Supplemental Table 1. Neuroimaging and Neurophysiology Findings and Clinical Impressions.
Suspected Epileptogenic Zone*
Subject MRI Findings Interictal SEEG Ictal SEEG Surgery Performed Outcome
Subj. 1 Right mesial temporal sclerosis, right thalamic and periventricular white matter loss, cystic change near right caudothalamic notch, severe thinning of corpus callosum, right cerebral peduncle smaller than the left, and punctate foci of hemosiderin in both hemispheres (likely perinatal stroke)
Frequent-to-abundant IEDs in right hippocampus and amygdala;
occasional IEDs seen in temporal neocortex
Onset in right hippocampus and amygdala
Right hippocampus and amygdala
R temporal lobectomy sz-free
Subj. 2 Subtle left temporal/hippocampal T2 hyperintensity
Frequent-to-abundant IEDs in the left hippocampus, amygdala, and anterior temporal neocortex;
occasional IEDs in the insula, temperoparietal junction, and lateral temporal neocortex
Initial seizures with onset isolated to left
hippocampus and early spread to amygdala; later seizures in a cluster included concurrent or initial onset in the insula
Left hippocampus and amygdala with possible secondary insular site
L hippocampus laser ablation
sz-persist
Subj. 3 Mild volume loss of right anterior
temporal lobe Frequent IEDs in right hippocampus;
occasional IEDs in the lateral temporal neocortex
Seizures arising from the right hippocampus
Right hippocampus R temporal lobectomy sz-free
Subj. 4 Postoperative changes showing partial left anterior medial temporal lobectomy, T2 hyperintensity in the remaining anterior left temporal lobe, and nodular subependymal gray matter heterotopia adjacent to the right frontal horn
IEDs were abundant in the anterior insula, posterior margin of the insula, temporal operculum, and superior temporal gyrus
Two seizure onset zones:
1) posterior margin of insula; 2) temporal operculum (6 seizures)
L insula, temporal operculum, and superior temporal gyrus
L temporal lobe, anterior/inferior L insula resection
sz-free
Subj. 5 Small right temporal pole with abnormal signal and blurring of the gray-white junction; malrotated right hippocampus with intrinsic signal abnormality and loss of internal architecture
IEDs abundant in anterior and posterior hippocampus and amygdala; occasional IEDs in anterior and posterior insula and posterior cingulate
Anterior hippocampus and amygdala
R hippocampus and amygdala
R temporal lobectomy sz-free
Subj. 6 Nonspecific punctate T2
hyperintensities in frontal lobe Frequent IEDs arising from L amygdala, anterior and posterior hippocampus, and anterior and posterior insula
Eight seizures arising from the left hippocampus and a single seizure arising from the anterior insula
Left hippocampus L Temporal lobectomy sz-persist
(semiologically similar to the others and amygdala electrode was non- functional during this event)
Subj. 7 Subtle volume loss of left temporal lobe; increased left hippocampus T2 signal without volume loss
Intrinsic epileptogenicity at the temporal operculum, abundant IEDs in the anterior and posterior insula, frequent IEDs in the hippocampus, and occasional IEDs in the amygdala
Temporal operculum onset with rapid spread to anterior insula
Temporal operculum and anterior insula
L STG and inferior anterior insula resection
sz-free
Subj. 8 Subtle cortical thickening and gray- white matter blurring in the anterior left frontal lobe
Abundant IEDs in superior frontal sulcus (aligned with MRI lesion)
Superior frontal sulcus seizure onset
Superior frontal sulcus lesion
L superior frontal gyrus and neighboring sulcal resection
sz-persist
Subj. 9 Originally had a left parietal vascular lesion resected prior to epilepsy;
pre-surgical MRI showed left parietal and posterior temporal resection cavity with T2 hyperintense margins, areas of cystic encephalomalacia along the mesial left parietal region
Abundant IEDs in primary sensory cortex; frequent IEDs in the supramarginal gyrus, precuneus, and inferior parietal lobule
Earliest onset in primary sensory cortex with rapid spread across anterior parietal lobe and supplementary sensorimotor cortex
Sensory cortex and surrounding tissue
L parietal lobe resection
sz-free
Subj. 10 Focal area of gliosis and atrophy in right posterior parasagittal parietal lobe
Frequent IEDs near parietal lesion and throughout the hippocampus;
occasional IEDs at the temporal- occipital junction, calcarine cortex, and inferior occipital gyrus
Majority of seizures arose from anterior
hippocampus with a single atypical seizure arising from the isthmus of the cingulate
R hippocampus R partial temporal lobectomy and amygdalohippocampe ctomy
sz-persist
Subj. 11 Subtle area of gray/white blurring along a gyrus at the mesial posterior left frontal lobe
Frequent-to-abundant IEDs from inferior frontal gyrus near the lesion, mid cingulate gyrus, and leg motor cortex
Seizures arose from mid- cingulate gyrus
Medial frontal lobe lesion near primary leg motor and cingulate
L medial frontal lesionectomy
sz-persist
Subj. 12 Foreshortened corpus callosum and
incompletely inverted hippocampi Frequent synchronous IEDs across medial and lateral temporal cortex with spread to TPOJ, supramarginal gyrus, and orbitofrontal cortex
Single atypical seizure with diffuse onset maximal in anterior temporal neocortex
R temporal lobe R temporal lobectomy sz-persist
Subj. 13 Small right hippocampus with obscured internal architecture; right frontal/anterior insula heterotopia and neighboring dysplasia
Abundant IEDs in pars triangularis and anterior insula; occasional-to- frequent discharges in orbitofrontal cortex, gyrus rectus, and middle temporal gyrus
Seizure onset in right anterior insula with broad perisylvian spread
R anterior insula R anterior insula resection
sz-persist
Subj. 14 Right frontal subcortical lesion, involving cortex, non-enhancing and stable over time
Frequent IEDs in the frontal pole, orbitofrontal cortex, anterior cingulate, and medial frontal lobe.
Heralding spikes in anterior cingulate followed by evolving fast activity in the medial frontal lobe lesion
R medial frontal lobe lesion
R motor-sparing frontal lobectomy
sz-free
Subj. 15 Remote infarct with posterior frontal and perirolandic cortical and white matter volume loss with gliosis;
encephalomalacia extends from the trigone of the left lateral ventricle to the posterior parietal cortex with mild cortical and white matter volume loss; a third small focus of
encephalomalacia in the deep white matter adjacent to the trigone of the right lateral ventricle is identified
Abundant IEDs arising from anterior parietal lobe around area of encephalomalacia; occasional-to- frequent IEDs seen in lateral parietal cortex, posterior insula, and middle and superior frontal gyri
Seizures arising from superior parietal lobe
Right parietal area of encephalomalacia and surrounding parietal cortex
R lateral parietal lobe partial resection
sz-persist
Subj. 16 Probable focal cortical dysplasia in
the anterior right temporal lobe IEDs continuous at temporal tip, frequent in hippocampus and posterior insula
Seizures arose from posterior insula
Suspected posterior insula seizure onset but resection planned to include suspected FCD in temporal lobe
R anterior temporal lobectomy,
amygdalohippocampe ctomy, mid insula resection
sz-persist
Subj. 17 Subtle focal blurring in orbitofrontal
region Frequent-to-abundant IEDs broadly
distributed across the frontal lobe including the inferior and middle frontal gyri, orbitofrontal cortex, and middle and anterior cingulate;
rare IEDs in the posterior insula, hippocampus, and superior temporal gyrus
Seizures arose
synchronously across the inferior and middle frontal gyri and orbitofrontal cortex
Broad onset through frontal lobe centered around orbitofrontal cortex
R frontal lobe disconnection
sz-free
Subj. 18 No abnormalities identified Frequent IEDs arising from the hippocampus and amygdala; rare IEDs arising from the inferior frontal gyrus
Seizures arising from anterior and posterior hippocampus and amygdala
Right medial temporal lobe
R temporal lobectomy sz-free
Subj. 19 R>L hippocampal T2 hyperintensity, obscured internal architecture;
similar in anterior temporal lobes R>L
Abundant IEDs in the hippocampus, frequent IEDs in the insula
150 seizures arose from the right temporal lobe; 2 seizures started in the anterior insula
Multifocal:
Hippocampus and anterior insula
R temporal lobectomy sz-free
Subj. 20 Embolized AVM in right temporal
lobe Occasional-to-frequent IEDs arising
from anterior hippocampus and amygdala
Onset in right anterior hippocampus and amygdala
Right medial temporal lobe
R temporal lobectomy sz-free
Subj. 21 Left anterior and medial temporal cortical dysplasia, left hippocampal sclerosis
Abundant IEDs in the temporal tip, anterior superior temporal gyrus, amygdala, and hippocampus;
frequent IEDs in the orbitofrontal cortex and anterior insula
Two patterns with one seizure population arising from the amygdala and anterior hippocampus and the second arising from the temporal tip
Medial temporal lobe and anterior temporal neocortex
L temporal, hippocampal, basal frontal lobectomy
sz-persist
Subj. 22 No abnormalities identified. Abundant IEDs in the superior temporal gyrus, middle temporal gyrus, temporal tip, amygdala, and hippocampus; occasional IEDs in the precuneus, cuneus, hand motor, primary visual cortex, middle temporal gyrus, and basal temporal cortex
Seizures arising from anterior temporal neocortex
Anterior temporal lobe L temporal neocortex resection
sz-persist
*This is the suspected epileptogenic zone based on a combination of the pre-implantation imaging and neurophysiology as well as the results of the SEEG findings. Abbreviations: IED, interictal epileptiform discharge; R, right; L, left; FCD, focal cortical dysplasia; AVM: arteriovenous malformation.