Introduction from Dr Markus Reuber, editor-in-chief of Seizure
Electrographic seizures are frequent in critically ill neonates . In one of the most common conditions in the neonatal intensive care unit – hypoxic ischemic encephalopathy – seizures occur in approximately 30-60% of patients. Most electrographic seizures occur in high-risk populations such as patients with hypoxic-ischemic encephalopathy, stroke, cardiac surgery, extracorporeal membrane oxygenation or meningitis, but seizures can also occur in other neurologic and systemic conditions. Many neonatal seizures present with subtle or no clinical signs . Only the recent widespread use of continuous electro-encephalographic (cEEG) monitoring has revealed the burden of electrographic seizures in critically ill patients.
In the USA, cEEG monitoring is growing exponentially at an approximate pace of 30% per year in both, adults and children. Further, this increase in cEEG use is likely to continue: a survey of 137 intensivists and neurophysiologists from 97 ICUs in the USA showed that, in an ideal situation with unlimited resources, respondents would monitor 10-30% of their patients (depending on the specific indication for cEEG) and 18% of respondents would increase cEEG duration . It is currently unknown whether electrographic seizures independently damage the brain or whether they are merely biomarkers of a worse underlying brain injury that is not going to improve with antiepileptic drug treatment. However, a growing body of literature demonstrates that electrographic seizure burden is independently associated with worse outcomes and suggests that electrographic seizures independently contribute to brain damage. If we assume that electrographic seizures are damaging the brain and antiepileptic drug stop seizures and improve outcomes, then we would not want to miss electrographic seizures.
Unfortunately, cEEG monitoring requires significant investment in equipment and personnel. The more frequent and more prolonged use of cEEG would therefore have very significant resource implications and may not be feasible in less well-resourced healthcare systems. This consideration has increased interest in amplitude-integrated EEG (aEEG), as a simpler and cheaper alternative to cEEG. aEEG uses a much more limited montage – typically 2-4 electrodes – and can be applied and interpreted by healthcare professionals with little specialist knowledge of EEG patterns.
In our editor’s choice from this issue of Seizure, Rakshasbhuvankar et al. provide a systematic review on the diagnostic efficacy of aEEG compared with the current gold standard of cEEG . They show that aEEG yields highly variable sensitivities and specificities and therefore cannot be recommended as the mainstay for the diagnosis and management of neonatal seizures at present. However, aEEG is a very good screening tool that identifies neonates who need a cEEG: those with EEG backgrounds associated with a high risk for seizures and those with seizures suspected on aEEG. (By Ivan Sanchez Fernandez & Tobias Loddenkemper, read full editorial in this issue of Seizure).
 Abend NS, Wusthoff CJ, Goldberg EM, Dlugos DJ. Electrographic seizures and status epilepticus in critically ill children and neonates with encephalopathy. Lancet Neurol 2013;12:1170-9.
 Nash KB, Bonifacio SL, Glass HC, Sullivan JE, Barkovich AJ, Ferriero DM et al. Video-EEG monitoring in newborns with hypoxic-ischemic encephalophathy treated with hypothermia. Neurology 2011;76: 556–62.
 Gavvala J, Abend N, La Roche S, Hahn C, Herman ST, Claassen J et al. Continuous EEG monitoring: a survey of neurophysiologists and neurointensivists. Epilepsia 2014;55:1864-71.
 Rakshasbhuvankar et al. Amplitude integrated EEG for detection of neonatal seizures: a systematic review. Seizure 2015;33:90-98.