Reproducibility of Test-Retest Cortical Evoked Responses in Patients with Focal Epilepsy

This exploratory study examined the short-term reliability of cortical auditory evoked responses recorded from patients undergoing whole-head scalp elec-troencephalography (EEG) monitoring to assess their candidacy for surgical treatment intractable focal seizures. Participants were 26 with either left-sided (N = 13) or right-sided epilepsy admitted hospital continuous EEG possible surgery planning. Cortical over multiple days electrodes using tones presented binaurally in a passive oddball paradigm. Test-retest intervals 1 - 6 (mean 2 days). reproducibility N1 response was assessed by paired t-test (latency) and cross-correlation analysis (amplitude latency). Within-patient comparisons test-retest peak latencies revealed no significant differences. The coefficient indicated high waveform (rcc 0.88). Seizure lateralization not associated asymmetries amplitudes. An amplitude asymmetry (right > left) seizures originating left hemisphere initially observed, but disappeared when prior resections excluded, suggesting that reduced tissue volume may account smaller unexpectedly regardless seizure localization. These findings challenge view neural are intrinsically unstable (unreliable)