Abstracts

Rationale: Lateralized periodic discharges (LPDs) and non-convulsive status epilepticus (NCSE) are considered distinct but can be challenging to distinguish clinically and on EEG.  Seizures are prevalent in patients with LPDs, and both LPDs and NCSE have high associated morbidity and mortality.  There is emerging evidence suggesting LPDs share pathophysiologic similarities with seizures, leading some to question whether they represent a form of focal NCSE. There is limited data comparing clinical outcomes in these groups. We hypothesize that outcomes are better in NCSE as these patients will presumably be treated more aggressively than patients with LPDs alone.  The aim of this study was to compare clinical features and outcomes in patients with LPDs and NCSE in an ICU population. Methods: We performed a retrospective study of consecutive adult ICU patients undergoing EEG monitoring at Mayo Clinic Rochester diagnosed with LPDs or NCSE from our ICU-EEG database between January, 2015 to October, 2017. EEG diagnosis was based on ACNS Critical Care EEG Guidelines. Demographic data, etiology, medical complications, antiseizure drug (ASD) utilization, EEG and clinical response to treatment, and clinical outcome at discharge (classified by modified Rankin scale (MRS)) were abstracted from the EMR.  Diagnosis of NCSE was based on specific statements of this as a diagnosis in the EMR.  Categorical data was evaluated using Bowker’s test and Chi-squared tests, continuous data with Student’s T-test (two-tailed). Results: 118 patients were identified (LPDs only = 35, NCSE with or without LPDs = 61); 22 were excluded due to age < 18 years; 35 patients in the NCSE group had LPDs.  There was no major difference in etiology except intracranial hemorrhage was greater in the LPD only group (34 % vs 16%, P < 0.05).  The NCSE group received more intensive medication treatment than the LPD only group (At least 2 ASDs, excluding benzodiazepine 77% vs 14%, P < 0.0003; anesthetic agents 26% vs 6%, P < 0.002). Improvement in level of consciousness occurred after treatment in both groups (P < 0.05).   Clinical outcome did not differ between groups (P = 0.71).  In addition, there was no difference in outcome between patients with NCSE with or without LPDs.  In the LPD group, 54% had seizures, yet there was no difference in outcome between the LPD group with seizures and LPDs without seizures.  The NCSE group with LPDs showed an increased association with EEG LPD terminology modifiers compared to LPDs without NCSE (71% vs 29%, P = 0.05). Conclusions: Our study supports the close relationship between LPDs and NCSEas indicated by the high prevalence of LPDs in the NCSE group and seizures in the LPD group.  Patients diagnosed with NCSE were treated more aggressively than LPDs without NCSE, but there was no difference in response to treatment or outcome.  The similarity of outcome raises questions as to the degree of fundamental difference between LPDs and NCSE. Funding: None