Table 3.
Seizure outcomes and associated factors
| Engel I | Engel II–IV | p value | ||
|---|---|---|---|---|
| A) Patient demographics | ||||
| Age at surgery | years | 26.3 ± 1.5 | 29.5 ± 2.4 | 0.26 |
| Gender | Male | 54 (74) | 19 (26) | 0.26 |
| Female | 38 (64) | 21 (36) | ||
| Handedness | Right | 66 (68) | 31 (32) | 0.91 |
| Left | 13 (72) | 5 (28) | ||
| Ambidextrous | 3 (75) | 1 (25) | ||
| Not yet lateralized or unknown | 10 (77) | 3 (23) | ||
| B) Epilepsy characteristics | ||||
| Duration epilepsy | years | 13.4 ± 1.2 | 15.5 ± 1.8 | 0.34 |
| Seizure frequency | no. per week | 10.2 ± 2.3 | 13.0 ± 3.5 | 0.50 |
| AED regimen tried | no. | 4.5 ± 0.3 | 5.7 ± 0.5 | 0.03* |
| Epilepsy risk factors | no. | 0.78 ± 0.10 | 0.85 ± 0.12 | 0.69 |
| Lobe involved | Temporal | 55 (73) | 20 (27) | 0.43 |
| Frontal | 16 (59) | 11 (41) | ||
| Parietal | 5 (71) | 2 (29) | ||
| Occipital | 4 (80) | 1 (20) | ||
| Multi-lobe | 8 (57) | 6 (43) | ||
| Hemispherectomy | 4 (100) | 0 | ||
| Primary Pathology | Gliosis only | 23 (55) | 19 (45) | 0.05 |
| FCD | 26 (79) | 7 (21) | ||
| MTS | 21 (84) | 4 (16) | ||
| Tumor | 17 (77) | 5 (23) | ||
| Ischemia/infarct | 3 (60) | 2 (40) | ||
| Other | 2 (40) | 3 (60) | ||
| History of generalized seizures | Yes | 48 (62) | 30 (38) | 0.02* |
| No | 44 (82) | 10 (18) | ||
| C) Pre-operative diagnostics | ||||
| MEG | Concordant and specific | 58 (85) | 10 (15) | < 0.001* |
| Non-specific or discordant | 13 (37) | 22 (63) | ||
| No spikes modelled | 21 (72) | 8 (28) | ||
| MRI | Abnormal | 79 (73) | 30 (27) | 0.14 |
| Normal | 13 (57) | 10 (43) | ||
| Ictal scalp EEG | Localized | 63 (80) | 16 (20) | < 0.01* |
| Not localized | 26 (52) | 24 (48) | ||
| Implanted ECoG | Performed | 35 (60) | 23 (40) | 0.06 |
| Not performed | 57 (77) | 17 (23) | ||
| PET (when performed) | Abnormal | 17 (65) | 9 (35) | 0.12 |
| Normal | 12 (92) | 1 (8) | ||
| D) Operative factors | ||||
| Side of surgery | Right | 39 (71) | 16 (29) | 0.85 |
| Left | 53 (69) | 24 (31) | ||
| Intra-operative ECoG | Performed | 76 (70) | 32 (30) | 0.81 |
| Not performed | 16 (67) | 8 (33) | ||
| Extent of resection (Tumor, vascular malformation, tuber, cyst only) | Gross-total | 16 (80) | 4 (20) | 0.05 |
| Subtotal | 2 (33) | 4 (67) | ||
| Previous resection | No | 80 (71) | 32 (29) | 0.30 |
| Yes | 12 (60) | 8 (40) | ||
| TOTAL | 92 (70) | 40 (30) | ||
Data are N (%) for categorical variables or mean ± SEM for continuous variables.
*
Statistically significant value (p < 0.05) from χ2 test (categorical) or t-test (continuous) comparing patients with Engel I versus II–IV seizure outcomes.
AED: anti-epileptic drug; ECoG: electrocorticography, EEG: electroencephalography; FCD: focal cortical dysplasia; MEG: magnetoencephalography; MRI: magnetic resonance imaging; MTS: mesial temporal sclerosis; PET: positron emission tomography.