Abstracts

Rationale: In urgent neurological settings, electroencephalography (EEG) with a reduced number of electrodes might be a timely alternative to traditional EEG. We compare the utility of reduced montage EEG (rm-EEG) using 10 lateral electrodes with that of full montage traditional EEG (fm-EEG). Methods: We retrospectively collected 212 adult EEGs recorded at Massachusetts General Hospital and studied the accuracy of epileptologists reading the first 4 hours of these EEGs that were digitally reduced to rm-EEG formats. We also studied the value of the first 4 hours of rm-EEG in predicting seizures in the subsequent fm-EEG recordings. Results: Of 117 EEGs with seizures identified in the first four hours of fm-EEG, readers of rm-EEG agreed with the presence of seizures, periodic patterns or isolated epileptiform activity in 111 (95%) cases and labeled clear seizures in 77 (69%) cases without access to clinical, trending or video information that were available to original readers of fm-EEG. Among the 95 EEGs without seizures in the first four hours of fm-EEG, readers of rm-EEG identified 92 (97%) cases as having no seizure activity. When discordant cases were reviewed in fm-EEG and rm-EEG, high concordance (95%) and intra-rater agreement (93%) were documented. Lastly, the detection of epileptiform abnormalities in the first four hours of rm-EEG was associated with increased odds of subsequent seizures during conventional EEG monitoring (OR 12.19, 95% CI 3.94-41.37). Conclusions: Reduced montage EEG may present a useful triage method for detecting pathological abnormalities and identifying high-risk patients who will benefit from continuous long-term EEG. Funding: This study was supported by a research grant from Ceribell Inc. to Massachusetts General Hospital.