Optimal Duration of Continuous Video-Electroencephalography in Term Infants With Hypoxic-Ischemic Encephalopathy and Therapeutic Hypothermia

Abstract

Continuous video-electroencephalography (EEG) is an important diagnostic and prognostic tool in newborns with hypoxic-ischemic encephalopathy undergoing therapeutic hypothermia. The optimal duration of continuous video-EEG during whole-body hypothermia is not known. We conducted a retrospective study of 35 neonates with hypoxic-ischemic encephalopathy undergoing whole-body hypothermia with continuous video-EEG. EEG ictal changes were detected in 9/35 infants (26%). Of these 9 infants, the seizures were initially observed within 30 minutes of EEG monitoring in 6 (67%), within 24 hours in 2 (22%), and during rewarming in 1 infant (11%). No new seizures were detected between 24-72 hours of therapeutic hypothermia. Background suppression was detected in 14 infants (40%) by 24 hours. In neonates with hypoxic-ischemic encephalopathy undergoing therapeutic hypothermia, continuous video-EEG has the highest diagnostic yield within the first 24 hours and during the rewarming phase. In the absence of prior seizures or antiepileptic therapy, limiting continuous video-EEG to these periods in resource-limited settings may reduce cost during therapeutic hypothermia.

Predictive value of early EEG for seizures in neonates with hypoxic–ischemic encephalopathy undergoing therapeutic hypothermia

“…Seizure onset after 24 h of EEG monitoring is reported in the literature. 5,6,8,17,23,24 Information on EEG background in those cases are scarce, although most reported neonates had severe encephalopathy. Some studies have included in the definition of excessively discontinuous pattern also more severe patterns such as burst-suppression and longer interburst interval.…”

“…This proportion of neonates with normal or mildly abnormal EEG is higher than previously reported in neonates treated with TH. 5,27 Possible explanations include a drift toward cooling neonates with milder encephalopathy as described in other cohorts, 28,29 earlier recognition of encephalopathy, and faster implementation of cooling leading to the possibility that, by the time EEG is started, the brain activity has already improved in some neonates. Furthermore, our definition of excessively discontinuous background encompasses a wide range of interburst intervals (up to 15 s).…”

“…1 It is now a widely used treatment that has been shown to be both safe and effective in improving neuro-developmental outcome. 2 Seizures are common in neonates with hypoxic-ischemic encephalopathy (HIE) [3][4][5][6] and are associated with short-and long-term unfavorable developmental outcomes 7 and an increased risk of moderate to severe injury on magnetic resonance imaging (MRI). 8,9 Conventional electroencephalography (cEEG) monitoring is the gold standard for evaluating brain function and for recording seizures.…”

“…4,6 However, neonates with seizures during rewarming have been described, 6,8,[15][16][17] prompting many neonatal units to monitor neonates undergoing TH for the entire duration of cooling and rewarming. 4,5,18 This appears to be the current clinical practice in centers using cEEG to monitor neonates undergoing TH.…”

Predictors of Long-Term Neurodevelopmental Outcome of Hypoxic-Ischemic Encephalopathy Treated with Therapeutic Hypothermia

“…This resulted in adaptation of cvEEG, which allows evaluation of the site of onset and propagation of seizures along with information on background activity, having the highest diagnostic yield within the first 24 hours and during the rewarming phase. 76,77 A combination of abnormal neurological exam and EEG traits can help decide on the likelihood of seizures and length of cvEEG recording needed. In the absence of seizures or antiseizure medication, cvEEG can be limited to these periods, making it more cost-effective.…”