Current management and surgical outcomes of medically intractable epilepsy

Outcomes following resective and disconnective strategies in the treatment of epileptic spasms: a systematic review of the literature and individual patient data meta-analysis

Epileptic spasms (ES) are a unique seizure type typically presenting in the form of infantile epileptic spasms syndrome (IESS) with characteristic hypsarrhythmia on scalp EEG and a preponderance with developmental delay or regression. While pharmacotherapy is the mainstay of treatment, surgical options, including disconnective or resective procedures, are increasingly recognized as viable therapeutic options for recurrent or persistent ES. However, limited data on safety, effectiveness, and prognostic factors hinder informed decision-making regarding surgery indications, timing, and intervention type. We performed a systematic review and an individual patient data meta-analysis (IPDMA) in accordance with PRISMA guidelines, focusing on surgical interventions for ES and reporting seizure outcomes using the Engel or ILAE scales. Twenty-six studies encompassing 358 ES patients undergoing resection/callosotomy were included. Participants undergoing other approaches (e.g., multiple subpial transections) or multimodality approaches were excluded from analysis. The median age at spasm onset was 6 months (IQR = 3.0-15.6), with a median age at surgery of 37 months (IQR = 17.2-76.8). Most patients (74.1%) exhibited additional seizure types. A total of 136 patients (35.8%) underwent corpus callosotomy (CC), of whom 125 (91.9%) had a complete callosotomy, while 11 (8.1%) had a partial callosotomy. Resective surgery was performed on 222 patients (58.4%). Among those who underwent resection, 109 (49.1%) had both lesional MRI findings and lateralized EEG abnormalities. Overall, 201 patients (56.1%) remained spasm-free at a median postoperative follow-up of 36 months (interquartile range, IQR = 21-60), including 52 (38.2%) from the callosotomy group and 149 (67.1%) from the resective surgery group. In the resective surgery cohort, patients with MRI-confirmed lesions (p = 0.026; HR = 0.53, 95% CI = 0.31-0.93) and those who underwent hemispherectomy (p = 0.026, HR = 0.46, 95% CI = 0.23-0.91) had better seizure outcomes. Only a minority (24.4%) underwent invasive EEG monitoring prior to ES surgery. Surgical treatment of ES proves effective, with two thirds of patients undergoing resective surgery and a third undergoing CC becoming spasm free. Post-operative developmental improvement was observed in 44 participants (65.7% of those with available data). The presence of lesional MRI and more extensive resection/disconnection (e.g., hemispherectomy) emerged as significant prognostic factors for spasm freedom and can inform clinical decision-making.

Positron Emission Tomography (PET) in presurgical planning of anterior temporal lobectomy: A systematic review of efficacy and limitations

INTRODUCTION

Temporal lobe epilepsy (TLE), a debilitating neurological disorder, necessitates refined diagnostic and treatment strategies. This comprehensive review appraises the potential of positron emission tomography (PET) in enhancing the presurgical planning of Anterior Temporal Lobectomy (ATL) for patients afflicted with TLE.

METHODS

A comprehensive literature search was conducted using the PubMed, SCOPUS, and ScienceDirect databases from 1985 to 2022, following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for studies investigating PET and ATL. This review studied a range of radiotracers, including FDG, H2O, FMZ, MPPF, and FCWAY, analyzing their efficacy in detecting epileptogenic foci, establishing resection boundaries, and predicting postoperative outcomes. The study paid special attention to cases where MRI findings were inconclusive.

RESULTS

A total of 52 studies were included in the final analysis. Our analysis revealed that FDG-PET imaging was instrumental in identifying seizure foci and predicting postoperative results. It exhibited significant value in situations where structural abnormalities were absent on MRI scans. Furthermore, newer radiotracers such as 5-HT1A antagonists, FCWAY and MPPF, presented promising potential for localizing seizure foci, particularly in MRI-negative TLE, despite their comparatively limited current usage.

CONCLUSION

PET imaging, although challenged by issues such as radiation exposure, limited accessibility, and high costs, offers considerable promise. Integration with other imaging modalities, such as EEG and MRI, has contributed to improved localization of epileptogenic foci and subsequently, enhanced surgical outcomes. Further research must focus on establishing the relative efficacy and optimal combinations of these radiotracers in the orchestration of ATL surgical planning and prognostication of postoperative outcomes for TLE patients. Encouragingly, these advancements hold the potential to revolutionize the management of TLE, delivering a better quality of life for patients.

Network excitability of stimulation-induced spectral responses helps localize the seizure onset zone

OBJECTIVE

While evoked potentials elicited by single pulse electrical stimulation (SPES) may assist seizure onset zone (SOZ) localization during intracranial EEG (iEEG) monitoring, induced high frequency activity has also shown promising utility. We aimed to predict SOZ sites using induced cortico-cortical spectral responses (CCSRs) as an index of excitability within epileptogenic networks.

METHODS

SPES was conducted in 27 epilepsy patients undergoing iEEG monitoring and CCSRs were quantified by significant early (10-200 ms) increases in power from 10 to 250 Hz. Using response power as CCSR network connection strengths, graph centrality measures (metrics quantifying each site's influence within the network) were used to predict whether sites were within the SOZ.

RESULTS

Across patients with successful surgical outcomes, greater CCSR centrality predicted SOZ sites and SOZ sites targeted for surgical treatment with median AUCs of 0.85 and 0.91, respectively. We found that the alignment between predicted and targeted SOZ sites predicted surgical outcome with an AUC of 0.79.

CONCLUSIONS

These findings indicate that network analysis of CCSRs can be used to identify increased excitability of SOZ sites and discriminate important surgical targets within the SOZ.

SIGNIFICANCE

CCSRs may supplement traditional passive iEEG monitoring in seizure localization, potentially reducing the need for recording numerous seizures.

A Comprehensive Review of Recent Trends in Surgical Approaches for Epilepsy Management

Epilepsy is a neurological disorder that affects millions of people worldwide, with a significant proportion of patients experiencing drug-resistant epilepsy, where seizures remain uncontrolled despite medical treatment. This review evaluates the latest surgical techniques for managing epilepsy, focusing on their effectiveness, safety, and the ongoing challenges that hinder their broader adoption. We explored various databases including PubMed, Google Scholar, and Cochrane Library to look for relevant literature using the following keywords: Epilepsy, Resective Surgery, Corpus Collectumy, and Antiepileptic Drugs. A total of 54 relevant articles were found and thoroughly explored. Recent advancements in surgical interventions include resective procedures such as anterior temporal lobectomy, corpus callosotomy, and hemispherectomy, which have been particularly effective in reducing seizures for specific types of epilepsy. Minimally invasive techniques, including laser interstitial thermal therapy and focused ultrasound, are increasingly being used, offering promising outcomes for certain patient groups. Additionally, neuromodulation methods such as deep brain stimulation, vagus nerve stimulation, and responsive neurostimulation provide alternative treatment options, especially for patients who are not suitable candidates for resective surgery. Despite these advancements, the full potential of epilepsy surgery is often underutilized due to various challenges. Inconsistent referral practices, a lack of standardized surgical protocols, and significant socioeconomic barriers continue to limit access to these procedures. Addressing these issues through improved referral processes, better education for healthcare providers and patients, and ensuring equitable access to advanced surgical treatments is crucial for optimizing patient outcomes. Future research should focus on overcoming these barriers and assessing long-term outcomes to further enhance the care of patients with epilepsy.

The anterior sylvian point as a reliable landmark for the anterior temporal lobectomy in mesial temporal lobe epilepsy: technical note, case series, and cadaveric dissection

Introduction

Mesial temporal lobe epilepsy (MTLE) is one of the most prevalent forms of focal epilepsy in surgical series, particularly among adults. Over the decades, different surgical strategies have been developed to address drug-resistant epilepsy while safeguarding neurological and cognitive functions. Among these strategies, anterior temporal lobectomy (ATL), involving the removal of the temporal pole and mesial temporal structures, has emerged as a widely employed technique. Numerous modifications have been proposed to mitigate the risks associated with aphasia, cognitive issues, and visual field defects.

Methods

Our approach is elucidated through intraoperative and cadaveric dissections, complemented by neuroradiological and cadaveric measurements of key anatomical landmarks. A retrospective analysis of patients with drug-resistant MTLE who were treated using our ATL technique at IRCCS Neuromed (Pozzilli) is presented.

Results

A total of 385 patients were treated with our ATL subpial technique anatomically focused on the anterior Sylvian point (ASyP). The mean FU was 9.9 ± 5.4 years (range 1-24). In total, 84%of patients were free of seizures during the last follow-up, with no permanent neurological deficits. Transient defects were as follows: aphasia in 3% of patients, visual field defects in 2% of patients, hemiparesis in 2% of patients, and cognitive/memory impairments in 0.8% of patients. In cadaveric dissections, the ASyP was found at a mean distance from the temporal pole of 3.4 ± 0.2 cm (range 3-3.8) at the right side and 3.5 ± 0.2 cm (3.2-3.9) at the left side. In neuroimaging, the ASyP resulted anterior to the temporal horn tip in all cases at a mean distance of 3.2 ± 0.3 mm (range 2.7-3.6) at the right side and 3.5 ± 0.4 mm (range 2.8-3.8) at the left side.

Discussion

To the best of our knowledge, this study first introduces the ASyP as a reliable and reproducible cortical landmark to perform the ATL to overcome the patients' variabilities, the risk of Meyer's loop injury, and the bias of intraoperative measurements. Our findings demonstrate that ASyP can be a safe cortical landmark that is useful in MTLE surgery because it is constantly present and is anterior to risky temporal regions such as temporal horn and language networks.

Super-selective Wada test for pre-surgical leg motor function assessment: A case report

INTRODUCTION

Wada test is well-known to assess lateralization of memory and language functions; however, super-selective Wada (ss-Wada) to evaluate motor leg function is rare. We present a ss-Wada test within the anterior cerebral artery (ACA) to assess the motor function of the leg.

METHODS

Retrospective chart review.

RESULTS

Comprehensive phase-I/II surgical evaluation revealed an ictal focus around the left post-central gyrus with immediate involvement around the left para-central regions. To avoid potential right leg motor dysfunction with the surgery, the patient underwent a ss-Wada procedure. Angiography revealed bilateral ACAs were supplied by the left A1 segment. Super-selective microcatheter injection of amobarbital into the left ACA was performed to avoid cross-filling the contralateral ACA. The ss-Wada test confirmed no right leg motor impairment. Afterward, a craniotomy with direct cortical stimulation confirmed that the left-sided ictal/peri-ictal zone had no clear leg motor function. The patient underwent disconnection of that region and remained seizure-free at 10-month post-op follow-up without any motor or sensory deficits in the right limbs.

CONCLUSION

This case demonstrates the proof of concept for ss-Wada in assessing lower extremity motor function. The ss-Wada procedure accurately predicted no motor deficits in the right leg, consistent with preserved motor function post-surgery.

Correlation of magnetic resonance spectroscopy and magnetic resonance imaging with findings of electroencephalography in patients with temporal lobe epilepsy

INTRODUCTION

This research aimed to see how well magnetic resonance spectroscopy (MRS) could identify the lateralization side in individuals with temporal lobe epilepsy (TLE) compared to electroencephalography (EEG) and magnetic resonance imaging (MRI) results.

METHODS

Twenty-three individuals were included in this research and diagnosed with TLE (both clinically and by EEG). Clinical exams, interictal EEG, and MRI were performed on all patients. In addition, the individuals were also subjected to proton MRS.

RESULTS

The age range of 23 participants was 20-55 years (mean = 34.6 ± 8.5); 10 were male (44%), and 13 were female (56%). The right temporal lobe MRI showed a sensitivity and specificity of 60% and 55% for detecting mesial temporal lobe sclerosis (MTS) foci, respectively (positive predictive value (PPV) of 27% and negative predictive value (NPV) of 83%). MRI showed 83% sensitivity and 35% specificity for MTS foci in the left temporal lobe (PPV of 31% and NPV of 86%). MRS showed 61% sensitivity and 100% specificity in the right temporal lobe (PPV 100%) and 80% sensitivity and specificity in the left temporal lobe (PPV 100%) for identifying MTS foci. Overall, MRS (both left and right) results matched EEG findings.

CONCLUSION

MRS is a potential noninvasive neuroradiology technique for assessing epilepsy patients because it is more sensitive than structural MRI in identifying MTS. The results of the study overall appears to be of interest but still need further support from future studies with larger sample sizes.

Electrode Tip Shift During the Stereotactic Electroencephalography Evaluation Period with Boltless Suture Fixation

BACKGROUND

Electrodes for stereotactic electroencephalography (SEEG) are typically fixed to the skull with anchor bolts. When anchor bolts are unavailable, electrodes have to be fixed using other methods, carrying the possibility of electrode shift. This study, therefore, evaluated the characteristics of electrode tip shift during SEEG monitoring in patients with electrodes fixed using the suture technique.

METHODS

We retrospectively included patients who underwent SEEG implantation with suture fixation and evaluated the tip shift distance (TSD) of electrodes. Possible influences evaluated included: 1) implantation period, 2) lobe of entry, 3) unilateral or bilateral implantation, 4) electrode length, 5) skull thickness, and 6) scalp thickness difference.

RESULTS

A total of 50 electrodes in 7 patients were evaluated. TSD was 1.4 ± 2.0 mm (mean ± standard deviation). Implantation period was 8.1 ± 2.2 days. Entry lobe was frontal for 28 electrodes and temporal for 22 electrodes. Implantation was bilateral for 25 electrodes and unilateral for 25 electrodes. Electrode length was 45.4 ± 14.3 mm. Skull thickness was 6.0 ± 3.7 mm. Scalp thickness difference was -1.5 ± 2.1 mm, which was found greater in temporal lobe entry compared with frontal lobe entry. According to univariate analyses, neither implantation period nor electrode length correlated with TSD. Multivariate regression analysis showed that only greater scalp thickness difference correlated significantly with greater TSD (P = 0.0018).

CONCLUSIONS

Greater scalp thickness difference correlated with greater TSD. Surgeons need to consider the degree of scalp thickness difference and electrode shift when using suture fixation, especially with temporal lobe entry.

Cortico-cortical evoked potentials in response to varying stimulation intensity improves seizure localization

OBJECTIVE

As single pulse electrical stimulation (SPES) is increasingly utilized to help localize the seizure onset zone (SOZ), it is important to understand how stimulation intensity can affect the ability to use cortico-cortical evoked potentials (CCEPs) to delineate epileptogenic regions.

METHODS

We studied 15 drug-resistant epilepsy patients undergoing intracranial EEG monitoring and SPES with titrations of stimulation intensity. The N1 amplitude and distribution of CCEPs elicited in the SOZ and non-seizure onset zone (nSOZ) were quantified at each intensity. The separability of the SOZ and nSOZ using N1 amplitudes was compared between models using responses to titrations, responses to one maximal intensity, or both.

RESULTS

At 2 mA and above, the increase in N1 amplitude with current intensity was greater for responses within the SOZ, and SOZ response distribution was maximized by 4-6 mA. Models incorporating titrations achieved better separability of SOZ and nSOZ compared to those using one maximal intensity.

CONCLUSIONS

We demonstrated that differences in CCEP amplitude over a range of current intensities can improve discriminability of SOZ regions.

SIGNIFICANCE

This study provides insight into the underlying excitability of the SOZ and how differences in current-dependent amplitudes of CCEPs may be used to help localize epileptogenic sites.

Suppressing interferences of EIT on synchronous recording EEG based on comb filter for seizure detection

Background and objective

The purpose of this study was to eliminate the interferences of electrical impedance tomography (EIT) on synchronous recording electroencephalography (EEG) for seizure detection.

Methods

The simulated EIT signal generated by COMSOL Multiphysics was superimposed on the clinical EEG signal obtained from the CHB-MIT Scalp EEG Database, and then the spectrum features of superimposed mixed signals were analyzed. According to the spectrum analysis, in addition to high-frequency interference at 51.2 kHz related to the drive current, there was also low-frequency interference caused by switching of electrode pairs, which were used to inject drive current. A low pass filter and a comb filter were used to suppress the high-frequency interference and low-frequency interference, respectively. Simulation results suggested the low-pass filter and comb filter working together effectively filtered out the interference of EIT on EEG in the process of synchronous monitoring.

Results

As a result, the normal EEG and epileptic EEG could be recognized effectively. Pearson correlation analysis further confirmed the interference of EIT on EEG was effectively suppressed.

Conclusions

This study provides a simple and effective interference suppression method for the synchronous monitoring of EIT and EEG, which could be served as a reference for the synchronous monitoring of EEG and other medical electromagnetic devices.

Source-sink connectivity: a novel interictal EEG marker for seizure localization

Over 15 million epilepsy patients worldwide have drug-resistant epilepsy. Successful surgery is a standard of care treatment but can only be achieved through complete resection or disconnection of the epileptogenic zone, the brain region(s) where seizures originate. Surgical success rates vary between 20% and 80%, because no clinically validated biological markers of the epileptogenic zone exist. Localizing the epileptogenic zone is a costly and time-consuming process, which often requires days to weeks of intracranial EEG (iEEG) monitoring. Clinicians visually inspect iEEG data to identify abnormal activity on individual channels occurring immediately before seizures or spikes that occur interictally (i.e. between seizures). In the end, the clinical standard mainly relies on a small proportion of the iEEG data captured to assist in epileptogenic zone localization (minutes of seizure data versus days of recordings), missing opportunities to leverage these largely ignored interictal data to better diagnose and treat patients. IEEG offers a unique opportunity to observe epileptic cortical network dynamics but waiting for seizures increases patient risks associated with invasive monitoring. In this study, we aimed to leverage interictal iEEG data by developing a new network-based interictal iEEG marker of the epileptogenic zone. We hypothesized that when a patient is not clinically seizing, it is because the epileptogenic zone is inhibited by other regions. We developed an algorithm that identifies two groups of nodes from the interictal iEEG network: those that are continuously inhibiting a set of neighbouring nodes ('sources') and the inhibited nodes themselves ('sinks'). Specifically, patient-specific dynamical network models were estimated from minutes of iEEG and their connectivity properties revealed top sources and sinks in the network, with each node being quantified by source-sink metrics. We validated the algorithm in a retrospective analysis of 65 patients. The source-sink metrics identified epileptogenic regions with 73% accuracy and clinicians agreed with the algorithm in 93% of seizure-free patients. The algorithm was further validated by using the metrics of the annotated epileptogenic zone to predict surgical outcomes. The source-sink metrics predicted outcomes with an accuracy of 79% compared to an accuracy of 43% for clinicians' predictions (surgical success rate of this dataset). In failed outcomes, we identified brain regions with high metrics that were untreated. When compared with high frequency oscillations, the most commonly proposed interictal iEEG feature for epileptogenic zone localization, source-sink metrics outperformed in predictive power (by a factor of 1.2), suggesting they may be an interictal iEEG fingerprint of the epileptogenic zone.

Paediatric epilepsy surgery: Techniques and outcomes

Epilepsy is a neurological condition characterised by recurrent and persistent seizures. For paediatric patients, achieving early seizure freedom can have positive impacts on cognition, development, social integration and mental health, leading to improved quality of life. In general, one third of patients with epilepsy are refractory to medication; for these patients, epilepsy surgery may offer the only chance for improved seizure control. Epilepsy surgery as a therapeutic intervention has become increasingly accepted in the past few decades, with more diverse options available (including neuromodulatory and minimally invasive techniques). In this context, we discuss here the pre-operative workup for paediatric patients with medically refractory epilepsy and provide an updated review on current and emerging surgical therapies for this condition. We also discuss the clinical, neuropsychological, quality of life and economic impacts of epilepsy surgery.

Seizure Latency and Epilepsy Localization as Predictors of Recurrence Following Epilepsy Surgery

OBJECTIVE

The primary purpose is to determine if the time between epilepsy surgery and first seizure recurrence can estimate the timing of the next seizure event for temporal and extratemporal epilepsy. A secondary endpoint aimed to compare temporal and extratemporal epilepsy surgery and examine which subgroup has a higher hazard of subsequent seizure recurrence.

METHODS

Data was used from a retrospective database at Thomas Jefferson University Hospital. Records were stratified into temporal (N = 943) and extratemporal (N = 125) surgeries. Analyses were done using SAS and utilized Cox-Proportional hazards models while controlling for demographics and clinical factors. The primary predictor of time between surgery and first recurrence was treated as a nominal variable binned into six segments, while secondary endpoints used a categorical predictor of epilepsy location while controlling for seizure latency.

RESULTS

Generally, as seizure latency following surgery increased, the time between first seizure and second seizure increased. These results were statistical meaningful in the temporal set (Wald Chi Square: 40.4715, df = 5, p<0.0001). Outcomes could also be interpreted based on predictor group, for instance, if seizure one occurred between one to two months following surgery in the temporal set, the median number of days until the next seizure was 35.5 days (95% CIs: 21 - 89 days). Secondary analysis showed that temporal lobe epilepsy had a lower hazard of a second seizure than extratemporal lobe epilepsy (89.2% reduction in hazard; 95% CIs: 0.015 - 0.795).

SIGNIFICANCE

This analysis provides a framework to use initial seizure latency to predict the median number of days until the next seizure event, while stratifying based on epilepsy location and controlling for multiple variables. It also suggests that the hazard of seizure recurrence in temporal lobe epilepsy is lower than extratemporal lobe epilepsy.

The Neuroprotective Effect of miR-136 on Pilocarpine-Induced Temporal Lobe Epilepsy Rats by Inhibiting Wnt/β-Catenin Signaling Pathway

Objective

To explore the effect of miR-136 on temporal lobe epilepsy (Ep) and its mechanism of action.

Methods

30 male rats were injected intraperitoneally with 30 mg/kg pilocarpine to construct a rat temporal lobe epilepsy model, and they were randomly divided into 5 groups (n = 6 per group): control group, Ep group, agomir NC group, miR-136 agomir group, and miR-136+LiCl group. The brain tissues of the rats were collected 7 days after the treatment. The expression of miR-136 in the hippocampus tissue was detected by qRT-PCR. H&E and Nissl staining were used to observe the histopathological changes and neuron damage in the hippocampus tissue. IL-1β, IL-6, and TNF-α levels in the hippocampus tissue were detected by ELISA. Flow cytometry was used to detect the apoptosis rate in the hippocampus tissue. Western blot was used to detect the expression levels of c-Caspase-3, Bcl-2, β-catenin, Cyclin D1, and c-myc protein in the hippocampus.

Results

The expression of miR-136 was significantly downregulated in the hippocampus tissue of epileptic rats. After overexpression of miR-136, the number of seizures and the duration of epilepsy in rats were significantly reduced. At the same time, hippocampal tissue damage was improved considerably, and the degree of neuronal damage decreased. Overexpression of miR-136 also significantly reduced the apoptosis rate in the hippocampus tissue and inhibited the levels of inflammatory factors. Meanwhile, miR-136 downregulates the expression of Wnt/β-catenin signaling pathway-related proteins. However, Wnt pathway activator LiCl could destroy the protective effect of miR-136.

Conclusion

miR-136 could exert its neuroprotective influence on temporal lobe epilepsy rats by inhibiting the Wnt/β-catenin signaling pathway.

A Novel method of seizure onset zone localization by serial Tc-99 m ECD brain perfusion SPECT clearance patterns

In this prospective study, we postulate that there is a difference between clearance of [99mTc]Tc- ethyl cysteinate dimer (ECD) in the seizure onset zone (SOZ) and other brain areas and thus SOZ localization by clearance patterns might become a potential novel method for SOZ localization in epilepsy. The parametric images of brain ECD clearance were generated by linear regression model analysis from serial brain SPECT scans from 30 to 240 min after ECD injection (7-times point) in 7 patients with drug-resistant epilepsy and 3 normal volunteers. Clearance patterns of the SOZ confirmed by good surgical outcome or consensus with other investigations were analyzed quantitatively and semi-quantitatively by visual grading (slower or faster washout than contralateral brain regions). The average [^99mTc]Tc-ECD clearance rates of SOZs were + 1.08% ± 2.57%/hr (wash in), -7.02% ± 2.56%/hr (washout), and -5.37% ± 1.71%/hr (washout) in ictal, aura and interictal states, respectively. Paired t-tests between the SOZ and contralateral regions showed statistically significant difference (p = 0.039 in interictal state). Clearance patterns that can define the SOZs were 1) wash in and slow washout on ictal slope, 2) fast washout on aura slope and interictal slope with 100% (6/6), 100% (2/2) and 75% (6/8) localization using ictal, aura, and interictal slope maps, respectively. Our study provided the evidence that clearance pattern methods are potential additive diagnostic tools for SOZ localization when routine one-time point SPECT are unable to define the SOZ.

Right temporal lobe epilepsy surgery activates suppressed post-traumatic stress disorder 31 years after a robbery

Hippocampus and amygdala play central roles in the development of post-traumatic stress disorder (PTSD). Changes in neurological structures due to surgery leading to PTSD have previously been reported. In this case, we present a patient that develops PTSD right after epilepsy surgery in the right temporal lobe. The case adds knowledge to the mechanisms of storage of PTSD memories. A 56-year-old male suffering from refractory temporal lobe epilepsy was treated with an anteromesial temporal lobe resection on the right side. A few weeks after the surgery, he developed strong PTSD symptoms. They included flashbacks from a robbery he was subjected to three decades ago when he was 25 years old. In addition, he suffered from hypervigilance, irritability, and avoidance behavior. Psychotherapy eventually eased his symptoms. No previous disorders were recorded. No psychiatry symptoms were present before surgery. This case is one of few reports on the sudden occurrence of PTSD after epilepsy-surgery in the form of right-sided anteromesial temporal lobe resection. The disorder may not have been detected if not included in the Danish Epilepsy-Surgery-Protocol, among them both the pre-surgery psychiatric management and in the post-operative monitoring.

Combined quantitative T2 mapping and [18F]FDG PET could improve lateralization of mesial temporal lobe epilepsy

OBJECTIVES

To investigate whether quantitative T2 mapping is complementary to [¹⁸F]FDG PET in epileptogenic zone detection, thus improving the lateralization accuracy for drug-resistant mesial temporal lobe epilepsy (MTLE) using hybrid PET/MR.

METHODS

We acquired routine structural MRI, T2-weighted FLAIR, whole brain T2 mapping, and [¹⁸F]FDG PET in 46 MTLE patients and healthy controls on a hybrid PET/MR scanner, followed with computing voxel-based z-score maps of patients in reference to healthy controls. Asymmetry indexes of the hippocampus were calculated for each imaging modality, which then enter logistic regression models as univariate or multivariate for lateralization. Stereoelectroencephalography (SEEG) recordings and clinical decisions were collected as gold standard.

RESULTS

Routine structural MRI and T2w-FLAIR lateralized 47.8% (22/46) of MTLE patients, and FDG PET lateralized 84.8% (39/46). T2 mapping combined with [¹⁸F]FDG PET improved the lateralization accuracy by correctly lateralizing 95.6% (44/46) of MTLE patients. The asymmetry indexes of hippocampal T2 relaxometry and PET exhibit complementary tendency in detecting individual laterality, especially for MR-negative patients. In the quantitative analysis of z-score maps, the ipsilateral hippocampus had significantly lower SUVR (LTLE, p < 0.001; RTLE, p < 0.001) and higher T2 value (LTLE, p < 0.001; RTLE, p = 0.001) compared to the contralateral hippocampus. In logistic regression models, PET/T2 combination resulted in the highest AUC of 0.943 in predicting lateralization for MR-negative patients, followed by PET (AUC = 0.857) and T2 (AUC = 0.843).

CONCLUSIONS

The combination of quantitative T2 mapping and [¹⁸F]FDG PET could improve lateralization for temporal lobe epilepsy.

KEY POINTS

• Quantitative T2 mapping and¹⁸F-FDG PET are complementary in the characterization of hippocampal alterations of MR-negative temporal lobe epilepsy patients. • The combination of quantitative T2 and¹⁸F-FDG PET obtained from hybrid PET/MR could improve lateralization for temporal lobe epilepsy.

Sources and Sinks in Interictal iEEG Networks: An iEEG Marker of the Epileptogenic Zone

Around 30% of epilepsy patients have seizures that cannot be controlled with medication. The most effective treatments for medically resistant epilepsy are interventions that surgically remove the epileptogenic zone (EZ), the regions of the brain that initiate seizure activity. A precise identification of the EZ is essential for surgical success but unfortunately, current success rates range from 20-80%. Localization of the EZ requires visual inspection of intracranial EEG (iEEG) recordings during seizure events. The need for seizure occurrence makes the process both costly and time-consuming and in the end, less than 1% of the data captured is used to assist in EZ localization. In this study, we aim to leverage interictal (between seizures) data to localize the EZ. We develop and test the source-sink index as an interictal iEEG marker by identifying two groups of network nodes from a patient's interictal iEEG network: those that inhibit a set of their neighboring nodes ("sources") and the inhibited nodes themselves ("sinks"). Specifically, we i) estimate patient-specific dynamical network models from interictal iEEG data and ii) compute a source-sink index for every network node (iEEG channel) to identify pathological nodes that correspond to the EZ. Our results suggest that in patients with successful surgical outcomes, the source-sink index clearly separates the clinically identified EZ (CA-EZ) channels from other channels whereas in patients with failed outcomes CA-EZ channels cannot be distinguished from the rest of the network.

Transfer Entropy between Intracranial EEG Nodes Highlights Network Dynamics that Cause and Stop Epileptic Seizures

Transfer entropy (TE) is used to examine the connectivity between nodes and the roles of nodes in epileptic neural networks during rest, moments before seizure, during seizure, and moments after seizure. There is a set of nodes that dominate information flow to epileptogenic zone (EZ) nodes, regions that trigger seizure, and non-EZ nodes during rest. The TE from the dominant to the EZ nodes decreases shortly before a seizure event and reaches a minimum during seizure. During the seizure, the dominant nodes cease or only weakly interact with the EZ nodes. This supports the hypothesis that seizure occurs when some nodes stop inhibiting the EZ nodes. The TE from the dominant to the EZ nodes peaks immediately after seizure, suggesting that seizure may stop when the brain exerts the highest level of information flow/activation/communication to the EZ nodes. The information flow from the dominant to EZ nodes is different from that to non-EZ nodes. This TE dynamics entering and exiting seizures may identify more accurately the EZ nodes, which may improve surgical planning.

Seizure outcomes of large volume temporo-parieto-occipital and frontal surgery in children with drug-resistant epilepsy

OBJECTIVE

In this study, we investigate the seizure outcomes of temporo-parieto-occipital (TPO) and frontal disconnections or resections in children with drug-resistant epilepsy (DRE) in order to determine factors which may predict surgical results.

METHODS

Children with DRE, who underwent either TPO or frontal disconnection or resection at Great Ormond Street Hospital for Children between 2000 and 2017, were identified from a prospectively collated operative database. Demographic data, age at surgery, type of surgery, scalp EEGs and operative histopathology were collected. Magnetic resonance imaging (MRI) was assessed to determine completeness of disconnection and presence of radiological lesion beyond the disconnection margins. Seizure outcome at 6, 12, and 24 months post-surgery was assessed using the Engel Scale (ES). Logistic regression was used to identify relationships between data variables and seizure outcome.

RESULTS

46 children (males = 28, females = 18; age range 0.5-16.6 years) who underwent TPO (n = 32, including a re-do disconnection) or frontal disconnection or resection (n = 15) were identified. Patients in the TPO treatment group had more favourable seizure outcomes than those in the frontal treatment group (ES I-II in 56 %vs 47 % at 6 months, 52 % vs 46 % at 12 months). Presence of the lesion beyond disconnection boundaries and older age at the time of surgery were associated with poorer seizure outcome. Gender, surgery type, completeness of disconnection, scalp EEG findings and underlying pathology were not related to seizure outcome, but subgroup numbers were small.

CONCLUSIONS

Both TPO and frontal disconnection are effective treatments for selected children with posterior multi-lobar or diffuse frontal lobe epilepsy. Confinement of the MRI lesion within the disconnection margins and a younger age at surgery are associated with favourable seizure outcomes. Further studies are required to elucidate these findings.

MR spectroscopic imaging at 3 T and outcomes in surgical epilepsy

For the spectroscopic assessment of brain disorders that require large-volume coverage, the requirements of RF performance and field homogeneity are high. For epilepsy, this is also challenging given the inter-patient variation in location, severity and subtlety of anatomical identification and its tendency to involve the temporal region. We apply a targeted method to examine the utility of large-volume MR spectroscopic imaging (MRSI) in surgical epilepsy patients, implementing a two-step acquisition, comprised of a 3D acquisition to cover the fronto-parietal regions, and a contiguous parallel two-slice Hadamard-encoded acquisition to cover the temporal-occipital region, both with T_R /T_E = 2000/40 ms and matched acquisition times. With restricted (static, first/second-order) B₀ shimming in their respective regions, the Cramér-Rao lower bounds for creatine from the temporal lobe two-slice Hadamard and frontal-parietal 3D acquisition are 8.1 ± 2.2% and 6.3 ± 1.9% respectively. The datasets are combined to provide a total 60 mm axial coverage over the frontal, parietal and superior temporal to middle temporal-occipital regions. We applied these acquisitions at a nominal 400 mm³ voxel resolution in n = 27 pre-surgical epilepsy patients and n = 20 controls. In controls, 86.6 ± 3.2% voxels with at least 50% tissue (white + gray matter, excluding CSF) survived spectral quality inclusion criteria. Since all patients were clinically followed for at least 1 year after surgery, seizure frequency outcome was available for all. The MRSI measurements of the total fractional metabolic dysfunction (characterized by the Cr/NAA metric) in FreeSurfer MRI gray matter segmented regions, in the patients compared with the controls, exhibited a significant Spearman correlation with post-surgical outcome. This finding suggests that a larger burden of metabolic dysfunction is seen in patients with poorer post-surgical seizure control.

Magnetic Resonance Imaging Characterization of the Hippocampi in Temporal Lobe Epilepsy: Correlation of Volumetry and Apparent Diffusion Coefficient with Laterality and Duration of Seizures

Background and Purpose It is estimated that hippocampal damage is seen in 50 to 70% of patients with temporal lobe epilepsy (TLE). Although most magnetic resonance imaging (MRI) studies are adequate to detect gross hippocampal atrophy, subtle changes that may characterize early disease in TLE, such as visually nonappreciable volume loss, may often be missed if objective volumetric analysis is not undertaken. Materials and Methods We conducted a hospital-based prospective analytical study in which 40 patients with partial seizures of temporal lobe origin were included and their hippocampal volumes (HVs) were determined by manual volumetric analysis. The findings were recorded and correlated with the side of seizure and its duration. The quantitative assessment was allotted different grades accordingly. Also, the apparent diffusion coefficient (ADC) values of bilateral hippocampi were estimated and their correlation with the side of seizure was determined. Results Most patients in the study were in the age group of 11 to 20 years (37.5%). In total, 57.5% had seizures for a period of 1 to 5 years. While 67.5% ( n = 27) had seizure on the right, 32.5% ( n = 13) had on the left. The mean HV estimated on the right and left were correlated with the side of seizure and found to be statistically significant ( p < 0.001 in those with right-sided seizures and p = 0.02 in those with left-sided seizures). Simultaneously the ADC values estimated were found to correlate with the laterality of seizures with a statistical difference ( p < 0.01) . Duration of seizures however did not show a positive correlation with the HV. Conclusion MRI with quantitative estimation of HV and ADC values can depict the presence and laterality in TLE with accuracy rates that exceed those achieved by visual inspection alone. Thus, quantitative MRI provides a useful means for translating volumetric analysis into clinical practice.

Focal Cortical Dysplasia IIIa in Hippocampal Sclerosis-Associated Epilepsy: Anatomo-Electro-Clinical Profile and Surgical Results From a Multicentric Retrospective Study

BACKGROUND

Hippocampal sclerosis (HS) may be associated with focal cortical dysplasia IIIa (FCD IIIa) in patients undergoing surgery for temporal lobe epilepsy (TLE).

OBJECTIVE

To investigate whether the anatomo-electro-clinical profile and surgical outcome in patients with HS-related TLE are affected by coexisting FCD IIIa.

METHODS

A total of 220 patients, operated in 5 centers, with at least 24 mo follow-up (FU), were retrospectively studied. Preliminary univariate and subsequent multivariate analyses were performed to investigate possible associations between several potential presurgical, surgical, and postsurgical predictors and different variables (Engel's class I and Engel's class Ia, co-occurrence of FCD IIIa).

RESULTS

At last available postoperative control (FU: range 24-95 mo, median 47 mo), 182 (82.7%) patients were classified as Engel's class I and 142 (64.5%) as Engel's class Ia. At multivariate analysis, extension of neocortical resection and postoperative electroencephalogram were significantly associated with Engel's class I, whereas length of FU had a significant impact on class Ia in the whole cohort and in isolated HS (iHS) patients, but not in the FCD IIIa group. No differences emerged in the anatomo-electro-clinical profile and surgical results between patients with FCD IIIa and with iHS.

CONCLUSION

Coexistence of FCD IIIa did not confer a distinct anatomo-electro-clinical profile to patients with HS-related epilepsy. Postoperative seizure outcome was similar in FCD IIIa and iHS cases. These findings indicate limited clinical relevance of FCD IIIa in HS-related epilepsy and might be useful for refining future FCD classifications. Further studies are needed to clarify the correlation of class Ia outcome with the duration of FU.

Multipronged Attack of Stem Cell Therapy in Treating the Neurological and Neuropsychiatric Symptoms of Epilepsy

Epilepsy stands as a life-threatening disease that is characterized by unprovoked seizures. However, an important characteristic of epilepsy that needs to be examined is the neuropsychiatric aspect. Epileptic patients endure aggression, depression, and other psychiatric illnesses. Therapies for epilepsy can be divided into two categories: antiepileptic medications and surgical resection. Antiepileptic drugs are used to attenuate heightened neuronal firing and to lessen seizure frequency. Alternatively, surgery can also be conducted to physically cut out the area of the brain that is assumed to be the root cause for the anomalous firing that triggers seizures. While both treatments serve as viable approaches that aim to regulate seizures and ameliorate the neurological detriments spurred by epilepsy, they do not serve to directly counteract epilepsy's neuropsychiatric traits. To address this concern, a potential new treatment involves the use of stem cells. Stem cell therapy has been employed in experimental models of neurological maladies, such as Parkinson's disease, and neuropsychiatric illnesses like depression. Cell-based treatments for epilepsy utilizing stem cells such as neural stem cells (NSCs), mesenchymal stem cells (MSCs), and interneuron grafts have been explored in preclinical and clinical settings, highlighting both the acute and chronic stages of epilepsy. However, it is difficult to create an animal model to capitalize on all the components of epilepsy due to the challenges in delineating the neuropsychiatric aspect. Therefore, further preclinical investigation into the safety and efficacy of stem cell therapy in addressing both the neurological and the neuropsychiatric components of epilepsy is warranted in order to optimize cell dosage, delivery, and timing of cell transplantation.

Use of Innovative SPECT Techniques in the Presurgical Evaluation of Patients with Nonlesional Extratemporal Drug-Resistant Epilepsy

Up to 30% of patients with epilepsy may not respond to antiepileptic drugs. Patients with drug-resistant epilepsy (DRE) should undergo evaluation for seizure onset zone (SOZ) localization to consider surgical treatment. Cases of drug-resistant nonlesional extratemporal lobe epilepsy (ETLE) pose the biggest challenge in localizing the SOZ and require multiple noninvasive diagnostic investigations before planning the intracranial monitoring (ICM) or direct resection. Ictal Single Photon Emission Computed Tomography (i-SPECT) is a unique functional diagnostic tool that assesses the SOZ using the localized hyperperfusion that occurs early in the seizure. Subtraction ictal SPECT coregistered to MRI (SISCOM), statistical ictal SPECT coregistered to MRI (STATISCOM), and PET interictal subtracted ictal SPECT coregistered with MRI (PISCOM) are innovative SPECT methods for the determination of the SOZ. This article comprehensively reviews SPECT and sheds light on its vital role in the presurgical evaluation of the nonlesional extratemporal DRE.

Leveraging the lessons learned from studies on the cultural context of epilepsy care in Uganda: Opportunities and future directions

In this summary paper, we review the body of research contained in this special issue, The Intersection of Culture, Resources, and Disease: Epilepsy Care in Uganda, and corollary recommendations for a way forward. We review key findings and conclusions for the studies, which tell a story of culture and care-seeking through discussions and data gleaned from a rich research landscape traversing community village dwellings, shared communal areas, churches, and urban hospitals. The voices and perspectives of over 16,000 study participants inclusive of people living with epilepsy, their neighbors and healthcare workers, traditional healers, and faith leaders are reported. From this, we synthesize findings and prioritize a set of recommendations to advance epilepsy care in Uganda. Progress will require infrastructure strengthening, multilevel educational investments, and an ambitious, extensive program of community sensitization. These proposed priorities and actions outline a way forward through formidable but surmountable challenges but require harmonized efforts by government and other relevant stakeholders, scholars, clinicians, and community leaders. This article is part of the Special Issue "The Intersection of Culture, Resources, and Disease: Epilepsy Care in Uganda".

Plasma Exosomal MiRNAs Expression Profile in Mesial Temporal Lobe Epilepsy With Hippocampal Sclerosis: Case-Control Study and Analysis of Potential Functions

Background

To explore an expression profile in plasma exosomal miRNAs of mesial temporal lobe epilepsy with hippocampal sclerosis (mTLE + HS) patients and investigate the associated clinical significance and putative pathways involved.

Methods

Plasma exosomal miRNAs were measured in six mTLE + HS patients who were confirmed with pre-surgical stereo-electroencephalography and six without hippocampal sclerosis (mTLE−HS) using Illumina HiSeq 2500. Then six dysregulated miRNAs were chosen for validation in an independent sample of 18 mTLE + HS patients and 18 mTLE−HS controls using RT-qPCR. Receiver operating characteristic curve was conducted to evaluate the diagnostic value of miRNAs in HS. Bioinformatic analyses were conducted to reveal in which pathways these miRNAs were involved.

Results

We revealed that a total of 42 exosomal miRNAs were differentially expressed in mTLE + HS. Among them, 25 were increased and 17 decreased. After validation, hsa-miR-129-5p, -214-3p, -219a-5p, and -34c-5p were confirmed as being upregulated, while hsa-miR-421 and -184 were significantly downregulated in mTLE + HS. Moreover, hsa-miR-184 had the best diagnostic value for discriminating mTLE + HS with 88.9% sensitivity and 83.3% specificity. These six miRNAs regulated several genes from neurotrophin-, hippo-, p53-, TGF- beta-, HIF- 1-, mTOR-related pathways.

Conclusion

Six miRNAs were dysregulated in mTLE + HS patients and targeted several genes. This result might facilitate pathological mechanistic studies of miRNAs in HS and represent potential diagnostic biomarkers. These provided the rationale for further confirmation studies in larger cohorts of prospective patients.

Surgical Treatments of Epilepsy

Nearly 30% of epilepsy patients are refractory to medical therapy. Surgical management of epilepsy is an increasingly viable option for these patients. Although surgery has historically been used as a palliative option, improvements in technology and outcomes show its potential in certain subsets of patients. This article reviews the two main categories of surgical epilepsy treatment-resective surgery and neuromodulation. Resective surgery includes temporal lobe resections, extratemporal resections, laser interstitial thermal therapy, and disconnection procedures. We discuss the three main types of neuromodulation-vagal nerve stimulation, responsive neurostimulation, and deep brain stimulation for epilepsy. The history and indications are explored for each type of treatment. Given the myriad types of resection and neuromodulation techniques, patient selection is reviewed in detail, with a discussion on which patients are most likely to benefit from different treatment strategies. We also discuss outcomes with examples of the pertinent landmark trials and their results. Finally, complications and surgical technique are reviewed. As new indications emerge and patient selection is refined, surgical management will continue to evolve as an adjuvant therapy for epileptic patients.

Intravenous infusion of bone marrow mononuclear cells promotes functional recovery and improves impaired cognitive function via inhibition of Rho guanine nucleotide triphosphatases and inflammatory signals in a model of chronic epilepsy

Temporal lobe epilepsy is the most common form of intractable epilepsy in adults. More than 30% of individuals with epilepsy have persistent seizures and have drug-resistant epilepsy. Based on our previous findings, treatment with bone marrow mononuclear cells (BMMC) could interfere with early and chronic phase epilepsy in rats and in clinical settings. In this pilocarpine-induced epilepsy model, animals were randomly assigned to two groups: control (Con) and epileptic pre-treatment (Ep-pre-t). The latter had status epilepticus (SE) induced through pilocarpine intraperitoneal injection. Later, seizure frequency was assessed using a video-monitoring system. Ep-pre-t was further divided into epileptic treated with saline (Ep-Veh) and epileptic treated with BMMC (Ep-BMMC) after an intravenous treatment with BMMC was done on day 22 after SE. Analysis of neurobehavioral parameters revealed that Ep-BMMC had significantly lower frequency of spontaneous recurrent seizures (SRS) in comparison to Ep-pre-t and Ep-Veh groups. Hippocampus-dependent spatial and non-spatial learning and memory were markedly impaired in epileptic rats, a deficit that was robustly recovered by treatment with BMMC. Moreover, long-term potentiation-induced synaptic remodeling present in epileptic rats was restored by BMMC. In addition, BMMC was able to reduce abnormal mossy fiber sprouting in the dentate gyrus. Molecular analysis in hippocampal tissue revealed that BMMC treatment down-regulates the release of inflammatory cytokine tumor necrosis factor-α (TNF-α) and Allograft inflammatory factor-1 (AIF-1) as well as the Rho subfamily of small GTPases [Ras homolog gene family member A (RhoA) and Ras-related C3 botulinum toxin substrate 1 (Rac)]. Collectively, delayed BMMC treatment showed positive effects when intravenously infused into chronic epileptic rats.

Serum Exosomal Proteins F9 and TSP-1 as Potential Diagnostic Biomarkers for Newly Diagnosed Epilepsy

Epilepsy is one of the most common chronic neurological diseases in the world, with a high incidence, a high risk of sudden unexplained death, and diagnostic challenges. Exosomes are nanosized extracellular vesicles that are released into physical environments and carry a variety of biological information. Moreover, exosomes can also be synthesized and released from brain cells, passing through the blood-brain barrier, and can be detected in peripheral blood or cerebrospinal fluid. Our study using the tandem mass tag (TMT) approach showed that a total of 76 proteins were differentially expressed in serum exosomes between epilepsy patients and healthy controls, with 6 proteins increasing and 70 proteins decreasing. Analysis of large clinical samples and two mouse models of chronic epilepsy indicated that two significantly differentially expressed serum exosomal proteins, coagulation factor IX (F9) and thrombospondin-1 (TSP-1), represent promising biomarkers for the diagnosis of epilepsy, with area under the curve (AUC) values of up to 0.7776 (95% CI, 0.7306–0.8246) and 0.8534 (95% CI, 0.8152–0.8916), respectively. This is the first study of exosomal proteins in epilepsy, and it suggests that exosomes are promising new tools for the diagnosis of epilepsy.

Convection-enhanced delivery of botulinum toxin serotype A into the nonhuman primate cisterna magna and hippocampus

OBJECTIVE

Botulinum toxin serotype A (BoNT/A) was reported to raise the seizure threshold when injected into the seizure focus of a kindled rodent model. Delivering BoNT/A to the nonhuman primate (NHP) central nervous system via convection-enhanced delivery (CED) has not been performed. The objective of this study was to determine the toxicity and distribution characteristics of CED of BoNT/A into the NHP hippocampus and cisterna magna.

METHODS

Escalating BoNT/A doses were delivered by CED into the NHP hippocampus (n = 4) and cisterna magna (n = 5) for behavioral and histological assessment and to determine the highest nonlethal dose (LD0) and median lethal dose (LD50). Hippocampal BoNT/A was coinfused with Gd-albumin, a surrogate MRI tracer. Gd-albumin and radioiodinated BoNT/A (125I-BoNT/A) were coinfused into the hippocampus of 3 additional NHPs to determine BoNT/A distribution by in vivo MRI and postmortem quantitative autoradiography. Scintillation counting of CSF assessed the flow of 125I-BoNT/A from the hippocampus to CSF postinfusion.

RESULTS

LD0 and LD50 were 4.2 and 18 ng/kg, and 5 and > 5 ng/kg for the NHP hippocampus and cisterna magna, respectively. Gd-albumin and 125I-BoNT/A completely perfused the hippocampus (155-234 mm3) in 4 of 7 NHPs. Fifteen percent of BoNT/A entered CSF after hippocampal infusion. The MRI distribution volume of coinfused Gd-albumin (VdMRI) was similar to the quantitative autoradiography distribution of 125I-BoNT/A (VdQAR) (mean VdMRI = 139.5 mm3 [n = 7]; VdQAR = 134.8 mm3 [n = 3]; r = 1.00, p < 0.0001). No infusion-related toxicity was identified histologically except that directly attributable to needle placement.

CONCLUSIONS

Gd-albumin accurately tracked BoNT/A distribution on MRI. BoNT/A did not produce CNS toxicity. BoNT/A LD0 exceeded 10-fold the dose administered safely to humans for cosmesis and dystonia.

Ketogenic diet for the treatment of pediatric epilepsy: review and meta-analysis

The ketogenic diet (KD), containing high levels of fat and low levels of carbohydrates, has been used to treat refractory epilepsy since the 1920s. In the past few decades, there has been more interest in less restrictive KDs such as the modified Atkins diet (MAD).

PURPOSE

Our aim was to review all evidence regarding the efficacy and tolerability of the KD and MAD from randomized controlled trials (RCTs) in children and adolescents with refractory epilepsy.

METHODS

We reviewed the current literature using Cochrane, EMBASE, and MEDLINE (using PubMed). We implemented predefined criteria regarding dataextraction and study quality.

RESULTS

We identified five RCTs that generated seven publications and recruited 472 children and adolescents with refractory epilepsy (≤ 18 years). The primary outcome (seizure frequency reduction (SFR) ≥ 50%) was attained in 35-56.1% of the participants in the intervention group, compared with 6-18.2% in the control group. Our meta-analysis underlined the significant efficacy of the KD compared with the control group: RR = 5.1 (95% CI 3.18-8.21, p < 0.001). Additionally, only two studies mentioned possible biomarkers to objectively evaluate the efficacy. Secondary outcomes, such as seizure severity and quality of life, were studied in three trials, leading to indecisive generalization of these findings. Gastro-intestinal adverse effects were the most prevalent, and no severe adverse effects were reported.

CONCLUSION

Despite the heterogeneity between all studies, the beneficial results underline that dietary interventions should be considered for children and adolescents with refractory epilepsy who are not eligible for epilepsy surgery. Future studies should be multi-center and long-term, and evaluate potential biomarkers and adverse effects.

Selective posterior cerebral artery amobarbital test: a predictor of memory following subtemporal selective amygdalohippocampectomy

BACKGROUND

The selective posterior cerebral artery (PCA) amobarbital test, or PCA Wada test, is used to predict memory impairment after epilepsy surgery in patients who have previously had a failed internal carotid artery (ICA) amobarbital test.

METHODS

Medical records from 2012 to 2018 were retrospectively reviewed for all patients with seizures who underwent a selective PCA Wada test at our institution following a failed or inconclusive ICA Wada test. Standardized neuropsychological testing was performed before and during the Wada procedure and postoperatively in patients who underwent resection.

RESULTS

Thirty-three patients underwent a selective PCA Wada test, with no complications. Twenty-six patients with medically refractory epilepsy had a seizure focus amenable to selective amygdalohippocampectomy (AHE). Six patients (23%, n=26) had a failed PCA Wada test and did not undergo selective AHE, seven (27%) declined surgical resection, leaving 13 patients who underwent subtemporal selective AHE. Hippocampal sclerosis was found in all 13 patients (100%). Twelve patients (92%) subsequently underwent formal neuropsychological testing and all were found to have stable memory. Ten patients (77%) were seizure-free (Engel Class I), with average follow-up of 13 months.

CONCLUSION

The selective PCA Wada test is predictive of memory outcomes after subtemporal selective AHE in patients with a failed or inconclusive ICA Wada test. Furthermore, given the low risk of complications and potential benefit of seizure freedom, a selective PCA Wada test may be warranted in patients with medically intractable epilepsy who are candidates for a selective AHE and who have a prior failed or inconclusive ICA Wada test.

New insights into a spectrum of developmental malformations related to mTOR dysregulations: challenges and perspectives

In recent years the role of the mammalian target of rapamycin (mTOR) pathway has emerged as crucial for normal cortical development. Therefore, it is not surprising that aberrant activation of mTOR is associated with developmental malformations and epileptogenesis. A broad spectrum of malformations of cortical development, such as focal cortical dysplasia (FCD) and tuberous sclerosis complex (TSC), have been linked to either germline or somatic mutations in mTOR pathway-related genes, commonly summarised under the umbrella term 'mTORopathies'. However, there are still a number of unanswered questions regarding the involvement of mTOR in the pathophysiology of these abnormalities. Therefore, a monogenetic disease, such as TSC, can be more easily applied as a model to study the mechanisms of epileptogenesis and identify potential new targets of therapy. Developmental neuropathology and genetics demonstrate that FCD IIb and hemimegalencephaly are the same diseases. Constitutive activation of mTOR signalling represents a shared pathogenic mechanism in a group of developmental malformations that have histopathological and clinical features in common, such as epilepsy, autism and other comorbidities. We seek to understand the effect of mTOR dysregulation in a developing cortex with the propensity to generate seizures as well as the aftermath of the surrounding environment, including the white matter.

Magnetoencephalography as a Prognostic Tool in Patients with Medically Intractable Temporal Lobe Epilepsy

BACKGROUND

Most surgical treatments for medically intractable temporal lobe epilepsy are helpful. When a patient has persistent symptoms after surgery, there are no tests that accurately predict whether a patient will have remnant epileptic foci. The aim of this study was to evaluate the usefulness of magnetoencephalography (MEG) as a prognostic tool in patients with temporal lobe epilepsy.

METHODS

From July 2012 to July 2016, 21 patients underwent preoperative and postoperative MEG at our center. Postoperative MEG was performed within 2 weeks after surgery. We analyzed MEG by estimating the time-frequency component of the signal to define gamma oscillations (GOs), which are an indicator of epileptogenic foci. We analyzed the relationship between GOs on MEG and surgical outcomes.

RESULTS

Mean follow-up period was 28.3 months (range, 13-44 months). At the last follow-up visit, patients were divided into 2 groups according to surgical outcome. All patients showed spike waves and GOs on preoperative electroencephalography and MEG. In the seizure control group (16 patients), spike waves (2 patients) and GOs (2 patients) were seen postoperatively despite absence of symptoms. In the recurrent seizure group (5 patients), whereas 3 patients showed spike waves, all 5 patients showed GOs on MEG postoperatively. There was a significant association between presence of GOs on postoperative MEG and surgical outcome (P = 0.01).

CONCLUSIONS

MEG can provide valuable postsurgical information on epileptic foci in patients with recurrent symptoms; GOs on postoperative MEG were especially correlated with epileptic recurrence. Our data show that GOs on postoperative MEG may have prognostic value.

Connectivity and Centrality Characteristics of the Epileptogenic Focus Using Directed Network Analysis

Accurate epileptogenic focus localization is required prior to surgical resection of brain tissue for the treatment of patients with antiepileptic drug-resistant (intractable) epilepsy. This clinical need is only partially fulfilled through a subjective, and at times inconclusive, the evaluation of the recorded electroencephalogram (EEG) at seizures' onset (the so-called gold standard for focus localization in epilepsy). We herein present a novel method of multivariate analysis of the EEG that appears to be very promising for an objective and robust localization of the epileptogenic focus at seizures' onset. Using the measure of generalized partial directed coherence, combined with surrogate data analysis, we first estimated from multichannel intracranial EEG the statistically significant causal interactions between brain regions at the onset of 92 clinical seizures from nine patients with temporal lobe intractable epilepsy. From the networks that were formed based on the thus derived interactions, a set of centrality metrics was estimated per network node (brain site). Brain sites located anatomically within the epileptogenic focus were shown to be associated with greater inward centrality values than non-focal brain regions at high frequencies ( γ band), and particular inward centrality metrics accurately localized the focus in all nine patients. In addition to focus localization from seizure (ictal) onset, the developed novel framework for analysis of EEG could be employed to identify the changes of the focal network over time, peri-ictally and interictally, and thus shed light onto the dynamics of ictogenesis, which could then have a significant impact on automated prediction and closed-loop control of seizures by neuromodulation.

MicroRNA-22 Controls Aberrant Neurogenesis and Changes in Neuronal Morphology After Status Epilepticus

Prolonged seizures (status epilepticus, SE) may drive hippocampal dysfunction and epileptogenesis, at least partly, through an elevation in neurogenesis, dysregulation of migration and aberrant dendritic arborization of newly-formed neurons. MicroRNA-22 was recently found to protect against the development of epileptic foci, but the mechanisms remain incompletely understood. Here, we investigated the contribution of microRNA-22 to SE-induced aberrant adult neurogenesis. SE was induced by intraamygdala microinjection of kainic acid (KA) to model unilateral hippocampal neuropathology in mice. MicroRNA-22 expression was suppressed using specific oligonucleotide inhibitors (antagomir-22) and newly-formed neurons were visualized using the thymidine analog iodo-deoxyuridine (IdU) and a green fluorescent protein (GFP)-expressing retrovirus to visualize the dendritic tree and synaptic spines. Using this approach, we quantified differences in the rate of neurogenesis and migration, the structure of the apical dendritic tree and density and morphology of dendritic spines in newly-formed neurons.SE resulted in an increased rate of hippocampal neurogenesis, including within the undamaged contralateral dentate gyrus (DG). Newly-formed neurons underwent aberrant migration, both within the granule cell layer and into ectopic sites. Inhibition of microRNA-22 exacerbated these changes. The dendritic diameter and the density and average volume of dendritic spines were unaffected by SE, but these parameters were all elevated in mice in which microRNA-22 was suppressed. MicroRNA-22 inhibition also reduced the length and complexity of the dendritic tree, independently of SE. These data indicate that microRNA-22 is an important regulator of morphogenesis of newly-formed neurons in adults and plays a role in supressing aberrant neurogenesis associated with SE.

Construction of a novel Chinese normal brain database using 18F-FDG PET images and MIMneuro software, the initial application in epilepsy

PURPOSE

To create a standard Western Chinese normal functional brain database for quantitative analysis using 2-deoxy-2-[18F] fluoro-d-glucose (¹⁸F-FDG) positron emission tomography (PET) images and MIMneuro software.

METHODS

78 healthy right-handed Chinese volunteers from Tangdu Hospital were scanned using ¹⁸F-FDG PET to evaluate brain metabolism between March and October 2016. All PET images were processed using MIMneuro software to create a normal database platform. The platform included anatomical optimization to facilitate spatial localization of abnormalities and a statistical comparison with normal cases utilizing the Z-scores, which represent the number of standard deviations from the mean of the normal controls in the database.

RESULTS

The novel Chinese brain metabolism database platform including 78 healthy volunteers (male: female 40:38; age 3-78 years, mean age, 45 years) was constructed based on the MIMneuro software, which increased the diagnostic confidence in the test patient by quantifying and emphasizing the abnormality. The BrainAlign^TM deformation algorithm of MIMneuro matched the size, shape, and orientation of the patient's brain scan to a template brain for comparison against a database of normal controls. The quantitative analysis performed on a voxel and regional level was useful in assessing the areas of abnormalities.

CONCLUSIONS

A novel Chinese ¹⁸F-FDG PET-based normal brain function database was created to highlight the local regions of abnormal metabolic activity through quantitative comparisons against the normal database. The Z-scores obtained by MIMneuro potentially aid in visualizing and quantifying the subtle lesions on ¹⁸FDG-PET scan images as observed in a patient diagnosed with epilepsy.

Automated detection of epileptic ripples in MEG using beamformer-based virtual sensors

OBJECTIVE

In epilepsy, high-frequency oscillations (HFOs) are expressively linked to the seizure onset zone (SOZ). The detection of HFOs in the noninvasive signals from scalp electroencephalography (EEG) and magnetoencephalography (MEG) is still a challenging task. The aim of this study was to automate the detection of ripples in MEG signals by reducing the high-frequency noise using beamformer-based virtual sensors (VSs) and applying an automatic procedure for exploring the time-frequency content of the detected events.

APPROACH

Two-hundred seconds of MEG signal and simultaneous iEEG were selected from nine patients with refractory epilepsy. A two-stage algorithm was implemented. Firstly, beamforming was applied to the whole head to delimitate the region of interest (ROI) within a coarse grid of MEG-VS. Secondly, a beamformer using a finer grid in the ROI was computed. The automatic detection of ripples was performed using the time-frequency response provided by the Stockwell transform. Performance was evaluated through comparisons with simultaneous iEEG signals.

MAIN RESULTS

ROIs were located within the seizure-generating lobes in the nine subjects. Precision and sensitivity values were 79.18% and 68.88%, respectively, by considering iEEG-detected events as benchmarks. A higher number of ripples were detected inside the ROI compared to the same region in the contralateral lobe.

SIGNIFICANCE

The evaluation of interictal ripples using non-invasive techniques can help in the delimitation of the epileptogenic zone and guide placement of intracranial electrodes. This is the first study that automatically detects ripples in MEG in the time domain located within the clinically expected epileptic area taking into account the time-frequency characteristics of the events through the whole signal spectrum. The algorithm was tested against intracranial recordings, the current gold standard. Further studies should explore this approach to enable the localization of noninvasively recorded HFOs to help during pre-surgical planning and to reduce the need for invasive diagnostics.

Hippocampal sclerosis: volumetric evaluation of the substructures of the hippocampus by magnetic resonance imaging

OBJECTIVE

The pathological classification of hippocampal sclerosis is based on the loss of neurons in the substructures of the hippocampus. This study aimed to evaluate these substructures in patients with hippocampal sclerosis by magnetic resonance imaging and to compare the usefulness of this morphological analysis compared to that of volumetric analysis of the entire hippocampus.

MATERIAL AND METHODS

We included 25 controls and 25 patients with hippocampal sclerosis whose diagnosis was extracted from the institutional epilepsy board. We used FreeSurfer to process the studies and obtain the volumetric data. We evaluated overall volume and volume by substructure: fimbria, subiculum, presubiculum, hippocampal sulcus, CA1, CA2-CA3, CA4, and dentate gyrus (DG). We considered p < 0.05 statistically significant.

RESULTS

We observed statistically significant decreases in the volume of the hippocampus ipsilateral to the epileptogenic focus in 19 (76.0%) of the 25 cases. With the exception of the hippocampal sulcus, we observed a decrease in all ipsilateral hippocampal substructures in patients with right hippocampal sclerosis (CA1, p=0.0223; CA2-CA3, p=0.0066; CA4-GD, p=0.0066; fimbria, p=0.0046; presubiculum, p=0.0087; subiculum, p=0.0017) and in those with left hippocampal sclerosis (CA1, p<0.0001; CA2-CA3, p<0. 0001; CA4-GD, p<0. 0001; fimbria, p=0.0183; presubiculum, p<0. 0001; subiculum, p<0. 0001). In four patients with left hippocampal sclerosis, none of the substructures had statistically significant alterations, although a trend toward atrophy was observed, mainly in CA2-CA3 and CA4-GD.

CONCLUSION

The findings suggest that it can be useful to assess the substructures of the hippocampus to improve the performance of diagnostic imaging in patients with hippocampal sclerosis.

Effects of dexamethasone on the Li-pilocarpine model of epilepsy: protection against hippocampal inflammation and astrogliosis

Background

Temporal lobe epilepsy (TLE) is the most common form of partial epilepsy and is accompanied, in one third of cases, by resistance to antiepileptic drugs (AED). Most AED target neuronal activity modulated by ionic channels, and the steroid sensitivity of these channels has supported the use of corticosteroids as adjunctives to AED. Assuming the importance of astrocytes in neuronal activity, we investigated inflammatory and astroglial markers in the hippocampus, a key structure affected in TLE and in the Li-pilocarpine model of epilepsy.

Methods

Initially, hippocampal slices were obtained from sham rats and rats subjected to the Li-pilocarpine model of epilepsy, at 1, 14, and 56 days after status epilepticus (SE), which correspond to the acute, silent, and chronic phases. Dexamethasone was added to the incubation medium to evaluate the secretion of S100B, an astrocyte-derived protein widely used as a marker of brain injury. In the second set of experiments, we evaluated the in vivo effect of dexamethasone, administrated at 2 days after SE, on hippocampal inflammatory (COX-1/2, PGE2, and cytokines) and astroglial parameters: GFAP, S100B, glutamine synthetase (GS) and water (AQP-4), and K⁺ (Kir 4.1) channels.

Results

Basal S100B secretion and S100B secretion in high-K⁺ medium did not differ at 1, 14, and 56 days for the hippocampal slices from epileptic rats, in contrast to sham animal slices, where high-K⁺ medium decreased S100B secretion. Dexamethasone addition to the incubation medium per se induced a decrease in S100B secretion in sham and epileptic rats (1 and 56 days after SE induction). Following in vivo dexamethasone administration, inflammatory improvements were observed, astrogliosis was prevented (based on GFAP and S100B content), and astroglial dysfunction was partially abrogated (based on Kir 4.1 protein and GSH content). The GS decrease was not prevented by dexamethasone, and AQP-4 was not altered in this epileptic model.

Conclusions

Changes in astroglial parameters emphasize the importance of these cells for understanding alterations and mechanisms of epileptic disorders in this model. In vivo dexamethasone administration prevented most of the parameters analyzed, reinforcing the importance of anti-inflammatory steroid therapy in the Li-pilocarpine model and possibly in other epileptic conditions in which neuroinflammation is present.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1109-5) contains supplementary material, which is available to authorized users.

New prospects of mesenchymal stem cells for ameliorating temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is present in 30% of epileptic patients and does not respond to conventional treatments. Bone marrow derived mesenchymal stem cells (BMSCs) induce endogenous neural stem cells, inhibit neurodegeneration, and promote brain self-repair mechanisms. The present study addresses the feasibility of BMSCs transplantation against pilocarpine-induced TLE experimentally. BMSCs were injected either intravenously (IV) or in hippocampus bilaterally (IC). Increased cell count of BMSCs was achieved via IC route. BMSCs treatment ameliorated the pilocarpine-induced neurochemical and histological changes, retained amino acid neurotransmitters to the normal level, downregulated the immunoreactivity to insulin growth factor-1 receptor, synaptophysin, and caspase-3 and reduced oxidative insult and inflammatory markers detected in epileptic model. It is worth noting that BMSCs IC-administered showed more pronounced effects than those administered via IV route. BMSCs transplantation presents a promise for TLE treatment that has to be elucidated clinically.

SRR intronic variation inhibits expression of its neighbouring SMG6 gene and protects against temporal lobe epilepsy

D‐serine is a predominant N‐methyl‐D‐aspartate receptor co‐agonist with glutamate, and excessive activation of the receptor plays a substantial role in epileptic seizures. Serine racemase (SRR) is responsible for transforming L‐serine to D‐serine. In this study, we aimed to investigate the genetic roles of SRR and a neighbouring gene, nonsense‐mediated mRNA decay factor (SMG6), in temporal lobe epilepsy (TLE). Here, a total of 496 TLE patients and 528 healthy individuals were successfully genotyped for three SRR tag single nucleotide polymorphisms. The frequencies of the GG genotype at rs4523957 T > G were reduced in the TLE cases in the initial cohort (cohort 1) and were confirmed in the independent cohort (cohort 2). An analysis of all TLE cases in cohort 1 + 2 revealed that the seizure frequency and drug‐resistant incidence were significantly decreased in carriers of the GG genotype at rs4523957. Intriguingly, the activity of the SMG6 promoter with the mutant allele at rs4523957 decreased by 22% in the dual‐luciferase assay, and up‐regulated expression of SMG6 was observed in an epilepsy rat model. This study provides the first demonstration that the GG genotype is a protective marker against TLE. In particular, variation at rs4523957 likely inhibits SMG6 transcription and plays a key role against susceptibility to and severity of TLE. The significance of SMG6 hyperfunction in epileptic seizures deserves to be investigated in future studies.

MiR-153 regulates expression of hypoxia-inducible factor-1α in refractory epilepsy

Mesial temporal lobe epilepsy (mTLE), the most common type of temporal lobe epilepsy (TLE), is particularly relevant due to its high frequency of therapeutic resistance of anti-epileptic therapies. MicroRNAs (miRNAs) have been shown to be dysregulated in epilepsy and neurodegenerative diseases, and we hypothesized that miRNAs could be involved in the pathogenesis of MTLE. The present study aimed to explore the expression and functions of miRNA-153 in mTLE. The expression levels of miRNA-153 in refractory TLE patients were evaluated. The bioinformatics analysis showed that the potential target genes of miR-153 were involved in biological processes, molecular functions, and cellular components. miRNA-153 is significantly dysregulated in temporal cortex and plasma of mTLE patients. We identify HIF-1α as a direct target of miRNA-153, and luciferase reporter assays demonstrated that miR-153 could regulate the HIF-1αexpression via 3'-UTR pairing. These data suggest that miR-153 might represent a useful biomarker and treatment target for patients with mTLE.

Harnessing neural stem cells for treating psychiatric symptoms associated with fetal alcohol spectrum disorder and epilepsy

Brain insults with progressive neurodegeneration are inherent in pathological symptoms that represent many psychiatric illnesses. Neural network disruptions characterized by impaired neurogenesis have been recognized to precede, accompany, and possibly even exacerbate the evolution and progression of symptoms of psychiatric disorders. Here, we focus on the neurodegeneration and the resulting psychiatric symptoms observed in fetal alcohol spectrum disorder and epilepsy, in an effort to show that these two diseases are candidate targets for stem cell therapy. In particular, we provide preclinical evidence in the transplantation of neural stem cells (NSCs) in both conditions, highlighting the potential of this cell-based treatment for correcting the psychiatric symptoms that plague these two disorders. Additionally, we discuss the challenges of NSC transplantation and offer insights into the mechanisms that may mediate the therapeutic benefits and can be exploited to overcome the hurdles of translating this therapy from the laboratory to the clinic. Our ultimate goal is to advance stem cell therapy for the treatment of psychiatric disorders.

Diagnosis of mesial temporal sclerosis: sensitivity, specificity and predictive values of the quantitative analysis of magnetic resonance imaging

In the diagnosis of mesial temporal sclerosis (MTS), sensitivity, specificity and predictive values of qualitative assessment using conventional magnetic resonance imaging are low, mainly in mild or bilateral atrophy. Quantitative analysis may improve this performance. We evaluated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of quantitative analysis using the hippocampal volumetric index (HVI) and hippocampal asymmetry index (HAI) compared with qualitative assessment in the MTS diagnosis. Twenty-five patients diagnosed with MTS, and 25 healthy subjects underwent conventional magnetic resonance imaging. Hippocampal volumes were obtained using an automated software (FreeSurfer); HVI and HAI were calculated. Receiver operating characteristic curve analysis was performed to obtain the optimal threshold values. Sensitivity, specificity and predictive values were calculated. Sensitivity, specificity, PPV and NPV for qualitative analysis were 44.00%, 96.00%, 91.67% and 63.16%, respectively. In the quantitative analysis, a threshold value of K = 0.22 for HVI provided a sensitivity value of 76.00%, specificity value of 96.00%, PPV of 95.00% and NPV of 80.00%. A threshold value of K = 0.06 for HAI provided the minimum C1 and C2 errors, with a sensitivity value of 88.00%, specificity value of 100%, PPV of 100% and NPV of 89.30%. A statistically significant difference was observed for HAI ( P < 0.0001), and ipsilateral HVI (left MTS, P = 0.0152; right MTS, P < 0.0001), between MTS and healthy groups. The HVI and HAI, both individually and in conjunction, improved the sensitivity, specificity and predictive values of magnetic resonance imaging in the diagnosis of MTS compared to the qualitative analysis and other quantitative techniques. The HAI is highly accurate in the diagnosis of unilateral MTS, whereas the HVI may be better for bilateral MTS cases.