• Clinical and Experimental Pediatrics
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• v.63 no.5
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• pp.171-177
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• 2020

Low-grade epilepsy-associated neuroepithelial tumors (LEATs) are responsible for drug-resistant chronic focal epilepsy, and are the second-most common reason for epilepsy surgery in children. LEATs are extremely responsive to surgical treatment, and therefore epilepsy surgery should be considered as a treatment option for LEATs. However, the optimal time for surgery remains controversial, and surgeries are often delayed. In this review, we reviewed published article on the factors associated with seizure and cognitive outcomes after epilepsy surgery for LEATs in children to help clinicians in their decision whether to pursue epilepsy surgery for LEATs. The achievement of gross total resection may be the most important prognostic factor for seizure freedom. A shorter duration of epilepsy, a younger age at surgery, and extended resection of temporal lobe tumors have also been suggested as favorable prognostic factors in terms of seizure control. Poor cognitive function in children with LEATs is associated with a longer duration of epilepsy and a younger age at seizure onset.

• Journal of Korean Neurosurgical Society
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• v.62 no.3
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• pp.321-327
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• 2019

Focal cortical dysplasia (FCD) is the major cause of intractable focal epilepsy in childhood leading to epilepsy surgery. The overall seizure freedom after surgery ranges between 50-75% at 2 years after surgery and the long-term seizure freedom remain relatively stable. Seizure outcome after surgery depends on a various factors such as pathologic etiologies, extent of lesion, and types of surgery. Therefore, seizure outcome after surgery for FCD should be analyzed carefully considering cohorts' characteristics. Studies of pediatric epilepsy surgery emphasize the early surgical intervention for a better cognition. Early surgical intervention and cessation of seizure activity are important for children with intractable epilepsy. However, there are limited data on the cognitive outcome after surgery in pediatric FCD, requiring further investigation. This paper reviews the seizure and cognitive outcomes of epilepsy surgery for FCD in children. Several prognostic factors influencing seizure outcome after surgery will be discussed in detail.

• Journal of Korean Neurosurgical Society
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• v.62 no.3
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• pp.328-335
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• 2019

Epilepsy is one of the most common chronic neurological disorder affecting 6-7 per 1000 worldwide. Nearly one-third of patients with newly diagnosed epilepsy continue to have recurrent seizures despite adequate trial of more than two anti-seizure drugs : drug-resistant epilepsy (DRE). Children with DRE often experience cognitive and psychosocial co-morbidities requiring more urgent and aggressive treatment than adults. Epilepsy surgery can result in seizure-freedom in approximately two-third of children with improvement in cognitive development and quality of life. Understanding fundamental differences in etiology, co-morbidity, and neural plasticity between children and adults is critical for appropriate selection of surgical candidates, appropriate presurgical evaluation and surgical approach, and improved overall outcome.

• Clinical and Experimental Pediatrics
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• v.56 no.10
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• pp.431-438
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• 2013

Magnetoencephalography (MEG) records the magnetic field generated by electrical activity of cortical neurons. The signal is not distorted or attenuated, and it is contactless recording that can be performed comfortably even for longer than an hour. It has excellent and decent temporal resolution, especially when it is combined with the patient's own brain magnetic resonance imaging (magnetic source imaging). Data of MEG and electroencephalography are not mutually exclusive and it is recorded simultaneously and interpreted together. MEG has been shown to be useful in detecting the irritative zone in both lesional and nonlesional epilepsy surgery. It has provided valuable and additive information regarding the lesion that should be resected in epilepsy surgery. Better outcomes in epilepsy surgery were related to the localization of the irritative zone with MEG. The value of MEG in epilepsy surgery is recruiting more patients to epilepsy surgery and providing critical information for surgical planning. MEG cortical mapping is helpful in younger pediatric patients, especially when the epileptogenic zone is close to the eloquent cortex. MEG is also used in both basic and clinical research of epilepsy other than surgery. MEG is a valuable diagnostic modality for diagnosis and treatment, as well as research in epilepsy.

• Journal of Korean Neurosurgical Society
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• v.62 no.3
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• pp.336-343
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• 2019

Epilepsy surgery revealed dramatically improved seizure outcomes over medical therapy in drug-resistant epilepsy patients. Children with epilepsy, however, have multiple epileptic focuses which require multilobar resection for better seizure outcome. Multilobar resection has not only the several severe surgical complications, such as hydrocephalus and shunt-related craniosynostosis, due to intracranial volume reduction. Isolation method (disconnection surgery) was progressively studied over epileptic focus removal (resective surgery) for seizure control. This concept was first introduced for functional hemispherotomy, and its primary principle is to preserve the vital vascularized brain that is functionally disconnected from the contralateral healthy brain. Currently in most epilepsy centers, the predominant disconnection surgical methods, including functional hemispherotomy, are continually being refined and are showing excellent results. They allow the functional isolation of the hemisphere or multi-lobe, affected by severe epilepsy. This review describes recent findings concerning the indication, surgical technique, seizure outcome and complications in several disconnection surgeries including the functional hemispherotomy for refractory pediatric epilepsy.

• Journal of Korean Neurosurgical Society
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• v.48 no.3
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• pp.230-235
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• 2010

Objective : The aim of this study is to compare the surgical outcome of the initial and recent surgical cases, during our 15-years experience, in terms of the surgical strategies and the prognostic factors for surgically remediable epilepsy. Methods : We retrospectively reviewed and compared the surgical outcomes between the initial 256 (Group I) and recent 139 (Group II) patients according to the time period of operation for a total of 518 consecutive epilepsy surgeries at our institution since 1992. The patients of the middle intermediate period, which were subjected to changed surgical strategies, were excluded. Results : The surgical outcome data from the initial and recent groups showed a much improved outcome for patients who underwent temporal lobe epilepsy (TLE) surgery over time. The number of patients with a good outcome (Engel class I-II) was much increased from 87.7% (178 TLE cases of Group I) to 94.8% (79 TLE cases of Group II) and this was statistically significant (p = 0.0324) on univariate analysis. Other remarkable changes were the decreased performance of intracranial invasive studies from 43.5% in Group I to 30.9% in Group II due to the advanced neuroimaging tools. The strip/grid ratio was reduced from 131/32 in Group I to 17/25 in Group II, because of a markedly reduced mesial TLE surgery and an increased extratemporal epilepsy surgery. Conclusion : Our results show that surgical outcome of epilepsy surgery has improved over time and it has shown to be efficient to control medically intractable epilepsy. Appropriate patient selection, comprehensive preoperative assessments and more extensive resection are associated with good postoperative outcomes.

• Journal of Korean Neurosurgical Society
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• v.44 no.4
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• pp.196-198
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• 2008

Objective : Vagus nerve stimulation (VNS) has been used in epilepsy patients refractory to standard medical treatments and unsuitable candidates for resective or disconnective surgery. In this study, we investigated the efficacy of VNS to patients who had refractory result to epilepsy surgery and patients with post-traumatic epilepsy. Methods : We analyzed the effect of VNS in 11 patients who had undergone previous epilepsy surgery and patients with intractable post-traumatic epilepsy associated with brain injury. All patients underwent VNS implantation between October 2005 and December 2006. Results : We evaluated seizure frequency before and after implantation of VNS and maximum follow up period was 24 months. In the first 6 months, 11 patients showed an average of 74.3% seizure reduction. After 12 months, 10 patients showed 85.2% seizure reduction. Eighteen months after implantation, 9 patients showed 92.4% seizure reduction and 7 patients showed 97.2% seizure reduction after 24 months. Six patients were seizure-free at this time. Conclusion : We conclude that the VNS is a helpful treatment modality in patients with surgically refractory epilepsy and in patients with post-traumatic epilepsy due to severe brain injury.

• Clinical and Experimental Pediatrics
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• v.63 no.3
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• pp.88-95
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• 2020

Accurate localization of the seizure onset zone is important for better seizure outcomes and preventing deficits following epilepsy surgery. Recent advances in neuroimaging techniques have increased our understanding of the underlying etiology and improved our ability to noninvasively identify the seizure onset zone. Using epilepsy-specific magnetic resonance imaging (MRI) protocols, structural MRI allows better detection of the seizure onset zone, particularly when it is interpreted by experienced neuroradiologists. Ultra-high-field imaging and postprocessing analysis with automated machine learning algorithms can detect subtle structural abnormalities in MRI-negative patients. Tractography derived from diffusion tensor imaging can delineate white matter connections associated with epilepsy or eloquent function, thus, preventing deficits after epilepsy surgery. Arterial spin-labeling perfusion MRI, simultaneous electroencephalography (EEG)-functional MRI (fMRI), and magnetoencephalography (MEG) are noinvasive imaging modalities that can be used to localize the epileptogenic foci and assist in planning epilepsy surgery with positron emission tomography, ictal single-photon emission computed tomography, and intracranial EEG monitoring. MEG and fMRI can localize and lateralize the area of the cortex that is essential for language, motor, and memory function and identify its relationship with planned surgical resection sites to reduce the risk of neurological impairments. These advanced structural and functional imaging modalities can be combined with postprocessing methods to better understand the epileptic network and obtain valuable clinical information for predicting long-term outcomes in pediatric epilepsy.

• Journal of Korean Neurosurgical Society
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• v.62 no.3
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• pp.344-352
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• 2019

Epilepsy is one of the major chronic neurological diseases affecting many patients. Resection surgery is the most effective therapy for medically intractable epilepsy, but it is not feasible in all patients. Vagus nerve stimulation (VNS) is an adjunctive neuromodulation therapy that was approved in 1997 for the alleviation of seizures; however, efforts to control epilepsy by stimulating the vagus nerve have been studied for over 100 years. Although its exact mechanism is still under investigation, VNS is thought to affect various brain areas. Hence, VNS has a wide indication for various intractable epileptic syndromes and epilepsy-related comorbidities. Moreover, recent studies have shown anti-inflammatory effects of VNS, and the indication is expanding beyond epilepsy to rheumatoid arthritis, chronic headaches, and depression. VNS yields a more than 50% reduction in seizures in approximately 60% of recipients, with an increase in reduction rates as the follow-up duration increases. The complication rate of VNS is 3-6%, and infection is the most important complication to consider. However, revision surgery was reported to be feasible and safe with appropriate measures. Recently, noninvasive VNS (nVNS) has been introduced, which can be performed transcutaneously without implantation surgery. Although more clinical trials are being conducted, nVNS can reduce the risk of infection and subsequent device failure. In conclusion, VNS has been demonstrated to be beneficial and effective in the treatment of epilepsy and various diseases, and more development is expected in the future.

• Journal of Korean Neurosurgical Society
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• v.62 no.3
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• pp.353-360
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• 2019

Epilepsy surgery that eliminates the epileptogenic focus or disconnects the epileptic network has the potential to significantly improve seizure control in patients with medically intractable epilepsy. Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has been an established option for epilepsy surgery since the US Food and Drug Administration cleared the use of MRgLITT in neurosurgery in 2007. MRgLITT is an ablative stereotactic procedure utilizing heat that is converted from laser energy, and the temperature of the tissue is monitored in real-time by MR thermography. Real-time quantitative thermal monitoring enables titration of laser energy for cellular injury, and it also estimates the extent of tissue damage. MRgLITT is applicable for lesion ablation in cases that the epileptogenic foci are localized and/or deep-seated such as in the mesial temporal lobe epilepsy and hypothalamic hamartoma. Seizure-free outcomes after MRgLITT are comparable to those of open surgery in well-selected patients such as those with mesial temporal sclerosis. Particularly in patients with hypothalamic hamartoma. In addition, MRgLITT can also be applied to ablate multiple discrete lesions of focal cortical dysplasia and tuberous sclerosis complex without the need for multiple craniotomies, as well as disconnection surgery such as corpus callosotomy. Careful planning of the target, the optimal trajectory of the laser probe, and the appropriate parameters for energy delivery are paramount to improve the seizure outcome and to reduce the complication caused by the thermal damage to the surrounding critical structures.