Table 2.
Interictal data and earliest solution source localization results
| Patient | IEDs | IED lead time | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Total, n | EEG only, n | MEG only, n | Both, n | Peaks averaged, n (modalitya) | Earliest source solution | Earliest EZ agreement | EEG take-off to early ESL, ms | Earliest source to ESL, ms | MEG take-off to early MSL, ms | Earliest source to MSL, ms | EMEG take-off to early EMSL, ms | Earliest source to EMSL, ms | |
| Preoperative | |||||||||||||
| 1 | 176 | 66 | 40 | 70 | 110 (MEG) | ESL, EMSL | ESL | 5 | 0 | 10 | 45 | 5 | 0 |
| 2 | 11 | 0 | 0 | 11 | 8 (EEG) | MSL | MSL | 8 | 4 | 14 | 0 | 15 | 1 |
| 3 | 63 | 17 | 37 | 9 | 46 (MEG) | MSL, EMSL | MSL, EMSL | 7 | 22 | 6 | 0 | 6 | 0 |
| 4 | 98 | 35 | 23 | 40 | 63 (MEG) | MSL, EMSL | MSL | 4 | 15 | 6 | 0 | 6 | 0 |
| 5 | 34 | 11 | 6 | 17 | 23 (MEG) | MSL, EMSL | MSL | 0 | 43 | 6 | 0 | 6 | 0 |
| 6 | 36 | 16 | 10 | 10 | 26 (EEG) | MSL, EMSL | MSL, EMSL | 9 | 33 | 0 | 0 | 0 | 0 |
| 7 | 279 | 234 | 7 | 38 | 272 (EEG) | MSL | ESL | 12 | 12 | 5 | 0 | 8 | 3 |
| 8 | 87 | 30 | 42 | 15 | 57 (MEG) | MSL, ESL, EMSL | MSL, EMSL | 0 | 0 | 0 | 0 | 0 | 0 |
| 9 | 84 | 50 | 8 | 26 | 76 (EEG) | ESL | ESL | 4 | 0 | 13 | 1 | 14 | 2 |
| 10 | 122 | 70 | 11 | 41 | 111 (EEG) | ESL, EMSL | ESL, EMSL | 0 | 0 | 5 | 5 | 0 | 0 |
| 11 | 133 | 0 | 2 | 131 | 131 (EEG) | MSL, EMSL | MSL, EMSL | 1 | 23 | 3 | 0 | 3 | 0 |
| 12 | 181 | 94 | 46 | 41 | 135 (EEG) | MSL, EMSL | MSL | 14 | 14 | 2 | 0 | 2 | 0 |
| 13 | 170 | 3 | 0 | 167 | 170 (EEG) | MSL,ESL, EMSL | MSL, ESL, EMSL | 24 | 0 | 24 | 0 | 24 | 0 |
| All | 1474 | 626 (42%) | 232 (16%) | 616 (42%) | Median | 5 | 12 | 6 | 0 | 6 | 0 | ||
| Range | 0–24 | 0–43 | 0–24 | 0–45 | 0–24 | 0–3 | |||||||
| Postoperative | |||||||||||||
| 1 | 151 | 10 | 21 | 120 | 130 (EEG) | MSL | 10 | 29 | 5 | 0 | 5 | 0 | |
| 5 | 92 | 64 | 6 | 22 | 28 (MEG) | ESL, EMSL | 0 | 0 | 0 | 5 | 0 | 0 | |
| 10 | 155 | 41 | 40 | 74 | 114 (MEG) | ESL | 0 | 0 | 3 | 8 | 7 | 7 | |
A higher proportion of discharges were seen in HDEEG alone against MEG alone. EMSL solutions that agreed with the epileptogenic zone (based on ICEEG or SU concordance) never occurred in isolation as opposed to ESL (three patients) and MSL (four patients).
aModality (HDEEG or MEG) chosen for averaging was based on relative discharge count and SNR maxima. Note that the modality used for averaging had no bearing on the modality that gave rise to the earliest source solution (Fisher’s exact test, not shown).