Low density electrical source imaging of the ictal onset zone in the surgical evaluation of children with epilepsy

PURPOSE

To investigate the utility of Low Density (LD) Electrical Source Imaging (ESI) to model the ictal onset zone (IOZ) for the surgical work up of children with medically refractory epilepsy.

METHODS

This was a retrospective review of 12 patients from a district and regional pediatric epilepsy center, who underwent focal resections between 2014 and 2019. ESI was generated using the Curry 8 software, incorporating T1 Magnetic Resonance Imaging (MRI) scans and scalp electroencephalogram (EEG) recordings. Concordance of the ictal LD-ESI localizations to the epileptogenic zone was assessed by comparing the location of the ictal LD-ESI to the focal resection margins on neuroimaging and noting the post-operative outcomes at one year. Localizations determined by ictal LD-ESI were also compared to interictal LD-ESI, positron emission tomography (FDG-PET) and interictal magnetoencephalography (MEG).

RESULTS

Ictal ESI correctly localized the ictal onset zone in 4/6 patients, with all four being seizure free at one year. Similarly, interictal ESI localized the irritative zone in 7/9 patients with focal resections, with 6/7 being seizure free at one year. Additionally, we observed ictal ESI to be concordant to interictal ESI in 5/6 patients. Ictal ESI and interictal ESI were concordant to interictal MEG in 3/6 patients. Ictal ESI was concordant with FDG-PET in 6/7 cases.

CONCLUSION

IOZ source localization through LD-ESI is a promising complementary method of assessing the epileptogenic focus in children. These findings may support the inclusion of ictal LD-ESI within the pre-surgical evaluation of children to supplement current diagnostic tools.

Mapping connectivity fingerprints for presurgical evaluation of temporal lobe epilepsy

Background

Surgery may render temporal lobe epilepsy (TLE) patients seizure-free. However, TLE is a heterogenous entity and surgical prognosis varies between patients. Network-based biomarkers have been shown to be altered in TLE patients and hold promise for classifying TLE subtypes and improving pre-surgical prognosis. The aim of the present study is to investigate a network-based biomarker, the weighted degree of connectivity (wDC), on an individual level, and its relation to TLE subtypes and surgical prognosis.

Methods

Thirty unilateral TLE patients undergoing the same surgical procedure (anterior temporal resection) and 18 healthy controls were included. All patients were followed-up in the same center for a mean time of 6.85 years and classified as seizure-free (SF) and non seizure-free (non-SF). Using pre-surgical resting state functional MRI, whole brain wDC values for patients and controls were calculated. Then, we divided both temporal lobes in three Regions-of-interest (ROIs) -mesial, pole and lateral- as these areas are known to behave differently in seizure onset and propagation, delimiting different TLE profiles. The wDC values for the defined ROIs of each individual patient were compared with the healthy group.

Results

After surgery, 14 TLE patients remained SF. As a group, patients had higher wDC than controls in both the temporal pole (p < 0.05) as well as in the mesial regions (p < 0.002) of the to-be-resected temporal lobe. When comparing between SF and non-SF patients, a step-wise binary logistic regression model including all the ROIs, showed that having an increased wDC of the temporal pole (p < 0.05) and the mesial area (p < 0.05) of the to-be-resected temporal lobe was associated with seizure freedom long-term after surgery.

Conclusions

This study provides a network-based presurgical biomarker that could pave the way towards personalized prediction. In patients with TLE undergoing anterior temporal resections, having an increased wDC at rest could be a signature of the epileptogenic area, and could help identifying those patients who would benefit most from surgery.

Optimal Surgical Extent for Memory and Seizure Outcome in Temporal Lobe Epilepsy

OBJECTIVE

Postoperative memory decline is an important consequence of anterior temporal lobe resection (ATLR) for temporal lobe epilepsy (TLE), and the extent of resection may be a modifiable factor. This study aimed to define optimal resection margins for cognitive outcome while maintaining a high rate of postoperative seizure freedom.

METHODS

This cohort study evaluated the resection extent on postoperative structural MRI using automated voxel-based methods and manual measurements in 142 consecutive patients with unilateral drug refractory TLE (74 left, 68 right TLE) who underwent standard ATLR.

RESULTS

Voxel-wise analyses revealed that postsurgical verbal memory decline correlated with resections of the posterior hippocampus and inferior temporal gyrus, whereas larger resections of the fusiform gyrus were associated with worsening of visual memory in left TLE. Limiting the posterior extent of left hippocampal resection to 55% reduced the odds of significant postoperative verbal memory decline by a factor of 8.1 (95% CI 1.5-44.4, p = 0.02). Seizure freedom was not related to posterior resection extent, but to the piriform cortex removal after left ATLR. In right TLE, variability of the posterior extent of resection was not associated with verbal and visual memory decline or seizures after surgery.

INTERPRETATION

The extent of surgical resection is an independent and modifiable risk factor for cognitive decline and seizures after left ATLR. Adapting the posterior extent of left ATLR might optimize postoperative outcome, with reduced risk of memory impairment while maintaining comparable seizure-freedom rates. The current, more lenient, approach might be appropriate for right ATLR. ANN NEUROL 2021.

Effects of Vagus Nerve Stimulation following Corpus Callosotomy for Patients with Drug-Resistant Epilepsy

Objective: The effectiveness of vagus nerve stimulation (VNS) for residual seizures after corpus callosotomy (CC) has not yet been fully investigated. We hypothesized that seizure control would be improved by VNS after CC. The purpose of this study was to compare seizure frequency between patients with implantation of a VNS generator (post-VNS group) or without VNS (non-post-VNS group) following CC. Methods: We retrospectively reviewed patients who underwent CC between January 2009 and May 2019 in our institution. We evaluated proportions of ≥50% reduction in seizure frequency (responders) and seizure reduction rate 1 and 2 years after VNS. To investigate factors related to responders, uni- and multivariate logistic regression analyses were performed regarding age, number of anti-seizure medications (ASMs), addition of novel ASMs (levetiracetam, lacosamide or perampanel), and post-VNS or non-post-VNS status. Results: Thirteen post-VNS patients and 24 non-post-VNS patients were analyzed in this study. Responder rate at 1 year after VNS differed significantly between the post-VNS group (53.9%) and non-post-VNS group (12.5%, p = 0.017). Number of ASMs at the time of CC and post-VNS were significantly associated with responders in univariate analyses (odds ratio [OR] 0.34, 95% confidence interval [CI] 0.13–0.88, p = 0.025 and OR 8.2, 95%CI 1.6–41.6, p = 0.011, respectively), whereas age, sex, seizure frequency, and addition of novel ASMs were not. In multivariate analysis, the presence of VNS procedures after CC was the only factor favorably associated with responder status (OR 82.2, 95%CI 1.55–4355.7, p = 0.03). Conclusions: VNS therapy after CC may increase the proportion of responders independent of the addition of novel ASMs.

Metabolic network is related to surgical outcome in temporal lobe epilepsy with hippocampal sclerosis: A brain FDG-PET study

BACKGROUND AND PURPOSE

The aim of this study was to investigate differences in metabolic networks based on preoperative fluorodeoxyglucose (FDG)-positron emission tomography (PET) in temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS) between patients with complete seizure-free (SF) and those with noncomplete seizure-free (non-SF) after anterior temporal lobectomy.

METHODS

This study was retrospectively performed at a tertiary hospital. We recruited pathologically confirmed 75 TLE patients with HS who underwent preoperative FDG-PET. All patients underwent a standard anterior temporal lobectomy. The surgical outcome was evaluated at least 12 months after surgery, and we divided the subjects into patients with SF (International League Against Epilepsy [ILAE] class I) and those with non-SF (ILAE class II-VI). We evaluated the metabolic network using graph theoretical analysis based on FDG-PET. We investigated the differences in network measures between the two groups.

RESULTS

Of the 75 TLE patients with HS, 32 patients (42.6%) had SF, whereas 43 patients (57.3%) had non-SF. There were significant differences in global metabolic networks according to surgical outcomes. The patients with SF had a lower assortative coefficient than those with non-SF (-0.020 vs. -0.009, p = .044). We also found widespread regional differences in local metabolic networks according to surgical outcomes.

CONCLUSION

Our study demonstrates significant differences in preoperative metabolic networks based on FDG-PET in TLE patients with HS according to surgical outcomes. This work introduces a metabolic network based on FDG-PET and can be used as a potential tool for predicting surgical outcome in TLE patients with HS.

Determinants of seizure outcome after resective surgery following stereoelectroencephalography

OBJECTIVE

The aim of this study was to investigate seizure outcomes after resective epilepsy surgery following stereoelectroencephalography (SEEG), including group characteristics, comparing surgical and nonsurgical groups and assess predictors of time to seizure recurrence.

METHODS

Clinical and EEG data of 536 consecutive patients who underwent SEEG at Cleveland Clinic Epilepsy Center between 2009 and 2017 were reviewed. The primary outcome was defined as complete seizure freedom since the resective surgery, discounting any auras or seizures that occurred within the 1st postoperative week. In addition, the rate of seizure freedom based on Engel classification was determined in patients with follow-up of ≥ 1 year. Presumably significant outcome variables were first identified using univariate analysis, and Cox proportional hazards modeling was used to identify outcome predictors.

RESULTS

Of 527 patients satisfying study criteria, 341 underwent resective surgery. Complete and continuous seizure freedom after surgery was achieved in 55.5% of patients at 1 year postoperatively, 44% of patients at 3 years, and 39% of patients at 5 years. As a secondary outcome point, 58% of patients achieved Engel class I seizure outcome for at least 1 year at last follow-up. Among surgical outcome predictors, in multivariate model analysis, the seizure recurrence rate by type of resection (p = 0.039) remained statistically significant, with the lowest risk of recurrence occurring after frontal and temporal lobe resections compared with multilobar and posterior quadrant surgeries. Patients with a history of previous resection (p = 0.006) and bilateral implantations (p = 0.023) were more likely to have seizure recurrence. The absence of an MRI abnormality prior to resective surgery did not significantly affect seizure outcome in this cohort.

CONCLUSIONS

This large, single-center series shows that resective surgery leads to continuous seizure freedom in a group of patients with complex and severe pharmacoresistant epilepsy after SEEG evaluation. In addition, up to 58% of patients achieved seizure freedom at last follow-up. The authors' results suggest that SEEG is equally effective in patients with frontal and temporal lobe epilepsy with or without MRI identified lesions.

Mapping Epileptic Networks Using Simultaneous Intracranial EEG-fMRI

Background: Potentially curative epilepsy surgery can be offered if a single, discrete epileptogenic zone (EZ) can be identified. For individuals in whom there is no clear concordance between clinical localization, scalp EEG, and imaging data, intracranial EEG (icEEG) may be needed to confirm a predefined hypothesis regarding irritative zone (IZ), seizure onset zone (SOZ), and EZ prior to surgery. However, icEEG has limited spatial sampling and may fail to reveal the full extent of epileptogenic network if predefined hypothesis is not correct. Simultaneous icEEG-fMRI has been safely acquired in humans and allows exploration of neuronal activity at the whole-brain level related to interictal epileptiform discharges (IED) captured intracranially.

Methods: We report icEEG-fMRI in eight patients with refractory focal epilepsy who had resective surgery and good postsurgical outcome. Surgical resection volume in seizure-free patients post-surgically reflects confirmed identification of the EZ. IEDs on icEEG were classified according to their topographic distribution and localization (Focal, Regional, Widespread, and Non-contiguous). We also divided IEDs by their location within the surgical resection volume [primary IZ (IZ1) IED] or outside [secondary IZ (IZ2) IED]. The distribution of fMRI blood oxygen level-dependent (BOLD) changes associated with individual IED classes were assessed over the whole brain using a general linear model. The concordance of resulting BOLD map was evaluated by comparing localization of BOLD clusters with surgical resection volume. Additionally, we compared the concordance of BOLD maps and presence of BOLD clusters in remote brain areas: precuneus, cuneus, cingulate, medial frontal, and thalamus for different IED classes.

Results: A total of 38 different topographic IED classes were identified across the 8 patients: Focal (22) and non-focal (16, Regional = 9, Widespread = 2, Non-contiguous = 5). Twenty-nine IEDs originated from IZ1 and 9 from IZ2. All IED classes were associated with BOLD changes. BOLD maps were concordant with the surgical resection volume for 27/38 (71%) IED classes, showing statistical global maximum BOLD cluster or another cluster in the surgical resection volume. The concordance of BOLD maps with surgical resection volume was greater (p < 0.05) for non-focal (87.5%, 14/16) as compared to Focal (59%, 13/22) IED classes. Additionally, BOLD clusters in remote cortical and deep brain areas were present in 84% (32/38) of BOLD maps, more commonly (15/16; 93%) for non-focal IED-related BOLD maps.

Conclusions: Simultaneous icEEG-fMRI can reveal BOLD changes at the whole-brain level for a wide range of IEDs on icEEG. BOLD clusters within surgical resection volume and remote brain areas were more commonly seen for non-focal IED classes, suggesting that a wider hemodynamic network is at play.

Outcomes of epilepsy surgery in the older population: not too old, not too late

OBJECTIVE

The prevalence of epilepsy in the older adult population is increasing. While surgical intervention in younger patients is supported by level I evidence, the safety and efficacy of epilepsy surgery in older individuals is less well established. The aim of this study was to evaluate seizure freedom rates and surgical outcomes in older epilepsy patients.

METHODS

The authors' institutional electronic database was queried for patients older than 50 who had undergone epilepsy surgery during 2002-2018. Cases were grouped into 50-59, 60-69, and 70+ years old. Seizure freedom at the last follow-up constituted the primary outcome of interest. The institutional analysis was supplemented by a literature review and meta-analysis (random effects model) of all published studies on this topic as well as by an analysis of complication rates, mortality rates, and cost data from a nationwide administrative database (Vizient Inc., years 2016-2019).

RESULTS

A total of 73 patients (n = 16 for 50-59 years, n = 47 for 60-69, and n = 10 for 70+) were treated at the authors' institution. The median age was 63 years, and 66% of the patients were female. At a median follow-up of 24 months, seizure freedom was 73% for the overall cohort, 63% for the 50-59 group, 77% for the 60-69 group, and 70% for the 70+ group. The literature search identified 15 additional retrospective studies (474 cases). Temporal lobectomy was the most commonly performed procedure (73%), and mesial temporal sclerosis was the most common pathology (52%), followed by nonspecific gliosis (19%). The pooled mean follow-up was 39 months (range 6-114.8 months) with a pooled seizure freedom rate of 65% (95% CI 59%-72%). On multivariable meta-regression analysis, an older mean age at surgery (coefficient [coeff] 2.1, 95% CI 1.1-3.1, p < 0.001) and the presence of mesial temporal sclerosis (coeff 0.3, 95% CI 0.1-0.6, p = 0.015) were the most important predictors of seizure freedom. Finally, analysis of the Vizient database revealed mortality rates of 0.5%, 1.1%, and 9.6%; complication rates of 7.1%, 10.1%, and 17.3%; and mean hospital costs of $31,977, $34,586, and $40,153 for patients aged 50-59, 60-69, and 70+ years, respectively.

CONCLUSIONS

While seizure-free outcomes of epilepsy surgery are excellent, there is an expected increase in morbidity and mortality with increasing age. Findings in this study on the safety and efficacy of epilepsy surgery in the older population may serve as a useful guide during preoperative decision-making and patient counseling.

Machine learning models for decision support in epilepsy management: A critical review

PURPOSE

There remain major challenges for the clinician in managing patients with epilepsy effectively. Choosing anti-seizure medications (ASMs) is subject to trial and error. About one-third of patients have drug-resistant epilepsy (DRE). Surgery may be considered for selected patients, but time from diagnosis to surgery averages 20 years. We reviewed the potential use of machine learning (ML) predictive models as clinical decision support tools to help address some of these issues.

METHODS

We conducted a comprehensive search of Medline and Embase of studies that investigated the application of ML in epilepsy management in terms of predicting ASM responsiveness, predicting DRE, identifying surgical candidates, and predicting epilepsy surgery outcomes. Original articles addressing these 4 areas published in English between 2000 and 2020 were included.

RESULTS

We identified 24 relevant articles: 6 on ASM responsiveness, 3 on DRE prediction, 2 on identifying surgical candidates, and 13 on predicting surgical outcomes. A variety of potential predictors were used including clinical, neuropsychological, imaging, electroencephalography, and health system claims data. A number of different ML algorithms and approaches were used for prediction, but only one study utilized deep learning methods. Some models show promising performance with areas under the curve above 0.9. However, most were single setting studies (18 of 24) with small sample sizes (median number of patients 55), with the exception of 3 studies that utilized large databases and 3 studies that performed external validation. There was a lack of standardization in reporting model performance. None of the models reviewed have been prospectively evaluated for their clinical benefits.

CONCLUSION

The utility of ML models for clinical decision support in epilepsy management remains to be determined. Future research should be directed toward conducting larger studies with external validation, standardization of reporting, and prospective evaluation of the ML model on patient outcomes.

Pediatric Epilepsy Surgery: Indications and Evaluation

Epilepsy is a common neurological condition in children. It is usually amenable to drug therapy. However, nearly one-third of patients may be refractory to antiseizure drugs. Poor compliance and nonepileptic events should be ruled out as possible causes of drug-resistant epilepsy (DRE). After failing adequate trials of two appropriate antiseizure drugs, patients with focal DRE or poorly classifiable epilepsy or epileptic encephalopathy with focal electro-clinical features should be worked up for surgical candidacy. A randomized controlled trial provided a class I evidence for epilepsy surgery in pediatric DRE. Pre-surgical screening workup typically includes a high-resolution epilepsy protocol brain magnetic resonance imaging (MRI) and a high-quality in-patient video electroencephalography evaluation. Advanced investigations such as positron emission tomography (PET), single-photon emission computed tomography (SPECT), and magnetoencephalography (MEG) may be required in selected cases especially when brain MRI is normal, and further evidence for anatomo-electro-clinical concordance is necessary to refine candidacy for surgery and surgical strategy. Some children may also need functional MRI to map eloquent regions of interest such as motor, sensory, and language functions to avoid unacceptable neurological deficits after surgery. Selected children may need invasive long-term electroencephalographic monitoring using stereotactically implanted intracranial depth electrodes or subdural grids. Surgical options include resective surgeries (lesionectomy, lobectomy, multilobar resections) and disconnective surgeries (corpus callosotomy, etc.) with the potential to obtain seizure freedom. Other surgical procedures, typically considered to be palliative are neuromodulation [deep brain stimulation (DBS), vagal nerve stimulation (VNS), and responsive neural stimulation (RNS)]. DBS and RNS are currently not approved in children. Pediatric DRE should be evaluated early considering the risk of epileptic encephalopathy and negative impact on cognition.

Molecular Alterations in Meningioangiomatosis Causing Epilepsy

Meningioangiomatosis (MA) is a rare process at the intersection of cerebral developmental and neoplastic disorders that often results in epilepsy. We evaluated molecular alterations in MA to characterize its biology and pathogenesis. We searched a comprehensive institutional database for patients with MA treated between 2004 and 2019. Demographic, clinical, surgical, and radiographical data were collected. MA and associated meningioma tissues were evaluated using a next-generation sequencing assay interrogating 1425 cancer-related genes. We studied 5 cases: 3 with MA and 2 with MA associated with a meningioma. Of the MAs associated with a meningioma, 1 had deletions in the NF2 gene in both the MA and the meningioma components, whereas the other had an NF2 deletion in only the MA component. Additional mutations were identified in the MA components, suggesting that MA arises from the meningioma rather than the meningioma resulting from a transformation of the MA. The 3 cases of pure MA showed variants of unknown significance with no alterations in known oncogenic drivers. Our findings provide a starting point to a better understanding of the pathogenesis of this rare lesion. Our study indicates that MA-meningiomas have a neoplastic nature that differs from the hamartomatous/developmental nature of pure MA.

Long-term seizure outcomes in patients with hypothalamic hamartoma treated by stereotactic radiofrequency thermocoagulation

OBJECTIVE

To investigate long-term seizure outcomes in patients with hypothalamic hamartoma (HH) following stereotactic radiofrequency thermocoagulation (SRT).

METHODS

A total of 131 patients with HH who underwent SRT and were followed for at least three years after the last SRT were enrolled. Seizure outcomes were evaluated for gelastic seizures (GS) and other types of seizures (nGS) separately using the International League Against Epilepsy classification. Classes 1 and 2 were considered seizure-free. Kaplan-Meier survival analyses were used to estimate the proportion remaining seizure-free after the first and last SRTs. Risk factors relating to outcomes were analyzed by log-rank tests and a multivariate Cox proportional hazards model.

RESULTS

Reoperation was performed in 34 patients (26.2%). Median total follow-up was 61 (range, 36-202) months. Seizure freedom was obtained in 116 patients (88.6%) for GS and 85 of 108 patients (78.7%) for nGS at the last follow-up. Mean GS-free survival times improved from after the first (64.1 [95%CI 57.3-70.9] months) to after the last SRT (80.2 [95%CI 75.7-84.8] months). About 90% of GS recurrences after the first SRT were found within 6 months, though a few patients recurred more than 2 years after the first SRT. On the other hand, mean nGS-free survival times after the first and last SRTs were not different between after the first SRT (84.4 [95%CI 73.0-90.7] months) and after the last SRT (83.1 [95%CI 74.1-92.0] months). There was no factor related to GS outcomes, but the significant factor for nGS-free survival after the last SRT was multiple previous treatments (p=0.01, hazard ratio=15.65, 95%CI 1.79-137.16).

SIGNIFICANCE

The last SRT was almost equivalent to achieving complete disconnection of HHs from the hypothalamus according to our strategy. Considering the epileptogenic network, GS outcomes depend on complete disconnection, whereas nGS outcomes are not affected by surgical factors but independency of secondary epileptogenesis.

Intrinsic Thalamic Network in Temporal Lobe Epilepsy With Hippocampal Sclerosis According to Surgical Outcomes

Background: The aim of this study was to identify the differences of intrinsic amygdala, hippocampal, or thalamic networks according to surgical outcomes in temporal lobe epilepsy (TLE) patients with hippocampal sclerosis (HS).

Methods: We enrolled 69 pathologically confirmed TLE patients with HS. All patients had pre-operative three-dimensional T1-weighted MRI using a 3.0 T scanner. We obtained the structural volumes of the amygdala nuclei, hippocampal subfields, and thalamic nuclei. Then, we investigated the intrinsic networks based on volumes of these structures using structural covariance and graph theoretical analysis.

Results: Of the 69 TLE patients with HS, 21 patients (42.1%) had poor surgical outcomes, whereas 40 patients (57.9%) had good surgical outcomes. The volumes in the amygdala nuclei, hippocampal subfields, and thalamic nuclei were not different according to surgical outcome. In addition, the intrinsic amygdala and hippocampal networks were not different between the patients with poor and good surgical outcomes. However, there was a significant difference in the intrinsic thalamic network in the ipsilateral hemisphere between them. The eccentricity and small-worldness index were significantly increased, whereas the characteristic path length was decreased in the patients with poor surgical outcomes compared to those with good surgical outcomes.

Conclusion: We successfully demonstrated significant differences in the intrinsic thalamic network in the ipsilateral hemisphere between TLE patients with HS with poor and good surgical outcomes. This result suggests that the pre-operative intrinsic thalamic network can be related with surgical outcomes in TLE patients with HS.

Predictors of Seizure Freedom in Patients Undergoing Surgery for Central Nervous System Infection-Related Epilepsy: A Systematic Review and Meta-Analysis

Objective: Central nervous system infections (CNSIs), especially viral encephalitis and meningitis, are well-recognized causes of medically refractory epilepsy. Although surgery is an effective and durable intervention against these infections, the seizure control outcomes described in previous surgical series have been variable. Accordingly, it is not clear which variables are most valuable in predicting seizure control following surgery for CNSI. The aim of this meta-analysis was to identify the predictors of favorable surgical outcomes in CNSI-related epilepsy.

Methods: The PubMed, EMBASE, Cochrane Library, WANGFANG, VIP, CBM, and CNKI databases were searched for studies according to the inclusion criteria. Prognostic factors, surgical outcomes, and patient characteristics were extracted. Heterogeneity was detected by the I² and Q statistics.

Results: Seventeen studies were included in our meta-analysis. Eight predictors of favorable outcomes (Engel Class I/II) were determined, including abnormal MRI findings, meningitis, temporal location only, regional ictal pattern, unilateral ictal pattern, older age at epilepsy, longer silent period, and longer time from infection, as follows: OR = 3.34 (95% CI 1.44–7.74), OR = 0.31 (95% CI 0.13–0.70), OR = 0.34 (95% CI 0.16–0.74), OR = 5.65 (95% CI 1.75–18.30), and OR = 9.53 (95% CI 2.36–38.48), respectively, and MD = 2.15 (95% CI 0.20–4.11), MD = 2.40 (95% CI 0.09–4.70), and MD = 8.49 (95% CI 1.50–15.48), respectively. A subgroup analysis found the following associations: regional and unilateral ictal patterns in viral encephalitis, a younger age at infection in parasitic encephalopathy, an older age at surgery, a longer time from onset, and a longer time from infection in unexplained meningitis. A sensitivity analysis restricted to studies that included each variable yielded robust results. Little evidence of publication bias was observed.

Conclusions: This meta-analysis suggests that abnormal MRI findings, meningitis, temporal location only, regional and unilateral ictal patterns, older age at epilepsy, longer silent period, and longer time from infection are predictive factors in patients with favorable surgical outcomes in CNSI-related epilepsy. In addition, different infective agents influenced the results in regional and unilateral ictal patterns in ictal electroencephalography, as well as the relationship between age at infection and surgery and the time from epilepsy onset and infection.

Resective temporal lobe surgery in refractory temporal lobe epilepsy: prognostic factors of postoperative seizure outcome

OBJECTIVE

Temporal lobe epilepsy (TLE) is one of the most common forms of epilepsy. In approximately 30% of patients, seizures are refractory to drug treatment. Despite the achievements of modern presurgical evaluation in recent years, the presurgical prediction of seizure outcome remains difficult. The aim of this study was to evaluate the seizure outcome in patients with drug-refractory TLE who underwent resective temporal lobe surgery (rTLS) and to determine features associated with unfavorable postsurgical seizure outcome.

METHODS

Patients with medically refractory TLE who underwent rTLS between 2012 and 2017 were reviewed from the prospectively collected epilepsy surgery database. A retrospective analysis of clinical, radiological, neuropsychological, histopathological, and perioperative findings of 161 patients was performed. The patients were divided into two groups according to seizure outcome (group I, International League Against Epilepsy [ILAE] class 1; group II, ILAE class ≥ 2). For identification of independent risk factors for unfavorable postoperative seizure outcome (ILAE class ≥ 2), a multivariate logistic regression analysis was performed.

RESULTS

Seizure freedom (ILAE class 1) was achieved in 121 patients (75.2%). The neuropsychological evaluation demonstrated that losses in cognitive performance were more pronounced in verbal memory after resections in the left temporal lobe and in nonverbal memory after right-sided resections, whereas attention improved after surgery. Overall, postoperative visual field deficits (VFDs) were common and occurred in 51% of patients. There was no statistically significant difference in the incidence of VFD in patients with selective surgical procedures compared to the patients with nonselective procedures. The lack of MRI lesions and placement of depth electrodes were preoperatively identified as predictors for unfavorable seizure outcome.

CONCLUSIONS

rTLS is an effective treatment method in patients with refractory TLE. However, patients with a lack of MRI lesions and placement of depth electrodes prior to rTLS are at higher risk for an unfavorable postsurgical seizure outcome.

The relation of etiology based on the 2017 ILAE classification to the effectiveness of the ketogenic diet in drug-resistant epilepsy in childhood

Objective

To investigate the effectiveness and safety of the ketogenic diet (KD) in drug‐resistant epilepsy in childhood in relation to the new 2017 International League Against Epilepsy (ILAE) classification of etiology.

Methods

A consecutive cohort of patients treated with the KD were categorized according to the ILAE classification into known (structural, genetic, metabolic, infectious, and immune‐mediated) and unknown etiology. Primary outcome was the frequency of patients achieving seizure freedom with the KD at 3 months, secondary outcomes were seizure reduction >50% at 3 months, and both seizure freedom and seizure reduction >50% at 6, 12 months, and at last follow‐up (LFU), and adverse effects. Outcomes were compared between etiology groups.

Results

Etiology was known in 70% (129/183). Outcomes did not differ at 3 months (known vs unknown: seizure freedom 28% vs 33%, seizure reduction 62 vs 67%), but seizure freedom was significantly less frequent in known etiology at 6 months (26% vs 43%) and beyond (22% vs 37%). Logistic regression identified duration of epilepsy, number of previous antiseizure medications (ASMs), and age‐appropriate psychomotor development as positive determinants of outcome. Among individual etiology groups, the effectiveness of KD was relatively best for genetic (33% at LFU) and poorest for metabolic etiology (8% at LFU). The small number of patients with infectious and immune‐mediated etiology requires larger numbers in each etiology group to corroborate our results. No differences in type and frequency of adverse effects (in 71%) between etiology groups were observed, requiring medical intervention in 21%.

Significance

The KD was most effective in genetic and unknown etiology, many unknowns probably represent yet unidentified genetic causes. We recommend consequent diagnostic and genetic work‐up to identify etiologies that respond best to the KD. The KD should be offered early to infants with genetic epilepsy before deterioration of epileptic symptoms and of psychomotor development.

Insular epilepsy surgery: lessons learned from institutional review and patient-level meta-analysis

OBJECTIVE

Insular lobe epilepsy is a challenging condition to diagnose and treat. Due to anatomical intricacy and proximity to eloquent brain regions, resection of epileptic foci in that region can be associated with significant postoperative morbidity. The aim of this study was to review available evidence on postoperative outcomes following insular epilepsy surgery.

METHODS

A comprehensive literature search (PubMed/MEDLINE, Scopus, Cochrane) was conducted for studies investigating the postoperative outcomes for seizures originating in the insula. Seizure freedom at last follow-up (at least 12 months) comprised the primary endpoint. The authors also present their institutional experience with 8 patients (4 pediatric, 4 adult).

RESULTS

A total of 19 studies with 204 cases (90 pediatric, 114 adult) were identified. The median age at surgery was 23 years, and 48% were males. The median epilepsy duration was 8 years, and 17% of patients had undergone prior epilepsy surgery. Epilepsy was lesional in 67%. The most common approach was transsylvian (60%). The most commonly resected area was the anterior insular region (n = 42, 21%), whereas radical insulectomy was performed in 13% of cases (n = 27). The most common pathology was cortical dysplasia (n = 68, 51%), followed by low-grade neoplasm (n = 16, 12%). In the literature, seizure freedom was noted in 60% of pediatric and 69% of adult patients at a median follow-up of 29 months (75% and 50%, respectively, in the current series). A neurological deficit occurred in 43% of cases (10% permanent), with extremity paresis comprising the most common deficit (n = 35, 21%), followed by facial paresis (n = 32, 19%). Language deficits were more common in left-sided approaches (24% vs 2%, p < 0.001). Univariate analysis for seizure freedom revealed a significantly higher proportion of patients with lesional epilepsy among those with at least 12 months of follow-up (77% vs 59%, p = 0.032).

CONCLUSIONS

These findings may serve as a benchmark when tailoring decision-making for insular epilepsy, and may assist surgeons in their preoperative discussions with patients. Although seizure freedom rates are quite high with insular epilepsy treatment, the associated morbidity needs to be weighed against the potential for seizure freedom.

Epilepsy surgery in children under 3 years of age: surgical and developmental outcomes

OBJECTIVE

Pediatric epilepsy surgery is known to be effective, but early surgery in infancy is not well characterized. Extensive cortical dysplasia, such as hemimegalencephaly, can cause refractory epilepsy shortly after birth, and early surgical intervention is indicated. However, the complication rate of early pediatric surgery is significant. In this study, the authors assessed the risk-benefit balance of early pediatric epilepsy surgery as relates to developmental outcomes.

METHODS

This is a retrospective descriptive study of 75 patients who underwent their first curative epilepsy surgery at an age under 3 years at the authors' institution between 2006 and 2019 and had a minimum 1-year follow-up of seizure and developmental outcomes. Clinical information including surgical complications, seizure outcomes, and developmental quotient (DQ) was collected from medical records. The effects of clinical factors on DQ at 1 year after surgery were evaluated.

RESULTS

The median age at surgery was 6 months, peaking at between 3 and 4 months. Operative procedures included 27 cases of hemispherotomy, 19 cases of multilobar surgery, and 29 cases of unilobar surgery. Seizure freedom was achieved in 82.7% of patients at 1 year and in 71.0% of patients at a mean follow-up of 62.8 months. The number of antiseizure medications (ASMs) decreased significantly after surgery, and 19 patients (30.6%) had discontinued their ASMs by the last follow-up. Postoperative complications requiring cerebrospinal fluid (CSF) diversion surgery, such as hydrocephalus and cyst formation, were observed in 13 patients (17.3%). The mean DQ values were 74.2 ± 34.3 preoperatively, 60.3 ± 23.3 at 1 year after surgery, and 53.4 ± 25.1 at the last follow-up. Multiple regression analysis revealed that the 1-year postoperative DQ was significantly influenced by preoperative DQ and postoperative seizure freedom but not by the occurrence of any surgical complication requiring CSF diversion surgery.

CONCLUSIONS

Early pediatric epilepsy surgery has an acceptable risk-benefit balance. Seizure control after surgery is important for postoperative development.

Experiences of emotional and psychosocial functioning after frontal lobe resection for epilepsy

PURPOSE

Frontal lobe resection (FLR) is the second most common epilepsy surgery procedure in adults. Few studies address neuropsychological consequences after FLR. The aim of this study was to explore patients' and relatives' experiences of cognitive, emotional and social cognitive functioning after frontal lobe epilepsy surgery.

METHODS

Semi-structured interviews were held with 14 patients having gone through FLR as adults during the years 2000-2016 and 12 of their relatives. Interviews were audio-recorded, transcribed and analyzed with inductive qualitative content analysis.

RESULTS

Positive as well as negative consequences were described both by patients and relatives. Feelings of relief and an increased capacity to experience emotions of well-being were mainly experienced as related to seizure freedom. A newfound autonomy and a more grown-up identity as opposed to a self-image based on epilepsy was also highlighted. However, results also showed that even for seizure free patients, FLR could give rise to negative experiences, the most prominent of which were mental fatigue, lowered mood and social withdrawal. Coping strategies included planning ahead to avoid mental exhaustion. Over all, respondents considered that the epilepsy surgery had been a risk well worth taking and that positive consequences outweighed the negative ones.

CONCLUSIONS

This study shows a range of positive as well as negative outcomes after FLR for epilepsy. The findings indicate that lowered mood and mental fatigue could affect the life situation in a negative way, regardless of seizure outcome. This is important to consider in the preoperative counselling of patients and their families, as well as in the postsurgical follow-up. It is also crucial that the epilepsy surgery team has the possibility to offer rehabilitation and support to families regarding these aspects after surgery.

Subtraction ictal SPECT co-registered to MRI (SISCOM) patterns in children with temporal lobe epilepsy

OBJECTIVE

We evaluated SISCOM patterns and their relationship with surgical outcome in children with temporal lobe epilepsy (TLE) who had undergone a temporal lobe surgery.

METHODS

This was an observational study evaluating SISCOM patterns in 40 children with TLE. We classified SISCOM patterns into 4 categories; (i) unilateral anteromesial and/or anterolateral temporal pattern; (ii) unilateral anteromesial and/or anterolateral temporal plus posterior extension pattern; (iii) bilateral anteromesial and/or anterolateral temporal pattern; and (iv) atypical pattern. Determinants of SISCOM pattern and correlation between postoperative outcomes and SISCOM patterns were evaluated.

RESULTS

Pattern (i), (ii), (iii), and (iv) were identified in 10 (25%), 14 (35%), 0 (0%), and 16 (40%) patients, respectively. There was no significant correlation between patterns and postoperative outcomes. SISCOM patterns significantly associated with the presence of hippocampal sclerosis and type of focal cortical dysplasia (p-value = 0.048 and 0.036, respectively). Patients with HS had 5 times the odds of having unilateral temporal pattern, compared to patients with other neuropathology (OR = 5, 95% CI 0.92 to 27.08). Patients with FCD type 2 had 9.71 times the odds of having atypical pattern, compared to patients with other types of FCD (OR = 9.71, 95% CI 0.92 to 103.04). Lobar concordance of SISCOM and ictal and interictal scalp EEG significantly correlated with postoperative outcomes (p-value = 0.018 and 0.013, respectively).

CONCLUSION

Three SISCOM patterns were seen. Patients with HS had increased odds of having unilateral temporal pattern while patients with FCD type 2 had increased odds of having atypical pattern. However, there was no significant correlation between SISCOM patterns and postoperative outcomes. Lobar concordance of SISCOM and ictal and interictal scalp EEG significantly correlated with postoperative outcome.

SIGNIFICANCE

This study shows that the distribution of SISCOM patterns and their relationship with postoperative outcomes in children with TLE are different from adult population. Besides, SISCOM may add only limited diagnostic and prognostic information in children with drug-resistant TLE undergoing epilepsy surgery. Further evaluation to identify patient populations that may benefit from SISCOM is desirable.

Predictors of surgical outcome in focal cortical dysplasia and its subtypes

OBJECTIVE

The authors analyzed predictors of surgical outcome in patients with focal cortical dysplasia (FCD) and its ILAE (International League Against Epilepsy) subtypes after noninvasive multimodal evaluation and calculated time to first seizure.

METHODS

Data of 355 patients with refractory epilepsy, confirmed FCD pathology, and 2-13 years of postsurgical follow-up were analyzed to determine the predictive roles of clinical, EEG, imaging, and surgical factors that influence seizure freedom.

RESULTS

The mean ± SD age at surgery was 20.26 ± 12.18 years. In total, 142 (40.0%) patients had daily seizures and 90 (25.3%) had multiple seizure types. MRI showed clear-cut FCD in 289 (81.4%) patients. Pathology suggested type I FCD in 27.3% of patients, type II in 28.4%, and type III in 42.8% of patients. At latest follow-up, 72.1% of patients were seizure free and 11.8% were seizure free and not receiving antiepileptic drugs. Among the subtypes, 88.8% of patients with type III, 69.3% with type II, and 50.5% with type I FCD were seizure free. Multiple seizure types, acute postoperative seizures (APOS), and type I FCD were predictors of persistent seizures, whereas type III FCD was the strongest predictor of seizure freedom. Type I FCD was associated with daily seizures, frontal and multilobar distribution, subtle findings on MRI, incomplete resection, and persistent seizures. Type II and III FCD were associated with clear-cut lesion on MRI, regional interictal and ictal EEG onset pattern, focal pattern on ictal SPECT, complete resection, and seizure freedom. Type III FCD was associated with temporal location, whereas type I and II FCD were associated with extratemporal location. Nearly 80% of patients with persistent seizures, mostly those with type I FCD, had their first seizure within 6 months postsurgery.

CONCLUSIONS

Long-term seizure freedom after surgery can be achieved in more than two-thirds of patients with FCD after noninvasive multimodal evaluation. Multiple seizure types, type I FCD, and APOS were predictors of persistent seizures. Seizures recurred in about 80% of patients within 6 months postsurgery.

Apparent diffusion coefficient is associated with seizure outcome after magnetic resonance-guided laser interstitial thermal therapy for mesial temporal lobe epilepsy

BACKGROUND

Magnetic resonance-guided laser interstitial thermal therapy (MRgLiTT) is becoming a first-line surgical therapy for mesial temporal lobe epilepsy (mTLE) due to good seizure control and low complication risk. However, seizure outcomes after MRgLiTT remain highly variable and there is a need to improve patient selection and post-operative prognostication. In this retrospective study, we investigated whether the pre-operative MRI-derived apparent diffusion coefficient (ADC), used as a marker of tissue pathology in the mesial temporal structures could help predict seizure outcome.

METHODS

Thirty-five patients who underwent MRgLiTT at our institution between 2014 and 2019 were included in the study. Demographic and clinical data were retrospectively collected. Seizure outcome was defined as good (ILAE Class I-II) and poor (ILAE Class III-VI). Volumetrics were performed on pre-ablation hippocampus and amygdala. Ablation volumes, and the proportion of ablated hippocampus and amygdala calculated via their respective mean voxel-wise ADC intensities were quantified from pre-operative and intra-operative post-ablation MRIs and statistically compared between the two outcome cohorts. Univarate and multivariate regression analysis was performed to identify demographic, clinical, and radiographic predictors of seizure outcome.

RESULTS

Mean age at LiTT was 36 years and 14 (40 %) were female. Mean follow-up duration was 1.90 ± 0.17 years. Twenty-seven (77 %) patients had mesial temporal sclerosis. There was no significant difference in the ablation volumes and proportion of ablated volume of hippocampus and amygdala between the two outcome groups. Patients with good seizure outcome had significantly higher normalized ADC intensities in the ablated mesial temporal structures compared to those with poor outcome (0.01 ± 0.08 vs.-0.29 ± 0.06; p = 0.015).

CONCLUSIONS

mTLE patients with higher ADC intensities in the ablated regions of the hippocampus and the amygdala are more likely to have good seizure outcome following MRgLiTT. Our results suggest that pre-operative ADC analysis may improve both patient selection and epileptogenic zone targeting during MRgLiTT. Further investigation with large, prospective cohorts is needed to validate the clinical utility of ADC in improving seizure outcome following MRgLiTT.

Surgical outcomes in children with bottom-of-sulcus dysplasia and drug-resistant epilepsy: a retrospective cohort study

OBJECTIVE

Bottom-of-sulcus dysplasia (BOSD) is challenging to identify radiologically. The aim of this study was to explore seizure outcomes after resective surgery or MR-guided laser interstitial thermal therapy (MRgLITT) in children with BOSD.

METHODS

Children with radiologically defined BOSD who underwent resective surgery or MRgLITT, with at least 1 year of follow-up were included. Clinical, radiological, neurophysiological, and histological data were extracted from medical records. Invasive video EEG (IVEEG) was used to evaluate the ictal onset zone or motor/language mapping, wherever appropriate. Histology of MRI-visible BOSD, including the overlying and adjacent cortex, was also evaluated.

RESULTS

Forty-one children with BOSD underwent surgical treatment. The lesion was initially overlooked on MRI in 20 patients (48.8%). Of 34 patients who underwent IVEEG and who had available ictal data, the ictal onset zone extended beyond the MRI-visible BOSD in 23 patients (67.6%). Surgical treatment included lesionectomy (24 patients), extended lesionectomy (12 patients), lobectomy (1 patient), and ablation of BOSD (4 patients). The pathology in 37 patients who underwent resection showed focal cortical dysplasia type IIB and type IIA in 21 (53.8%) and 16 patients (41%), respectively. Seizure freedom was achieved in 32 patients (78.1%) after a mean follow-up of 4.3 years.

CONCLUSIONS

Seizure outcomes after resective surgery or MRgLITT in children with BOSD were generally favorable. The authors found that the neurophysiological abnormality and pathology often extended beyond the MRI-visible BOSD.

Epilepsy in patients with focal cortical dysplasia may be associated with autism spectrum disorder

INTRODUCTION

Patients with epilepsy associated with focal cortical dysplasia (FCD) may be associated with autism spectrum disorder (ASD). Therefore, the purpose of this study was to compare surgically treated patients with epilepsy secondary to FCD and normal volunteers without epilepsy and to review the neuropathological findings of patients with FCD.

METHODS

This study involved 38 patients with medically intractable focal onset epileptic seizures who underwent epilepsy surgery (Group 1). All patients had epilepsy associated with FCD. These patients and 38 normal volunteers without epilepsy (Group 2) were administered the autism spectrum quotient (AQ) test, and the groups were compared.

RESULTS

The 38 patients in Group 1 included 16 females and 22 males (age range 20-60, mean age, 33.0; standard deviation (SD), 11.8 years). The normal volunteers in Group 2 included 22 females and 16 males (age range 20-57, mean age, 30.6 years; SD, 8.8 years). Total AQ scores were significantly higher in Group 1 than Group 2 (p = 0.027). Patients with FCD I showed a higher AQ score than those with FCD II in the AQ test (p ≤ 0.001).

CONCLUSION

Patients with epilepsy secondary to FCD were associated with higher ASD score than normal volunteers. This tendency was seen more strongly in patients with FCD I than FCD II.

Intraoperative magnetic resonance imaging in epilepsy surgery: A systematic review and meta-analysis

This systematic review investigated the added value of intraoperative magnetic resonance imaging (iMRI)-guidance in epilepsy surgery, compared to conventional non-iMRI surgery, with respect to the rate of gross total resection (GTR), postoperative seizure freedom, neurological deficits, non-neurological complications and reoperations. A comprehensive literature search was conducted using Medline, Embase, PubMed, and Cochrane Reviews databases. Randomized control trials, case control or cohort studies, and surgical case series published from January 1993 to February 2021 that reported on iMRI-guided epilepsy surgery outcomes for either adults or children were eligible for inclusion. Studies comparing iMRI-guided epilepsy surgery to non-iMRI surgery controls were selected for meta-analysis using random-effects models. Forty-two studies matched the selection criteria and were used for qualitative synthesis and ten of these were suitable for meta-analysis. Overall, studies included various 0.2-3.0 Tesla iMRI systems, contained small numbers with heterogenous clinical characteristics, utilized subjective GTR reporting, and had variable follow-up durations. Meta-analysis demonstrated that the use of iMRI-guidance led to statistically significant higher rates of GTR (RR = 1.31 [95% CI = 1.10-1.57]) and seizure freedom (RR = 1.44 [95% CI = 1.12-1.84]), but this was undermined by moderate to significant statistical heterogeneity between studies (I² = 55% and I² = 71% respectively). Currently, there is only level III-2 evidence supporting the use of iMRI-guidance over conventional non-iMRI epilepsy surgery, with respect to the studied outcomes.

Navigated transcranial magnetic stimulation mapping of the motor cortex for preoperative diagnostics in pediatric epilepsy

OBJECTIVE

Navigated transcranial magnetic stimulation (nTMS) is a noninvasive technique often used for localization of the functional motor cortex via induction of motor evoked potentials (MEPs) in neurosurgical patients. There has, however, been no published record of its application in pediatric epilepsy surgery. In this study, the authors aimed to investigate the feasibility of nTMS-based motor mapping in the preoperative diagnostic workup within a population of children with medically refractory epilepsy.

METHODS

A single-institution database was screened for preoperative nTMS motor mappings obtained in pediatric patients (aged 0 to 18 years, 2012 to present) with medically refractory epilepsy. Patient clinical data, demographic information, and mapping results were extracted and used in statistical analyses.

RESULTS

Sixteen patients met the inclusion criteria, 15 of whom underwent resection. The median age was 9 years (range 0-17 years). No adverse effects were recorded during mapping. Specifically, no epileptic seizures were provoked via nTMS. Recordings of valid MEPs induced by nTMS were obtained in 10 patients. In the remaining patients, no MEPs could be elicited. Failure to generate MEPs was associated significantly with younger patient age (r = 0.8020, p = 0.0001863). The most frequent seizure control outcome was Engel Epilepsy Surgery Outcome Scale class I (9 patients).

CONCLUSIONS

Navigated TMS is a feasible, effective, and well-tolerated method for mapping the motor cortex of the upper and lower extremities in pediatric patients with epilepsy. Patient age modulates elicitability of MEPs, potentially reflecting various stages of myelination. Successful motor mapping has the potential to add to the existing presurgical diagnostic workup in this population, and further research is warranted.

Automated volumetry of hippocampal subfields in temporal lobe epilepsy

INTRODUCTION

Hippocampal sclerosis is the most frequent pathological substrate in drug resistant temporal lobe epilepsy (TLE). Recently 4 types of hippocampal sclerosis (HS) have been defined in a task force by the International League Against Epilepsy (ILAE), based on patterns of cell loss in specific hippocampal subfields. Type 1 HS is most frequent and has the most favorable outcome after epilepsy surgery. We hypothesized that volume loss in specific hippocampal subfields determined by automated volumetry of high resolution MRI would correspond to cell loss in histological reports.

MATERIAL AND METHODS

In a group of well characterized patients with drug resistant TLE (N = 26 patients, 14 with right-sided focus, 12 with left-sided focus) volumes of the right and left hippocampus and the hippocampal subfields CA1, CA2 + 3, CA4 and dentate gyrus (DG) were estimated automatically using FreeSurfer version 6.0 from high-resolution cerebral MRI and compared to a large group of healthy controls (N = 121). HS subtype classification was attempted based on histological reports.

RESULTS

Volumes of the whole hippocampus and all investigated hippocampal subfields (CA1, CA2 + 3, CA4 and DG) were significantly lower on the ipsilateral compared the contralateral side (p < 0.001) and compared to the healthy controls (p < 0.001). Conversely, whole hippocampal and hippocampal subfield volumes were not significantly different from healthy control values on the contralateral side. In 12 of 20 patients the pattern of hippocampal volume loss in specific subfields was in accordance with HS types from histology. The highest overlap between automated MRI and histology was achieved for type 1 HS (in 10 of 12 cases).

CONCLUSION

The automated volumetry of hippocampal subfields, based on high resolution MRI, may have the potential to predict the pattern of cell loss in hippocampal sclerosis before operation.

Operative variations in temporal lobe epilepsy surgery and seizure and memory outcome in 226 patients suffering from hippocampal sclerosis

Objective: The aim of this retrospective cohort study was to assess seizure and memory outcomes following temporal lobe surgery in patients suffering from medically refractory temporal lobe epilepsy (TLE) and hippocampal sclerosis (HS).Methods: A retrospective monocentric data analysis was performed in consecutive patients who were operated on during 2002-2018. In the first decennium, standard temporal lobe resections (TLR) were predominately performed, and later, antero-temporal lobe resections (ATLR) were mainly performed. Seizure and memory outcomes over time were assessed according to ILAE/Engel classification and the Berlin Amnesia Test (BTA), respectively.Results: Altogether, 231 surgeries were performed on 226 patients (mean age, 40 years [range, 10-68 years]; male: female, 1:1.4; mean seizure duration, 25 years; and mean follow-up duration, 4.75 years [range, 1-16]). Recently, outcomes of 78.3% of the patients in the total cohort were classified as Engel class I, with 54.9% of patients being completely seizure free. The recent cohort of ATLR since 2012 showed significant more completely seizure-free patients than before 2012 (Engel IA 46.6% versus 67.7%, p < 0.0025, χ²), although the Kaplan Meier analysis of all patients favors TLR for better seizure outcome (61% ATLR vs 73% TLR seizure free after 5 yrs, log rank p < 0.001). Verbal memory improved significantly in non-dominant patients. Minor neurological complications were noted (permanent severe complications, 0.4%; temporary severe complications, 4.8%).Conclusion: Significant improvements in seizure and memory outcomes were observed over time, with surgical technique and seizure duration as important prognostic factors. Early admittance for surgery may favor an excellent seizure outcome in patients undergoing temporal lobe resection for HS.

Corpus callosotomy in pediatric patients with non-lesional epileptic encephalopathy with electrical status epilepticus during sleep

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Corpus callosotomy (CC) was performed in 3 pediatric patients with refractory epileptic encephalopathy with ESES.

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IQ was improved after CC with complete resolution of ESES in one patient.

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Developmental regression ceased after CC with worthwhile seizure reduction and temporary improvement of ESES in 2 patients.

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Epileptiform discharges disappeared or became lateralized after CC.

Epileptic encephalopathy with electrical status epilepticus during sleep (ESES) is often refractory to medical treatment and leads to poor cognitive outcomes. Corpus callosotomy may be an effective treatment option for drug-resistant ESES with no focal etiology. We retrospectively identified three patients who underwent corpus callosotomy for drug-resistant ESES in our institution. Electroencephalography (EEG) findings and cognitive functions were evaluated before surgery, at 3 months, 6 months, 1 year, and 2 years after surgery. Age at surgery was 6 years 10 months, 7 years 9 months, and 8 years 4 months, respectively. Period between the diagnosis of ESES and surgery ranged from 7 to 25 months. All patients had no obvious structural abnormalities and presented with cognitive decline despite multiple antiseizure medications and steroid therapies. One patient showed complete resolution of ESES and an improvement of intelligence quotient after surgery. Epileptiform EEG was lateralized to one hemisphere after surgery and spike wave index (SWI) was decreased with moderate improvement in development and seizures in the other 2 patients. SWI re-exacerbated from 6 months after surgery, but without subsequent developmental regression in these 2 patients. Corpus callosotomy may become an important treatment option for drug-resistant ESES in patients with no structural abnormalities.

Epilepsy Outcome at Four Years in a Randomized Clinical Trial Comparing Oral Prednisolone and Intramuscular ACTH in West Syndrome

BACKGROUND

This article explores the role of initial treatment on control of spasms and other epilepsies at four years in children previously treated for West syndrome.

METHODS

The Sri Lanka Infantile Spasm Study is a prospective clinical trial evaluating response to intra-muscular adrenocorticotropic hormone (ACTH) versus oral prednisolone. A previous report documented response through age 12 months. This article provides four-year follow-up data.

RESULTS

At age four years, 65 of the original 97 were available for follow-up; another 13 had died, and 19 moved and could not be contacted. Of the 65 children, 37 (57%) continued to have seizures and 28 were seizure free. In the 37 children with ongoing epilepsy, 32.4% continued to have spasms, either alone or in combination with other seizure types. The epilepsy types seen in these children were focal epilepsy (59.4%), mixed focal and generalized epilepsy (24%), generalized epilepsy only (10.8%), and uncertain (5%). The majority of those still having epilepsy (66.7%) were controlled on medication. There was no significant difference in the rate of epilepsy or spasms or their control by medication between those treated with ACTH or oral prednisolone. Spasm control at day 14 did not influence the four-year spasm or epilepsy outcome.

CONCLUSIONS

A majority of children diagnosed with West syndrome continued to have seizures at age four years, although most were controlled on antiseizure medication. The long-term risk of developing epilepsy or its control was the same, regardless of whether ACTH or prednisolone was initially used as treatment.

Epileptogenic zone detection in MRI negative epilepsy using adaptive thresholding of arterial spin labeling data

Drug-resistant epilepsy is a diagnostic and therapeutic challenge, mainly in patients with negative MRI findings. State-of-the-art imaging methods complement standard epilepsy protocols with new information and help epileptologists to increase the reliability of their decisions. In this study, we investigate whether arterial spin labeling (ASL) perfusion MRI can help localize the epileptogenic zone (EZ). To that end, we developed an image processing method to detect the EZ as an area with hypoperfusion relative to the contralateral unaffected side, using subject-specific thresholding of the asymmetry index in ASL images. We demonstrated three thresholding criteria (termed minimal product criterion, minimal distance criterion, and elbow criterion) on 29 patients with MRI-negative epilepsy (age 32.98 ± 10.4 years). The minimal product criterion showed optimal results in terms of positive predictive value (mean 0.12 in postoperative group and 0.22 in preoperative group) and true positive rate (mean 0.71 in postoperative group and 1.82 in preoperative group). Additionally, we found high accuracy in determining the EZ side (mean 0.86 in postoperative group and 0.73 in preoperative group out of 1.00). ASL can be easily incorporated into the standard presurgical MR protocol, and it provides an additional benefit in EZ localization.

An electronic neuromorphic system for real-time detection of high frequency oscillations (HFO) in intracranial EEG

The analysis of biomedical signals for clinical studies and therapeutic applications can benefit from embedded devices that can process these signals locally and in real-time. An example is the analysis of intracranial EEG (iEEG) from epilepsy patients for the detection of High Frequency Oscillations (HFO), which are a biomarker for epileptogenic brain tissue. Mixed-signal neuromorphic circuits offer the possibility of building compact and low-power neural network processing systems that can analyze data on-line in real-time. Here we present a neuromorphic system that combines a neural recording headstage with a spiking neural network (SNN) processing core on the same die for processing iEEG, and show how it can reliably detect HFO, thereby achieving state-of-the-art accuracy, sensitivity, and specificity. This is a first feasibility study towards identifying relevant features in iEEG in real-time using mixed-signal neuromorphic computing technologies.

Functional Outcomes and Health-Related Quality of Life Following Glioma Surgery

Functional outcome following glioma surgery is defined as how the patient functions or feels. Functional outcome is a coprimary end point of surgery in patients with diffuse glioma, together with oncological outcome. In this review, we structure the functional outcome measurements following glioma surgery as reported in the last 5 yr. We review various perspectives on functional outcome of glioma surgery with available measures, and offer suggestions for their use. From the recent neurosurgical literature, 160 publications were retrieved fulfilling the selection criteria. In these publications, neurological outcomes were reported most often, followed by activities of daily living, seizure outcomes, neurocognitive outcomes, and health-related quality of life or well-being. In more than a quarter of these publications functional outcome was not reported. A minimum essential consensus set of functional outcome measurements would benefit comparison across neurosurgical reports. The consensus set should be based on a combination of clinician- and patient-reported outcomes, assessed at a predefined time before and after surgery. The selected measurements should have psychometric properties supporting the intended use including validity-related evidence, reliability, and sensitivity to detect meaningful change with minimal burden to ensure compliance. We circulate a short survey as a start towards reporting guidelines. Many questions remain to better understand, report, and improve functional outcome following glioma surgery.

Tumor-associated epilepsy in patients with brain metastases: necrosis-to-tumor ratio forecasts postoperative seizure freedom

Surgical resection is highly effective in the treatment of tumor-related epilepsy (TRE) in patients with brain metastases (BM). Nevertheless, some patients suffer from postoperative persistent epilepsy which negatively impacts health-related quality of life. Therefore, early identification of patients with potentially unfavorable seizure outcome after BM resection is important. Patients with TRE that had undergone surgery for BM at the authors’ institution between 2013 and 2018 were analyzed with regard to preoperatively identifiable risk factors for unfavorable seizure outcome. Tumor tissue and tumor necrosis ratios were assessed volumetrically. According to the classification of the International League Against Epilepsy (ILAE), seizure outcome was categorized as favorable (ILAE 1) and unfavorable (ILAE 2–6) after 3 months in order to avoid potential interference with adjuvant cancer treatment. Among all 38 patients undergoing neurosurgical treatment for BM with concomitant TRE, 34 patients achieved a favorable seizure outcome (90%). Unfavorable seizure outcome was significantly associated with larger tumor volumes (p = 0.012), a midline shift > 7 mm (p = 0.025), and a necrosis/tumor volume ratio > 0.2 (p = 0.047). The present study identifies preoperatively collectable risk factors for unfavorable seizure outcome in patients with BM and TRE. This might enable to preselect for highly vulnerable patients with postoperative persistent epilepsy who might benefit from accompanying neuro-oncological expertise during further systemical treatment regimes.

Noninvasive high-frequency oscillations riding spikes delineates epileptogenic sources

Millions of people affected by epilepsy may undergo surgical resection of the epileptic tissues to stop seizures if such epileptic foci can be accurately delineated. High-frequency oscillations (HFOs), existing in electroencephalography, are highly correlated with epileptic brain, which is promising for guiding successful neurosurgery. However, it is unclear whether and how pathological HFOs can be differentiated to localize the epileptogenic tissues given the presence of various nonepileptic high-frequency activities. Here, we show morphological and source imaging evidence that pathological HFOs can be identified by the concurrence of epileptiform spikes. We describe a framework to delineate the underlying epileptogenicity using this biomarker. Our work may offer translational tools to improve treatments by noninvasively demarking pathological activities and hence epileptic foci.

High-frequency oscillations (HFOs) are a promising biomarker for localizing epileptogenic brain and guiding successful neurosurgery. However, the utility and translation of noninvasive HFOs, although highly desirable, is impeded by the difficulty in differentiating pathological HFOs from nonepileptiform high-frequency activities and localizing the epileptic tissue using noninvasive scalp recordings, which are typically contaminated with high noise levels. Here, we show that the consistent concurrence of HFOs with epileptiform spikes (pHFOs) provides a tractable means to identify pathological HFOs automatically, and this in turn demarks an epileptiform spike subgroup with higher epileptic relevance than the other spikes in a cohort of 25 temporal epilepsy patients (including a total of 2,967 interictal spikes and 1,477 HFO events). We found significant morphological distinctions of HFOs and spikes in the presence/absence of this concurrent status. We also demonstrated that the proposed pHFO source imaging enhanced localization of epileptogenic tissue by 162% (∼5.36 mm) for concordance with surgical resection and by 186% (∼12.48 mm) with seizure-onset zone determined by invasive studies, compared to conventional spike imaging, and demonstrated superior congruence with the surgical outcomes. Strikingly, the performance of spike imaging was selectively boosted by the presence of spikes with pHFOs, especially in patients with multitype spikes. Our findings suggest that concurrent HFOs and spikes reciprocally discriminate pathological activities, providing a translational tool for noninvasive presurgical diagnosis and postsurgical evaluation in vulnerable patients.

Robotic thermocoagulative hemispherotomy: concept, feasibility, outcomes, and safety of a new "bloodless" technique

OBJECTIVE

The authors present a new "bloodless" technique for minimally invasive robotic thermocoagulative hemispherotomy (ROTCH). Such a method is being described in the literature for the first time.

METHODS

A robotic system was used to plan five sets of different trajectories: anterior disconnection, middle disconnection, posterior disconnection, corpus callosotomy, and temporal stem and amygdalar disconnection. A special technique, called the "X" technique, allowed planar disconnection. Registration was performed with surface landmarks (n = 5) and bone fiducials (n = 1). Coregistration with O-arm images was performed one or two times to confirm the trajectories (once for middle disconnection, and once for disconnection of the temporal stem and amygdala or body of the corpus callosum). Impedance measured before ablation allowed for minor adjustments. Radiofrequency ablation was performed at 75°C-80°C for 60 seconds. Surgical procedures were performed with multiple twist drills. After removal of the electrode, glue was used to prevent CSF leak, and a single stitch was applied. Follow-up CT and MRI were immediately performed.

RESULTS

The pathologies included Rasmussen's encephalitis (n = 2), hemispheric cortical dysplasia (n = 2), posttraumatic encephalomalacia (n = 1), and perinatal insult (n = 1). The mean ± SD (range) age was 6.7 ± 3.6 years (5 months to 10.2 years), and the right side was affected in 4 patients. The mean ± SD seizure frequency was 7.4 ± 5.6 seizures per day (1 patient had epilepsia partialis continua). The mean ± SD number of trajectories was 15.3 ± 2.5, and the mean ± SD number of lesions was 108 ± 25.8. The mean ± SD maximum numbers of trajectories and lesions required for middle disconnection were 7.1 ± 1.7 and 57.5 ± 18.4, respectively. All but 1 patient had class 1 outcomes according to the International League Against Epilepsy Outcome Scale at a mean ± SD (range) follow-up of 13.5 ± 1.6 (12-16) months; the remaining patient had a class 2 outcome. The estimated blood loss was < 5 ml for all patients. Complications included repeat surgery (after 2 weeks) for a "skip" area (n = 1) and a small temporal hematoma (n = 1), which resolved.

CONCLUSIONS

ROTCH seems to be a safe, feasible, and bloodless procedure, with a very low morbidity rate and promising outcomes.

The surgical treatment of epilepsy

In 2009, the Commission for Epilepsy Surgery of the Italian League Against Epilepsy (LICE) conducted an overview about the techniques used for the pre-surgical evaluation and the surgical treatment of epilepsies. The recognition that, in selected cases, surgery can be considered the first-line approach, suggested that the experience gained by the main Italian referral centers should be pooled in order to provide a handy source of reference. In light of the progress made over these past years, some parts of that first report have accordingly been updated. The present revision aims to harmonize the general principles regulating the patient selection and the pre-surgical work-up, as well as to expand the use of epilepsy surgery, that still represents an underutilized resource, regrettably. The objective of this contribution is drawing up a methodological framework within which to integrate the experiences of each group in this complex and dynamic sector of the neurosciences.

Predictors and Long-term Outcome of Resective Epilepsy Surgery in Patients with Tuberous Sclerosis Complex: A Single-centre Retrospective Cohort Study

OBJECTIVE

To identify prognostic factors and long-term seizure outcomes for patients with tuberous sclerosis complex (TSC) who underwent resective treatment for epilepsy.

METHODS

We enrolled 81 patients with TSC who had undergone resective epilepsy surgery at Sanbo Brain Hospital, Capital Medical University, between April 2004 and June 2019. We estimated cumulative probability of remaining seizure-free and plotted survival curves. Variables were compared using Mann-Whitney U, Pearson's correlation, continuity correction, and Fisher's exact chi-square tests. Prognostic predictors were analysed using log-rank (Mantel-Cox) tests and Cox regression models.

RESULTS

At the last follow-up, 48 (59.3%) patients were classified as International League Against Epilepsy Class 1 (including 14 patients who had seizures <3 times postoperatively on the same or different day and were seizure-free at all other times). The estimated cumulative probability of remaining seizure-free postoperatively was 69.0% (95% confidence interval [CI] 58.8-79.2%), 61.9% (95% CI 51.1-72.7%), and 55.0% (95% CI 42.8-67.2%) at 2, 5, and 10 years, respectively. The mean time of remaining seizure-free was 7.24 ± 0.634 years (95% CI 6.00-8.49); en bloc resection was an essential positive predictor of postoperative seizure freedom, as was age at seizure onset, regional interictal video-electroencephalography pattern, and temporal lobe surgery. The longer the seizure-free time, the less likely a relapse. Patients who postoperatively experienced seizures remained likely to recover.

CONCLUSIONS

We demonstrated the efficacy of surgical treatment for patients with TSC and intractable epilepsy. Detailed perioperative tests are a reliable predictor of postoperative seizure freedom.

Stereotactic depth electrode placement surgery in paediatric and adult patients with the Neuromate robotic device: Accuracy, complications and epileptological results

OBJECTIVE

The number of patients requiring depth electrode implantation for invasive video EEG diagnostics increases in most epilepsy centres. Here we report on our institutional experience with frameless robot-assisted stereotactic placement of intracerebral depth electrodes using the Neuromate® stereotactic robot-system.

METHODS

We identified all patients who had undergone robot-assisted stereotactic placement of intracerebral depth electrodes for invasive extra-operative epilepsy monitoring between September 2013 and March 2020. We studied technical (placement) and diagnostic accuracy of the robot-assisted procedure, associated surgical complications and procedural time requirements.

RESULTS

We evaluated a total of 464 depth electrodes implanted in 74 patients (mean 6 per patient, range 1-12). There were 27 children and 47 adults (age range: 3.6-64.6 yrs.). The mean entry and target point errors were 1.82±1.15 and 1.98±1.05 mm. Target and entry point errors were significantly higher in paediatric vs. adult patients and for electrodes targeting the temporo-mesial region. There were no clinically relevant haemorrhages and no infectious complications. Mean time for the placement of one electrode was 37±14 min and surgery time per electrode decreased with the number of electrodes placed. 55 patients (74.3%) underwent definitive surgical treatment. 36/51 (70.1%) patients followed for >12 months or until seizure recurrence became seizure-free (ILAE I).

CONCLUSION

Frameless robot-guided stereotactic placement of depth electrodes with the Neuromate® stereotactic robot-system is safe and feasible even in very young children, with good in vivo accuracy and high diagnostic precision. The surgical workflow is time-efficient and further improves with increasing numbers of implanted electrodes.

Intraoperative Ultrasound Shear-Wave Elastography in Focal Cortical Dysplasia Surgery

Previous studies reported interest in intraoperative shear-wave elastography (SWE) guidance for brain-tumor and epilepsy surgeries. Focal cortical dysplasia (FCD) surgery is one of the most appropriate indications for using SWE guidance. The aim of this study was to evaluate the efficacy of ultrasound SWE techniques for the intraoperative detection of FCDs. We retrospectively analyzed data from 18 adult patients with drug-resistant epilepsy associated with FCD who had undergone SWE-guided surgery. Conventional B-mode images detected FCD in 2 patients (11.1%), while SWE detected FCD in 14 patients (77.8%). The stiffness ratios between MRI-positive and -negative cases were significantly different (3.6 ± 0.4 vs. 2.2 ± 0.6, respectively; p < 0.001). FCDs were significantly more frequently detected by interoperative SWE in women (OR 4.7, 95% CI (1.7–12.7); p = 0.004) and in patients in whom FCD was visible on magnetic resonance imaging (MRI; OR 2.3, 95% CI (1.3–4.3); p = 0.04). At 1 year after surgery and at last follow-up (mean = 21 months), seizure outcome was good (International League Against Epilepsy (ILAE) Class 1 or 2) in 72.2% and 55.6% of patients, respectively. Despite some limitations, our study highlighted the potential of SWE as an intraoperative tool to detect FCD. Future technical developments should allow for optimizing intraoperative surgical-cavity evaluation from the perspective of complete FCD resection. Interobserver reliability of SWE measurements should also be assessed by further studies.

Predictors of early postoperative epileptic seizures after awake surgery in supratentorial diffuse gliomas

OBJECTIVE

Functional-based resection under awake conditions had been associated with a nonnegligible rate of intraoperative and postoperative epileptic seizures. The authors assessed the incidence of intraoperative and early postoperative epileptic seizures after functional-based resection under awake conditions.

METHODS

The authors prospectively assessed intraoperative and postoperative seizures (within 1 month) together with clinical, imaging, surgical, histopathological, and follow-up data for 202 consecutive diffuse glioma adult patients who underwent a functional-based resection under awake conditions.

RESULTS

Intraoperative seizures occurred in 3.5% of patients during cortical stimulation; all resolved without any procedure being discontinued. No predictor of intraoperative seizures was identified. Early postoperative seizures occurred in 7.9% of patients at a mean of 5.1 ± 2.9 days. They increased the duration of hospital stay (p = 0.018), did not impact the 6-month (median 95 vs 100, p = 0.740) or the 2-year (median 100 vs 100, p = 0.243) postoperative Karnofsky Performance Status score and did not impact the 6-month (100% vs 91.4%, p = 0.252) or the 2-year (91.7 vs 89.4%, p = 0.857) postoperative seizure control. The time to treatment of at least 3 months (adjusted OR [aOR] 4.76 [95% CI 1.38–16.36], p = 0.013), frontal lobe involvement (aOR 4.88 [95% CI 1.25–19.03], p = 0.023), current intensity for intraoperative mapping of at least 3 mA (aOR 4.11 [95% CI 1.17–14.49], p = 0.028), and supratotal resection (aOR 6.24 [95% CI 1.43–27.29], p = 0.015) were independently associated with early postoperative seizures.

CONCLUSIONS

Functional-based resection under awake conditions can be safely performed with a very low rate of intraoperative and early postoperative seizures and good 6-month and 2-year postoperative seizure outcomes. Intraoperatively, the use of the lowest current threshold producing reproducible responses is mandatory to reduce seizure occurrence intraoperatively and in the early postoperative period.

Dynamic gray matter and intrinsic activity changes after epilepsy surgery

OBJECTIVES

To explore the dynamic changes of gray matter volume and intrinsic brain activity following anterior temporal lobectomy (ATL) in patients with unilateral mesial temporal lobe epilepsy (mTLE) who achieved seizure-free for 2 years.

MATERIALS AND METHODS

High-resolution T1-weighted MRI and resting-state functional MRI data were obtained in ten mTLE patients at five serial timepoints: before surgery, 3, 6, 12, and 24 months after surgery. The gray matter volume (GMV) and amplitude of low-frequency fluctuations (ALFF) were compared among the five scans to depict the dynamic changes after ATL.

RESULTS

After successful ATL, GMV decreased in several ipsilateral brain regions: ipsilateral insula, thalamus, and putamen showed gradual gray matter atrophy from 3 to 24 months, while ipsilateral superior temporal gyrus, middle temporal gyrus, inferior temporal gyrus, middle occipital gyrus, inferior occipital gyrus, caudate nucleus, lingual gyrus, and fusiform gyrus showed significant GMV decrease at 3 months follow-up, without further changes. Ipsilateral insula showed gradual ALFF decrease from 3 to 24 months after surgery. Ipsilateral superior temporal gyrus showed ALFF decrease at 3 months follow-up, without further changes. Ipsilateral thalamus and cerebellar vermis showed obvious ALFF increase after surgery.

CONCLUSIONS

Surgical resection may lead to a short-term reduction of gray matter volume and intrinsic brain activity in neighboring regions, while the progressive gray matter atrophy may be due to possible intrinsic mechanism of mTLE. Dynamic ALFF changes provide evidence that disrupted focal spontaneous activities were reorganized after successful surgery.

Single-Institutional Experience of Chronic Intracranial Electroencephalography Based on the Combined Usage of Subdural and Depth Electrodes

Implantation of subdural electrodes on the brain surface is still widely performed as one of the “gold standard methods” for the presurgical evaluation of epilepsy. Stereotactic insertion of depth electrodes to the brain can be added to detect brain activities in deep-seated lesions to which surface electrodes are insensitive. This study tried to clarify the efficacy and limitations of combined implantation of subdural and depth electrodes in intractable epilepsy patients. Fifty-three patients with drug-resistant epilepsy underwent combined implantation of subdural and depth electrodes for long-term intracranial electroencephalography (iEEG) before epilepsy surgery. The detectability of early ictal iEEG change (EIIC) were compared between the subdural and depth electrodes. We also examined clinical factors including resection of MRI lesion and EIIC with seizure freedom. Detectability of EIIC showed no significant difference between subdural and depth electrodes. However, the additional depth electrode was useful for detecting EIIC from apparently deep locations, such as the insula and mesial temporal structures, but not in detecting EIIC in patients with ulegyria (glial scar). Total removal of MRI lesion was associated with seizure freedom. Depth electrodes should be carefully used after consideration of the suspected etiology to avoid injudicious usage.

Auras in intractable frontal lobe epilepsy: Clinical characteristics, values, and limitations

Auras are essential in preoperative evaluation and can provide valuable information for delineating seizure onset zones. Frontal lobe epilepsy (FLE) is the second most common focal epilepsy, while a few studies have focused on auras in FLE. To better understand FLE, we analyzed the clinical characteristics, values, and limitations of auras in FLE. The incidence rate of aura in FLE was 37.9% in our study. We included 54 patients and 76 auras in 11 categories were reported. The rate of auras in the decreasing order are as follows: autonomic aura; emotional aura; somatosensory aura; psychic aura; cephalic aura; abdominal aura; whole-body sensory aura, visual aura; auditory aura; and vestibular and unclassified aura. A significant number of aura types can be reported by FLE patients; autonomic aura was the most frequent category and somatosensory auras are most likely associated with the contralateral motor areas.

Higher intelligence may be a risk factor for postoperative transient disturbance of consciousness after corpus callosotomy

INTRODUCTION

Corpus callosotomy (CC) is an established surgical option for palliative treatment of medically intractable epilepsy, especially for seizures with drop attacks. We postulated that specific risk factors for post-CC transient disturbance of consciousness (pCTDC) are associated with CC. The purpose of this study was to review patients with intractable epilepsy who underwent CC and to statistically analyze risk factors for pCTDC.

METHODS

Inclusion criteria for patients who underwent CC between January 2009 and November 2019 were: (1) ≥2 years old and (2) followed up for more than 8 months. The state of consciousness before and after CC was evaluated with the Glasgow coma scale. We statistically assessed predictors for pCTDC as the primary outcome.

RESULTS

Fifty-six patients (19 females, 37 males) were enrolled, and the age range was 2-57 years old. Thirty-seven (66.1%) patients developed pCTDC. The mean period from the beginning of the state of pCTDC to recovery to their baseline conscious level was 4.9 days (range: 2-25 days). All three (100%) normal intelligence level patients, 13 (81%) of 16 patients with a moderately impaired level of intelligence, and 21 (57%) of 37 patients with a severely impaired level of intelligence exhibited pCTDC. Univariate (p = 0.044) and multivariate (p = 0.006) logistic regression analyses for predictors of pCTDC showed that intellectual function was statistically significant.

CONCLUSION

Two-thirds of patients developed pCTDC. One risk factor for pCTDC may be higher intellectual function.

Epileptogenic zone localization using intraoperative gamma oscillation regularity analysis in epilepsy surgery for cavernomas: patient series

BACKGROUND

In epilepsy surgery for cavernoma with intractable focal epilepsy, removal of the cavernoma with its surrounding hemosiderin deposition and other extended epileptogenic zone has been shown to improve postsurgical seizures. However, there has been no significant association between such an epileptogenic zone and intraoperative electrocorticography (ECoG) findings. The authors recently demonstrated that high regular gamma oscillation (30–70 Hz) regularity (GOR) significantly correlates with epileptogenicity.

OBSERVATIONS

The authors evaluated the utility of intraoperative GOR analysis in epilepsy surgery for cavernomas. The authors also analyzed intraoperative ECoG data from 6 patients with cavernomas. The GOR was calculated using a sample entropy algorithm. In 4 patients, the GOR was significantly high in the area with the pathological hemosiderin deposition. In 2 patients with temporal cavernoma, the GOR was significantly high in both the hippocampus and the area with the pathological hemosiderin deposition. ECoG showed no obvious epileptic waveforms in 3 patients, whereas extensive spikes were observed in 3 patients. All patients underwent cavernoma removal plus resection of the area with significantly high GOR. The 2 patients with temporal cavernomas underwent additional hippocampal transection. All patients were seizure free after surgery.

LESSONS

The high GOR may be a novel intraoperative marker of the epileptogenic zone in epilepsy surgery for cavernomas.

Intraoperative seizure outcome of levetiracetam combined with perampanel therapy in patients with glioma undergoing awake brain surgery

OBJECTIVE

This study aimed to evaluate the efficacy of levetiracetam (LEV) combined with perampanel (PER) therapy for intraoperative seizure treatment to determine whether a combination of LEV and PER can aid in the prevention of intraoperative intractable seizures during awake surgery.

METHODS

The authors performed a retrospective cohort study in 78 consecutive patients with glioma who underwent awake surgery using intraoperative direct electrical stimulation mapping. To prevent intraoperative seizures, 50 patients were treated with the antiepileptic drug LEV only (LEV group) from January 2017 to January 2019, while the remaining 28 patients were treated with LEV plus PER (LEV + PER group) between March 2019 and January 2020. LEV (1000-3000 mg) and/or PER (2-4 mg) were administered before the surgery.

RESULTS

Preoperative seizures with International League Against Epilepsy (ILAE) class II-VI occurred in 44% of the patients in the LEV group and in 35.7% of patients in the LEV + PER group, with no significant difference between groups (p = 0.319). Total intraoperative seizures occurred in 18 patients (36.0%) in the LEV therapy group and in 2 patients (7.1%) in the LEV + PER group (p = 0.009). Of these, there were no patients (0%) with intractable seizures in the LEV + PER group. Regarding factors that influence intraoperative seizures in glioma patients during awake brain surgery, multivariate logistic regression models revealed that the occurrence of intraoperative seizures was significantly related to the involvement of motor-related regions (positive vs negative, HR 6.98, 95% CI 1.71-28.56, p = 0.007), preoperative seizure (ILAE class II-VI vs ILAE class I, HR 4.44, 95% CI 1.22-16.11, p = 0.024), and LEV + PER group (positive vs negative, HR 0.07, 95% CI 0.01-0.44, p = 0.005). Treatment-related adverse effects were rare and mild, including sleepiness, tiredness, and dizziness in both treatment groups.

CONCLUSIONS

This study demonstrates that LEV + PER therapy is significantly associated with a lower risk of intraoperative seizures compared with LEV therapy alone in patients with glioma during awake brain mapping. These findings will help neurosurgeons conduct safe and reliable awake surgeries and reduce the rate of intraoperative intractable seizures during such procedures.

Glucose Metabolism Characteristics of Extra-Hypothalamic Cortex in Patients With Hypothalamic Hamartomas (HH) Undergoing Epilepsy Evaluation: A Retrospective Study of 16 Cases

Purpose: There are few studies on the glucose metabolic characteristics of the extra-hypothalamic cortex in the hypothalamic hamartomas (HH). A comprehensive understanding of pathogenic progression of the disease is required from the perspective of cortical metabolism; therefore, we aimed to characterize metabolic characteristics of extra-hypothalamic in HH patients.

Methods: We investigated the metabolic characteristics of 16 HH patients, all of whom underwent epilepsy evaluation at Xuan Wu Hospital between 2017 and 2019. The lateralization and cortical distribution pattern of hypometabolism was assessed and related to HH mass neuroanatomy on magnetic resonance imaging (MRI) as well as scalp-electroencephalogram (scalp-EEG) abnormalities. Furthermore, asymmetry measurements of region of interest (ROI) in the temporal cortex (hippocampal formation, amygdala, and lateral temporal neocortex) were quantitatively assessed based on the normalized average positron emission tomography (PET) voxel values. The surgery prognosis was assessed using the International League Against Epilepsy (ILAE) classification system.

Results: The lateralization of hypometabolism in global visual ratings was consistent with the HH mass lateralization seen on MRI. Cortical hypometabolism showed three patterns depending whether the HH mass involved mammillary bodies, middle hypothalamus nucleus, or both. The three patterns were hypometabolism of the mesial temporal cortex with symptom of mesial temporal epilepsy (3/16, pattern I), lateral temporal, and extratemporal (frontal or parietal) cortex with symptom of neocortex temporal or frontal epilepsy (5/16, pattern II), and mesial and lateral temporal cortex and extratemporal (frontal or parietal) cortex with varied symptoms (8/16, pattern III), respectively. A significant difference in PET voxel values was found between bilateral hippocampal formation (P = 0.001) and lateral temporal neocortex in the third group (P = 0.005). We suggest that the hypometabolic characteristics of the extra-hypothalamic cortex in HH patients have three patterns. The final cortical hypometabolic pattern depends on the neuroanatomic location of the HH mass and was consistent with the main involved cortex of the interictal and ictal discharges. The third hypometabolic pattern with the most extensive cortical hypometabolism has a poorer prognosis.

Posttraumatic epilepsy may be a state in which underlying epileptogenicity involves focal cortical dysplasia

INTRODUCTION

The occurrence rate of posttrauma epilepsy ranges widely from 1% to 30%. Little is known about the underlying epileptogenesis of traumatic brain injury (TBI)-related epilepsy (TRE), because no comparison between TRE and TBI without epilepsy has been performed in terms of neuropathology. Therefore, we postulated that different neuropathological factors may be present between TRE and TBI without epilepsy. The purpose of this study was to clarify differences between TRE and TBI without epilepsy.

METHODS

We studied patients who experienced severe head trauma and underwent brain surgery. The age range of the patients was 9-71 years old. Patients with medically resistant epilepsy were included in the Epilepsy group, and patients without epilepsy were included in the nonepilepsy group. Pathological findings, age, sex, and cause of head trauma were statistically compared between these two groups.

RESULTS

This study involved 10 patients, nine of whom met the inclusion criteria. Pathological findings for all patients in the Epilepsy group included focal cortical dysplasia (FCD) (p = 0.012).

CONCLUSION

The difference between TRE and TBI without epilepsy was underlying FCD in patients with TRE.