An 18-year follow-up of seizure outcome after surgery for temporal lobe epilepsy and hippocampal sclerosis

Impact of intracranial subclinical seizures on seizure outcomes after SLAH in patients with mesial temporal lobe epilepsy

OBJECTIVE

To investigate the association between subclinical seizures detected on intracranial electroencephalographic (i-SCSs)recordings and mesial temporal sclerosis (MTS), as well as their impact on surgical outcomes of stereotactic laser amygdalohippocampotomy (SLAH).

METHODS

A retrospective review was conducted on 27 patients with drug-resistant mesial temporal lobe epilepsy (MTLE) who underwent SLAH. The number of seizures detected on scalp EEG and iEEG was assessed. Patients were followed for a minimum of 3 years after SLAH.

RESULTS

Of the 1715 seizures recorded from mesial temporal regions, 1640 were identified as i-SCSs. Patients with MTS were associated with favorable short- and long-term surgical outcomes. Patients with MTS had a higher number of i-SCSs compared to patients without MTS. The numbers of i-SCSs were higher in patients with Engel I-II outcomes, but no significant statistical difference was found. However, it was observed that patients with MTS who achieved Engel I-II classification had higher numbers of i-SCSs than patients without MTS (P < 0.05).

CONCLUSION

Patients with MTS exhibited favorable short-term and long-term surgical outcome after SLAH. A higher number of i-SCSs was significantly associated with MTS in patients with MTLE. The number of i-SCSs tended to be higher in patients with Engel Ⅰ-Ⅱ surgical outcomes.

SIGNIFICANCE

The association between i-SCSs, MTS, and surgical outcomes in MTLE patients undergoing SLAH has significant implications for understanding the underlying mechanisms and identifying potential therapeutic targets to enhance surgical outcomes.

Regulation of Keap1-Nrf2 axis in temporal lobe epilepsy-hippocampal sclerosis patients may limit the seizure outcomes

BACKGROUND

Accumulation of reactive oxygen species (ROS) exacerbates neuronal loss during seizure-induced excitotoxicity. Keap1 (Kelch-like ECH-associated protein1)-nuclear factor erythroid 2-related factor 2 (Nrf2) axis is one of the known active antioxidant response mechanisms. Our study focused on finding the factors influencing Keap1-Nrf2 axis regulation in temporal lobe epilepsy (TLE) associated with hippocampal sclerosis (HS) patients.

METHODS

Based on post-surgical follow-up data, patient samples (n = 26) were categorized into class 1 (completely seizure-free) and class 2 (only focal-aware seizures/auras), as suggested by International League Against Epilepsy (ILAE). For molecular analyses, double immunofluorescence assay and Western blot analysis were employed.

RESULTS

A significant decrease in expression of Nrf2 (p < 0.005), HO-1; p < 0.02) and NADPH Quinone oxidoreductase1 (NQO1; p < 0.02) was observed in ILAE class 2. Keap1 (p < 0.02) and histone methyltransferases (HMTs) like SetD7 (SET7/9; SET domain-containing 7 histone lysine methyltransferase) (p < 0.009) and enhancer of zeste homolog 2 (EZH2; p < 0.02) and methylated histones viz., H3K4me1 (p < 0.001), H3K9me3 (p < 0.001), and H3K27me3 (p < 0.001) was upregulated in ILAE class 2. Nrf2-interacting proteins viz., p21 (p < 0.001) and heat shock protein 90 (HSP90; p < 0.03) increased in class 1 compared to class 2 patients.

CONCLUSION

Upregulation of HMTs and methylated histones can limit phase II antioxidant enzyme expression. Also, HSP90 and p21 that interfere with Keap1-Nrf2 interaction could contribute to a marginal increase in HO-1 and NQO1 expression despite histone methylation and Keap1. Based on our findings, we conclude that TLE-HS patients prone to seizure recurrence were found to have dysfunctional antioxidant response, in part, owing to Keap1-Nrf2 axis. The significance of Keap1-Nrf2 signaling mechanism in generation of phase II antioxidant response. Keap1-Nrf2 controls antioxidant response through regulation of phase II antioxidant enzymes like HO-1 (heme oxygenase-1), NQO1 (NADPH-Quinone Oxidoreductase1), and glutathione S-transferase (GST). Release of Nrf2 from negative regulation by Keap1 causes its translocation into nucleus, forming a complex with cAMP response-element binding protein (CBP) and small Maf proteins (sMaf). This complex subsequently binds antioxidant response element (ARE) and elicits and antioxidant response involving expression of phase II antioxidant enzymes. Reactive oxygen species (ROS) modify Cysteine 151 residue, p62 (sequsetosome-1), and interacts with Nrf2- binding site in Keap 1. p21 and HSP90 prevent Nrf2 interaction with Keap1. At transcriptional level, histone methyltransferases like EZH2 (enhancer of zeste homologue2), and SetD7 (SET7/9; SET domain-containing 7 histone lysine methyltransferase) and corresponding histone targets viz., H3K27me3, H3K9me3, and H3K4me1 influence Nrf2 and Keap1 expression respectively.

Resting-state fMRI in patients with refractory epilepsy with and without drop attacks: exploring the connectivity of sensorimotor cortex

OBJECTIVE

Patients with multifocal or generalized epilepsies manifesting with drop attacks have severe refractory seizures and significant cognitive and behavioural abnormalities. It is unclear to what extent these features relate to network abnormalities and how networks in sensorimotor cortex differ from those in patients with refractory focal epilepsies. Thus, in this study we sought to provide preliminary data on connectivity of sensorimotor cortex in patients with epileptic drop attacks, in comparison to patients with focal refractory epilepsies.

METHODS

Resting-state fMRI (rs-fMRI) data was available for 5 patients with epileptic drop attacks and 15 with refractory focal epilepsies undergoing presurgical evaluation. Functional connectivity was analyzed with a seed-based protocol, with primary seeds placed at the precentral gyrus, the postcentral gyrus and the premotor cortex. For each seed, the subjects' timeseries were extracted and transformed to Z scores. Between-group analysis was then performed using the 3dttest+ + AFNI program.

RESULTS

Two clusters of reduced connectivity in the group with drop attacks (DA group) in relation to those with focal epilepsies were found in the between-group analysis: the precentral seed showed reduced connectivity in the surrounding motor area, and the postcentral seed, reduced connectivity with the ipsilateral posterior cingulate gyrus. In the intra-group analyses, sensorimotor and premotor networks were abnormal in the DA group, whereas patients with focal epilepsies had the usual connectivity maps with each seed.

CONCLUSION

This pilot study shows differences in the cerebral connectivity in the sensorimotor cortex of patients with generalized epilepsies and drop attacks which should be further explored to better understand the biological bases of the seizure generation and cognitive changes in these people.

Long-Term Seizure Freedom, Resolution of Epilepsy and Perceived Life Changes in Drug Resistant Temporal Lobe Epilepsy With Hippocampal Sclerosis: Comparison of Surgical Versus Medical Management

BACKGROUND

Outcome of temporal lobe epilepsy associated with hippocampal sclerosis (TLE-HS) has rarely been evaluated exclusively.

OBJECTIVE

To compare long-term seizure freedom, resolution of epilepsy, and perceived life changes in patients with drug-resistant TLE-HS who underwent surgery vs those who opted for best medical management.

METHODS

In this retrospective longitudinal study, 346 patients with TLE-HS who underwent surgery were compared with 325 who received best medical management. Predictors for long-term remission, resolution of epilepsy, and seizure recurrence were analyzed.

RESULTS

The duration of follow-up ranged from 3-18 (mean 12.61) years. The average age of study population was 28.54 ± 12.27 years with 321 (47.8%) women. Age at onset of epilepsy (11.84 ± 8.48 vs 16.29 ± 11.88; P ≤ .001) was lower, and duration of epilepsy (15.65 ± 9.33 vs 12.97 ± 11.44; P < .001) was higher in the surgery group. Seizure freedom at 3 (81.8 vs 19.0%; P < .001), 5 (73% vs 16.1%; P < .001), and 10 years (78.3% vs 18.5; P < .001) and resolution of epilepsy (30.5% vs 0.6%; P < .001) was higher in the surgery group. The overall perceived life changes score was higher in the surgery group (80.96 ± 25.47 vs 66.24 ± 28.13; P < .001). At long-term follow-up (≥10 years), the presence of an aura was the strongest predictor for resolution of epilepsy (β: 2.29 [95% CI; 1.06-4.93]; P = .035), whereas acute postoperative seizures (APOS) (β: 6.06 [95% CI 1.57-23.42]; P < .001) and an abnormal postoperative EEG (β: 0.222 [95% CI 0.100-0.491]; P < .001) were predictors of persistent seizures. Seizure freedom both at 3 and 5 years predicted seizure freedom at 10 years.

CONCLUSION

Surgery for drug-resistant TLE-HS was associated with higher rate of long-term seizure-freedom, resolution of epilepsy, and reduction of anti-seizure medications with improvement in perceived life changes compared with best medical management. The presence of an aura was predictor for resolution of epilepsy while APOS and an abnormal postoperative EEG were predictors of persistent seizures.

Evaluation of epilepsy surgery scope and training in Latin America

INTRODUCTION

To describe the variety of surgical epilepsy procedures offered in Latin America and characterize the training in surgical management for epilepsy and neurophysiology fellows.

MATERIALS & METHODS

A 15-question survey was sent to Spanish-speaking epilepsy specialists in Latin America (members of the International Consortium in Epilepsy Surgery Education) to characterize their epilepsy surgery practices and formal training programs when present, including fellowship program characteristics, trainee involvement, and assessment of trainee performance. Epilepsy surgery procedures included resective/ablative interventions and neuromodulation therapies approved for drug-resistant epilepsy. Associations between categorical variables were evaluated using the Fisher Exact test.

RESULTS

There were 42 responses from a total of 57 survey recipients (73% response rate). Most surgical programs performed either 1 to 10 procedures (36%) or 11 to 30 procedures (31%) per year. Most centers (88%) performed resective procedures, while none of the surveyed institutions performed laser ablations. Most of the centers performing intracranial EEG (88%) and advanced neuromodulation (93%) were in South America. Centers with formal fellowship training programs were more likely to perform intracranial EEG procedures compared to centers without fellows (92% vs 48%, respectively, OR = 12.2 [95% CI 1.45-583], p = 0.007).

DISCUSSION

There is significant variability in surgical procedures performed across epilepsy centers in a Latin American educational consortium. Advanced surgical diagnostic procedures and interventions are performed in a fair number of surveyed institutions. Strategies to enhance access to epilepsy surgery procedures and facilitate formal training in surgical management are necessary.

Predictors of surgical outcomes in patients with drug-resistant temporal lobe epilepsy

Aim. To identify predictors of surgical outcomes in patients with drug-resistant temporal lobe epilepsy in a multivariate model.

Materials and methods. Aretrospective study included 69 patients with drug-resistant temporal lobe epilepsy who underwent microsurgical anterior temporal lobectomy. The study included 31 (45%) men and 38 (55%) women. The median age was 28 (21; 36). Surgical treatment outcomes were assessed at 6, 12, 36, and 60 months after surgical intervention according to the Engel Epilepsy Surgery Outcome Scale. Logistic regression equations were calculated, a ROC curve was constructed, and odds ratio (OR) with 95% confidence interval (CI), sensitivity, specificity, area under the ROC curve (AUC) were calculated.

Results. In all assessed time periods, 88.3–93.0% of patients had outcomes consistent with Engel classes I and II. The distribution of patients by outcome classes did not change statistically significantly over the entire follow-up period. There were the following predictors of high efficacy of surgical treatment at 6 months after surgery: relatively shorter duration of active disease course (OR 0.719, 95%, CI: 0.437–0.966, p < 0.05), absence of status epilepticus (OR 0.048, 95% CI: 0.002–0.472, p < 0.05), absence of subdominant foci of irritative activity (OR 0.123, 95% CI: 0.012–0.845, p < 0.01), presence of mesial temporal sclerosis (OR 1008, 95% CI: 21.59–1310851, p < 0.01), a relatively longer resection margin on the temporal lobe (OR 637.32, 95% CI: 5.43–1960062, p < 0.05), lateralization of epileptogenic zone in subdominant hemisphere (OR 0.103, 95% CI 0.004–0.937, p = 0.0532). AUC was 0.957 (0.917–0.997), p < 0.0001; sensitivity 87.5%, and specificity 82.8%.

Conclusion. Independent predictors of the efficacy of microsurgical anterior temporal lobectomy in patients with drug-resistant temporal lobe epilepsy are the following: shorter duration of active disease course, absence of status epilepticus in the history, absence of subdominant foci, presence of mesial temporal sclerosis, a relatively longer resection margin on the temporal lobe, and lateralization of the epileptogenic zone in the temporal lobe of the subdominant hemisphere.

Extended follow-up after anterior temporal lobectomy demonstrates seizure recurrence 20+ years postsurgery

OBJECTIVE

Anterior temporal lobectomy (ATL) for medication-resistant localized epilepsy results in ablation or reduction of seizures for most patients. However, some individuals who attain an initial extended period of postsurgical seizure freedom will experience a later seizure recurrence. In this study, we examined the prevalence and some risk factors for late recurrence in an ATL cohort with extensive regular follow-up.

METHODS

Included were 449 patients who underwent ATL at Austin Health, Australia, from 1978 to 2008. Postsurgical follow-up was undertaken 2-3 yearly. Seizure recurrence was tested using Kaplan-Meier analysis, log-rank test, and Cox regression. Late recurrence was qualified as a first disabling seizure >2 years postsurgery. We examined risks within the ATL cohort according to broad pathology groups and tested whether late recurrence differed for the ATL cohort compared to patients who had resections outside the temporal lobe (n = 98).

RESULTS

Median post-ATL follow-up was 22 years (range = .1-38.6), 6% were lost to follow-up, and 12% had died. Probabilities for remaining completely seizure-free after surgery were 51% (95% confidence interval [CI] = 53-63) at 2 postoperative years, 36% (95% CI = 32-41) at 10 years, 32% (95% CI = 27-36) at 20 years, and 30% (95% CI = 25-34) at 25 years. Recurrences were reported up to 23 years postoperatively. Late seizures occurred in all major ATL pathology groups, with increased risk in the "normal" and "distant lesion" groups (p ≤ .03). Comparison between the ATL cohort and patients who underwent extratemporal resection demonstrated similar patterns of late recurrence (p = .74).

SIGNIFICANCE

Some first recurrences were very late, reported decades after ATL. Late recurrences were not unique to any broad ATL pathology group and did not differ according to whether resections were ATL or extratemporal. Reports of these events by patients with residual pathology suggest that potentially epileptogenic abnormalities outside the area of resection may be implicated as one of several possible underlying mechanisms.

Case report: Successful anterior temporal lobectomy in drug-resistant temporal lobe epilepsy associated with Sotos syndrome

The Sotos syndrome is an autosomal dominant disorder characterized by haploinsufficiency of NSD1 gene, with some individuals affected by epilepsy and, rarely, drug-resistant seizures. A 47-years-old female patient with Sotos syndrome was diagnosed with focal-onset seizures in left temporal lobe, left-side hippocampal atrophy, and neuropsychological testing with decreased performance in several cognitive domains. Patient was treated with left-side temporal lobe resection and developed complete awake seizure control in 3-years of follow-up, with marked improvement in quality-of-life. In selected, clinically concordant patients, resective surgeries may play a significant role in improving patient's quality of life and seizure control.

Mesial Temporal Lobe Epilepsy (MTLE) Drug-Refractoriness Is Associated With P2X7 Receptors Overexpression in the Human Hippocampus and Temporal Neocortex and May Be Predicted by Low Circulating Levels of miR-22

Objective: ATP-gated ionotropic P2X7 receptors (P2X7R) actively participate in epilepsy and other neurological disorders. Neocortical nerve terminals of patients with Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis (MTLE-HS) express higher P2X7R amounts. Overexpression of P2X7R bolsters ATP signals during seizures resulting in glial cell activation, cytokines production, and GABAergic rundown with unrestrained glutamatergic excitation. In a mouse model of status epilepticus, increased expression of P2X7R has been associated with the down-modulation of the non-coding micro RNA, miR-22. MiR levels are stable in biological fluids and normally reflect remote tissue production making them ideal disease biomarkers. Here, we compared P2X7R and miR-22 expression in epileptic brains and in the serum of patients with MTLE-HS, respectively.

Methods: Quantitative RT-PCR was used to evaluate the expression of P2X7R in the hippocampus and anterior temporal lobe of 23 patients with MTLE-HS and 10 cadaveric controls. Confocal microscopy and Western blot analysis were performed to assess P2X7R protein amounts. MiR-22 expression was evaluated in cell-free sera of 40 MTLE-HS patients and 48 healthy controls.

Results: Nerve terminals of the hippocampus and neocortical temporal lobe of MTLE-HS patients overexpress (p &lt; 0.05) an 85 kDa P2X7R protein whereas the normally occurring 67 kDa receptor protein dominates in the brain of the cadaveric controls. Contrariwise, miR-22 serum levels are diminished (p &lt; 0.001) in MTLE-HS patients compared to age-matched control blood donors, a situation that is more evident in patients requiring multiple (&gt;3) anti-epileptic drug (AED) regimens.

Conclusion: Data show that there is an inverse relationship between miR-22 serum levels and P2X7R expression in the hippocampus and neocortex of MTLE-HS patients, which implies that measuring serum miR-22 may be a clinical surrogate of P2X7R brain expression in the MTLE-HS. Moreover, the high area under the ROC curve (0.777; 95% CI 0.629–0.925; p = 0.001) suggests that low miR-22 serum levels may be a sensitive predictor of poor response to AEDs among MTLE-HS patients. Results also anticipate that targeting the miR-22/P2X7R axis may be a good strategy to develop newer AEDs.

Prediction and control of focal seizure spread: Random walk with restart on heterogeneous brain networks

Whole-brain models offer a promising method of predicting seizure spread, which is critical for successful surgical treatment of focal epilepsy. Existing methods are largely based on structural connectome, which ignores the effects of heterogeneity within the regional excitability of brains. In this study we used a whole-brain model to show that heterogeneity in nodal excitability had a significant impact on seizure propagation in the networks and compromised the prediction accuracy with structural connections. We then addressed this problem with an algorithm based on random walk with restart on graphs. We demonstrated that by establishing a relationship between the restarting probability and the excitability for each node, this algorithm could significantly improve the seizure spread prediction accuracy in heterogeneous networks and was more robust against the extent of heterogeneity. We also strategized surgical seizure control as a process to identify and remove the key nodes (connections) responsible for the early spread of seizures from the focal region. Compared to strategies based on structural connections, virtual surgery with a strategy based on a modified random walk with extended restart generated outcomes with a high success rate while maintaining low damage to the brain by removing fewer anatomical connections. These findings may have potential applications in developing personalized surgery strategies for epilepsy.

Long-Term Outcome of Temporal Lobe Epilepsy Surgery in 621 Patients With Hippocampal Sclerosis: Clinical and Surgical Prognostic Factors

Temporal lobe epilepsy (TLE) is the most common type of focal epilepsy and is frequently drug-resistant (DR) to antiseizure medication (ASM), corresponding to approximately one-third of the cases. When left inadequately treated, it can worsen the quality of life, cognitive deficits, and risk of death. The standard treatment for drug-resistant TLE is the surgical removal of the structures involved, with good long-term outcome rates of 60–70 % and a low rate of adverse effects. The goal of successful treatment is sustained seizure freedom. In our study, we evaluated sustained long-term (up to 23 years) surgical outcomes in 621 patients with DR-TLE associated with hippocampal sclerosis, who underwent a temporal lobectomy. We analyzed the main predictive factors that influence the surgical outcome related to seizure control, through a longitudinal and retrospective study, using a multivariable regression model. We found that 73.6% of the patients were free from disabling seizures (Engel Class I), maintained over time in 65% of patients followed up to 23 years after surgery. We found that four independent variables predicted seizure outcomes. The presence of dysmnesic and olfactory aura predicted a less favorable outcome. The history of febrile seizure and the surgical technique predicted a good outcome. Regarding the type of surgical technique, the standard anteromesial temporal lobectomy (ATL) led to significantly better outcomes (78.6% Engel Class I) when compared to the selective amygdalohippocampectomy via subtemporal approach (67.2% Engel Class I; p = 0.002), suggesting that the neuronal networks involved in the epileptogenic zone may be beyond mesial temporal structures. The multivariable regression model with the above-mentioned predictor variables revealed an ExpB = 3.627 (N = 621, p < 0.001), indicating that the model was able to distinguish between patients with a seizure-free. We conclude that epilepsy surgery is a safe procedure, with low rates of postoperative complications and good long-term results.

Surgical outcome of temporal plus epilepsy is improved by multilobar resection

OBJECTIVE

Temporal plus epilepsy (TPE) represents a rare type of epilepsy characterized by a complex epileptogenic zone including the temporal lobe and the close neighboring structures. We investigated whether the complete resection of temporal plus epileptogenic zone as defined through stereoelectroencephalography (SEEG) might improve seizure outcome in 38 patients with TPE.

METHODS

Inclusion criteria were as follows: epilepsy surgery performed between January 1990 and December 2001, SEEG defining a temporal plus epileptogenic zone, unilobar temporal operations ("temporal lobe epilepsy [TLE] surgery") or multilobar interventions including the temporal lobe ("TPE surgery"), magnetic resonance imaging either normal or showing signs of hippocampal sclerosis, and postoperative follow-up of at least 12 months. For each assessment of postoperative seizure outcome, at 1, 2, 5, and 10 years, we carried out descriptive analysis and classical tests of hypothesis, namely, Pearson χ² test or Fisher exact test of independence on tables of frequency for each categorical variable of interest and Student t-test for each continuous variable of interest, when appropriate.

RESULTS

Twenty-one patients underwent TPE surgery and 17 underwent TLE surgery with a follow-up of 12.4 ± 8.16 years. In the multivariate models, there was a significant effect of the time from surgery on Engel Class IA versus IB-IV outcome, with a steadily worsening trend from 5-year follow-up onward. TPE surgery was associated with better results than TLE surgery.

SIGNIFICANCE

This study suggests that surgical outcome in patients with TPE can be improved by a tailored, multilobar resection and confirms that SEEG is mandatory when a TPE is suspected.

Surgery procedures in temporal lobe epilepsies

Temporal lobe epilepsy (TLE) is the most common cause of refractory epilepsy amenable for surgical treatment and seizure control. Surgery for TLE is a safe and effective strategy. The seizure-free rate after surgical resection in patients with mesial or neocortical TLE is about 70%. Resective surgery has an advantage over stereotactic radiosurgery in terms of seizure outcomes for mesial TLE patients. Both techniques have similar results for safety, cognitive outcomes, and associated costs. Stereotactic radiosurgery should therefore be seen as an alternative to open surgery for patients with contraindications for or with reluctance to undergo open surgery. Laser interstitial thermal therapy (LITT) has also shown promising results as a curative technique in mesial TLE but needs to be more deeply evaluated. Brain-responsive stimulation represents a palliative treatment option for patients with unilateral or bilateral MTLE who are not candidates for temporal lobectomy or who have failed a prior mesial temporal lobe resection. Overall, despite the expansion of innovative techniques in recent years, resective surgery remains the reference treatment for TLE and should be proposed as the first-line surgical modality. In the future, ultrasound therapies could become a credible therapeutic option for refractory TLE patients.

Anterior temporal lobectomy: A cross-sectional observational study of potential surgical candidates at a single institute

BACKGROUND

Epilepsy is a common neurological disorder, associated with serious cognitive, physical, and psychosocial burdens. Mesial temporal lobe epilepsy (mTLE) is the commonest form of focal epilepsy. The aim of this study was to establish the incidence of patients with electroencephalographic epileptiform discharges consistent with mTLE attending a tertiary hospital in South Africa, and determine whether these patients may be candidates for anterior temporal lobectomy.

METHODS

This was a cross-sectional observational study of all patients receiving scalp electroencephalograms (EEG) performed at the Groote Schuur Hospital Neurophysiology laboratory during the period January 1, 2017-December 31, 2019. Where magnetic resonance imaging (MRI) brain scans had been performed, these were assessed for corroborative evidence of mTLE.

RESULTS

Over the 3-year period, 4 342 EEGs were assessed. A total of 411 (11%) showed epileptiform discharges consistent with all epilepsy types. Of these, 327 (69%) were of focal onset and 108 (33% of all focal onset epilepsies) were consistent with mTLE. Of the patients with electroencephalographic features of mTLE, only 27 (25%) had had MRI brain scans performed according to an epilepsy surgery protocol. None of these patients had been considered for surgery.

CONCLUSION

Surgery, especially anterior temporal lobectomy, is widely acknowledged to be an efficacious and cost-effective intervention in patients with drug-resistant mTLE. The findings of our study suggest that patients with mTLE in our setting are under-investigated for potential surgery; and that it is under-utilized. These findings are in line with similar studies in both well-resourced and resource-constrained countries. Our study also highlights the utility of EEG as a practical screening tool to identify potential surgical candidates, as well as the establishment of an EEG and MRI database to assist in recognizing these patients.

[Surgical treatment of drug-resistant epilepsy following hippocampal sclerosis]

Surgery is an effective approach for drug-resistant temporal lobe epilepsy following hippocampal sclerosis. There is still no clear and unanimous opinion about advantages and disadvantages of certain surgical technique.

MATERIAL AND METHODS

There were 103 surgical interventions in 101 patients. Females prevailed (1.45:1). Age of patients ranged from 16 to 56 years (median 28). Anteromedial temporal lobectomy and selective amygdaloghippocampectomy were performed in 49 (47.6%) and 54 (52.4%) patients, respectively. In the latter group, 30 patients were operated via a 14-mm burr hole-subtemporal approach. Postoperative outcomes were assessed using the Engel grading system. The follow-up period ranged from 2 to 8 years (median 4 years).

RESULTS

By the 2^nd year, Engel class I was observed in 74 (72%) patients, Engel II, III and IV - in 20 (19.4%), 6 (5.8%) and 3 (2.9%) patients, respectively. Engel class I was achieved after anteromedial temporal lobectomy in 68% of cases, selective amygdaloghippocampectomy via standard approaches in 75% of cases, amygdaloghippocampectomy via subtemporal burr hole approach - in 80% of cases. Neurocognitive impairments after anteromedial lobectomy and selective amygdaloghippocampectomy were similar. At the same time, mental disorders de novo prevailed in the group of anteromedial lobectomy (p<0.05). There were no severe visual field disorders after subtemporal burr-hole access. In other cases, these disorders occurred in 36.2% of patients (p<0.05). There were 8 (7.8%) postoperative complications: 5 (10.2%) - after anterior temporal lobectomy, 3 (5.5%) - after selective surgeries via standard approaches. There were no complications after burr-hole surgery.

CONCLUSION

Selective amygdaloghippocampectomy is not inferior to anteromedial lobectomy. Moreover, this procedure is associated with a lower risk of complications and adverse events.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Epilepsy surgery: Late seizure recurrence after initial complete seizure freedom

OBJECTIVE

This study was undertaken to improve understanding of late relapse following epilepsy surgery in pharmacoresistant epilepsy.

METHODS

Retrospective comparison was made of 99 of 1278 patients undergoing surgery during 1999-2015 with seizure relapses after at least 2 years of complete seizure freedom with matched controls experiencing continued long-term seizure freedom. Univariate and multivariate analyses were performed.

RESULTS

With a mean follow-up of 9.7 years, mean time to seizure relapse was 56.6 months. In multivariate analysis, incomplete resection based on magnetic resonance imaging (MRI), bilateral lesions on preoperative MRI, and epilepsy onset in the first year of life carried a significantly higher risk of late relapse. In patients with late relapse, additional functional imaging with positron emission tomography had been performed significantly more often. Although the differences were not significant in multivariate analysis, doses of antiepileptic drugs were higher in the relapse group preoperatively and in the first 24 months and complete withdrawal was more frequent in the control group (68% vs. 51%). Regarding seizure frequency, most patients had mild seizure relapse (single relapse seizure or <1/month).

SIGNIFICANCE

In our predominantly lesional cohort, complete resection of the MRI lesion is the most important factor to maintain long-term seizure freedom. Two patterns of recurrence were identified: (1) incomplete resected lesions with seizure generation in proximity to the initial resection and (2) epileptogenic networks not detected preoperatively or evolving in the postoperative interval and manifesting with new clinical and diagnostic features.

Safety of the paramedian supracerebellar-transtentorial approach for selective amygdalohippocampectomy

OBJECTIVE

The goal of this study was to assess the reproducibility and safety of the recently introduced paramedian supracerebellar-transtentorial (PST) approach for selective amygdalohippocampectomy (SA).

METHODS

The authors performed a retrospective analysis of prospectively collected data originating from their surgical register of patients undergoing SA via a PST approach for lesional medial temporal lobe epilepsy. All patients received thorough pre- and postoperative clinical (neurological, neuropsychological, psychiatric) and instrumental (ictal and long-term EEG, invasive EEG if needed, MRI) workup. Surgery-induced complications were assessed at discharge and at every follow-up thereafter and were classified according to Clavien-Dindo grade (CDG). Epilepsy outcome was defined according to Engel classification. Data were reported according to common descriptive statistical methods.

RESULTS

Between May 2015 and May 2018, 17 patients underwent SA via a PST approach at the authors' institution (hippocampal sclerosis in 13 cases, WHO grade II glioma in 2 cases, and reactive gliosis in 2 cases). The median postoperative follow-up was 7 months (mean 9 months, range 3-19 months). There was no surgery-related mortality and no complication (CDG ≥ 2) in the whole series. Transitory CDG 1 surgical complications occurred in 4 patients and had resolved in all of them by the first postoperative follow-up. One patient showed a deterioration of neuropsychological performance with new slight mnestic deficits. No patient experienced a clinically relevant postoperative visual field defect. No morbidity due to semisitting position was recorded. At last follow-up 13/17 (76.4%) patients were in Engel class I (9/17 [52.9%] were in class IA).

CONCLUSIONS

The PST approach is a reproducible and safe surgical route for SA. The achievable complication rate is in line with the best results in the literature. Visual function outcome particularly benefits from this highly selective, neocortex-sparing approach. A larger patient sample and longer follow-up will show in the future if the seizure control rate and neuropsychological outcome also compare better than those achieved with current common surgical techniques.

Transsylvian amygdalohippocampectomy for mesial temporal lobe epilepsy: Comparison of three different approaches

OBJECTIVE

This study's objective was to compare the transinsular (TI-AH), transuncus (TU-AH), and temporopolar (TP-AH) amygdalohippocampectomy approaches regarding seizure control, temporal stem (TS) damage, and neurocognitive decline.

METHODS

We included 114 consecutive patients with unilateral hippocampal sclerosis (HS) who underwent TI-AH, TU-AH, or TP-AH between 2002 and 2017. We evaluated seizure control using Engel classification. We used diffusion tensor imaging and postoperative Humphrey perimetry to assess the damage of the TS. We also performed pre- and postoperative memory performance and intelligence quotient (IQ).

RESULTS

There were no significant differences in the proportion of patients free of disabling seizures (Engel IA+IB) among the three surgical approaches in the survival analysis. However, more patients were free of disabling seizures (Engel IA+IB) at 2 years of postsurgical follow-up with TP-AH (69.5%) and TI-AH (76.7%) as compared to the TU-AH (43.5%) approach (p = .03). The number of fibers of the inferior fronto-occipital fasciculus postoperatively was reduced in the TI-AH group compared with the TU-AH and TP-AH groups (p = .001). The rate of visual field defects was significantly higher with TI-AH (14/19, 74%) in comparison to the TU-AH (5/15, 33%) and TP-AH (13/40, 32.5%) approaches (p = .008). Finally, there was a significant postoperative decline in verbal memory in left-sided surgeries (p = .019) and delayed recall for both sides (p < .001) regardless of the surgical approach. However, TP-AH was the only group that showed a significant improvement in visual memory (p < .001) and IQ (p < .001) for both right- and left-sided surgeries.

SIGNIFICANCE

The TP-AH group had better short-term seizure control than TU-AH, a lower rate of visual field defects than TI-AH, and improved visual memory and IQ compared to the other groups. Our findings suggest that TP-AH is a better surgical approach for temporal lobe epilepsy with HS than TI-AH and TU-AH.

Development and validation of a predictive model for the diagnosis of neural antibody-mediated epilepsy/ seizure in patients with new-onset seizure or established epilepsy

PURPOSE

Currently, the diagnosis of neural antibody-mediated epilepsy/seizure (NAME/S)relies heavily on neural antibody testing, which is time-consuming, costly and introduces diagnostic delays. A statistical tool to predict the probability of a patient with NAME/S is lacking. We aimed to construct a predictive model to help clinicians expedite the diagnostic process.

METHODS

We retrospectively recruited subjects (206 in the development group and 62 in the validation group) with new-onset seizures or established epilepsy suspected to have presented with antibody-mediated seizures between January 2014 and December 2019. We collected data about demographics, medical history, clinical manifestations and follow up. Binary logistic regression was used to select potential predictors for the construction of a predictive model. Five-fold cross and bootstrap validation were applied to avoid overfitting. Concordance index, calibration plots and decision curve analysis were used to assess its performance.

RESULTS

The model, incorporating presence/absence of tumour, psychiatric/cognitive/emotional changes, language disturbances, sensory auras, tonic-clonic seizures, multiple seizure events, hyponatremia and MRI inflammation, was visualized as a nomogram. The crude and adjusted concordance indices were both 0.88 with a cut-off value of 0.62, sensitivity of 83.2 % and specificity of 77.4 %. The slope and intercept of the calibration curve were 0 and 1, respectively. The model also showed good performance in the validation group with a concordance index of 0.82, cut-off value of 0.33, sensitivity of 75.5 % and specificity of 73.1 %. The slope was 0.86 and the intercept was 0.039. Decision curve analysis showed that the model was useful with an optimal threshold probability of ＞4 % in both groups.

CONCLUSIONS

Despite limitations such as sample volume and selection bias in subject enrolment, this model may be used to estimate the individualized probability of having NAME/S, deserving further exploration and validation.

Long-term outcomes after epilepsy surgery, a retrospective cohort study linking patient-reported outcomes and routine healthcare data

OBJECTIVE

The objective of the study was to assess the long-term outcomes of epilepsy surgery between 1995 and 2015 in South Wales, UK, linking case note review, postal questionnaire, and routinely collected healthcare data.

METHOD

We identified patients from a departmental database and collected outcome data from patient case notes, a postal questionnaire, and the QOLIE-31-P and linked with Welsh routinely collected data in the Secure Anonymised Information Linkage (SAIL) databank.

RESULTS

Fifty-seven patients were included. Median age at surgery was 34 years (11-70), median: 24 years (2-56) after onset of habitual seizures. Median follow-up was 7 years (2-19). Twenty-eight (49%) patients were free from disabling seizures (Engel Class 1), 9 (16%) experienced rare disabling seizures (Class 2), 13 (23%) had worthwhile improvements (Class 3), and 7 (12%) had no improvement (Class 4). There was a 30% mean reduction in total antiepileptic drug (AED) load at five years postsurgery. Thirty-eight (66.7%) patients experienced tonic-clonic seizures presurgery verses 8 (14%) at last review. Seizure-free patients self-reported a greater overall quality of life (QOL; QOLIE-31-P) when compared with those not achieving seizure freedom. Seizure-free individuals scored a mean of 67.6/100 (100 is best), whereas those with continuing seizures scored 46.0/100 (p < 0.006). There was a significant decrease in the median rate of hospital admissions for any cause after epilepsy surgery (9.8 days per 1000 patient days before surgery compared with 3.9 after p < 0.005).

SIGNIFICANCE

Epilepsy surgery was associated with significant improvements in seizures, a reduced AED load, and an improved QOL that closely correlated with seizure outcomes and reduced hospital admission rates following surgery. Despite this, there was a long delay from onset of habitual seizures to surgery. The importance of long-term follow-up is emphasized in terms of evolving medical needs and health and social care outcomes.

Initiating a new national epilepsy surgery program: Experiences gathered in Georgia

Surgery is the most effective therapeutic approach for medically refractory epilepsies and a safe and cost-efficient treatment in terms of long-term expenses of direct, indirect, and intangible costs. Georgia is a Caucasian low- to middle-income country with a remarkable effort to deal with epileptic diseases, but without an appropriate epilepsy surgery program. To address the needs for such a service in this country, two joint German-Georgian projects were initiated in 2017 and 2019. In the framework of these projects, a productive exchange program involving German and Georgian experts was undertaken in the past two years. This program included training and mentoring for Georgian clinical colleagues, as well as joint case conferences and workshops with the aim of optimizing presurgical diagnostics and preparing for an epilepsy surgery program in Georgia. Finally, a postsurgical medium- and long-term follow-up scheme was organized as the third component of this comprehensive approach. As a result of our efforts, the first patients underwent anterior temporal lobectomy and all of them remain seizure-free up to the present day. Hence, epilepsy surgery is not only feasible, but also already available in Georgia. In this report, we aim to share our experiences in the initiation and implementation of surgical epilepsy intervention in Georgia and illustrate our recent endeavor and achievements.

Correlations between interictal extratemporal spikes and clinical features, imaging characteristics, and surgical outcomes in patients with mesial temporal lobe epilepsy

PURPOSE

The significance of interictal epileptiform discharges (IEDs) observed in the extratemporal lobe has not been fully evaluated in patients with mesial temporal lobe epilepsy (MTLE). This study aimed to evaluate the surgical outcomes, clinical features, and functional neuroimaging characteristics of patients in relation to the presence or absence of extratemporal IED in MTLE with hippocampal sclerosis (HS).

METHODS

A total of 165 patients with HS-induced MTLE who had undergone anterior temporal lobectomy were enrolled and stratified into the extratemporal interictal epileptiform discharges (ETD) and the temporal lobe discharges (TD) groups. We analyzed the differentiating features of pre- and postsurgical evaluation data between the two groups. For outcome assessment, only patients with a follow-up of at least 2 years were enrolled, and the outcomes were classified based on Engel classification.

RESULTS

The ETD group showed extensive glucose hypometabolism involving the temporal lobe and extratemporal regions (p < 0.001), and IEDs were observed bilaterally or contralateral to the ictal focus (p = 0.02). However, there was no difference in the surgical outcomes between the two groups. On multivariate analysis, statistically significant variables related to ETD occurrence including seizure onset age were not identified nevertheless.

CONCLUSION

Our results indicate that ETD had a surgical outcome comparable to that of TD. Therefore, a surgical intervention need not be delayed even if extratemporal IED may be found in presurgical long-term scalp EEG monitoring.

Interpretation of the Intracranial Stereoelectroencephalography Signal

The intracranial electroencephalogram (iEEG) is essential in decision making for epilepsy surgery. Although localization of epileptogenic brain regions by means of iEEG has been the gold standard for surgical decision-making for more than 70 years, established guidelines for what constitutes genuine iEEG epileptic activity and what is normal brain activity are not available. This review provides a summary of the current state of knowledge and understanding on normal iEEG entities and variants, the effects of sleep on regional and lobar iEEG, iEEG patterns of interictal and ictal epileptic activity and their relation to well-described epileptogenic pathologies and surgical outcome.

Predictors of meaningful improvement in quality of life after selective amygdalohippocampectomy in Chinese patients with refractory temporal lobe epilepsy: A prospective study

PURPOSE

Our aim was to determine the independent predictors of minimum clinically important difference (MCID) in quality of life (QOL) after selective amygdalohippocampectomy (SAH) among Chinese patients with refractory mesial temporal lobe epilepsy (MTLE).

METHODS

We conducted a prospective study and enrolled 50 consecutive patients with refractory MTLE who underwent SAH after their presurgical evaluations. The variables independently associated with MCID in the Quality of Life in Epilepsy Inventory-31 (QOLIE-31) overall score 1 year after SAH were analyzed by multiple binary logistic regression analysis.

RESULTS

Significant improvements in the QOLIE-31 overall score and all subscale scores were observed after SAH (p < 0.001). Among 50 patients with refractory MTLE, 78% reached the criteria for MCID of QOL overall score after SAH. In the multiple binary logistic regression model, the presurgical independent predictors of significant improvement by MCID in QOL were absence of depression diagnosis (adjusted odds ratio [OR] = 8.391, 95% confidence interval [CI] = 1.240-56.776, p = 0.029) and good cognitive function (adjusted OR = 8.427, 95% CI = 1.115-63.670, p = 0.039); the postoperative independent predictor was seizure freedom (adjusted OR = 8.477, 95% CI = 1.195-60.122, p = 0.032). The sensitivity and specificity for significant improvement in the QOL were 97.4% and 45.5% respectively, with an overall model accuracy of 86.0%.

CONCLUSIONS

Presurgical depression, cognitive function, and postsurgical seizure freedom are independent predictors for meaningful improvement in QOL after SAH among the Chinese patients with refractory MTLE. Preoperative evaluation of patients with refractory MTLE should consider the cognitive dysfunction and psychological disorders.

Epilepsy surgery in low- and middle-income countries: A scoping review

BACKGROUND

Epilepsy surgery is an important treatment option for people with drug-resistant epilepsy. Surgical procedures for epilepsy are underutilized worldwide, but it is far worse in low- and middle-income countries (LMIC), and it is less clear as to what extent people with drug-resistant epilepsy receive such treatment at all. Here, we review the existing evidence for the availability and outcome of epilepsy surgery in LMIC and discuss some challenges and priority.

METHODS

We used an accepted six-stage methodological framework for scoping reviews as a guide. We searched PubMed, Embase, Global Health Archives, Index Medicus for South East Asia Region (IMSEAR), Index Medicus for Eastern Mediterranean Region (IMEMR), Latin American & Caribbean Health Sciences Literature (LILACS), African Journal Online (AJOL), and African Index Medicus (AIM) to identify the relevant literature.

RESULTS

We retrieved 148 articles on epilepsy surgery from 31 countries representing 22% of the 143 LMIC. Epilepsy surgery appears established in some of these centers in Asia and Latin America while some are in their embryonic stage reporting procedures in a small cohort performed mostly by motivated neurosurgeons. The commonest surgical procedure reported was temporal lobectomies. The postoperative seizure-free rates and quality of life (QOL) are comparable with those in the high-income countries (HIC). Some models have shown that epilepsy surgery can be performed within a resource-limited setting through collaboration with international partners and through the use of information and communications technology (ICT). The cost of surgery is a fraction of what is available in HIC.

CONCLUSION

This review has demonstrated the availability of epilepsy surgery in a few LMIC. The information available is inadequate to make any reasonable conclusion of its existence as routine practice. Collaborations with international partners can provide an opportunity to bring high-quality academic training and technological transfer directly to surgeons working in these regions and should be encouraged.

Systematic review and network meta-analysis of resective surgery for mesial temporal lobe epilepsy

OBJECTIVE

To evaluate the effectiveness of anterior temporal lobectomy (ATL) versus selective amygdalohippocampectomy (SAH) on seizure-free outcome in patients with temporal lobe epilepsy, using both direct and indirect evidence from the literature.

METHODS

MEDLINE, Embase and Cochrane databases were searched for original research articles and systematic reviews comparing ATL versus SAH, and ATL or SAH versus medical management (MM). The outcome was seizure freedom at 12 months of follow-up or longer. Direct pairwise meta-analyses were conducted, followed by a random-effect Bayesian network meta-analysis (NMA) combining direct and indirect evidence.

RESULTS

Twenty-eight articles were included (18 compared ATL vs SAH, 1 compared ATL vs SAH vs MM, 8 compared ATL vs MM, and 1 compared SAH vs MM). Direct pairwise meta-analyses showed no significant differences in seizure-free outcome of ATL versus SAH (OR 1.14, 95% CI 0.93 to 1.39; p=0.201), but the odds of seizure-free outcome were higher for ATL versus MM (OR 29.16, 95% CI 10.44 to 81.50; p<0.00001), and SAH versus MM (OR 28.42, 95% CI 10.17 to 79.39; p<0.00001). NMA also showed that the odds of seizure-free outcome were no different in ATL versus SAH (OR 1.15, 95% credible interval (CrI) 0.84-1.15), but higher for ATL versus MM (OR 27.22, 95% CrI 15.38-27.22), and SAH versus MM (OR 23.57, 95% CrI 12.67-23.57). There were no significant differences between direct and indirect comparisons (all p>0.05).

CONCLUSION

Direct evidence, indirect evidence and NMA did not identify a difference in seizure-free outcome of ATL versus SAH.

[Seizure outcome after surgery for medically intractable mesial temporal lobe epilepsy and its predictors]

OBJECTIVE

To evaluate seizure outcome in patients receiving surgery for chronic medically intractable mesial temporal lobe epilepsy (MTLE) and analyze its possible predictors.

METHODS

This retrospective study was conducted in patients with chronic medically intractable MTLE undergoing anterior temporal lobectomy (ATL) or selective amygdalohippocampectomy (SAH) in our department between September, 2011 and October, 2013. The patients were followed up for 3.5 to 5.5 years, during which the seizure outcome was evaluated according to Engel's classification. The clinical data were collected from the patients to identify the possible predictors that affected the outcome of the patients using Mann-Whitney U test or Kruskal-Wallis test.

RESULTS

Atotal of 34 patients were included in this study with a definite diagnosis of chronic medically intractable MTLE after preoperative noninvasive and invasive evaluation. In 4 of these patients, invasive EEG monitoring confirmed that epileptic discharges originated from the bilateral mesial temporal lobe, and hence surgical resection of the epileptogenic zone was not performed. The other 30 patients underwent surgical resection of the epileptogenic zone with ALT or SAH, and favorable outcomes were achieved in 23 (76.7%) of the patients. Of the 7 (23.3%) patients with poor outcomes, 6 patients presented with typical automatism and aura with frequent secondary generalized tonic-clonic seizure, and the other one patient exhibited impaired intelligence. Statistical analysis suggested that the patients without a special disease history (trauma, febrile seizure, or encephalitis) tended to have a more favorable seizure outcome.

CONCLUSIONS

Surgical interventions can achieve good therapeutic effect on chronic medically intractable MTLE, and patients without a special disease history may have more favorable outcomes after the surgery. SAH via the superior temporal sulcus approach can be a better surgical option for intractable MTLE.

The long-term outcomes of epilepsy surgery

Objective

Despite modern anti-epileptic drug treatment, approximately 30% of epilepsies remain medically refractory and for these patients, epilepsy surgery may be a treatment option. There have been numerous studies demonstrating good outcome of epilepsy surgery in the short to median term however, there are a limited number of studies looking at the long-term outcomes. The aim of this study was to ascertain the long-term outcome of resective epilepsy surgery in a large neurosurgery hospital in the U.K.

Methods

This a retrospective analysis of prospectively collected data. We used the 2001 International League Against Epilepsy (ILAE) classification system to classify seizure freedom and Kaplan-Meier survival analysis to estimate the probability of seizure freedom.

Results

We included 284 patients who underwent epilepsy surgery (178 anterior temporal lobe resections, 37 selective amygdalohippocampectomies, 33 temporal lesionectomies, 36 extratemporal lesionectomies), and had a prospective median follow-up of 5 years (range 1–27). Kaplan-Meier estimates showed that 47% (95% CI 40–58) remained seizure free (apart from simple partial seizures) at 5 years and 38% (95% CI 31–45) at 10 years after surgery. 74% (95% CI 69–80) had a greater than 50% seizure reduction at 5 years and 70% (95% CI 64–77) at 10 years. Patients who had an amygdalohippocampectomy were more likely to have seizure recurrence than patients who had an anterior temporal lobe resection (p = 0.006) and temporal lesionectomy (p = 0.029). There was no significant difference between extra temporal and temporal lesionectomies. Hippocampal sclerosis was associated with a good outcome but declined in relative frequency over the years.

Conclusion

The vast majority of patients who were not seizure free experienced at least a substantial and long-lasting reduction in seizure frequency. A positive long-term outcome after epilepsy surgery is possible for many patients and especially those with hippocampal sclerosis or those who had anterior temporal lobe resections.

Curative and palliative MRI-guided laser ablation for drug-resistant epilepsy

Epilepsy is a common neurological disorder occurring in 3% of the US adult population. It is characterised by seizures resulting from aberrant hypersynchronous neural activity. Approximately one-third of newly diagnosed epilepsy cases fail to become seizure-free in response to antiseizure drugs. Optimal seizure control, in cases of drug-resistant epilepsy, often requires neurosurgical intervention targeting seizure foci, such as the temporal lobe. Advances in minimally invasive ablative surgical approaches have led to the development of MRI-guided laser interstitial thermal therapy (LITT). For refractory epilepsy, this surgical intervention offers many advantages over traditional approaches, including real-time lesion monitoring, reduced morbidity, and in some reports increased preservation of cognitive and language processes. We review the use of LITT for epileptic indications in the context of its application as a curative (seizure freedom) or palliative (seizure reduction) measure for both lesional and non-lesional forms of epilepsy. Furthermore, we address the use of LITT for a variety of extratemporal lobe epilepsies. Finally, we describe clinical outcomes, limitations and future applications of LITT for epilepsy.

A classification system for verifying the long-term efficacy of resective surgery for drug-resistant seizures

OBJECTIVE

To verify the long-term efficacy of resective surgery, we created a classification system in which strictly defined patterns of postoperative seizure emergence are incorporated as basic components and the seizure states throughout the entire follow-up period are assessed comprehensively.

METHODS

In our system, Class I has three subclasses (A-C); subclasses A and B are identical to Engel I-A and I-B, respectively. Subclass C comprises patients whose disabling seizures remit within the first 2 years postoperatively. Patients in Class II have only 1-3 days with disabling seizures throughout follow-up after the first 2 years. Patients in Class III have a maximum of 3 seizure days annually, and those in Class IV have ≥4 seizure days annually after the first 2 years. Classes II-IV each have 2 subclasses (A and B): subclass A, late recurrence (i.e., the first seizure occurs after 2 years postoperatively); and subclass B, early recurrence (i.e., first seizure within 2 years). In 646 patients who underwent resective surgery (temporal lobe resection, 74.6%) and were followed for at least 8 years (mean, 14.6 years), we analyzed three patterns of postoperative seizures: early remission, late recurrence, and occasional seizures. In addition, we investigated the differences between the long-term seizure outcomes of the cohort as determined according to our system and the Engel scale.

RESULTS

Overall, 52.9% of the cohort experienced at least one disabling seizure postoperatively throughout the follow-up period; in 1/3 of these patients, the first seizure occurred after 2 years. In 73.8% of the 80 patients who manifested the running-down phenomenon, seizure remission occurred within the first 2 years. In addition, 36.7% of the 283 patients who had disabling seizures after 2 years experienced only 1-3 seizure days. Engel Class I-C included about 30% of the patients who had ≥4 seizure days after 2 years. The long-term seizure outcomes, determined according to our system, were: Class I, 56.2% (C, 9.1%) of the overall cohort; Class II, 16.1% (A, 11.0%); and Class III/IV, 27.7% (A, 6.6%).

CONCLUSION

Our system clarifies the actual effect of resective surgery more precisely than the Engel scale and thus may be useful for comparing outcomes between different surgical procedures or for identifying potential risk factors predicting unfavorable outcome.

Brain expression of inflammatory mediators in Mesial Temporal Lobe Epilepsy patients

Neuroinflammation may be central in epileptogenesis. In this study we analysed inflammatory reaction markers in brain tissue of Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis (MTLE-HS) patients. TLR4, IL-1β and IL-10 gene expression as well as the presence of activated HLA-DR+ microglia was evaluated in 23 patients and 10 cadaveric controls. Inflammation characterized by the presence of HLA-DR⁺ microglia and TLR4, IL-1β overexpression was evident in hippocampus and anterior temporal cortex of MTLE-HS patients. Anti-inflammatory IL-10 was also overexpressed in MTLE-HS patients. Our results show that hippocampal neuroinflammation extends beyond lesional limits, as far as the anterior temporal cortex.

Factors affecting seizure outcome after epilepsy surgery: an observational series

IMPORTANCE

Surgical treatment can bring seizure remission in people with focal epilepsy but requires careful selection of candidates.

OBJECTIVES

To determine which preoperative factors are associated with postoperative seizure outcome.

DESIGN

We audited seizure outcome of 693 adults who had resective epilepsy surgery between 1990 and 2010 and used survival analysis to detect preoperatively identifiable risk factors of poor seizure outcome.

RESULTS

Seven factors were significantly associated with increased probability of recurrence of seizures with impaired awareness postsurgery: MRI findings (eg, HR adjusted for other variables in the model 2.5; 95% CI 1.6 to 3.8 for normal MRI compared with hippocampal sclerosis), a history of secondarily generalised convulsive seizures (2.3; 95% CI 1.7 to 3.0 for these seizures in the previous year vs never), psychiatric history (1.3; 95% CI 1.1 to 1.7), learning disability (1.8; 95% CI 1.2 to 2.6) and extratemporal (vs temporal) surgery (1.4; 95% CI 1.02, 2.04). People with an older onset of epilepsy had a higher probability of seizure recurrence (1.01; 95% CI 1.00, 1.02) as did those who had used more antiepileptic drugs (1.05; 95% CI 1.01 to 1.09). Combinations of variables associated with seizure recurrence gave overall low probabilities of 5-year seizure freedom (eg, a normal MRI and convulsive seizures in the previous year has a probability of seizure freedom at 5 years of approximately 0.19).

CONCLUSIONS AND RELEVANCE

Readily identified clinical features and investigations are associated with reduced probability of good outcome and need consideration when planning presurgical evaluation.

Mesial temporal lobe epilepsy: long-term seizure outcome of patients primarily treated with transsylvian selective amygdalohippocampectomy

OBJECTIVE The aim of this study was to present long-term seizure outcome data in a consecutive series of patients with refractory mesial temporal lobe epilepsy primarily treated with transsylvian selective amygdalohippocampectomy (SAHE). METHODS The authors retrospectively analyzed prospectively collected data for all patients who had undergone resective surgery for medically refractory epilepsy at their institution between July 1994 and December 2014. Seizure outcome was assessed according to the International League Against Epilepsy (ILAE) and the Engel classifications. RESULTS The authors performed an SAHE in 158 patients (78 males, 80 females; 73 right side, 85 left side) with a mean age of 37.1 ± 10.0 years at surgery. Four patients lost to follow-up and 1 patient who committed suicide were excluded from analysis. The mean follow-up period was 9.7 years. At the last available follow-up (or before reoperation), 68 patients (44.4%) had achieved an outcome classified as ILAE Class 1a, 46 patients (30.1%) Class 1, 6 patients (3.9%) Class 2, 16 patients (10.4%) Class 3, 15 patients (9.8%) Class 4, and 2 patients (1.3%) Class 5. These outcomes correspond to Engel Class I in 78.4% of the patients, Engel Class II in 10.5%, Engel Class III in 8.5%, and Engel Class IV in 2.0%. Eleven patients underwent a second surgery (anterior temporal lobectomy) after a mean of 4.4 years from the SAHE (left side in 6 patients, right side in 5). Eight (72.7%) of these 11 patients achieved seizure freedom. The overall ILEA seizure outcome since (re)operation after a mean follow-up of 10.0 years was Class 1a in 72 patients (47.0%), Class 1 in 50 patients (32.6%), Class 2 in 7 patients (4.6%), Class 3 in 15 patients (9.8%), Class 4 in 8 patients (5.2%), and Class 5 in 1 patient (0.6%). These outcomes correspond to an Engel Class I outcome in 84.3% of the patients. CONCLUSIONS A satisfactory long-term seizure outcome following transsylvian SAHE was demonstrated in a selected group of patients with refractory temporal lobe epilepsy.

Dysplastic Cerebellar Epilepsy: Complete Seizure Control Following Resection of a Ganglioglioma

Subcortical epilepsy has been a controversial issue, partially settled by evidence showing seizure generation in hypothalamic hamartomas and also by reports of seizures caused by cerebellar lesions. We report 4-year-old girl with right hemifacial seizures and autonomic phenomena, in whom MRI showed an irregular mass in the right cerebellar peduncle. Despite several unremarkable video-EEG recordings, seizure origin in the lesion was hypothesized. Complete resection was feasible, histopathology showed a ganglioglioma, and she has been seizure free for 3 years. A fine line separates these developmental tumors from focal cortical dysplasia, and the homogeneous presentation of this entity led us to propose the terminology dysplastic cerebellar epilepsy.

Preoperative automated fibre quantification predicts postoperative seizure outcome in temporal lobe epilepsy

Approximately one in every two patients with pharmacoresistant temporal lobe epilepsy will not be rendered completely seizure-free after temporal lobe surgery. The reasons for this are unknown and are likely to be multifactorial. Quantitative volumetric magnetic resonance imaging techniques have provided limited insight into the causes of persistent postoperative seizures in patients with temporal lobe epilepsy. The relationship between postoperative outcome and preoperative pathology of white matter tracts, which constitute crucial components of epileptogenic networks, is unknown. We investigated regional tissue characteristics of preoperative temporal lobe white matter tracts known to be important in the generation and propagation of temporal lobe seizures in temporal lobe epilepsy, using diffusion tensor imaging and automated fibre quantification. We studied 43 patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis and 44 healthy controls. Patients underwent preoperative imaging, amygdalohippocampectomy and postoperative assessment using the International League Against Epilepsy seizure outcome scale. From preoperative imaging, the fimbria-fornix, parahippocampal white matter bundle and uncinate fasciculus were reconstructed, and scalar diffusion metrics were calculated along the length of each tract. Altogether, 51.2% of patients were rendered completely seizure-free and 48.8% continued to experience postoperative seizure symptoms. Relative to controls, both patient groups exhibited strong and significant diffusion abnormalities along the length of the uncinate bilaterally, the ipsilateral parahippocampal white matter bundle, and the ipsilateral fimbria-fornix in regions located within the medial temporal lobe. However, only patients with persistent postoperative seizures showed evidence of significant pathology of tract sections located in the ipsilateral dorsal fornix and in the contralateral parahippocampal white matter bundle. Using receiver operating characteristic curves, diffusion characteristics of these regions could classify individual patients according to outcome with 84% sensitivity and 89% specificity. Pathological changes in the dorsal fornix were beyond the margins of resection, and contralateral parahippocampal changes may suggest a bitemporal disorder in some patients. Furthermore, diffusion characteristics of the ipsilateral uncinate could classify patients from controls with a sensitivity of 98%; importantly, by co-registering the preoperative fibre maps to postoperative surgical lacuna maps, we observed that the extent of uncinate resection was significantly greater in patients who were rendered seizure-free, suggesting that a smaller resection of the uncinate may represent insufficient disconnection of an anterior temporal epileptogenic network. These results may have the potential to be developed into imaging prognostic markers of postoperative outcome and provide new insights for why some patients with temporal lobe epilepsy continue to experience postoperative seizures.

Cost-Utility of Video-Electroencephalography Monitoring Followed by Surgery in Adults with Drug-Resistant Focal Epilepsy in Thailand

OBJECTIVES

This study assessed whether video-electroencephalography (VEEG) monitoring followed by surgery was cost-effective in adult patients with drug-resistant focal epilepsy under Thai health care context, as compared with continued medical treatment without VEEG.

METHODS

The total cost (in Thai Baht, THB) and effectiveness (in quality-adjusted life years, QALYs) were estimated over a lifetime horizon, using a decision tree and a Markov model. Data on short-term surgical outcomes, direct health care costs, and utilities were collected from Thai patients in a specialized hospital. Long-term outcomes and relative effectiveness of the surgery over medical treatment were derived, using systematic reviews of published literature.

RESULTS

Seizure-free rates at years 1 and 2 after surgery were 79.4% and 77.8%, respectively. Costs of VEEG and surgery plus 1-year follow-up care were 216,782 THB, of which the VEEG and other necessary investigations were the main cost drivers (42.8%). On the basis of societal perspective, the total cost over a 40-year horizon accrued to 1,168,679 THB for the VEEG option, 64,939 THB higher than that for no VEEG. The VEEG option contributed to an additional 1.50 QALYs over no VEEG, resulting in an incremental cost-effectiveness ratio of 43,251 THB (USD 1236) per 1 QALY gained. Changes in key parameters had a minimal impact on the incremental cost-effectiveness ratio. Accounting for uncertainty, there was an 84% probability that the VEEG option was cost-effective on the basis of Thailand's cost-effective threshold of 160,000 THB/QALY.

CONCLUSIONS

For patients with drug-resistant epilepsy, VEEG monitoring followed by epilepsy surgery was cost-effective in Thailand. Therefore it should be recommended for health insurance coverage.

Combined 18F-FDG-PET and diffusion tensor imaging in mesial temporal lobe epilepsy with hippocampal sclerosis

Objectives

Several studies using ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET) or diffusion tensor imaging (DTI) have found both temporal and extratemporal abnormalities in patients with mesial temporal lobe epilepsy with ipsilateral hippocampal sclerosis (MTLE-HS), but data are lacking about the findings of both techniques in the same patients. We aimed to determine whether the extent of ¹⁸F-FDG-PET hypometabolism is related to DTI abnormalities.

Methods

Twenty-one patients with MTLE-HS underwent comprehensive preoperative evaluation; 18 (86%) of these underwent epilepsy surgery. We analyzed and compared the pattern of white matter (WM) alterations on DTI and cortical hypometabolism on ¹⁸F-FDG-PET.

Results

We found widespread temporal and extratemporal ¹⁸F-FDG-PET and DTI abnormalities. Patterns of WM abnormalities and cortical glucose hypometabolism involved similar brain regions, being more extensive in the left than the right MTLE-HS. We classified patients into three groups according to temporal ¹⁸F-FDG-PET patterns: hypometabolism restricted to the anterior third (n = 7), hypometabolism extending to the middle third (n = 7), and hypometabolism extending to the posterior third (n = 7). Patients with anterior temporal hypometabolism showed DTI abnormalities in anterior association and commissural tracts while patients with posterior hypometabolism showed WM alterations in anterior and posterior tracts.

Conclusions

Patients with MTLE-HS have widespread metabolic and microstructural abnormalities that involve similar regions. The distribution patterns of these gray and white matter abnormalities differ between patients with left or right MTLE, but also with the extent of the ¹⁸F-FDG-PET hypometabolism along the epileptogenic temporal lobe. These findings suggest a variable network involvement among patients with MTLE-HS.

•

There are widespread metabolic and microstructural abnormalities in MTLE-HS.

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Diffusion tensor imaging alterations differ with pattern of temporal hypometabolism.

•

This study suggests a variable network involvement among patients with MTLE-HS.

•

(MTLE-HS: mesial temporal lobe epilepsy with ipsilateral hippocampal sclerosis)

Long-term outcome and neuroradiologic changes after multiple hippocampal transection combined with multiple subpial transection or lesionectomy for temporal lobe epilepsy

OBJECTIVE

Multiple hippocampal transection (MHT) is a surgical procedure developed to avoid postoperative memory decline. Its efficacy has been documented in only a few small series with relatively short observation periods. We prospectively evaluated the long-term seizure and cognitive outcomes of MHT combined with multiple subpial transection or lesionectomy (MHT + MST/L). Moreover, we quantitatively evaluated the structural and metabolic neuroradiologic changes after the procedure to elucidate the anatomofunctional correlates of memory preservation.

METHODS

Twenty-four patients underwent MHT + MST/L for treatment of drug-resistant mesial temporal lobe epilepsy (mTLE) and were followed for more than 5 years. Indications for the procedure were the following: (1) verbally dominant-sided surgery in patients with a radiologically normal hippocampus or normal/near normal memory, and (2) surgery for patients with concomitant epileptic activity on the contralateral side, that is, when the surgery was considered a high risk for severe postoperative memory decline. Seizure outcome was evaluated using Engel's classification 1, 2, and 3 years after surgery, and at the last visit (LV). Three subgroups were evaluated as well: magnetic resonance imaging (MRI) negative (MN), hippocampal sclerosis (HS), and normal hippocampus with extrahippocampal lesion (NHEL). The long-term cognitive outcome was followed through to LV in patients who underwent verbally dominant-sided surgery. Hippocampal volume (HV), diffusion tensor parameters (DTP), and glucose utilization (GU) were determined from MRI and fluorodeoxyglucose-positron emission tomography (FDG-PET) studies performed before and >6 months after surgery.

RESULTS

Whereas the rate of Engel class I as a whole was 71% at 1 year and 67% at LV, the rates in the MN, HS, and NHEL groups were 60%, 67%, and 100% at 1 year, respectively, and 70%, 56%, and 80% at LV, respectively. Memory indices after verbally dominant-sided surgery transiently declined at 1 month but recovered to and remained at the preoperative level through LV. The HV, DTP of the fornix, and GU of the temporal lobe on the treated side showed pathologic changes even when the transiently declined memory indices had recovered to the preoperative level.

SIGNIFICANCE

The long-term outcome for complex partial seizures after MHT + MST/L was comparable to that seen after anterior temporal lobectomy. The long-term cognitive outcome was favorable, even for patients with a high risk of severe postoperative memory decline. MHT + MST/L may be a treatment option for mTLE in which resective surgery carries a risk of postoperative memory decline, particularly in patients without MRI lesion. A discrepancy between the preserved memory and the pathologic neuroradiologic changes indicates the necessity for further studies including functional MRI.