As a radiological term, MCD has become increasingly accepted by physicians as those non-occupying lesions of the cortex due to anatomical developmental abnormalities, including abnormalities of cortical structures and neurohypoplasmic translocations. Histopathologically, MCD includes Taylor-type localized cortical dysplasia, nodular heterotopia, polymicrogyria, schizencephaly, and hemispheric megalencephaly. Not all cases of MCD are suitable for surgical treatment, and those patients with paraventricular gray matter translocation who have undergone partial corticotomy have poor outcomes. MCD is a common cause of refractory epilepsy, accounting for approximately 28-56% of surgically treated pediatric epilepsy patients. The clinical features of this disorder include early onset seizures, diversity and refractoriness of seizure forms, and are often associated with localized neurological deficits and global cognitive impairment. The imaging features of MRI vary depending on the pathological changes. They can appear as normal or thickened cortex with poorly defined gray and white matter or long T2 signal under the cortex. Surgical success rates are lower in children or adults with MCD compared to surgical procedures for epilepsy due to other pathologic abnormalities. The main reason for failure of surgical treatment is incomplete excision of the lesion. lesions in MCD limit the extent of surgical excision because they often involve the central region. In addition, the extent of the developmental abnormalities may not be apparent on MRI images, and other methods need to be applied to localize the epileptogenic zone. To improve the accuracy of epileptic lesion localization, functional neuroimaging (PET or SPECT), preoperative subdural electrode EEG monitoring, and intraoperative cortical EEG monitoring have also been applied to localize MCD in children. Although data from the Cleveland Clinic show that neither PET nor preoperative subdural electrode EEG monitoring improves the prognosis of surgical treatment, the use of these techniques is relevant in some respects. Brain tumors and epilepsy The proportion of pediatric epilepsy patients caused by intracerebral tumors is not high, and most of the tumors are of low malignancy. However, brain tumors are a common cause of epilepsy in a large number of children who undergo surgery, accounting for about 1/3 to 1/2 of all surgical cases. clinically, epilepsy due to tumors appears later than epilepsy due to other pathological changes in children of the same age group. Because the lesions are relatively benign, they rarely present with localized neurolocalization signs or cause increased intracranial pressure. The preoperative evaluation procedure for this group of patients is approximately the same as for epilepsy due to other lesions.CT is less sensitive than MRI, especially for low-grade malignant focal lesions. When MRI reveals a clear lesion and video EEG also suggests abnormal discharges in the vicinity of the lesion, the need for other adjunctive tests such as SPECT and PET is worth discussing. The role of cortical EEG is also controversial, but cortical localization of abnormal discharges associated with the lesion is mandatory. Complete removal of the tumor is a prerequisite for the treatment of epilepsy, but there is considerable debate as to whether tissue with abnormal discharges in the cortical EEG surrounding the tumor should be removed. Previous studies in this area have reported opposite conclusions. Each epilepsy center applies the technique of cortical EEG monitoring according to its own experience. Among patients with epilepsy of various causes, the highest cure rate is achieved for tumor-related epilepsy, exceeding 80%. A low frequency of preoperative seizures and complete resection of the lesion predicts a good prognosis. The most common type of tumor pathology is ganglioneuroblastoma, accounting for approximately 40% of most studies. Other common tumors include low-grade malignant astrocytomas and neuroepithelial tumors such as teratomas. In pediatric patients, many tumors that originate in one temporal lobe and invade the insula or involve the basal ganglia region are limited in their ability to be completely resected by the surrounding vital structures. Tuberous sclerosis (TS) Epilepsy due to tuberous sclerosis is more common in children before the age of 10 years. Partial seizures are most often seen in children with infantile spasms and are also a common clinical presentation in children with tuberous sclerosis. The ability to achieve satisfactory results with resection of a single lesion in this multifocal disease greatly increases the potential surgical value of this disease. A case report from Miami Children’s Hospital (MCH) showed that seizures disappeared in approximately 69% of patients with epilepsy after localized lesion resection. Preoperative evaluation of patients with TS is a significant challenge, including multiple abnormal lesions on MRI and PET images and multiple epileptiform discharges during interictal periods. In contrast, areas of EEG abnormalities during seizures have a high compliance with areas of hyperperfusion on SPECT during seizures. The main reason for surgical failure was that the sclerotic nodules and the surrounding epileptogenic areas were not completely excised. The long-term prognosis of TS patients after successful epilepsy surgery is unclear. Theoretically, the possibility of epileptogenicity exists for other nodules postoperatively, but this risk is not only present in patients with TS. There is definite evidence that the low IQ of TS patients is directly related to the seizures of the children. In contrast, effective control of seizures by antiepileptic drugs and surgical treatment can significantly improve the cognitive function of the child. Sturge-Weber syndrome (SWS) SWS is a rare neurodevelopmental anomaly in which patients have congenital cutaneous hemangiomas on the frontal face and venous hemangiomas on the soft meninges of the ipsilateral hemisphere. Clinical features also include neurodevelopmental delay in more than half of the children and seizures in more than 80% of cases with an average age of first seizure at 6 months. SWS is a prime example of the indications and timing of surgical procedures in children with epilepsy. About 50% of the cases are well controlled with antiepileptic drugs. The deeper problem is that although some patients have seizures that can be controlled over a longer period of time, the regression remains unpredictable due to the natural course of this lesion. Progressive cognitive decompensation with local neurolocalization signs is a feature of this disease, and it is difficult to say whether this is caused by seizures or by progressive brain atrophy. The correct preoperative diagnosis relies on an enhanced MRI scan, which reveals a unilateral venous angioma and also provides a detailed understanding of the extent of the lesion. Scalp EEG monitoring can demonstrate epileptiform discharges in both hemispheres, which have no localizing value for surgery. The choice of surgical procedure depends on the extent of the lesion – whether it is a localized lesion resection or a hemispheric resection. Intraoperative EEG monitoring suggests that most of the most active discharges are located around the hemangioma, but studies have shown that the use of intraoperative EEG does not improve patient outcomes. Subdural electrode monitoring is rarely applied preoperatively because seizures can be significantly controlled after lesion removal. Two large case studies have shown complete seizure control in 65-85% of patients, and early surgery, especially before the age of two years, can significantly improve cognitive function in children. Infantile spasms (IS) IS is a catastrophic epilepsy syndrome that occurs in infancy and is associated with cognitive decompensation. It has been reported that patients with IS have poor outcomes with pharmacological treatment, raising the question of whether surgical treatment can be considered for those cases that are medically refractory. From a therapeutic point of view, local excision of the lesion alone is not a solution for generalized seizure syndromes, but this principle does not apply to patients with IS. Features that can demonstrate that IS is a local factor causing seizures include a history of partial seizures; asymmetric convulsions; high rhythm abnormalities in the hemispheres and mild hemiparesis. These features are determined by means of V-EEG and functional imaging. In surgically resected cases, common local pathological changes are abnormalities in cortical development and brain softening. A large number of IS cases from UCLA (University of California) reported short-term seizure control rates of 65% with multiple lobectomies and hemispherectomies, but the percentage of surgically controlled seizures also decreased significantly with time. In addition to seizure control, the goal of surgery in IS patients is to improve the cognitive abilities of the child. short-term follow-up results from UCLA showed that only 1 in 24 children achieved normal cognitive development after surgery, and standardized developmental scores were significantly lower two years after surgery than before surgery when looking at the entire group of cases. The authors discussed that the overall case data showed that functional improvement after surgery was significantly better than structural improvement. Patients who had early surgery had higher developmental scores, suggesting that early surgical intervention was better at halting cognitive deterioration. The issue of timing of surgery is not resolved. It requires weighing the risk of cognitive deterioration against the possibility that the child’s seizures can be controlled medically. Confusing symptoms, multifocal EEG abnormalities and the low detection rate of cortical lesions on conventional MRI within 12 months of birth hinder the selection of early suitable surgical cases. Currently, more prospective studies are needed for the surgical management of IS patients to determine the optimal timing of surgery to achieve the best seizure control and the greatest improvement in cognitive function.