Improving diagnostic accuracy of routine EEG for epilepsy using deep learning

The yield of routine EEG to diagnose epilepsy is limited by low sensitivity and the potential for misinterpretation of interictal epileptiform discharges. Our objective is to develop, train and validate a deep learning model that can identify epilepsy from routine EEG recordings, complementing traditional interpretation based on identifying interictal discharges. This is a retrospective cohort study of diagnostic accuracy. All consecutive patients undergoing routine EEG at our tertiary care centre between January 2018 and September 2019 were included. EEGs recorded between July 2019 and September 2019 constituted a temporally shifted testing cohort. The diagnosis of epilepsy was established by the treating neurologist at the end of the available follow-up period, based on clinical file review. Original EEG reports were reviewed for IEDs. We developed seven novel deep learning models based on Vision Transformers and Convolutional Neural Networks, training them to classify raw EEG recordings. We compared their performance to interictal discharge-based interpretation and two previously proposed machine learning methods. The study included 948 EEGs from 846 patients (820 EEGs/728 patients in training/validation, 128 EEGs/118 patients in testing). Median follow-up was 2.2 years and 1.7 years in each cohort, respectively. Our flagship Vision Transformer model, DeepEpilepsy, achieved an area under the receiver operating characteristic curve of 0.76 (95% confidence interval: 0.69-0.83), outperforming interictal discharge-based interpretation (0.69; 0.64-0.73) and previous methods. Combining DeepEpilepsy with interictal discharges increased the performance to 0.83 (0.77-0.89). DeepEpilepsy can identify epilepsy on routine EEG independently of interictal discharges, suggesting that deep learning can detect novel EEG patterns relevant to epilepsy diagnosis. Further research is needed to understand the exact nature of these patterns and evaluate the clinical impact of this increased diagnostic yield in specific settings.