Abstracts

Rationale: Electroencephalographic seizures (ES) are common in neonates with hypoxic-ischemic encephalopathy (HIE) but identification with continuous EEG monitoring (CEEG) is resource-intense. We aimed to (1) identify clinical and EEG risk factors for ES, (2) generate an ES prediction model, and (3) establish the necessary CEEG duration to identify ES for various risk profiles among neonates with HIE treated with therapeutic hypothermia (TH).


Methods: Using a prospective observational study of 260 neonates with HIE undergoing CEEG, we identified clinical and EEG risk factors for ES, evaluated model performance with areas under the receiver operating characteristic curve (AUROC), and calculated test characteristics emphasizing high sensitivity. We assessed ES incidence and timing in neonates subdivided by ES risk group (low, moderate, high) as determined by EEG risk factors.

Results: ES occurred in 32% (83/260) of neonates. Performing CEEG for only 24 hours would fail to identify the 7% (17/260) of neonates with later onset ES (20% of all neonates experiencing ES). Identifying 90% or 95% of neonates with ES would require CEEG for 63 or 74 hours, respectively. The optimal model included continuity and epileptiform discharges, both assessed in the initial 1-hour of CEEG. It yielded an AUROC 0.80, and at a cutoff that emphasized sensitivity, had sensitivity 94%, specificity 45%, positive predictive value 44%, and negative predictive value 95%. The model would avoid CEEG beyond 1-hour in 32% (84/260) of neonates but 6% (5/83) of neonates with ES would not have ES identified. ES incidence was significantly different (p< 0.01) across ES risk groups (6% low, 40% moderate, and 83% high). Only ~6 hours of CEEG would identify all neonates with ES in the low-risk group while 75 and 63 hours of CEEG would be required to identify 95% of neonates with ES in the moderate- and high-risk groups, respectively.