Detections of long epileptiform events (LEs) were compared to diary seizures.
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LEs covary with diary seizures (n = 101, mean r ± SEM = 0.26 ± 0.002, p < 10−18).
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LEs were more frequent than diary recorded seizures (PPV: 34 %).
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Diary recorded seizures were rare on days when there were no LEs (NPV: 90 %).
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Chronic ambulatory electrocorticographic data could supplement seizure diaries.
Abstract
Purpose
To determine the feasibility of using epileptiform events detected by continuous electrocorticographic monitoring via a brain-responsive neurostimulation system to supplement patient-maintained seizure diaries.
Methods
Data were retrospectively analyzed from a randomized controlled trial of brain-responsive neurostimulation (RNS® System) for adjunctive treatment of medically intractable focal onset seizures in 191 subjects. The long-term (≥3 months) correspondence between daily counts of diary-reported seizures and device-recorded “long epileptiform events” (LEs), a proxy for electrographic seizures (ESs), was assessed using cross-correlation and logistic generalized estimating equation models.
Results
Diary-reported seizures and LEs significantly co-varied across days in 124 patients whose detection settings were held constant, with a significantly higher correlation in 54 patients (44 %) whose LEs were usually ESs (high concordance patients). There were more days in which LEs were detected than days in which patients reported a seizure (positive predictive value (PPV): 34 %). On days when there were no LEs, there were typically no diary-reported seizures (negative predictive value (NPV): 90 %). In patients with a high concordance between LEs and ESs, the PPV and NPV were both slightly higher, 43 % (35–52 %) and 93 % (95 % CI: 86–97 %) respectively.
Conclusion
Although LEs can substantially outnumber diary reported seizures, the high across-day correlation and strong NPV between LEs and diary seizures suggests that LEs recorded by the RNS® System could potentially supplement seizure diaries by providing an objective biomarker for relative seizure burden.
Abbreviations
CV-EEG
continuous video-EEG
ECoG
electrocorticography, electrocorticographic
ES
electrographic seizure
GEE
generalized estimating equation
LE
long epileptiform events, epochs of ECoG that exceed a particular duration that are recorded when triggered by an RNS detection