Abstracts

Rationale: Continuous EEG monitoring (cEEG) is important to the detection of brief electrographic seizures (ES) and prolonged episodes of electroencephalographic status epilepticus (ESE). These seizures are often times subclinical and would go undetected without cEEG. CEEG is however, costly and resource intense. The objective of this report is to better define at-risk PICU populations and the optimal duration of cEEG monitoring needed to adequately capture ES(E) events. Methods: This is a retrospective descriptive study of patients aged 1 month to 21 years who underwent cEEG (>3 hours) in the PICUs at Boston Children's Hospital in the period of 2011-2013. In our institution we have a structured approach to cEEG monitoring after admission and the particular indication for monitoring is recorded. 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: 414 patients aged 4.2 (0.75 ?" 11.3) years (median [IQR]) were included. The overall PICU length-of-stay was 7.8 (2.7-22.7) days and mortality was 14.3% (59/414). With a median duration of 21 (16 ?" 42.2) hours of cEEG monitoring, we identified ES (E) in 1-in-4 cases, i.e., we did not identify ES(E) activity in 75% of the population. Three features could make the use of cEEG resources more efficient and provide a framework for decision-making. First, aspects from the clinical history may help with the decision to not initiate cEEG monitoring. Second, the initial EEG finding has the potential to inform the decision not to continue with cEEG monitoring (Table 1). Last, during cEEG monitoring, failure to record ES(E) within the first 4 to 6 hours of monitoring may be a sufficient test of whether there will be no further ES(E) activity, i.e., post-test probability of no ES(E) in subsequent cEEG monitoring 0.90. Conclusions: cEEG monitoring is considered standard of care to assess patient neurologic status and seizure activity. Individualized monitoring plans are necessary to increase the yield of seizure detection, while improving resource utilization. A strategy that uses information from the clinical history, initial EEG investigation and early background findings may be effective in accomplishing this goal. Funding: None