Case 1: Thirty-one-year-old, right-hand dominant male. He began having seizures at the age of 3 years. At the time of surgical evaluation, he presented two types of seizures. First type was nocturnal focal aware seizures with prominent type-1 hypermotor features.^{Reference Rheims, Ryvlin and Scherer12} Second type was less frequent, consisted of daytime focal unaware seizures with behavioral arrest and blurry vision that occasionally progressed to bilateral tonic-clonic (BTC) seizures. Neuropsychological evaluation showed left language dominance and non-lateralizing frontotemporal dysfunction. MRI was normal. Scalp EEG revealed bilateral frontotemporal spikes and seizures with activity more prominent in the right frontal lobe. The patient underwent invasive EEG recording in the form of subdural strips covering bifrontal and bitemporal regions on two occasions. On the first occasion, the patient had no seizures while admitted to the epilepsy unit. On the second occasion, orbitofrontal spikes were found, and supplementary strips in the orbitofrontal area were implanted. Four seizures were captured from the right orbitofrontal area and one from the right mesial temporal region. A staged resection was proposed: first, the orbitofrontal region was partially resected, but the patient continued having seizures with the same frequency and semiology. SEEG was then performed covering the right temporal and orbitofrontal regions: three independent seizures originating in the right mesial temporal region and in the ipsilateral orbitofrontal cortex, adjacent to the previous resection, were found. The patient underwent a right-sided ATL with additional orbitofrontal resection (Figure 1A). He has been seizure-free with persistence of occasional auras with a follow-up time of 2.4 years.

Case 2: Thirty-two-year-old, right-hand dominant male with a history of reflex epilepsy triggered by eating for 5 years. The patient sustained somatosensory seizures with oral automatisms, left head and eye deviation, and postictal right-hand nose wiping. Neuropsychological testing was normal with left language lateralization. MRI revealed hippocampal sulcus remnant cysts on the right. These were considered incidental findings with no abnormal changes in hippocampal volume or signal. PET scan was normal. Scalp EEG showed right temporal seizures extending to the suprasylvian region. The patient was investigated with SEEG, and seven seizures with simultaneous onset in the right hippocampus and inferior insula were recorded (Figure 2). The patient was offered a right ATL with partial resection of the insular cortex. The latter was performed with the aid of neuronavigation, accessing the insula transpially and resecting the tissue that overlapped the active contacts of the depth electrodes involved (Figures 1B, 3A–J and 4A and B). Patient has remained seizure-free since surgery, 1.3 years ago.

Case 3: Twenty-seven-year-old, right-hand dominant male with seizure onset at the age of 14 years. He experienced focal unaware sensory seizures with gustatory auras, left-head version and dystonic posturing. Ictal spitting was frequently present and BTC seizures were common. Neuropsychological evaluation lateralized language to the left hemisphere and was otherwise normal. MRI showed no focal abnormality. PET scan showed hypometabolism of the right temporal lobe. VEEG lateralized seizures to the right hemisphere but was non-localizing. SEEG identified 12 seizures arising from the right hippocampus and simultaneously in the right anterior and posterior insular electrodes (Figure 5). The surgery was a right ATL with partial insulectomy (Figure 1C). Patient is seizure-free after 1.3 years of follow-up.

Case 4: Forty-year-old, right-hand dominant female with seizure onset when she was 9 months old. Semiologically, she experienced focal emotional seizures with impaired awareness. Seizures began with fear/anxiety and occasionally with paresthesias in both her feet. This would typically progress to slurred speech or vocalization, rightward head deviation, clonic jerking of the left arm, and progression to BTC seizures. Neuropsychology revealed left language dominance which was confirmed during Wada test, and bilateral temporal memory dysfunction. MRI revealed bilateral hippocampal volume reduction. The scalp VEEG found left anterior temporal onset in all recorded seizures. The decision was made to proceed with invasive investigations using bilateral subdural strips, which revealed left-sided temporal lobe seizures. A left ATL was performed, which rendered her seizure-free for 3 years. After seizure recurrence, seizures seemed to have the same semiology. EEG showed mostly posterior left temporal seizures. A new invasive investigation with depth electrodes was suggested. The SEEG study revealed numerous spikes and electrographical seizures arising in the posterior hippocampus. Six clinical seizures were obtained with clear onset over the left anterior-inferior insula. Based on these findings, an additional anterior insulectomy was performed (Figure 1D). Despite having occasional auras, patient has remained seizure-free after 4.5 years following the procedure.

Case 5: Forty-six-year-old, left-hand dominant female with seizure onset at the age of 2 months. She had congenital hydrocephalus, which required shunting in the neonatal period. She experienced nocturnal progression to BTC and daytime focal unaware seizures with behavioral arrest and right-hand automatisms. Neuropsychology identified left language dominance and left frontal and neocortical dysfunction with memory preserved bilaterally. MRI showed moderately enlarged ventricles, but no focal abnormalities were found. Abundant right temporal spikes as well as right frontotemporal seizures were identified in scalp EEG. Five seizures were recorded during the SEEG study, four of them with onset in the right amygdala and hippocampus, and one seizure with clear onset in the right orbitofrontal cortex (posterior gyrus rectus and adjacent orbital gyrus). Unfortunately, during the fifth seizure, the electrodes were accidentally explanted. Despite this, sufficient information was obtained to recommend a right ATL with orbitofrontal corticectomy (Figure 1E). Patient is seizure-free at 1.3 years following the surgery.

Case 6: Forty-year-old, right-hand dominant female with seizure onset at the age of 27 years. A right-sided insular cavernoma was found and a resective surgery was undertaken initially. Seizures recurred within 3 months, mostly consisting of behavioral arrest, bimanual automatisms, and left arm jerking. Neuropsychology identified atypical language laterality and memory preserved bilaterally. MRI showed hemosiderosis in the right insula. Right frontotemporal spikes were identified in scalp EEG but no seizures were captured. She underwent invasive recording of the right frontotemporal region via subdural electrodes. Numerous seizures arose from the right mesial temporal region. An ATL with visual exploration of the insula was conducted; however, no tissue was resected in the latter structure. The patient was seizure-free for 3 years, after which the episodes recurred with the same semiology and became increasing in frequency after 5 years. Forty-seven seizures were recorded during the SEEG study, all arising from the right insula. A supplementary insular corticectomy was performed (Figure 1F) and the patient is free of disabling seizures at 4.7 years following the surgery (Engel 1c).