Abstracts

Rationale: Bilateral independent periodic lateralized epileptiform discharges (BIPLEDs, also known as BIPDs) are rare electroencephalographic findings that have been associated with various etiologies including CNS infection, vascular lesions, and hypoxic-ischemic encephalopathy. Previous studies of BIPLEDs suggest that they are generally associated with seizures, coma, and poor outcome. However, there is a paucity of data on this group, and no large published series utilizing continuous EEG (cEEG) . The objective of this study was to investigate the occurrence of BIPDs, clinical correlates, associated EEG findings including seizures, and outcomes in patients undergoing cEEG at our center.Methods: We searched the continuous EEG database at Columbia University Medical Center for all reports of BIPLEDs in adult patients from October 1, 2003 to February 28, 2011. The primary outcome was in-hospital death. We retrospectively reviewed EEG reports for associated EEG phenomena (seizures, other periodic discharges, etc.) and reviewed patient records to determine the presumed etiology of cerebral dysfunction.Results: 6094 adult patients underwent cEEG. BIPLEDs were identified in 84 patients (1.4%) during 85 hospital admissions. Ages ranged from 21 to 96 years (mean 66.6) and there were 59 females and 25 males. 50 subjects (59.5%) had seizures either prior to or during cEEG recording. The presumed etiology was an acute brain injury (stroke, trauma, hemorrhage, infectious or autoimmune encephalitis, posterior reversible encephalopathy syndrome) in 48 (57.1%) of the patients, while 15 patients (17.8%) had suffered chronic injury to the brain (prior stroke or hemorrhage, multiple sclerosis, Creutzfeld-Jakob disease, dementia) and were admitted due to an acute non-neurologic illness or seizure. 13 patients (15.4%) had hypoxic-ischemic encephalopathy, and 9 patients (10.7%) had systemic illness (end-stage renal disease, liver failure, sepsis, etc.) without evidence of primary brain injury. 47.6% of the patients died during their hospital admission, including 12 of 13 patients (92%) with hypoxic-ischemic encephalopathy (HIE) and 28 of 71 (39.4%) without HIE.Conclusions: BIPLEDs on cEEG are associated with a wide range of etiologies, and can be secondary to primary brain injury, systemic disease, or remote brain injury combined with metabolic disarray or seizures. In this series of 84 patients, nearly 60% of patients with BIPDs had seizures, and nearly 50% died during their hospital stay.