Prognostic value of histopathologic pattern for long-term surgical outcomes of 198 patients with confirmed mesial temporal lobe epilepsy

The Effect of Stereoelectroencephalography on the Long-Term Outcomes of Different Side Anterior Temporal Lobectomy: A Single-Center Retrospective Study

PURPOSE

Anterior temporal lobectomy (ATL) is the most common surgical treatment for temporal lobe epilepsy (TLE), and Stereoelectroencephalography (SEEG) plays a critical role in precisely localizing the epileptogenic zone (EZ). This study aimed to explore the effect of SEEG on the long-term outcomes of different side ATL.

METHODS

From March 2012 to February 2020, a retrospective analysis was conducted on 231 TLE patients who underwent standard ATL surgery. According to the surgical sides and the utilization of SEEG during preoperative evaluation, the patients were categorized into 4 groups, with a follow-up period exceeding 2 years.

RESULTS

Among the 231 TLE patients, the probability of being seizure-free 2 years after the surgery was 80.52%, which decreased to 65.65% after 5 years. There was no significant difference in outcomes between SEEG and non-SEEG patients. For overall and non-SEEG patients, there was no significant difference in short-term outcomes between different surgical sides. However, the long-term outcomes of right ATL patients were significantly better than left. Interestingly, for patients who underwent SEEG, there was no significant difference in both short-term and long-term outcomes between different surgical sides.

CONCLUSIONS

Some TLE patients encounter challenges in localizing the EZ through noninvasive evaluation, necessitating the use of SEEG for precise localization. Furthermore, their seizure outcomes after surgery can be the same with the patients who have a clear EZ in noninvasive evaluation. And SEEG patients can achieve a more stable long-term prognosis than non-SEEG patients.

Postoperative seizure and memory outcome of temporal lobe epilepsy with hippocampal sclerosis: A systematic review

We conducted a systematic review and meta-analysis to evaluate postoperative seizure and memory outcomes of temporal lobe epilepsy with different hippocampal sclerosis (HS) subtypes classified by International League Against Epilepsy (ILAE) Consensus Guidelines in 2013. Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and MOOSE (Meta-Analysis of Observational Studies in Epidemiology) guidelines, we searched PubMed, Embase, Web of Science, and Cochrane Library from January 1, 2013 to August 6, 2023. Observational studies reporting seizure and memory outcomes among different HS subtypes were included. We used the Newcastle-Ottawa scale to assess the risk of bias and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach to grade the quality of evidence. Seizure freedom and improved outcome (Engel 1 or ILAE class 1-2) ≥1 year after surgery were defined as the primary and secondary seizure outcome. A random-effects meta-analysis by DerSimonian and Laird method was performed to obtain pooled risk ratio (RRs) with 95% confidence interval (CIs). The memory impairment was narratively reviewed because of various evaluation tools. Fifteen cohort studies with 2485 patients were eligible for the meta-analysis of seizure outcome. Six cohorts with detailed information on postoperative memory outcome were included. The pooled RRs of seizure freedom, with moderate to substantial heterogeneity, were .98 (95% CI = .84-1.15) between HS type 2 and type 1, 1.11 (95% CI = .82-1.52) between type 3 and type 1, and .80 (95% CI = .62-1.03) between the no-HS and HS groups. No significant difference of improved outcome was found between different subtypes (p > .05). The quality of evidence was deemed to be low to very low according to GRADE. The long-term seizure outcome (≥5 years after surgery) and memory impairment remained controversial.

Ectopic expression of neuronal adenosine kinase, a biomarker in mesial temporal lobe epilepsy without hippocampal sclerosis

AIMS

Mesial temporal lobe epilepsy without hippocampal sclerosis (no-HS MTLE) refers to those MTLE patients who have neither magnetic resonance imaging (MRI) lesions nor definite pathological evidence of hippocampal sclerosis. They usually have resistance to antiepileptic drugs, difficulties in precise seizure location and poor surgical outcomes. Adenosine is a neuroprotective neuromodulator that acts as a seizure terminator in the brain. The role of adenosine in no-HS MTLE is still unclear. Further research to explore the aetiology and pathogenesis of no-HS MTLE may help to find new therapeutic targets.

METHODS

In surgically resected hippocampal specimens, we examined the maladaptive changes of the adenosine system of patients with no-HS MTLE. In order to better understand the dysregulation of the adenosine pathway in no-HS MTLE, we developed a rat model based on the induction of focal cortical lesions through a prenatal freeze injury.

RESULTS

We first examined the adenosine system in no-HS MTLE patients who lack hippocampal neuronal loss and found ectopic expression of the astrocytic adenosine metabolising enzyme adenosine kinase (ADK) in hippocampal pyramidal neurons, as well as downregulation of neuronal A1 receptors (A1 Rs) in the hippocampus. In the no-HS MTLE model rats, the transition of ADK from neuronal expression to an adult pattern of glial expression in the hippocampus was significantly delayed.

CONCLUSIONS

Ectopic expression of neuronal ADK might be a pathological hallmark of no-HS MTLE. Maladaptive changes in adenosine metabolism might be a novel target for therapeutic intervention in no-HS MTLE.

Neuropathology and epilepsy surgery

PURPOSE OF REVIEW

Neurosurgical treatment of patients suffering from drug-resistant focal epilepsy is recognized as a successful, yet underutilized medical treatment option. By searching PubMed for articles published between January 2020 and September 2021 with the broad search terms 'neuropathology' AND 'epilepsy surgery', this review highlights the active field of etiology-based epilepsy research in human tissue.

RECENT FINDINGS

All papers addressing the most common epileptogenic human brain disease entities, i.e. focal cortical dysplasia (FCD), brain tumors or hippocampal sclerosis, and written in English language were eligible for our review. We can conclude from this review that etiology-based studies are of foremost interest for (1) the development of prediction models for postsurgical seizure outcome; (2) decipher genetic and molecular alterations to better define disease entities and underlying molecular pathomechanisms, and (3) the translation of human tissue-derived biomarker into clinically useful diagnostics or novel therapeutic targets in the near future.

SUMMARY

Highlighting FCD brain somatic gain-of-function variants in mammalian target of Rapamycin are a leading pathway to better classify FCD. An integrated genotype-phenotype analysis enables to classify the broad spectrum of low-grade and epilepsy-associated brain tumors. Further DNA-methylation-based disease classification will increase the mechanistic understanding and diagnostic precision of difficult to classify pathologies in the future.

Expression Profile of miRs in Mesial Temporal Lobe Epilepsy: Systematic Review

Temporal lobe epilepsy (TLE) is one of the most common forms of focal epilepsy in children and adults. TLE is characterized by variable onset and seizures. Moreover, this form of epilepsy is often resistant to pharmacotherapy. The search for new mechanisms for the development of TLE may provide us with a key to the development of new diagnostic methods and a personalized approach to the treatment. In recent years, the role of non-coding ribonucleic acids (RNA) has been actively studied, among which microRNA (miR) is of the greatest interest. (1) Background: The purpose of the systematic review is to analyze the studies carried out on the role of miRs in the development of mesial TLE (mTLE) and update the existing knowledge about the biomarkers of this disease. (2) Methods: The search for publications was carried out in the databases PubMed, Springer, Web of Science, Clinicalkeys, Scopus, OxfordPress, Cochrane. The search was carried out using keywords and combinations. We analyzed publications for 2016–2021, including original studies in an animal model of TLE and with the participation of patients with TLE, thematic and systemic reviews, and Cochrane reviews. (3) Results: this thematic review showed that miR‒155, miR‒153, miR‒361‒5p, miR‒4668‒5p, miR‒8071, miR‒197‒5p, miR‒145, miR‒181, miR‒199a, miR‒1183, miR‒129‒2‒3p, miR‒143‒3p (upregulation), miR–134, miR‒0067835, and miR‒153 (downregulation) can be considered as biomarkers of mTLE. However, the roles of miR‒146a, miR‒142, miR‒106b, and miR‒223 are questionable and need further study. (4) Conclusion: In the future, it will be possible to consider previously studied miRs, which have high specificity and sensitivity in mTLE, as prognostic biomarkers (predictors) of the risk of developing this disease in patients with potentially epileptogenic structural damage to the mesial regions of the temporal lobe of the brain (congenital disorders of the neuronal migration and neurogenesis, brain injury, neuro-inflammation, tumor, impaired blood supply, neurodegeneration, etc.).

Uses and abuses of the neuropsychological assessment in the presurgical evaluation of epilepsy surgery candidates

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Results from the neuropsychological assessment must be integrated into the wider clinical picture for all epilepsy surgery candidates.

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Motivation for surgery must be fully explored to ensure informed consent, even in ‘ideal’ surgical candidates.

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Inappropriate weight should not be given to standalone neuropsychological scores in the surgical decision making process.

Recent guidelines from the International League Against Epilepsy (ILAE) delineating the role of the neuropsychologist in the assessment of epilepsy surgery patients stress the collaborative contribution neuropsychologists should make to seizure characterization, lateralization and localization in the pre-surgical setting. The role they should play in the comprehensive counselling of surgical candidates, including exploration of the patient’s expectations of surgical treatment is also mandated. In this paper we present two contrasting case studies which illustrate the importance of these roles and the impact they can have on patient outcomes. In Case A we describe the patient journey of a 69-year-old women with left hippocampal sclerosis and concordant neurophysiology and seizure semiology. We present the series of discussions and decisions which led her to reject the surgical option following a detailed exploration of her motivations for surgery and the likely cognitive consequences of the procedure. In Case B we describe the series of errors and omissions which led to the failure of a clinical team to correctly interpret and integrate neuropsychological findings into the larger clinical picture of a 19-year-old woman with a seven year history of seizures. These errors ultimately culminated in the patient undergoing a right temporal lobe resection to treat psychogenic nonepileptic seizures (PNES).

The extent of integration of the data from the clinical neuropsychological assessment in the full presurgical evaluation was critical in determining the outcomes in both of these cases. Surgery did not solve Case B’s problems and left her with the lifelong cognitive vulnerabilities that are associated with unilateral temporal lobe resection. In contrast, Case A was a good surgical candidate, but comprehensive integration of the neuropsychological findings into the larger clinical picture established that surgery was not the best solution to the problem she wished to solve.