Abstracts

Rationale: Nonconvulsive status epilepticus (NCSE) and nonconvulsive seizures are a complication of subarachnoid hemorrhage (SAH). Retrospective studies in SAH have shown an association with NCSE and poor outcome. Retrospective studies have shown NCSE in 18% of patients with intracranial hemorrhage. Due to the high incidence of NCSE in patients with SAH and the significant morbidity associated with untreated NCSE, we initiated a prospective observational study of patients admitted to our institution with aneurysmal SAH and depressed consciousness. Methods: Patients were enrolled from a single tertiary care center. Inclusion criteria were SAH secondary to a ruptured intracranial aneurysm, a Glasgow Coma Scale (GCS) ?8, decrease in GCS of 2 or more points, patients that did not return to baseline within 12 hours of treatment, or witnessed clinical seizure. Prospective data included clinical examination, prior medical history, imaging, angiographic findings, surgical and medical interventions and laboratory values. Outcomes were determined for all patients at the end of the acute hospital stay. Continuous EEG monitoring was performed and scored according to ACNS Subcommittee on Research Terminology for Continuous EEG Monitoring. All data was collected under approved IRB protocols. Results: Between May 2008 and April 2010, a total of 416 patients were admitted with a SAH associated with a ruptured intracranial aneurysm. Of these, 51 met inclusion criteria and underwent continuous EEG monitoring. 35 patients (69%) had periodic patterns (periodic discharges or rhythmic delta) at some point during monitoring (9 - periodic discharges only, 10 - rhythmic delta only, 16 - both). Only 2 patients (4%) had discrete electrographic seizures during continuous EEG monitoring. In our study population, 12 died (24%) and 28 were severely disabled (modified Rankin Score (mRS) of 5) (55%). With these preliminary results, there was no predictive value between the presence of rhythmical and periodic patterns and outcome (as determined by mRS). Conclusions: Our prospective study of patients with aneurysmal SAH consisted of patients with a low GCS score at time of presentation, and overall, included a more critically ill population. 69% of patients had rhythmical or periodic patterns on continuous EEG monitoring as defined by the ACNS research terminology. There was no significant correlation between the presence of these patterns and outcome in this high risk population. Further data analysis is underway to determine which other EEG factors, such as the abundance of periodic patterns, may be predictive of outcome and whether treatment had any impact on patient survival. Rhythmical and periodic patterns may not prove to be an independent risk factor for outcome in SAH; however, continuous EEG monitoring will likely continue to be a valuable tool in guiding treatment for critically ill patients.