Candidate Selection for Implantation: Noninvasive Predictors of Seizure Onset Zone Focality and Surgical Outcome in People with Drug-Resistant Epilepsy Evaluated by Intracranial Video-EEG Monitoring—A Retrospective Cohort Study
Table 1
Diagnostic and surgical cohort description.
Variable
Diagnostic cohorta ()
Surgical cohortb ()
Focal SOZ ()
Nonfocal SOZ ()
Good outcome ()
Poor outcome ()
Epilepsy duration (years)
Age at evaluation (years)
Gender (male)
22 (56.4)
29 (50)
13 (56.5)
21 (51.2)
Seizure frequency
Daily
7 (17.9)
13 (22.4)
2 (8.7)
11 (26.8)
Weekly
21 (53.8)
35 (60.3)
12 (52.2)
23 (56.1)
Monthly
11 (28.2)
10 (17.2)
9 (39.1)
7 (17.1)
Presence of FBTCS
25 (64.1)
42 (72.4)
15 (65.2)
31 (75.6)
Failed ASMs
MRI lesion group
Focal lesion
8 (20.5)
9 (15.5)
6 (26.1)
3 (7.3)
Nonfocal lesion
8 (20.5)
12 (20.7)
6 (26.1)
8 (19.5)
Nonlesional
23 (59)
37 (63.8)
11 (47.8)
30 (73.2)
MRI lesion type
MTS alone or associated
5 (12.8)
5 (8.6)
6 (26.1)
2 (4.9)
CDM
9 (23.1)
11 (19)
4 (17.4)
7 (17.1)
Others
2 (5.1)
5 (8.6)
2 (8.7)
2 (4.9)
Normal or nonspecific
23 (59)
37 (63.8)
11 (47.8)
30 (73.2)
SVEM IEDs
Normal or focal only
24 (61.5)
28 (48.3)
15 (65.2)
21 (51.2)
Multifocal only
12 (30.8)
15 (25.9)
6 (26.1)
11 (26.8)
Generalised
3 (7.7)
15 (25.9)
2 (8.7)
9 (22)
SVEM ictal onset
Focal
23 (59)
27 (46.6)
12 (52.2)
23 (56.1)
Multifocal
2 (5.1)
9 (15.5)
3 (13)
3 (7.3)
Nonlocalising
14 (35.9)
22 (37.9)
8 (34.8)
15 (36.6)
Localisation hypothesis
TLE
21 (53.8)
31 (53.4)
16 (69.6)
18 (43.9)
FLE
10 (25.6)
17 (29.3)
7 (30.4)
14 (34.1)
PLE or OLE
7 (17.9)
4 (6.9)
0
5 (12.2)
TLE and ETE
1 (2.6)
6 (10.3)
0
4 (9.8)
Lateralisation hypothesis
Left
20 (51.3)
26 (44.8)
9 (39.1)
21 (51.2)
Right
15 (38.5)
17 (29.3)
10 (43.5)
13 (31.7)
Unknown
4 (10.3)
15 (25.9)
4 (17.4)
7 (17.1)
IVEM type (SEEG/subdural electrodes)
30/9
44/14
17/6
25/16
Bilateral SEEG
15 (50)
29 (65.9)
11 (64.7)
15 (60)
electrodes
1 (3.3)
7 (15.9)
0
5 (20)
SOZ focality
Sublobar
39 (100)
NA
15 (65.2)
11 (26.8)
Lobar
NA
22 (37.9)
5 (21.7)
13 (31.7)
Multilobar
NA
20 (34.5)
2 (8.7)
11 (26.8)
Bilateral
NA
16 (27.6)
1 (4.3)
6 (14.6)
Surgical outcome
Engel class I
15 (38.5)
8 (13.8)
23 (100)
NA
Engel class II
6 (15.4)
9 (15.5)
NA
15 (36.6)
Engel class III
3 (7.7)
10 (17.2)
NA
13 (31.7)
Engel class IV
2 (5.1)
11 (19)
NA
13 (31.7)
year or no surgery
13 (33.3)
20 (34.5)
NA
NA
Follow-up after surgery (years)
NA
NA
Note: data are given in for continuous variables or number (percentage) for categorical variables. Abbreviations: ASMs: antiseizure medications; CDM: cortical development malformation; ETE: extratemporal epilepsy; FBTCS: focal to bilateral tonic-clonic seizures; FLE: frontal lobe epilepsy; IEDs: interictal epileptiform discharges; IVEM: intracranial video-EEG monitoring; MRI: magnetic resonance imaging; MTS: mesial temporal sclerosis; NA: not applicable; OLE: occipital lobe epilepsy; PLE: parietal lobe epilepsy; SEEG: stereoelectroencephalography; SOZ: seizure onset zone; SVEM: scalp video-EEG monitoring; TLE: temporal lobe epilepsy. aThe diagnostic cohort comprised people with DRE evaluated by IVEM with a conclusive result. Focal SOZ was defined as a sublobar ictal onset identified on IVEM. Nonfocal SOZ included a lobar, multilobar, or bilateral ictal onset on IVEM. bThe surgical cohort was defined as patients evaluated by IVEM who underwent a surgery and a minimum follow-up of one year. Good outcome was considered as a postoperative outcome of Engel class I. Poor outcome included a postoperative outcome of Engel class II or worse.
