S88. Classification for non-hypoxic ischemic encephalopathy based on standardized critical care EEG terminology: A pilot study

Introduction Though encephalopathy is commonly diagnosed on continuous EEG monitoring, no standardized classification exits. Current classification systems are not clinically validated or tested for inter-reader reliability. We prospectively evaluated an easy to use classification of encephalopathy based on standardized critical care EEG terminology (ACNS-2012) in this pilot study. Methods Patients were diagnosed with encephalopathy using continuous EEG monitoring during a two-week study period. Those with hypoxic ischemic encephalopathy/cardiac arrest were excluded. Encephalopathy was classified as mild, moderate and severe based on standard critical care EEG criteria. Patients with suppression, burst suppression, status epilepticus, acute frequent seizures, lack of reactivity and variability were classified as “severe encephalopathy”. Patients with preserved background and transitions for most of the recording without any main term 1 or main term 2 features were classified as “mild encephalopathy”. Patients with all other features including main term 1 or main term 2 features were classified as “moderate encephalopathy”. The patient’s mental status at the time of EEG recording was assessed using the Glasgow Coma Scale and categorized into three categories of increasing severity (GCS less than 5, GCS 6–10, GCS 10–15). The EEG based classification was then clinically validated using standard probability assessment. Results A total of 26 patients were evaluated. Mild, moderate and severe encephalopathy was diagnosed 12,10 and 4 patients respectively. The pre-and post-classification probabilities (sensitivity, specificity, positive predictive value (PPV), negative predicitive value (NPV) for the classification system are shown in the table below: - TABLE For mild encephalopathy: Sensitivity 85.7%, Specificity 100%, PPV 100%, NPV 85.7% For moderate encephalopathy: Sensitivity 100%, Specificity 94.1%, PPV 90%, NPV 100% For severe encephalopathy: Sensitivity 100%, Specificity 95.6%, PPV 75%, NPV 100% Conclusion A standardized classification for the severity of non-hypoxic hypoxic ischemic encephalopathy using standardized critical care EEG terminology (ACNS, 2012) was clinically validated in this pilot study. Further large prospective studies are needed to confirm these results.