Clinical outcomes of MR-guided laser interstitial thermal therapy corpus callosum ablation in drug-resistant epilepsy: a systematic review and meta-analysis.

OBJECTIVE: The goal of this systematic review and meta-analysis was to provide an updated analysis of studies investigating outcomes, morbidity, and mortality associated with MR-guided laser interstitial thermal therapy (MRgLITT) corpus callosum ablation (CCA). METHODS: Study inclusion criteria for screening required that studies report on human subjects only, including patients aged 1-52 years diagnosed with drug-resistant epilepsy who underwent CCA. Sixteen articles published between 2016 and 2023 were included for the systematic review and analysis, including 4 case reports, 11 case series, and 1 case-control study. Altogether, 85 pediatric and adult patients undergoing CCA were included in the systematic review (46 patients younger and 39 patients older than 21 years). The main outcome of seizure freedom was measured using the decrease in the frequency of atonic seizures following surgery, percentage of atonic seizure freedom following surgery, and percentage of overall seizure freedom following surgery. These measurements were made using data from the last follow-up for patients with at least 6 months of follow-up post-CCA. RESULTS: The extent of CCA differed across the pooled cohorts, including anterior two-thirds CCA (38.89%, n = 35) and posterior one-third CCA for completion of a prior partial CCA (22.22%, n = 20), complete CCA (27.78%, n = 25), or CCA of residual white matter in the case of subtotal initial ablation (5.56%, n = 5). Overall, 12.94% of the patients undergoing CCA experienced operational complications. The most common operative complications across 90 CCA operations were probe malpositioning (n = 6), hemorrhage (n = 5), off-target extension of splenium ablation to the thalamus (n = 1), infection (n = 1), and postoperative CSF leak (n = 1). Neurological deficits following CCA were reported as transient in 18.82% and permanent in 4.71% of patients across all studies. The most common neurological deficits were disconnection syndrome (n = 4) or transient hemiplegia (supplementary motor area-like syndrome; n = 4). The 6-month overall seizure freedom rate was 18.87% of 53 patients, and the atonic seizure freedom rate was 46.28% of 52 patients postoperatively. CCA resulted in an average decrease in atonic seizure rate from 8.30 to 1.65 atonic seizures per day (average decrease 80.12%). CONCLUSIONS: CCA is associated with an acceptable complication profile, and most patients experience a meaningful reduction in target seizure semiologies. Accurate MRgLITT probe placement is likely important for maximizing CCA while avoiding collateral damage. Avoidable complications of CCA include off-target ablation (and associated deficits), hemorrhage, and future surgery for residual CCA to palliate continued seizures.

Surgical Treatment of Drug-Resistant Generalized Epilepsy.

PURPOSE OF REVIEW: To summarize current evidence and recent developments in the surgical treatment of drug-resistant generalized epilepsy. RECENT FINDINGS: Current surgical treatments of drug-resistant generalized epilepsy include vagus nerve stimulation (VNS), deep brain stimulation (DBS) and corpus callosotomy (CC). Neurostimulation with VNS and/or DBS has been shown to be effective in reducing seizure frequency in patients with generalized epilepsy. DBS for generalized epilepsy is primarily consisted of open-loop stimulation directed at the centromedian (CM) nucleus in the thalamus, though closed-loop stimulation and additional targets are being explored. CC can be effective in treating some seizure types and can be performed using traditional surgical techniques or with the less invasive methods of laser ablation and radiosurgery. This current literature supports the use of VNS, DBS and CC, alone or in combination, as palliative treatments of drug-resistant generalized epilepsy.

Advances in Epilepsy Surgery.

BACKGROUND: A large number of patients have epilepsy that is intractable and adversely affects a child's lifelong experience with addition societal burden that is disabling and expensive. The last two decades have seen a major explosion of new antiseizure medication options. Despite these advances, children with epilepsy continue to have intractable seizures. An option that has been long available but little used is epilepsy surgery to control intractable epilepsy. METHODS: This article is a review of the literature as well as published opinions. RESULTS: Epilepsy surgery in pediatrics is an underused modality to effectively treat children with epilepsy. Adverse effects of medication should be weighed against risks of surgery as well as risks of nonefficacy. CONCLUSIONS: We discuss an approach to selecting the appropriate pediatric patient for consideration, a detailed evaluation including necessary evaluation, and the creation of an algorithm to approach patients with both generalized and focal epilepsy. We then discuss surgical options available including outcome data. New modalities are also addressed including high-frequency ultrasound and co-registration techniques including magnetic resonance imaging-guided laser therapy.

Cortex leads the thalamic centromedian nucleus in generalized epileptic discharges in Lennox-Gastaut syndrome.

OBJECTIVE: We aimed to assess the roles of the cortex and thalamus (centromedian nucleus [CM]) during epileptic activity in Lennox-Gastaut syndrome (LGS) patients undergoing deep brain stimulation (DBS) surgery as part of the ESTEL (Electrical Stimulation of the Thalamus for Epilepsy of Lennox-Gastaut Phenotype) trial. METHODS: Twelve LGS patients (mean age = 26.8 years) underwent bilateral CM-DBS implantation. Intraoperatively, simultaneous electroencephalogram (EEG) was recorded (range = 10-34 minutes) from scalp electrodes and bilateral thalamic DBS electrodes. Temporal onsets of epileptic discharges (generalized paroxysmal fast activity [GPFA] and slow spike-and-wave [SSW]) were manually marked on recordings from scalp (ie, "cortex") and thalamus (ie, CM-DBS electrodes). Phase transfer entropy (PTE) analysis quantified the degree of information transfer from cortex to thalamus within different frequency bands around GPFA events. RESULTS: GPFA was captured in eight of 12 patients (total event number across patients = 168, cumulative duration = 358 seconds). Eighty-six percent of GPFA events were seen in both scalp and thalamic recordings. In most events (83%), onset occurred first at scalp, with thalamic onset lagging by a median of 98 milliseconds (interquartile range = 78.5 milliseconds). Results for SSW were more variable and seen in 11 of 12 patients; 25.4% of discharges were noted in both scalp and thalamus. Of these, 74.5% occurred first at scalp, with a median lag of 75 milliseconds (interquartile range = 228 milliseconds). One to 0.5 seconds and 0.5-0 seconds before GPFA onset, PTE analysis showed significant energy transfer from scalp to thalamus in the delta (1-3 Hz) frequency band. For alpha (8-12 Hz) and beta (13-30 Hz) frequencies, PTE was greatest 1-0.5 seconds before GPFA onset. SIGNIFICANCE: Epileptic activity is detectable in CM of thalamus, confirming that this nucleus participates in the epileptic network of LGS. Temporal onset of GPFA mostly occurs earlier at the scalp than in the thalamus. This supports our prior EEG-functional magnetic resonance imaging results and provides further evidence for a cortically driven process underlying GPFA in LGS.

Altered integrity of corpus callosum in generalized epilepsy in relation to seizure lateralization after corpus callosotomy.

OBJECTIVE: Generalized-onset seizures are usually conceptualized as engaging bilaterally distributed networks with no clear focus. However, the authors previously reported a case series demonstrating that in some patients with generalized-onset seizures, focal seizure onset could be discovered after corpus callosotomy. The corpus callosum is considered to be a major pathway for seizure generalization in this group of patients. The authors hypothesized that, in patients with generalized-onset seizures, the structure of the corpus callosum could be different between patients who have lateralized seizures and those who have nonlateralized seizures after corpus callosotomy. The authors aimed to evaluate the structural difference through statistical analysis of diffusion tensor imaging (DTI) scalars between these two groups of patients. METHODS: Thirty-two patients diagnosed with generalized-onset motor seizures and without an MRI lesion were included in this study. Among them, 16 patients developed lateralized epileptic activities after corpus callosotomy, and the remaining 16 patients continued to have nonlateralized seizures after corpus callosotomy. Presurgical DTI studies were acquired to quantify the structural integrity of the corpus callosum. RESULTS: The DTI analysis showed significant reduction of fractional anisotropy (FA) and increase in radial diffusivity (RD) in the body of the corpus callosum in the lateralized group compared with the nonlateralized group. CONCLUSIONS: The authors' findings indicate the existence of different configurations of bilateral epileptic networks in generalized epilepsy. Generalized seizures with focal onset relying on rapid spread through the corpus callosum might cause more structural damage related to demyelination in the corpus callosum, showing reduced FA and increased RD. This study suggests that presurgical DTI analysis of the corpus callosum might predict the seizure lateralization after corpus callosotomy.

Epilepsy Surgery for Children With Low-Grade Epilepsy-Associated Tumors: Factors Associated With Seizure Recurrence and Cognitive Function.

OBJECTIVE: Low-grade epilepsy-associated tumors (LEATs) are associated with childhood seizures that are typically drug-resistant, necessitating surgical interventions. In this study, we aimed to investigate the efficacy of surgical intervention in children with LEATs and to identify factors associated with seizure and cognitive outcomes. METHODS: We reviewed 58 children less than 18 years of age who underwent epilepsy surgery due to histopathologically confirmed LEATs and had a minimum postoperative follow-up duration of 24 months. RESULTS: Of the 58 patients who were followed for a median duration of 5.6 (IQR 3.2 to 10.0) years, 51 (87.9%) were seizure-free after surgery. In univariate analysis, shorter epilepsy duration, fewer antiepileptic drugs at time of surgery, gross total resection, and unilobar tumor involvement were associated with seizure freedom. In multivariate analysis, gross total resection was independently associated with seizure freedom. The preoperative and postoperative full-scale intelligence quotient (FSIQ) scores were 78.9 ± 27.1 and 80.9 ± 28.7, respectively. In univariate analysis, younger age at seizure onset, longer epilepsy duration, more antiepileptic drugs at time of surgery, multilobar tumor involvement, and presence of generalized epileptic discharges were associated with lower preoperative FSIQ. In multivariate analysis, longer epilepsy duration was independently associated with lower preoperative FSIQ scores. Postoperative FSIQ scores were significantly influenced by preoperative FSIQ scores. CONCLUSIONS: Epilepsy surgery for LEATs in children resulted in excellent seizure outcome. Gross total resection was the only independent factor associated with favorable seizure outcome. Preoperative and postoperative cognitive abilities were significantly influenced by epilepsy duration, so early surgical intervention should be considered.

Corpus callosotomy via laser interstitial thermal therapy: a case series.

Corpus callosotomy has been used as a form of surgical palliation for patients suffering from medically refractory generalized seizures, including drop attacks. Callosotomy has traditionally been described as involving a craniotomy with microdissection. MR-guided laser interstitial thermal therapy (MRg-LITT) has recently been used as a minimally invasive method for performing surgical ablation of epileptogenic foci and corpus callosotomy. The authors present 3 cases in which MRg-LITT was used to perform a corpus callosotomy as part of a staged surgical procedure for a patient with multiple seizure types and in instances when further ablation of residual corpus callosum is necessary after a prior open surgical procedure. To the authors' knowledge, this is the first case series of corpus callosotomy performed using the MRg-LITT system with a 3.3-year average follow-up. Although MRg-LITT is not expected to replace the traditional corpus callosotomy in all cases, it is a safe, effective, and durable alternative to the traditional open corpus callosotomy, particularly in the setting of a prior craniotomy.

A modern epilepsy surgery treatment algorithm: Incorporating traditional and emerging technologies.

Epilepsy surgery has seen numerous technological advances in both diagnostic and therapeutic procedures in recent years. This has increased the number of patients who may be candidates for intervention and potential improvement in quality of life. However, the expansion of the field also necessitates a broader understanding of how to incorporate both traditional and emerging technologies into the care provided at comprehensive epilepsy centers. This review summarizes both old and new surgical procedures in epilepsy using an example algorithm. While treatment algorithms are inherently oversimplified, incomplete, and reflect personal bias, they provide a general framework that can be customized to each center and each patient, incorporating differences in provider opinion, patient preference, and the institutional availability of technologies. For instance, the use of minimally invasive stereotactic electroencephalography (SEEG) has increased dramatically over the past decade, but many cases still benefit from invasive recordings using subdural grids. Furthermore, although surgical resection remains the gold-standard treatment for focal mesial temporal or neocortical epilepsy, ablative procedures such as laser interstitial thermal therapy (LITT) or stereotactic radiosurgery (SRS) may be appropriate and avoid craniotomy in many cases. Furthermore, while palliative surgical procedures were once limited to disconnection surgeries, several neurostimulation treatments are now available to treat eloquent cortical, bitemporal, and even multifocal or generalized epilepsy syndromes. An updated perspective in epilepsy surgery will help guide surgical decision making and lay the groundwork for data collection needed in future studies and trials.

Case Report: Free Latissimus Dorsi Flap in Combination With Subdural Space Reduction for the Prevention of Recurrent Hemorrhage Following Hemispherectomy.

BACKGROUND AND IMPORTANCE: Extensive cerebral resections for the treatment of epilepsy may result in a large intracranial dead space that is prone to recurrent hemorrhage, either due to mechanical dislodgement or the development of extensive subdural membranes. Several techniques have been proposed to decrease the risk of hemorrhage by either reducing or filling the remaining intracranial dead space. CLINICAL PRESENTATION: We present a case of persistent hemorrhage following functional hemispherectomy in a patient with a large porencephalic cyst. A treatment strategy involving both subdural space reduction and cranial vault filling with a vascularized free latissimus dorsi flap is discussed. CONCLUSION: Subdural space reduction and cranial vault filling with a vascularized free latissimus dorsi flap is a viable treatment alternative in patients with large areas of intracranial dead space.

Successful corpus callosotomy for Doose syndrome.

Doose syndrome (epilepsy with myoclonic-atonic seizures) is an epilepsy syndrome with an incidence of approximately 1-2% of childhood-onset epilepsies. Although this syndrome is associated with multiple types of generalized seizures, the diagnosis is based on the presence of myoclonic-atonic seizures. Eighteen percent of patients have refractory seizures and intellectual disabilities. There have, however, been a few reports on the efficacy of surgical treatment for Doose syndrome. We describe a case of Doose syndrome in a 10-year-old boy. He developed generalized tonic-clonic seizures at 3years 8months of age and subsequently developed myoclonic-atonic, myoclonic, and tonic seizures. The frequent myoclonic seizures were refractory to multiple antiepileptic medications. His cognitive development was moderately delayed. Anterior four fifths corpus callosotomy was performed at 8years 5months of age. His seizures, especially myoclonic seizures, were markedly reduced. He was given vagus nerve stimulation therapy at 9years and 1month of age, which led to complete resolution of the myoclonic seizures. Corpus callosotomy can be a good treatment strategy in patients with Doose syndrome with medically refractory generalized seizures.

Clinical features and evolution of the gelastic seizures-hypothalamic hamartoma syndrome.

Gelastic seizures, usually with onset in early infancy, are the hallmark manifestation of hypothalamic hamartoma. This seizure type is directly generated by hamartoma itself, intrinsically epileptogenic because of its anatomofunctional organization. Other types of seizures, focal or generalized, may appear during the evolution, probably resulting from mechanisms of secondary epileptogenesis. Nevertheless, the clinical expression and the severity of the syndrome, ranging from a focal drug-resistant epilepsy to a catastrophic generalized encephalopathy with severe cognitive and behavioral impairments, depends on the size and the site of attachment of the hamartoma. Early suspicion, timely diagnosis, and appropriate treatment are mandatory to reverse a potential catastrophic evolution of this condition.

Identification of Focal Epileptogenic Networks in Generalized Epilepsy Using Brain Functional Connectivity Analysis of Bilateral Intracranial EEG Signals.

Simultaneous bilateral onset and bi-synchrony epileptiform discharges in electroencephalogram (EEG) remain hallmarks for generalized seizures. However, the possibility of an epileptogenic focus triggering rapidly generalized epileptiform discharges has been documented in several studies. Previously, a new multi-stage surgical procedure using bilateral intracranial EEG (iEEG) prior to and post complete corpus callosotomy (CC) was developed to uncover seizure focus in non-lateralizing focal epilepsy. Five patients with drug-resistant generalized epilepsy who underwent this procedure were included in the study. Their bilateral iEEG findings prior to complete CC showed generalized epileptiform discharges with no clear lateralization. Nonetheless, the bilateral ictal iEEG findings post complete CC indicated lateralized or localized seizure onset. This study hypothesized that brain functional connectivity analysis, applied to the pre CC bilateral iEEG recordings, could help identify focal epileptogenic networks in generalized epilepsy. The results indicated that despite diffuse epileptiform discharges, focal features can still be observed in apparent generalized seizures through brain connectivity analysis. The seizure onset localization/lateralization from connectivity analysis demonstrated a good agreement with the bilateral iEEG findings post complete CC and final surgical outcomes. Our study supports the role of focal epileptic networks in generalized seizures.

Clinical profiles for seizure remission and developmental gains after total corpus callosotomy.

PURPOSE: This study was aimed to determine what preoperative profiles were associated with seizure remission after corpus callosotomy and whether such seizure outcome was associated with the postoperative developmental outcome. METHODS: This retrospective study included 26 consecutive patients with childhood onset epilepsy who underwent one-stage total corpus callosotomy at our institution and were followed up for a minimum of 1 year. The age at surgery ranged from 13 months to 32 years (median 6 years). The association between postoperative seizure freedom and preoperative profiles, post-operative developmental gains was examined. RESULTS: Five patients achieved seizure freedom (Engel class I), and 10 patients achieved worthwhile reduction of seizures (class III), whereas the remaining patients had a class IV outcome. All five seizure-free patients had "lack of abnormal magnetic resonance imaging findings", "lack of proven etiology of seizures", and underwent "surgery at age 6 years or younger". These three factors were associated with seizure freedom (p<0.05, Fisher exact test). Post-operative gains in developmental quotient were significantly better in patients with seizure freedom than in those without (p<0.05, Mann Whitney U test). CONCLUSION: Our study replicated the notion that seizure remission can be achieved after total corpus callosotomy in subsets of patients with medically-uncontrolled epilepsy, and suggested that a better developmental outcome can be expected in patients benefiting from seizure freedom.

A unique ictal EEG pattern in a patient with the coexistence of generalized and focal epilepsy.

The coexistence of focal and generalized epilepsy is rare. We report on a 17-year-old male with drug-resistant focal epilepsy and idiopathic generalized epilepsy (IGE). He began to experience generalized tonic-clonic seizures (GTCS) at the age of 3 years, with a good response to phenobarbital. At the age of 14 years, he began to experience complex partial seizures (CPS). Video-electroencephalography (video-EEG) telemetry showed the coexistence of right temporal spikes and bursts of generalized spike-wave (GSW). The ictal EEG showed a unique EEG pattern characterized by a 4- to 5-second burst of GSW followed by rhythmic delta activity over the right temporal region. A magnetic resonance image (MRI) showed right hippocampal sclerosis. The patient underwent a right temporal lobectomy that significantly improved his seizure control. He was rendered seizure free of the complex partial seizures and improvement of the GTCS. This case illustrates a very uncommon ictal EEG pattern, and shows that the decision for surgery in patients with focal drug-resistant epilepsy should not be affected by coexistent generalized epilepsy.

Outcome of bipolar electrocoagulation with lesionectomy in the treatment of epilepsy involving eloquent areas.

BACKGROUND/AIMS: We have demonstrated previously that bipolar electrocoagulation on functional cortex (BCFC) is a safe and effective approach for epilepsy involving eloquent areas. Here, we report the results of BCFC with lesionectomy for patients with epileptogenic foci partially overlapping eloquent areas. METHODS: Forty patients who had been treated with lesionectomy with BCFC were retrospectively reviewed with regard to seizure outcome and neurological deficits. Ten similar patients who had received lesionectomy with multiple subpial transections (MST) were examined as a control group. RESULTS: In the lesionectomy group with BCFC, Engel class I was achieved in 18 (45%) patients, class II in 8 (20%) patients, class III in 8 (20%) patients and class IV in 6 (15%) patients. Five (12.5%) patients developed mild hemiparesis and 1 (2.5%) patient mild sensory dysphasia. In the lesionectomy group with MST, Engel class I was achieved in 3 (30%) patients, class II in 2 (20%) patients, class III in 3 (30%) patients and class IV in 2 (20%) patients. Two (20%) patients developed mild hemiparesis and 1 (10%) patient moderate hemiparesis. All these complications recovered within 1-12 months. CONCLUSIONS: Compared with MST, the outcome of BCFC with lesionectomy is similar. But since MST leads to mechanical injury, while BCFC causes thermal injury, the complications of BCFC seem less severe.

Functional reorganization in the patient with progressing glioma of the pure primary motor cortex: a case report with special reference to the topographic central sulcus defined by somatosensory-evoked potential.

BACKGROUND: The concept of human brain reorganization due to slow-growing lesions, including low-grade glioma, has been gradually and generally accepted. However, few cases have been reported in which the reorganization, especially in the topographic pure primary motor cortex, was observed during brain surgery. We report a case of slow-growing oligodendroglioma located in the pure primary motor cortex, as detected by magnetic resonance imaging that could be resected in part thanks to the brain plasticity. In addition, we describe a pitfall of topographic guidance using somatosensory-evoked potential (SEP) monitoring. CASE DESCRIPTION: A 36-year-old right-handed patient underwent resection of a gradually growing oligodendroglioma located in the right primary motor cortex, with no other adjacent lesions, 8 years after the initial biopsy. The central sulcus was defined with intraoperative SEP monitoring in both operations. Based on the findings of the intraoperative direct electrical stimulation under awake craniotomy, we suspect that motor function shifted posteriorly and reorganized beyond the central sulcus. CONCLUSIONS: Pure primary motor cortex could be reorganized by its own lesion. In reorganized brain, topographic central sulcus defined based on SEP findings may be an inappropriate guidance to estimate true functional area. In such a condition, intraoperative direct electrical stimulation under awake craniotomy makes it feasible to resect pure primary motor cortex invaded by tumors.

Losing the sound of concepts: damage to auditory association cortex impairs the processing of sound-related concepts.

Conceptual knowledge is classically supposed to be abstract and represented in an amodal unitary system, distinct from the sensory and motor brain systems. A more recent embodiment view of conceptual knowledge, however, proposes that concepts are grounded in distributed modality-specific brain areas which typically process sensory or action-related object information. Recent neuroimaging evidence suggested the significance of left auditory association cortex encompassing posterior superior and middle temporal gyrus in coding conceptual sound features of everyday objects. However, a causal role of this region in processing conceptual sound information has yet to be established. Here we had the unique chance to investigate a patient, JR, with a focal lesion in left posterior superior and middle temporal gyrus. To test the necessity of this region in conceptual and perceptual processing of sound information we administered four different experimental tasks to JR: Visual word recognition, category fluency, sound recognition and voice classification. Compared with a matched control group, patient JR was consistently impaired in conceptual processing of sound-related everyday objects (e.g., "bell"), while performance for non-sound-related everyday objects (e.g., "armchair"), animals, whether they typically produce sounds (e.g., "frog") or not (e.g., "tortoise"), and musical instruments (e.g., "guitar") was intact. An analogous deficit pattern in JR was also obtained for perceptual recognition of the corresponding sounds. Hence, damage to left auditory association cortex specifically impairs perceptual and conceptual processing of sounds from everyday objects. In support of modality-specific theories, these findings strongly evidence the necessity of auditory association cortex in coding sound-related conceptual information.

Surgically proven coexistence of focal and generalized epilepsy: a case report.

The coexistence of focal and idiopathic generalized epilepsy (IGE) is rarely observed, and the mechanism underlying this situation remains unknown. We report a 13-year-old girl with well-controlled generalized epilepsy and medically-refractory left temporal lobe epilepsy. She underwent intracranial EEG recording, which demonstrated two characteristic seizure patterns of generalized ictal onset and left mesial temporal onset. In addition, two types of interictal spike distribution, including the left mesial temporal region and generalized spikes, were also supportive of the coexistence of left mesial temporal lobe epilepsy and IGE. Thereafter, a left anterior temporal lobectomy and post-surgical medication significantly improved her seizure outcome. This case illustrates the importance of considering surgical management for patients with medically-intractable focal epilepsy coexisting with generalized epilepsy.

Transmantle sign in focal cortical dysplasia: a unique radiological entity with excellent prognosis for seizure control.

OBJECT: Focal cortical dysplasia (FCD) represents a spectrum of developmental cortical abnormalities and is one of the most common causes of intractable epilepsy in children and young adults. Outcomes after surgery for FCD are highly variable, and prognosticators of seizure freedom are unclear. In a subset of FCDs, a transmantle sign is observed on imaging that focally spans the entire cerebral mantle from the ventricle to the cortical surface. The aim of this study was to characterize seizure control outcomes and prognostic significance of the transmantle sign in FCD epilepsy. METHODS: Fourteen patients with the transmantle sign underwent epilepsy surgery for medically refractory epilepsy. Thirteen patients underwent resective surgery and 1 underwent multiple subpial transections with vagus nerve stimulator placement. Patient demographics, MRI, electroencephalography, intraoperative electrocorticography (ECoG), and pathology were reviewed. The results of this series were compared with those of 114 previously reported patients with FCD without the transmantle sign. RESULTS: All patients were found to have childhood seizure onset and concordant MRI and ECoG findings. The primary MRI findings associated with transmantle sign included gray-white junction blurring, appearance of cortical thickening, T2 or FLAIR abnormality, and bottom-of-the-sulcus dysplasia. The transmantle sign was usually a focal finding, typically confined to 1 or several gyri with well-circumscribed epileptic tissue. Correlation of the transmantle sign with FCD histopathological subtypes was highly variable. Patients who underwent complete resection of MRI and ECoG abnormalities (12 of 13 patients) became seizure free. When compared with 114 FCD patients without the transmantle sign, patients with the transmantle sign showed significantly improved seizure-free outcomes after complete resections (p = 0.04). CONCLUSIONS: The presence of the transmantle sign in patients with medically refractory partial epilepsy is associated with highly favorable seizure control outcomes after surgical treatment.