Do Neuroimaging Results Impact Prognosis of Epilepsy Surgery? A Meta-analysis

The neuroimaging results of drug-resistant epilepsy patients play an important role in the surgery decision and prognosis. The aim of this study was to evaluate the impact of these results on the efficacy of epilepay surgery, and then to explore surgical benefit for epilepsy patients with negative magnetic resonance （MR） images. Twenty-four subgroups describing the outcomes of 1475 epilepsy pa- tients with positive-neuroimaging results and 696 patients with negative-neuroimaging results were in- volved in the meta-analysis. Overall, the odds of postoperational seizurefree rate were 2.03 times higher in magnetic resonance imaging-positive （MRI-positive） patients than in MRI-negative patients [odds ratio （OR）=2.03, 95% CI （1.67, 2.47）, P〈0.00001]. For patients with temporal lobe epilepsy （TLE）, the odds were 1.76 times higher in those with MRI-positive results than in those with MRI-negative results [OR=1.76, 95% CI （1.34, 2.32）, P〈0.0001]. For patients with extra-temporal lobe epilepsy （extra-TLE）, the odds were 2.88 times higher in MRI-positive patients than in MRI-negative patients [OR=2.88, 95% CI （1.53, 5.43）, P=0.001]. It was concluded that the seizure-free rate of MRI-positive patients after surgery was higher than that of MRI-negative patients. For patients with negative results, an appropriate surgery should be concerned for TLE.

Neuroendoscopy in Epilepsy Surgery

Epilepsy surgery has constantly evolved in various fields of knowledge. Surgical criteria have shifted from standard procedures to individualized forms of treatment, depending on physiological tests and specific imagenology findings in an individual patient. New instruments and applications based upon older instruments have been described in the treatment of epilepsy surgery, including the use of endoscopes. Frequent indications of neuroendoscopy in epilepsy surgery have been mostly to assist in open procedures, particularly when fluid-filled spaces are present within the surgical field, such as cystic parasites, tumors, arachnoid, or other types of cysts. Other indications certainly include cases of temporal lobe epilepsy, where ventricular exploration precedes intraventricular electrode placing as a tool to localize epileptogenic zones. Although described several years ago, there has been a recent trend in performing endoscopy-assisted section of the corpus-callosum in patients with generalized seizures. As neurosurgical instruments and techniques continue their progress, endoscopy will be included more frequently as part of the armamentarium in epilepsy surgery.

Epilepsy surgery for tuberous sclerosis complex： a case report and literature review

Tuberous sclerosis complex （TSC） is a multisystem genetic disorder with variable phenotypic expression.Epilepsy is the most common neurological complication and up to 80%-90% of the individuals with TSC suffer from epilepsy at some point in their lifetime. Developmental delay, intellectual impairment, autism, behavioral problems, and neuropsychiatric disorders occur commonly in individuals with TSC and may be associated with poorly controlled epilepsy.~ In this paper we reported a case report of TSC, focusing on the patient＇s clinical symptom, surgical aspects and neuropathology through a comprehensive analysis.

Consensus on pediatric epilepsy Che up surgery for young children:an investigation by the China Association Against Epilepsy task force on epilepsy surgery

Researchers have widely acknowledged the therapeutic value of epilepsy surgery for drug-resistant epilepsy.None-theless,there is a substantial gap in the surgical treatment for appropriate candidates owing to several factors,particularly in the population of young children.To standardize the protocols of preoperative evaluation and sur-gery of young children for epilepsy surgery,the China Association Against Epilepsy has appointed an expert task force to standardize the protocols of preoperative evaluation and surgery in pediatric epilepsy patients.It adopted the modifed Delphi method and performed two rounds of surveys through an anonymous inquiry among 75 experts from four subgroups including pediatric neurologists,epileptologists,pediatric epilepsy surgeons,and functional neurosurgeons.The survey contents contained:(1)the participants,comprising children aged≤6 years;(2)adopted DRE definition proposed by the International League Against Epilepsy in 2010;and(3)investigated epilepsy surgery,principally referring to curative epilepsy surgeries.The neuromodulation therapies were excluded because of the differences in treatment mechanisms from the above-mentioned surgeries.According to the Delphi process,a con-sensus was achieved for most aspects by incorporating two rounds of surveys including preoperative assessment,sur-gical strategies and techniques,and perioperative and long-term postoperative management,despite controversial opinions on certain items.We hope the results of this consensus will improve the level of surgical treatment and man-agement of intractable epilepsy in young children.

Posterior quadrant epilepsy surgery: case series of a South American hospital

Background Posterior quadrant epilepsy(PCE)is a type of focal epilepsy that originates in the parietal lobe,occipital lobe,and the parietal-occipital border of the temporal lobe,or in any combination of these regions.PCE has a low incidence,but it can cause a great burden in disability-adjusted life years.In this retrospective cohort,patients of all ages with a diagnosis of PCE between 2006 and 2019 were evaluated in a referral center in Bogotá,Colombia.A descriptive analysis of demographic data,clinical history,imaging findings,type of surgery,histopathological diagnosis,outcome,and follow-up was performed using the Engel scale.Methods This study included refractory PCE patients of all ages who were evaluated by the epilepsy surgery group of the Hospital Universitario San Ignacio from 2006 to 2019.Clinical,imaging and surgical variables were obtained from the medical records and analyzed.Results Thirteen patients were included in the study,including 8 males and 5 females.The mean age of diagnosis was 8.8 years,while the mean age of surgery was 25 years.The most frequent clinical finding was intellectual disability.The most common findings on magnetic resonance imaging were encephalomalacia and gliosis.In 61.5%of the patients,the lateralization of video-EEG matched with brain magnetic resonance imaging alteration.The most frequent types of surgery performed were lobectomies,lesionectomies and cortical resections.Seizure-freedom was achieved in approximately one third of the patients;however,more than half of the patients were free of disabling seizures or had significant improvement after surgery.Conclusions PCE surgery is scarcely performed worldwide,therefore the effectiveness and outcomes are quite variable in the reported literature.In this study,we show that patients with PCE can obtain great benefits in terms of reduction of seizures with a low risk of surgical complications,encouraging the use of this type of procedure in carefully selected patients.

DIAGNOSTIC VALUE OF INTERICTAL DIFFUSION-WEIGHTED IMAGING IN EVALUATION OF INTRACTABLE TEMPORAL LOBE EPILEPSY

Objective To explore the ability of interictal diffusion-weighted imaging(DWI)to localize the temporal lobe of seizure origin and to predict postoperative seizure control in patients with temporal lobe epilepsy(TLE).Methods Twenty-seven patients with intractable TLE considered for surgery and 19 healthy volunteers were studied with conventional magnetic resonance imaging(MRI)and DWI.Apparent diffusion coefficients(ADCs)of bilateral hippocampi in both TLE patients and control subjects were obtained.Lateralization to either temporal lobe with hippocampal ADC was based on the threshold values derived from ±1SD of right/left ratios in normal subjects.And the postoperative pathology was reviewed.Results Hippocampal ADCs were higher on the side of surgery compared with those on the contralateral side as well as the ipsilateral side in control subjects [resected side(109.8±7.3)×10-5 cm2/s,contralateral side(91.7±4.7)×10-5 cm2/s,control subjects(81.6±5.2)×10-5 cm2/s,all P<0.01].Right/left hippocampal ADC ratio and conventional MRI lateralized to the operated temporal lobe in 21 of 27(77.8%)and in 18 of 27(66.7%)patients.Lateralization to the surgical side was not associated with postoperative seizure control with right/left hippocampal ADC ratio(P>0.05).Conclusions Conventional MRI is a sensitive method to detect hippocampal sclerosis.Accuracy of the right/left hippocampal ADC ratio for lateralizing to the side of surgery is very high,but it isn't a better predictor of surgical outcome.

Vagus Nerve Stimulation for Pediatric and Adult Patients with Pharmaco-resistant Epilepsy

Background：Over past two decades,vagus nerve stimulation （VNS） has been widely used and reported to alleviate seizure frequency worldwide,however,so far,only hundreds of patients with pharmaco-resistant epilepsy （PRE） have been treated with VNS in China's Mainland.The study aimed to evaluate the effectiveness of VNS for Chinese patients with PRE and compare its relationship with age cohort and gender.Methods：We retrospectively assessed the clinical outcome of 94 patients with PRE,who were treated with VNS at Beijing Fengtai Hospital and Beij ing Tiantan Hospital between November 2008 and April 2014 from our database of 106 consecutive patients.The clinical data analysis was retrospectively examined.Results：Seizure frequency significantly decreased with VNS therapy after intermittent stimulation of the vagus nerve.At last follow-up,we found McHugh classifications of Class Ⅰ in 33 patients （35.1％）,Class Ⅱ in 27 patients （28.7％）,Class Ⅲ in 20 patients （21.3％）,Class Ⅳ in 3 patients （3.2％）,and Class Ⅴ in 11 patients （l 1.7％）.Notably,8 （8.5％） patients were seizure-free while ≥50％ seizure frequency reduction occurred in as many as 60 patients （63.8％）.Furthermore,with regard to the modified Engel classification,12 patients （12.8％） were classified as Class Ⅰ,l l patients （11.7％） were classified as Class Ⅱ,37 patients （39.4％） were classified as Class Ⅲ,34 patients （36.2％） were classified as Class Ⅳ.We also found that the factors of gender or age are not associated with clinical outcome.Conclusions：This comparative study confirmed that VNS is a safe,well-tolerated,and effective treatment for Chinese PRE patients.VNS reduced the seizure frequency regardless of age or gender of studied patients.

Predictors of outcome in the surgical treatment for epilepsy

Background Knowledge about factors influencing the prognosis of resective epilepsy surgery can be used to identify which patients are most suitable for surgical treatment. The aim of this study was to identify preoperative prognostic factors associated with the chance of achieving long-term seizure freedom. Methods We retrospectively reviewed seizure outcomes and clinical, electroencephalography （EEG）, magnetic resonance imaging （MRI）, histopathology, and surgical variables from 99 epilepsy surgery patients with at least one year of postoperative follow-up. Seizure outcomes were categorized based on the modified classification by the International League Against Epilepsy. Results We found that the seizure-free rate was 27.9% after one year, and that it stabilized at about 20.0% between two and six years after surgery. Univariate analysis showed that medial temporal lobe epilepsy with hippocampal sclerosis, MRI with visible focal lesions concordant with EEG, and regional ictal EEG and electrocorticography patterns were associated with a favorable surgical outcome. On the other hand, seizure recurrence within six months, incomplete focus resection, and surgical complications were associated with a poor outcome. Multivariate analysis showed that medial temporal lobe epilepsy with hippocampal sclerosis and MRI with visible focal lesions were independent presurgical predictors of a favorable outcome （P 〈0.01）. Seizure recurrence within six months was the only significant independent predictor associated with a poor outcome （P〈0.01）. Conclusion Hippocampal sclerosis and abnormal MRI findings are strongly associated with a favorable surgical outcome, whereas seizure recurrence within six months is associated with a poor outcome.

Stereoelectroencephalography-guided radiofrequency thermocoagulation(SEEG-guided RF-TC) in patients with drug-resistant focal epilepsy

For some patients with drug-resistant focal epilepsy, we usually select conventional surgical resection, which has brought better outcomes. However, others are not eligible for a conventional open surgical resection of the epileptogenic zone because of the proximity of a functional area or the implication of a larger epileptogenic network. Initially, stereoelectroencephalography(SEEG) exploration was a method of electroencephalography recording that was used in the presurgical evaluation of epileptic patients with complex epilepsy. Later, intracerebral electrodes used for SEEG were applied to produce radio frequency thermocoagulation(RF-TC) in epileptic patients. SEEG-guided RF-TC has produced some promising results, especially in the last dacade. Now, it has become popular as a palliative treatment to reduce seizure frequency in patients with drug-resistant focal epilepsy. This article presents a review of SEEG-guided RF-TC.

Ganglioglioma surgery associated with postoperative status epilepticus:a case report

Background Gangliogliomas are brain tumors associated with drug-resistant focal epilepsy.In most cases,seizures improve after surgical treatment.It is still not concluded to what extent the lesion itself or the perilesional area contributes to the epileptogenicity.Case presentation In the case presented in this report,the patient,a 24-year-old Caucasian male,developed a refractory status epilepticus after a surgical attempt to remove a cerebral ganglioglioma.The postoperative magnetic resonance imaging revealed that the lesion was intact,and that inadvertently only the perilesional area and adjacent cortex had been resected.The patient underwent a new surgical procedure where the ganglioglioma was removed,and the status epilepticus cessated.Conclusions This clinical case suggests that the lesion itself plays an important role in seizure generation and propagation,and notably,that the surrounding cortex by an inhibitory action can act as a gate to seizure spread.

The cultivation of epilepsy neurosurgeons:requirements and challenges

Epilepsy surgery has been accepted as an effective treatment in drug-resistant focal epilepsy.However,the number of epilepsy neurosurgeons is not enough in China compared with the huge demand.The content of epilepsy neurosurgeon cultivation includes surgery itself as well as presurgical evaluation.In this article,we review not only different categories of epilepsy surgeries but also the presurgical evaluation approaches including non-invasive methods,such as semiology analysis,high-resolution structural and functional imaging techniques,scalp electroencephalography monitoring as well as invasive methods,such as electrocorticography (ECoG) and stereotactic electroencephalography (SEEG).We also discuss the importance of learning each method briefly.In addition,we suggest that epilepsy neurosurgeons should have a solid structural and functional anatomy basis as it plays pivotal role in localizing epileptogenic zone.Epilepsy neurosurgeons should also be familiar with the staged presurgical evaluation starting from the most preliminary examinations and progressing to more complex and invasive methods.During the diagnosis and therapeutic procedures,collaboration between epilepsy neurosurgeons and other specialists is essential.At last,the necessity of epilepsy neurosurgeon cultivation has been emphasized.

Vagus nerve stimulation for refractory epilepsy:long term efficacy and side-effects

Background In general vagus nerve stimulation (VNS) can serve as an adjunctive treatment for patients with refractory partial -onset seizures. And we evaluated the long-term efficacy and safety of VNS in a group of Chinese patients with refratory epilepsy. Methods Of 127 patients with refractory epilepsy,13 patients who were not eligible for surgical intervention were implanted with the Cyberonics VNS system. Seizure frequency,physical examination and side effects profile were recorded at follow-up visits for a minimum of 18 months. Results Mean duration of treatment was 47.4 months,and the longest follow-up period was 71 months. Mean baseline seizure frequency was 26.6 seizures per month. The mean percentage reductions in convulsions were 33.2%,47.1% and 40.0% at 6,12 and 18 months,respectively. One patient became seizure free,and six (46%) had 50% or more reduction in seizure frequency. Response was poor (<20% reduction) in five patients (39%). Side effects were uncommon. Conclusions The effectiveness of VNS was sustained and was well tolerated but benefited only a sub-group of patients with intractable convulsions.

Intracranial electroencephalography study in epileptic patients with dual pathology

Acommon dual pathology observed on presurgical magnetic resonance imaging （MRI） of epilepticpatients is extrahippocampal lesions combined with mesial temporal sclerosis. The hippocampus was highly vulnerable to many types of insults. However, it is difficult to detect subtle hippocampal atrophy in some patients. The most reliable method to confirm epileptogenicity is chronic intracranial electroencephalography （EEG） monitoring. In this study, we recorded intracranial EEG signals in 11 patients with dual pathology.METHODS Patient enrollment We evaluated ! 1 patients with a confirmed diagnosis of dual pathology in Yuquan Hospital, China between 2007 and 2010. The patients were satisfied with the following criteria： （1） MRI showed structural lesions in the extrahippocampal lobe; （2） a postoperative follow-up period lasting at least 24 months. For all 11 patients, both seizure frequency and impact on quality of life were judged as severe enough to justify presurgical evaluation using implanted electrodes. Detailed histories of prenatal, neonatal, and early childhood events were systematically reviewed through direct interviews with the patients. Patients were initially evaluated with noninvasive methods, including scalp EEG monitoring to capture spontaneous seizures and MRI. MRI was performed using a 1.5 T scanner and included axial images parallel to the long axis of the hippocampus. Ipsilateral and contralateral hippocampal images were visually compared to confirm mesial temporal sclerosis （MTS）. EEG recording and analysis Noninvasive data （scalp EEG and MRI） identified the mesial temporal region and a neocortical lesion site as the most likely ictal onset zones. Thus, all 11 patients were examined by implanted intracranial electrodes. To investigate the mesial temporal region, we used a stereo- eletroencephalography procedure. Depth electrodes were orthogonally directed through the middle temporal gyrus with the deepest contacts in the amygdala and anterior hippocampus. The number of neocortical electrodes implanted varied depending on the target region. Electrode positions were confirmed by post-implantation neuroimaging.