Diagnostic and prognostic value of EEG patterns recorded on foramen ovale and epidural peg electrodes.

OBJECTIVE: To describe and assess the significance of EEG characteristics recorded during presurgical video-EEG monitoring (VEM) utilizing foramen ovale (FO) and epidural peg electrodes. METHODS: Seizure onset (SOP) and termination pattern morphology and regions, ipsilateral and contralateral latencies, seizure duration, and interictal spike counts were examined in 106 patients (412 seizures). An EEG feature-based logistic regression model predicting one-year post-surgical seizure freedom was assessed using a 5-fold nested cross-validation approach. RESULTS: Four SOPs and five termination patterns were identified. Seventy-one percent of patients had a single unique SOP, the most common being sharp activity ≤ 13 Hz (28.9% of seizures). Seizures recorded by FO electrodes were associated with SOPs ≤ 13 Hz (OR 1.9, p = .008). Focal-to-bilateral tonic-clonic seizures were associated with SOPs > 13 Hz (p = .04) and bilateral spike and wave termination (p < .001). In patients with temporal lobe epilepsy, logistic regression based prediction of post-surgical outcome had a mean area under the curve of 0.69, with the most important features being SOP, right sided interictal epileptic activity, and contralateral latency. CONCLUSIONS: FO and peg recordings yield characteristic EEG patterns. SIGNIFICANCE: EEG features of FO and peg recordings may have diagnostic and prognostic utility in presurgical VEM.