Abstracts

Rationale: Neonatal encephalopathy is a heterogeneous condition caused by several disorders impairing central nervous system function. Therapeutic hypothermia is beneficial as it reduces mortality and disability in survivors. Amplitude-integrated electroencephalography (aEEG) is available in many Neonatal ICUs (NICUs); it is an easily applied tool that assesses brain function by the neonatologist. It can show seizure activity and predicts adverse outcomes if it remains severely abnormal 48 hours into therapy. Patients with hypoxic-ischemic encephalopathy are at increased risk for seizures, which are subclinical in almost 50% of the cases, making neuromonitoring an utmost for adequate management.

Methods: The aEEG uses simplified cerebral function monitoring, emphasizing EEG amplitude differences, whereas continuous video-EEG (VEEG) provides a high-resolution picture of cerebral electrical activity. The aEEG electrodes are placed on the left and right parietal regions overlying the apex of vascular watershed regions of the brain, the adequate location for detecting abnormalities caused by brain hypoperfusion. The tracing is shown on a highly compressed time scale at a rate of 6 cm/hour, and its interpretation depends on the background activity (bandwidth) difference. Normal margins for term infants are > 5 mV for the lower border and > 10 mV for the upper edge. _x000D_ _x000D_ Results: The aEEG monitors complement limited neurologic resources in the NICU as a screening tool that can provide important information regarding functional brain abnormalities, degree of encephalopathy, and electrographic seizures when VEEG is unavailable. Neonatal seizures on aEEG are shown as an abrupt, transient, sharp rise in the lower and upper margins, often followed by a short period of bandwidth narrowing. The seizure must be at least 30 seconds in duration and must be at 2 mV in amplitude to be detectable on aEEG. Neonatal seizures on VEEG may present in many distinct forms characterized by the sudden appearance of an abnormal electrical event, usually lasting 10 seconds or more, with evolving, repetitive waveforms that gradually build up and then decline in frequency and morphology. The most reliable and accurate method to detect subclinical seizures is VEEG. However, its interpretation requires years of training and practice, which is out of the scope of the neonatologist. In contrast, the aEEG is a readily available monitoring diagnostic instrument that can provide immediate information to guide treatment. Any infant in whom aEEG detects seizure should undergo VEEG to confirm the findings because very-low-amplitude artifacts might be misdiagnosed as seizures. _x000D_
Conclusions: Here, we review the utility of aEEG in detecting subclinical seizures in neonates with encephalopathy during therapeutic hypothermia. The aEEG is a screening tool but an accessible one that allows prompt treatment in NICUs where VEEG is out of reach at admission._x000D_
Funding: No funding was secured for this study.