Abstracts

Rationale: Previous studies show the best estimate of non-convulsive seizure (NCS) prevalence is 8-19% in patients with altered mental status (AMS). Non-convulsive status epilepticus (NCSE) may cause permanent neuronal damage via an increase in extracellular brain glutamate leading to brain swelling and apoptosis. Delayed diagnosis and treatment of NCS may lead to an increase in mortality in patients with acute brain injury if duration exceeds 20 hours. However, there is little data on which factors influence outcome in critically ill patients with NCSE. This study seeks to better understand the risk factors, characteristics and outcome of NCS/NCSE in critically sick patients in the neurological ICU. Methods: This is a preliminary report of our prospective observational study, recruiting patients with unexplained AMS admitted to the adult neuro ICU at Vanderbilt University Medical Center, collected from January to May 2012. Coma due to anoxic brain injury or induced hypothermia was excluded from the study. Patients underwent brain imaging (CT or/and MRI) and were placed on continuous EEG monitoring as medically indicated. NCSE is defined as continuous or recurrent ictal discharges for at least 30 minutes and subcategorized according to the EEG findings. Data was collected and analyzed for prevalence of NCSE or/and NCS, EEG patterns (lateral vs. generalized), associated risk factors (e.g. metabolic derangement, acute cerebral lesion, preexisting epilepsy), AED use, treatment response, and eventual outcome. Results: NCS/NCSE was detected in 21% of subjects (23 of 108): 9 NCS and 14 NCSE. 34% of the NCS/NCSE group, and 28% of the non-NCS/NCSE group were intubated. Most all subjects (87%) had abnormal brain imaging. Risk factors for NCSE/NCS were female gender (p=0.11), history of epilepsy (p=0.086), ventriculoperitoneal shunt (p=0.3), CNS tumor (p=0.004), and acute intracerebral hemorrhage (p=0.29)(Table 1). Though patients are comatose, subtle clinical signs such as twitching of mouth or ocular muscles, eye deviations were often found on exam in 57% (p=0.003) of the NCSE/NCS group (Table 2). Death rate was higher, 26% in NCSE/NCS vs. 12% in non-NCS/NCSE group (p=0.23). Among NCSE/NCS patients, generalized ictal EEG pattern had worse outcome, (death rate of 43%) compared to the unilateral (19%). All patients (4/4) placed on drug induced burst suppression died. Conclusions: The diagnosis of NCSE is challenging and requires urgent continuous EEG availability. This study highlights the importance of subtle clinical findings in combination with brain imaging abnormalities and medical history in raising the suspicion for NCSE/NCS. Mortality is high in NCSE, and the subtype of NCSE and its underlying etiology are likely important mortality. We are continuing this prospective study to better identify risk factors for NCSE and factors that are important in determining NCSE outcome in critically ill patients.