Surgical treatment of intractable epilepsy combined with bipolar electrocoagulation on functional cortex

OBJECTIVE: Resecting epileptogenic foci combined with bipolar electrocoagulation of functional cortex has been successfully used to treat intractable epilepsy. METHOD: 124 cases with intractable epilepsy have been treated from 1996 to 1999, 75 cases with temporal lobe epilepsy and 48 cases with extra-temporal lobe epilepsy, and one case with infantile hemiplegia. Electrocorticography (ECoG) was used pre- and postoperatively. 108 cases were followed-up from one to three years. RESULTS: The general efficiency of bipolar electrocoagulation on functional cortex (BCFC) for epilepsy is 91.7%. The pathological features indicate that the damage by coagulation of the cortex is only in the supra- and infra-granular layers, similar to multiple subpial transection (MST). CONCLUSION: When the epileptogenic foci are located in functional cortex, the method of resecting the foci combined with BCFC has been effective and improves the results greatly. BCFC is safe and easy to use.     

Application of neuronavigator coupled with an operative microscope and electrocorticography in epilepsy surgery

Application of neuronavigator coupled with an operative microscope and electrocorticography (ECoG) is a new trial for epilepsy surgery for achieving better seizure outcome and better efficiency for lesionectomy. We used a neuronavigator coupled with a microscope to delineate the magnetic resonance image-detected lesion for lesionectomy and used ECoG for evaluation of the epileptogenic foci. There were 46 patients with medically intractable partial seizures who underwent craniotomy for epilepsy surgery. Half of the patients had lesions at the temporal lobe and another half at the extratemporal lobe. Sixty-one percent of the patients were seizure-free (grade I) and 22% were nearly seizure-free (grade II). Overall, 83% of the patients had satisfactory seizure control. Complete lesion removal was successful in 37 patients (80%). For lesions with requiring complete removal, neuronavigator coupled with a microscope was 95% effective for lesionectomy. Class A of postresection ECoG had a higher rate of seizure-free outcome (92%) (P < .05). On the other hand, 93% of patients (26/28) with seizure-free outcome (grade I) needed complete lesion resection (P < .05). Lesions at the extratemporal lobe yielded a higher rate of seizure-free outcome (78.2%, 18/23) (P < .05). Application of neuronavigator and ECoG (additional cortical resection) is usually necessary for temporal lobe lesions. All patients with cavernous hemangioma were seizure-free. The complication rate in our study was 8.7%. Neuronavigator coupled with a microscope provides efficacy and safety to complete lesionectomy, which is a key point of seizure outcome. Intraoperative ECoG is valuable for evaluating the epileptogenic foci for epilepsy surgery especially for lesions at the temporal lobe.     

Surgical treatment of seizures from the peri-Sylvian area by perinatal insult: a case report of ictal hypersalivation

Summary Objectives and importance. It is important to evaluate the seizure manifestation of epilepsy before surgical planning. A patient with partial epilepsy manifesting hypersalivation who underwent resection of the epileptogenic foci with satisfactory postoperative seizure control is reported.Clinical presentation and intervention. A 26-year-old man, with a history of perinatal asphyxia, started having medically intractable partial epilepsy at the age of 10 years. His seizure was characterized by throat discomfort followed by hypersalivation. Brain MRI showed an atrophic lesion around the peri-Sylvian area. Scalp recorded EEG did not demonstrate robust epileptiform activity localized enough to define the epileptogenic zone. The patient underwent invasive recording by multiple subdural electrode grids, which showed that the seizure arose from the left anterior frontal operculum. After resection of epileptogenic opercular cortex, the seizures disappeared with no additional neurological deficits.Conclusion. Although the responsible sites for ictal drooling are distributed in multiple areas including insula, medial temporal area and operculum, the seizure can be successfully controlled by focus resection of the frontal opercular area in a selected patient with careful presurgical evaluation.     

Access to the posterior medial temporal lobe structures in the surgical treatment of temporal lobe epilepsy

The authors describe a surgical technique that allows access to the posterior temporal horn of the lateral ventricle with preservation of the most functional lateral temporal cortex. Development of the technique was stimulated by the need to resect posteromedial temporal lobe structures in patients with intractable complex partial epilepsy and well-identified unilateral posterior hippocampal foci. This technique has also been of value in the resection of some lateral ventricular and posteromedial temporal lobe masses. The operation consists of three steps. No more than 4.5 cm of the anterolateral temporal lobe is removed en bloc such that the most anterior aspect of the temporal horn is entered. An incision is carried from the floor of the temporal horn through the inferior longitudinal fasciculus to the middle fossa dura mater and posteriorally into the lateral ventricular atrium. The lateral temporal cortex and white matter are then elevated with a self-retaining retractor. This exposes the posteromedial temporal horn or intraaxial mass for excision or allows en bloc resection of the entire hippocampus and medial temporal lobe structures while preserving the functional association areas of the lateral temporal cortex, including speech and visual spatial function.     

Surgical therapy for medically intractable epilepsy

There has been a recent renewal of interest in surgical therapy for medically intractable epilepsies. Cortical resection and callosotomy are the most widely accepted modes of surgical management. The indications for each of these approaches are reviewed. Although there has been much interest in imaging techniques, including positron emission tomography, to identify epileptogenic zones, identification still depends primarily on the electroencephalogram (EEG). There are several approaches to the evaluation and intraoperative management of patients undergoing cortical resection for temporal lobe epileptogenic zones. These range from selection based on scalp interictal EEG criteria, with resections guided by electrocorticography and functional mapping, to selection based on the location of ictal onset as recorded by chronically implanted depth electrodes, with an anatomically standard resection of the temporal lobe or resection limited to amygdalohippocampectomy. No one approach provides the optimum balance of benefits to risks and costs for all patients. The relative value of the different approaches for various populations of patients with medically intractable partial complex seizures is reviewed. Techniques for minimizing the morbidity of these operations, especially in regard to language and memory, are also discussed, as are the contributions to an understanding of the neurobiology of human epilepsy and human higher functions derived from the surgical therapy of epilepsy.     

颞叶癫痫的诊断和外科治疗

目的　探讨颞叶癫痫的诊断和治疗方法。　方法　利用EEG和MR对 3 0例颞叶癫痫(TLE)病例的癫痫灶进行定位诊断 ,依据诊断结果对其中 15例实施前颞叶切除术 ,另 15例接受选择性海马杏仁切除术 ,并分析其近期疗效及随访结果。　结果　 3 0例病例中手术疗效满意 18例 ;显著11例 ;良好 1例 ,术后无并发症发生。　结论　MR有助于对TLE的定位诊断 ;手术是治疗顽固性TLE的重要手段 ,对于EEG和MR提示为颞叶内侧癫痫的病例应选用选择性海马杏仁核切除 ,采用经颧弓颞底入路使手术更为安全。     

Surgical treatment for extratemporal epilepsy

Opinion statement Partial seizures of extratemporal origin may present unique challenges in the patient with medically refractory seizures. The efficacy of an extratemporal focal cortical resection may be less effective than an anterior temporal lobectomy for intractable epilepsy. The potential operative complications may be increased in individuals with extratemporal epilepsy because of functional cerebral cortex involvement and the need for a large cortical resection to significantly reduce seizure tendency. Partial seizures of extratemporal origin are predominantly associated with frontal lobe epilepsy. The most effective treatment for intractable partial epilepsy is a focal cortical resection with excision of the epileptogenic zone, that is, an area of ictal onset and initial seizure propagation. The preoperative evaluation and operative strategy in patients with partial epilepsy of extratemporal origin associated with pharmacoresistant seizures is determined by the anatomic localization of the epileptogenic zone and the presence of a substrate-directed disorder. The goals of surgical treatment in extratemporal epilepsy include rendering the patient seizure-free, avoiding operative morbidity, and allowing the individual to become a participating and productive member of society. Before surgical treatment, the individual with extratemporal epilepsy will require a comprehensive preoperative evaluation, including routine electroencephalogram (EEG), long-term EEG monitoring, neuropsychologic studies, and magnetic resonance imaging (MRI). Patients with a normal MRI study, conflicting preoperative evaluation, or involvement of suspected functional cerebral cortex would require chronic intracranial EEG monitoring. The rationale for intracranial EEG includes localization of the ictal onset zone or intraoperative functional mapping, or both. Two-fluorodeoxyglucose positron emission tomography studies are usually unremarkable in patients with extratemporal epilepsy and normal MRI scans. Subtraction ictal single photon emission computed tomography coregistered to MRI (SISCOM) study may be useful to demonstrate a localized cerebral perfusion alteration in patients with intractable partial epilepsy. The diagnostic yield of SISCOM has been confirmed in patients with extratemporal epilepsy undergoing surgical treatment. The results of the SISCOM study may tailor the placement of intracranial EEG electrodes and affect the operative strategy. Patients with extratemporal epilepsy overall are less favorable operative candidates than individuals with medial temporal lobe epilepsy. However, individuals with MRI-identified lesional pathology of SISCOM-identified perfusion alterations concordant with the epileptogenic zone may be considered for surgical treatment. Chronic intracranial EEG monitoring may be necessary to confirm the localization of the ictal onset zone before epilepsy surgery. Patients with normal neuroimaging studies and extratemporal epilepsy are unlikely to be rendered seizurefree with focal cortical resection and should be considered candidates for other alternative forms of treatment for intractable partial epilepsy. Patients with non-substrate-directed extratemporal epilepsy should undergo a preoperative evaluation and surgical treatment at a comprehensive epilepsy center with extensive experience in chronic intracranial EEG monitoring and contemporary neuroimaging procedures because of the inherently high acuity associated with the operative management clinical disorder.     

Inferior temporal sulcus approach for amygdalohippocampectomy guided by a laser beam of stereotactic navigator

OBJECTIVE: To describe a surgical technique for a minimally invasive transcortical transventricular amygdalohippocampectomy via the inferior temporal sulcus (ITS) using a stereotactic navigator. METHODS: Seven patients with medically intractable mesial temporal lobe epilepsy underwent an amygdalohippocampectomy via the ITS. By use of a laser-guided navigation system, the epileptogenic foci of the mesial temporal lobe were resected through a small linear operative route that was made by a brain speculum inserted from the ITS to the anterolateral floor of the temporal horn in the lateral ventricle. RESULTS: All patients completed at least a 1-year follow-up (range, 14-45 mo) after surgery and had improved neuropsychological parameters as a result of the operation. All patients became seizure-free after surgery. A Humphrey visual field perimeter detected no hemianopsia. CONCLUSION: Combined with the stereotactic navigation system, the ITS approach provides the least invasive amygdalohippocampectomy that preserves optic radiation. This approach seems beneficial especially in patients in whom the epileptic lesions are limited to the anterior mesial temporal lobe.     

Seizure outcomes in nonresective epilepsy surgery: an update

In approximately 30 % of patients with epilepsy, seizures are refractory to medical therapy, leading to significant morbidity and increased mortality. Substantial evidence has demonstrated the benefit of surgical resection in patients with drug-resistant focal epilepsy, and in the present journal, we recently reviewed seizure outcomes in resective epilepsy surgery. However, not all patients are candidates for or amenable to open surgical resection for epilepsy. Fortunately, several nonresective surgical options are now available at various epilepsy centers, including novel therapies which have been pioneered in recent years. Ablative procedures such as stereotactic laser ablation and stereotactic radiosurgery offer minimally invasive alternatives to open surgery with relatively favorable seizure outcomes, particularly in patients with mesial temporal lobe epilepsy. For certain individuals who are not candidates for ablation or resection, palliative neuromodulation procedures such as vagus nerve stimulation, deep brain stimulation, or responsive neurostimulation may result in a significant decrease in seizure frequency and improved quality of life. Finally, disconnection procedures such as multiple subpial transections and corpus callosotomy continue to play a role in select patients with an eloquent epileptogenic zone or intractable atonic seizures, respectively. Overall, open surgical resection remains the gold standard treatment for drug-resistant epilepsy, although it is significantly underutilized. While nonresective epilepsy procedures have not replaced the need for resection, there is hope that these additional surgical options will increase the number of patients who receive treatment for this devastating disorder—particularly individuals who are not candidates for or who have failed resection.     

Pure lesionectomy versus tailored epilepsy surgery in treatment of cavernous malformations presenting with epilepsy

Cerebral cavernous malformations (CM) are well-circumscribed vascular malformations that often present with epileptic seizures. Although patients may initially benefit from antiepileptic drugs, surgical treatment may become necessary due to medically intractable seizures. However, it is unclear whether lesionectomy alone or tailored epilepsy surgery with previous invasive monitoring is the optimal strategy in such cases. We report two patients with epileptic seizures due to CM. One patient with few seizures prior to surgery became seizure-free following resection of the CM and the surrounding tissue. In the second patient with long-lasting epilepsy, lesionectomy was performed because of the proximity to a functioning left hippocampus. This limited resection failed and the patient still had seizures. Subsequently, invasive monitoring with intracranial depth and strip electrodes was performed in order to localize the epileptogenic area and determine whether the left hippocampus could be spared. The invasive study showed the seizure origin in the tissue around the former CM but no epileptic discharges in the hippocampus. In a second operation, an anterior temporal resection was performed with removal of the epileptogenic surrounding tissue and the patient became seizure-free without cognitive deficits. The optimal surgical strategy for CM presenting with epileptic seizures must take into account various factors such as underlying mechanisms and duration of epilepsy, and location of the lesion.     

静息态功能磁共振成像在内侧颞叶癫痫中的应用

内侧颞叶癫痫是一种最常见的难治性癫痫。目前临床评估主要目的是定位定侧癫痫灶、观察癫痫网络以及评价认知功能和手术疗效。利用血氧水平依赖静息态功能磁共振成像(rs-fMRI)可无创检测癫痫活动。本文就rs-fMRI的原理、技术及其在内侧颞叶癫痫、癫痫网络的应用进行综述。     

History of epilepsy surgery at The Hospital for Sick Children in Toronto, Canada

OBJECTIVE: To review the development of epilepsy surgery for pediatric patients with intractable epilepsy at The Hospital for Sick Children in Toronto, Canada. METHODS: We retrospectively collected and reviewed published papers regarding pediatric epilepsy surgery since 1930's. RESULTS: First, McKenzie started a hemispherectomy for children. Hendrick established anatomical hemispherectomy for pediatric patients with hemiparesis and intractable seizures since 1964. Hoffman performed anterior temporal lobectomy and neocortical temporal resection for lesional tempolal lobe epilepsy with or without mesial temporal sclerosis since 1974. Thereafter, multimodal neuroimaging studies of CT scan, MRI, and XenonCT, SPECT and PET have been used to identify and remove the epileptogenic lesion and zone. In 1996, magnetoencephalography (MEG) was introduced to localize interictal spike sources and somatosensory evoked fields for children with intractable seizures. Snead and Rutka started subdural grid electrodes that were constructed by scalp video EEG, MRI and MEG findings.The clustered MEG spike source coregistered with the intraoperative neuronavigation system delineated the epileptogenic zone requiring completely excision for neocortical lesional epilepsy from 2000. CONCLUSION: The pediatric epilepsy surgery at the Hospital for Sick Children has been progressing from anatomical hemispherectomy to complete clusterectomy of MEG spikes sources that localized the epileptogenic zone. Cortical excision, lobectomy, hemisphelotomy, corpus callosotomy and vagal nerve stimulation have been applied to appropriate seizure types identified by advanced neurodiagnostic modalities. We furthermore develop non-invasive methods for localizing and understanding the epileptic network in pediatric epilepsy patients with developing brain.     

Modifications of temporal lobectomy according to the extent of epileptic foci and speech-related areas

The authors applied combined depth and subdural electrodes in patients with intractable complex partial seizures to detect the precise extent of epileptic foci and functionally map speech-related areas. The medial temporal structures were explored with depth electrodes and the lateral temporal cortex with subdural electrodes. On the speech-dominant side, electrical stimulation was given to demarcate the speech-related areas in the lateral temporal cortex. Based on these data, the extent of surgical resections was tailored to include as much of the epileptogenic areas as possible while preserving the functionally essential zones of the lateral cortex. According to the range of resection, three different approaches were employed for en bloc ablation of the lateral cortex and opening of the inferior ventricle. The results thus acquired have been satisfactory in terms of seizure control and the preservation of speech function.     

Subtraction ictal single-photon emission computed tomography coregistered to magnetic resonance imaging in evaluating the need for repeated epilepsy surgery

OBJECT: The aim of this study was to determine whether ictal single-photon emission computed tomography (SPECT) is useful in localizing the site of seizure onset in patients in whom surgery for intractable epilepsy failed and who are being considered for repeated surgery. METHODS: Subtraction ictal SPECT coregistered to magnetic resonance imaging (SISCOM) studies were retrospectively analyzed in 58 patients who were being evaluated for possible repeated resection for intractable partial epilepsy between January 1, 1996, and October 31, 1999. All patients had persistent seizures subsequent to an initial resection and underwent another excision. The SISCOM-demonstrated abnormalities were classified as concordant, discordant, or indeterminate, compared with the localization of the epileptogenic zone revealed on video electroencephalography monitoring. The ability of SISCOM to predict operative outcome was also determined in patients who had undergone repeated surgical procedures. The SISCOM studies revealed a localized hyperperfused alteration in 46 (79%) of 58 patients. Forty-one (89%) of these 46 patients had a SISCOM-demonstrated alteration in the hemisphere of the previous epilepsy surgery. Imaging changes in 33 (72%) of the 46 patients were at the site of the previous focal cortical resection. Eight (17%) of the 46 had SISCOM-demonstrated abnormalities remote from the lobe in which surgery had been performed but in the ipsilateral hemisphere. The hyperperfusion focus was in the contralateral hemisphere in the remaining five patients (11%). The site of the epileptogenic zone was concordant with the SISCOM focus in 32 (70%) of 46 patients. Twenty-six patients underwent repeated resection and were followed up for a mean of 44 months thereafter; 11 of these patients (42%) had a significant reduction in seizure tendency. Only five patients (19%) were seizure free. Ten (50%) of 20 patients with a concordant SISCOM focus compared with none (0%) of three patients with a discordant focus had a favorable surgical outcome (p = 0.23). CONCLUSIONS: The SISCOM method might be useful in the evaluation of, and the surgical planning for, patients with intractable partial epilepsy in whom previous resective treatment has failed and who are being considered for reoperation.     

Cerebral metabolism of the remote area after epilepsy surgery

To clarify whether epilepsy surgery improves cerebral metabolism, pre- and postoperative positron emission tomography (PET) scans were performed, with special reference to hypometabolism outside the resected epileptogenic zones in nine patients (8 males, 1 female) with medically intractable complex partial seizures and multiple hypometabolic zones. Seven patients underwent unilateral anterior temporal lobectomy, one patient underwent selective amygdalohippocampectomy, and one patient underwent parieto-occipital cortical resection and anterior temporal lobectomy. PET scans were obtained at least 6 months after surgery. Eight patients became seizure-free, and one patient had fewer than three seizures per year. Four patients showed improved glucose metabolism in the formerly hypometabolic zones, which were remote to the surgical site and ipsilateral to the epileptogenic foci. Five patients, who showed bilateral temporal hypometabolism preoperatively, had contralateral temporal hypometabolism after surgery. The relative glucose uptake in four of these patients showed increased metabolism of the adjacent lobes ipsilateral to the surgical site. The lobes that showed increased glucose metabolism after surgery were mostly frontal. Hypometabolism is reversible in the ipsilateral remote area, and may be caused by inhibition via the intercortical pathway. Contralateral temporal hypometabolic zones that persist after surgery may be caused by a different mechanism, and neither indicate the presence of seizure foci nor affect the seizure outcome.     

Safety and efficacy of multiple subpial transections: report of a consecutive series of 30 cases

PURPOSE: To present our results using multiple subpial transections (MST) for the treatment of pharmacologically refractory epilepsy (PRE) with epileptogenic foci in eloquent areas. METHOD: Between January 2003 and March 2006, we treated 33 patients with PRE with epileptogenic foci in eloquent areas by MST "in rays", either isolated (MSTs group) or completing resection or disconnection of other cortical areas (MST+ group). Our first 30 patients had a follow-up of at least 24 months: eight in the MSTs group and 22 in the MST+ group. Four postoperative grades were distinguished based on a modified Engel classification: seizure-free (100% seizure reduction equals to Grade I), substantial significant seizure reduction (75% to 99% seizure reduction equals to Grade II), moderate significant reduction (50% to 74% seizure reduction equals to Grade III) and finally no significant reduction (seizure reduction less than 50% equals to Grade IV). RESULTS: In the MSTs group, two patients (25%) were in grade I and five (62%) in grade II or III. In the MST+ group, six patients (27%) were in grade I and 13 (59%) in grade II or III. All patients showed some seizure reduction and some improvement in behavior or cognitive function with no permanent neurological deficit. CONCLUSION: This series supports the notion that multiple subpial transections are associated with a significant seizure reduction (in 86.6% of the cases reported herein) and that the risk of permanent neurological deficit can be very low.     

多处软脑膜下横切术治疗顽固性癫痫

目的提高顽固性癫痫手术疗效。方法对１９９１年１月至１９９６年１２月实施多处软脑膜下横切除（ＭＳＴ）的１１６例患者的发作类型、病因及手术方法进行分析。结果随访１～５年者１００例,发作完全控制６２例,发作减少７５％以上２０例,发作减少５０％以上１２例（占１２％）,无变化６例。总有效率为９４％,显效率８２％,未发现任何功能损害。结论ＭＳＴ治疗顽固性癫痫十分有效,可替代某些传统的痫灶切除术;双额叶ＭＳＴ配合胼胝体前部切开术可作为治疗全身性顽固性癫痫的尝试性手段;手术方法的改良可明显提高手术效果并减少并发症的产生;对于远离功能区的器质性病变应尽量予以切除。     

The results of the surgical treatment of occipital lobe epilepsy

Summary Out of 502 patients with surgically treated drug-resistant chronic epilepsy (tumour cases excluded) in 12 (2%) a clear occipital focus was found. The pattern of seizures was in most cases nonspecific and polymorphic. EEG examination and neuroradiological findings led to proper localization of the epileptogenic focus. Partial or total occipital lobectomy was performed. Follow-up from 4 to 20 years revealed a satisfactory result in 11 of the surgical cases. One patient was lost to follow-up. Brain scarring was found in the histological examination of specimens in 9 out of 12 patents. The results of the surgical treatment of occipital lobe epilepsy are much better than in other localizations of epileptogenic foci.     

Temporal lobe epilepsy: a clinicopathological study with special reference to temporal neocortical changes

The number of patients undergoing surgical treatment for pharmacoresistant temporal lobe epilepsy is rapidly increasing. While there have been many clinicopathological studies concerning the medial structures of the temporal lobe in temporal lobe epilepsy, its lateral structures have received little attention. To examine the nature and frequency of lateral temporal lobe abnormalities that occur in temporal lobe epilepsy, 22 patients who underwent standard anterior temporal lobectomy with hippocampectomy for intractable temporal lobe epilepsy were studied. The mean ages at the onset of seizure and at surgery were 15.9 years and 27.7 years, respectively. The electroclinically determined epileptogenic zones were the medial structures of the temporal lobe in 16 patients and the lateral in six. There was histologic evidence of hippocampal sclerosis in 12 of the 16 patients with medial onset seizures and in three of the six patients with lateral onset seizures. The lateral structures of the temporal lobe showed variable degrees of histological abnormalities in 21 patients. Among these abnormalities, heterotopic white matter neurons were observed in six of the 16 medial patients and in all the lateral patients. Glial changes were also common abnormalities, and often glial fibrillary acidic protein (GFAP)-positive astrocytes were present over the entire temporal lobe. In addition to hippocampal sclerosis, cerebral microdysgenesis and gliosis in the lateral structures of the temporal lobe may have a significant role in epileptogenesis of temporal lobe epilepsy.     

Seizure control and extent of mesial temporal resection

Summary Controversy exists about the extent of mesial temporal lobe resection that improves seizure control in patients with temporal lobe epilepsy.In this retrospective study, 70 patients with mesial temporal seizure activity (without evidence of tumor or vascular malformation) were surgically treated and followed for at least 2 years. The extent of mesial temporal resection was based on the findings of interictal and ictal discharges using depth electrodes, which were inserted preoperatively or intraoperatively by the orthogonal approach to the amygdaloid and hippocampal regions. Only the amygdala was resected along with the limited lateral neocortex if no epileptiform activity involved the hippocampus. The amount of hippocampal excision was determined by the extent of interictal seizure activity.The following groups became seizure free: all 8 patients with only amygdalar resection; 6 of 10 patients with amygdalar and 1cm hippocampal resection; 23 of 38 with 1–2 cm hippocampal removal, and 11 of 14 with > 2cm hippocampal excision. In cases where there was no hippocampal resection, neuropsychological outcome compared favorably with controls.Our results suggest that although most patients with temporal lobe epilepsy require hippocampal resection of varying degrees, there is a subset in whom the amygdala may be the crucial element of a mesial temporal epileptogenic network. These patients can undergo a surgical resection sparing the hippocampus without compromising seizure outcome.