Abstracts

Rationale: Continuous electroencephalographic monitoring (cEEG) is frequently used in critically ill children admitted to the pediatric intensive care unit (PICU). Approximately 10-50% of children that undergo a clinically indicated cEEG have electrographic seizures, the majority of which are subclinical. In addition to seizure detection and characterization, cEEG provides information on the EEG background. The aim of this study is to describe background features and their potential association with electrographic seizures and in-hospital death. Methods: Retrospective descriptive study of children aged 1 month corrected gestational age to 21 years admitted to the PICU who underwent a clinically indicated cEEG (defined as greater than 3 hours of uninterrupted EEG) in the neonatal, pediatric, and cardiac intensive care units at Boston Children's Hospital from 2011 to 2013. In patients with multiple cEEG procedures, only the first recording was considered. Patients were excluded if they were admitted in the setting of epilepsy surgery. Electrographic seizures were defined as any seizure detected on cEEG, whether electro-clinical or electrographic-only. Electrographic status epilepticus (ESE) was defined as a continuous seizure lasting greater than 30 minutes or seizures totaling at least 50% of a 1 hour epoch. EEG background was categorized into normal, slow disorganized, attenuated and featureless, discontinuous, and burst suppression. The presence of epileptiform discharges was also documented as being either present or absent. Results: Four hundred and fourteen children were studied (54% male) with a median age of 4.2 years (IQR 0.8-11.3). Two hundred and thirteen patients (51%) had a structural lesion, while 147(35.5%) had a prior diagnosis of epilepsy. The main indications for monitoring were characterization of events concerning for seizures (240 patients; 58 %) and detection of nonconvulsive or subclinical seizures (112 patients; 27 %). Electrographic seizures (ES) were identified in 102 patients (25%), while electrographic status epilepticus (ESE) was noted in 12 patients (12%). Sporadic interictal epileptiform discharges were seen in 229 patients (55.3%). A slow disorganized background was seen in 307 patients (74%) followed by an attenuated pattern in 24 patients (6%). After correcting for etiology, the presence of epileptiform discharges was associated with ES (OR 9.5(95% CI 5-19.7), p < 0.001). An attenuated EEG (OR 14.6(95% CI 4.1-62.8, p < 0.001) and burst suppression pattern (OR 33.5(CI 7.5-186.2), p < 0.01) were independently associated with in-hospital mortality. The presence of ES was not associated with in-hospital mortality (0.2(0.07-0.5) p < 0.01). Conclusions: Epileptiform discharges are independently associated with electrographic seizures but not with in-hospital mortality. The presence of burst-suppression or attenuated patterns in the EEG background are independently associated with in-hospital death, but not with electrographic seizures. Funding: None