Abstracts

Rationale:
Recording seizures using personal seizure diaries can be challenging during everyday life and many seizures are missed or mis-reported. People living with epilepsy could benefit by having a more accurate and objective wearable EEG system for counting seizures that can be used outside of the hospital. The objective of this study was to (1) determine epileptologist ability to identify electrographic seizures from single-channels of EEG, and (2) compare EEG recordings from Epilog, a wireless single-channel EEG sensor, with standard-of-care, full montage, video-EEG.
Method:
Epileptologists were asked whether known seizure events were visible on specific single channels from full-montage EEG in scalp locations where Epilog could be placed below hairline. Blinded review was performed to identify electrographic seizure activity in single channels of EEG from both the Epilog sensor and extracted from full-montage EEG. Power spectral density, signal-to-noise ratio, and EEG band frequency decomposition were used to compare the signal quality of single-channel EEG from the Epilog sensor and extracted from full-montage wired EEG.
Results:
A total of 75 seizures were recorded from 22 of 40 adults that wore Epilog during their visit to the EMU. Epileptologists were able to visualize known seizure activity from full-montage EEG on at least one of the locations where Epilog could be placed. Epileptologists accurately identified seizures in 71% of Epilog recordings and 84% of single-channel wired recordings. Epilog signal quality was not significantly different than the nearest wired differential electrode pair and the lower frequency signal power was stronger, though not significantly different, in the Epilog EEG versus single-channels of wired EEG. Reviewers were more accurate in determining true seizure events in Epilog EEG when the seizures were electrographically generalized or progressed from a focal-onset to a generalized tonic-clonic convulsion where they were 87% accurate versus 56% accurate for electrographically focal seizures which did not evolve to a tonic-clonic convulsion. Epileptologists were nearly 100% accurate (12/13) identifying seizures with Epilog when those seizures ended in a clinical convulsion including focal-onset with motor, focal-onset evolving to bilateral tonic-clonic, and generalized tonic-clonic seizures. Epileptologists were least accurate in identifying seizures that did not end in a convulsion, including focal-onset with impaired awareness (55%) followed by generalized absence seizures (60%). In all scenarios, epileptologists were more confident about their decision when they were correct. The inter-rater reliability was consistent between all reviewers and across the group (≥ 0.79 for all values). The inter-rater reliability was greater when the group was reviewing the wired data versus the Epilog data (0.91 vs 0.81 group kappa). 
Conclusion:
Wearable EEG systems will be important for seizure monitoring outside of the hospital. Epileptologists can identify seizures in single-channel data with good accuracy, possibly better than patient self-reporting in seizure diaries based on the literature. Single-channel, discreet EEG sensors like Epilog, can record electrographic seizures comparable to standard-of-care multi-channel systems.
Funding:
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Funding:
provided through Phase I and II SBIR grants from the National Institute of Neurological Disorders and Stroke award NS100235.