Optimizing parameters for terminating cortical afterdischarges with pulse stimulation

Purpose: We previously reported that brief pulses of electrical stimulation (BPSs) can terminate afterdischarges (ADs) during cortical stimulation. We investigated conditions under which BPS is more likely to suppress ADs. Methods: We analyzed parameters altering BPS effectiveness on 200 ADs in seven patients with implanted subdural electrodes. Results: The odds of BPSs stopping ADs was 8.6 times greater at primary sites (directly stimulated electrodes) than at secondary sites (adjacent electrodes) (p = 0.016). BPS applied within 4.5 s after onset of AD had 2 times greater odds of stopping ADs (p - 0.014). BPS applied when AD voltage was negative was 1.9 times more likely to stop ADs (p = 0.012). ADs with rhythmic pattern responded best (p < 0.0001). BPS stopped 100% of ADs not starting immediately after localization stimulus (LS) versus 29% of those starting immediately (P < 0.0001). Conclusions: BPS is more likely to terminate ADs at primary electrodes, if given early, if applied to the negative peak of the AD waveform, if AD has a rhythmic pattern, and if AD did not start immediately after LS.