Tailoring epilepsy surgery with fast ripples in the intraoperative electrocorticogram

Abstract

FRs that persist before and after resection predict poor postsurgical outcome. These findings hold for different tailoring approaches. FRs can thus be used for tailoring epilepsy surgery with repeated intraoperative ECoG measurements. Ann Neurol 2017;81:664-676.

Phase‐amplitude coupling between interictal high‐frequency activity and slow waves in epilepsy surgery

“…It remains unknown how the utility of MI is altered by different electrode types (eg, disk vs depth electrodes), different montage (eg, common average reference vs bipolar montage), anesthesia conditions, and intracranial electrode placement approaches (eg, large vs limited coverage). A retrospective study of 54 patients reported that the occurrence of HFA >250 Hz on intraoperative ECoG immediately following cortical resection was associated with a greater risk of seizure recurrence . One logical next step would be to determine whether quantitative measurement of MI during intraoperative ECoG recording will provide useful information to localize the EZ.…”

“…A retrospective study of 54 patients reported that the occurrence of HFA >250 Hz on intraoperative ECoG immediately following cortical resection was associated with a greater risk of seizure recurrence. 15 One logical next step would be to determine whether quantitative measurement of MI during intraoperative ECoG recording will provide useful information to localize the EZ.…”

“…As the sampling rate of digital recording systems have recently improved, investigators have described the value of interictal high‐frequency activity at >80 Hz (HFA >80 Hz ) for localizing the EZ. Specifically, resection of recording sites showing frequent episodes of HFA during invasive monitoring has been associated with excellent seizure outcome . However, whether preresection interictal HFA can inform postresection clinical outcome, independently of the effects of resection size, SOZ on ictal recording, and neuroimaging data, remains an open question …”

“…Specifically, resection of recording sites showing frequent episodes of HFA during invasive monitoring has been associated with excellent seizure outcome. [9][10][11][12][13][14][15][16] However, whether preresection interictal HFA can inform postresection clinical outcome, independently of the effects of resection size, SOZ on ictal recording, and neuroimaging data, remains an open question. 16 To evaluate whether interictal coupling between HFA and slow waves could be used as a preoperative electrographic biomarker, we examined whether a modulation index (MI) was associated with postoperative success rates in 123 patients with drug-resistant focal epilepsy.…”

High‐frequency oscillations: The state of clinical research

“…46,47 This suggests that it is critical to disconnect networks generating HFOs rather than remove all areas that generate HFOs prior to surgery. 47 It might also explain the negative association with postoperative seizure outcome in some patients, in whom HFO rates were assessed in presurgical chronic intracranial EEG recordings. An example of a patient who had residual fast ripples in the postsurgical electrocorticogram and who was not seizure-free after surgery is given in Figure 1.…”