Abstracts

Rationale: Hemorrhage involving structures in or around the brain, including intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), and subdural hematoma (SDH), is associated with significant morbidity and mortality. One mechanism by which cerebral hemorrhage (CH) can cause further brain injury is through the generation of epileptic seizures. Epileptic seizures are a potentially treatable brain disorder; however, sub-clinical seizures are difficult to detect. Methods: We reviewed the records of over 950 patients consecutively admitted to the Intensive Care Unit from January 1, 2007 until May 31, 2010 with a diagnosis of SDH, SAH, or ICH. All EEG studies were performed on patients in the ICU. Epileptiform EEG abnormalities were characterized as spikes, sharp waves, PLEDs, or electrographic seizure activity. Non-epileptiform abnormalities were also characterized. Results: Routine EEG (rEEG) or continuous EEG (cEEG) was performed on 20% of all patients, with approximately equal percentages regardless of type of CH. Slowing was the most common electrographic finding. In this study population, the prevalence of epileptiform findings was 35% and of ictal findings was 25%, with no significant difference found between SAH, SDH, ICH. Continuous EEG detected ictal activity in a much higher percentage of cases than rEEG. In nearly all cases with ictal features, seizure activity was sub-clinical, and compatible with the diagnosis of non-convulsive status epilepticus. Conclusions: Cerebral hemorrhage is a significant cause of sub-clinical seizure activity. The fact that over 700 patients with CH did not ungergo EEG evaluation suggests that the diagnosis of sub-clinical seizures was missed in over 200 cases. Missing the diagnosis of sub-clinical seizures would be expected to have a negative impact on patient outcome, especially in this patient population. Continuous EEG is an important diagnostic tool in patients in the ICU setting and a more detailed analysis of the relationship of seizures in the acute setting of CH and outcome is warranted.