of the neonates remaining seizure-free for at least 72 hours.