How often does routine pediatric EEG have an important unexpected result?

Background: Electroencephalogram recordings are requested for the assessmen t of many childhood disorders. To assess the utility of the EEG in children , we studied how often routine EEG results can be correctly predicted from the EEG requisition. Method: Five hundred consecutive initial EEG requests from the IWK Grace Health Centre from two time epochs were examined. All EE Gs were 16 channel (10-20 electrode system). Based only on the requisition (patient demographics, referring physician, and reason for EEG), we coded o ur prediction of the result and then the actual result. When results were d iscordant from prediction, a judgment was made about the potential importan ce of the result. Results: Overall, EEG results were correctly predicted in 81%. Prediction for all nonepilepsy reasons was accurate in 91% (n=320) an d 96% for paroxysmal nonepileptic events (n=158) but only 59% for epileptic disorders (n=141) (p<0.0001). Neurologists ordered 45% of EEGs, pediatrici ans 32%, and GP's 17%. Predictions were least accurate for neurologists' re quests (p<0.006) however, neurologists were more likely to request EEG for epileptic disorders (p<0.0001), Age of the child and urban versus rural add ress did not affect the accuracy of prediction. Conclusion: Results of rout ine pediatric EEG for most nonepilepsy reasons appear highly predictable an d therefore, possibly of little value to an experienced clinician. When req uested for epilepsy, this "ancient" test remains full of surprises.