Abstracts

Rationale: With the growing use of continuous EEG in critically ill patients, lateralized periodic discharges (LPDs) and bilateral independent periodic discharges (BIPDs) are increasingly encountered in pediatric patients. LPDs and BIPDs are frequently present in the setting of acute brain injury, and are often associated with development of seizures (1-5). However, the risk of developing seizures in patients with LPDs or BIPDs with different etiologies is unknown. Further, the significance of LPDs and BIPDs in children is not as well-described as that in adults. Methods: We performed a retrospective review of all 470 continuous EEG recordings performed in the pediatric and neonatal intensive care units at Johns Hopkins Hospital in Baltimore, MD from 2011-2017. A key word search using the term ‘periodic’ was performed, yielding 51 eligible records. Generalized periodic discharges were excluded. 22 records with LPDs and/or BIPDs were identified. Chart review was performed and the incidence of seizures and the outcomes between etiologies were compared. Results: The incidence of LPDs or BIPDs in critically ill pediatric patients was 4.4%. LPDs or BIPDs were identified in 22 children, ranging from 25 days to 21 years of age. LPDs were present in 14/22 (63.6%), and BIPDs were present in 8/22 (36.3%). LPDs were most common in cerebral hemorrhage (6/14; 42.8%), followed by anoxic/hypoxic injury (2/14; 14.2%), status epilepticus with pre-existing epilepsy (2/14; 14.2%), cerebral ischemic infarct (2/14; 14.2%), cortical dysplasia (1/14; 7.1%), and severe systemic illness (1/14; 7.1%). BIPDS were most frequent in anoxic/hypoxic injury (3/8; 37.5%), followed by status epilepticus with pre-existing epilepsy (2/8; 25%), cerebral hemorrhage (2/8; 25%), and viral encephalitis (1/8; 12.5%). Electrographic seizures were observed in 81.8% (18/22 patients). BIPDs were associated with seizures in 62.5% (5/8 patients), and LPDs were associated with seizures in 92.8% (13/14 patients). Seizures were identified within 24 hours of recording 77.7% (14/18 patients) and within 48-72 hours of recording in 16.6 % (3/18 patients). LPDs or BIPDs were least associated with seizures following acute anoxic/hypoxic injury (2 of 5 cases; 40%), however, mortality was highest in this subgroup (4/5; 80%). Conversely, all of the patients with cerebral hemorrhage developed seizures (8/8), as did all patients with pre-existing epilepsy presenting in status epilepticus (4/4). Overall, in-hospital mortality was 6/22 (27.2%). Conclusions: LPDs and BIPDs are highly predictive of seizures in critically ill pediatric patients, with electrographic seizures identified within 24 hours of continuous EEG monitoring in the majority cases. The most common etiologies of LPDs and BIPDs in this population are cerebral hemorrhage, anoxic/hypoxic injury, and pre-existing epilepsy. This differs from the adult population in which stroke and tumor are the most common etiologies associated with LPDs (6). Anoxic/hypoxic injury was highly associated with death, though least associated with seizures. Patients with cerebral hemorrhage or pre-existing epilepsy are most likely to develop seizures. Funding: No funding support.