Tumor-related epilepsy and epilepsy surgery

Clinical Characteristics of BRAF V600E Gene Mutation in Patients of Epilepsy-Associated Brain Tumor: a Meta-analysis

Epilepsy-associated brain tumors (EATs) are usually slow-growing, with seizures as the primary and most dominant symptom. BRAF (v-raf murine sarcoma viral oncogene homolog B1) gene mutations have been found in several subsets of EATs; the V600E mutation is currently believed to contribute to the intrinsic epileptogenicity and tumor growth. However, the relationship between BRAF V600E gene mutation and clinical characteristics in EAT patients is not clear. In this study, we aimed to systematically review the frequency of BRAF V600E gene mutation, as well as the relationship between BRAF V600E gene mutation and clinical characteristics, which may help with the diagnosis and treatment of EATs. Cochrane Library, PubMed, Embase, CNKI, WanFang Data, CQVIP, and SinoMed databases were searched up to October 2020 to identify peer-reviewed human studies on assessing the relationship between BRAF V600E gene mutations and clinical characteristics in EATs. The following data were calculated: the frequency of BRAF V600E mutation and clinical feature comparison between BRAF V600E mutations and wild type in EATs, such as gender, age of seizure onset, duration of epilepsy, location of tumors, and Engel outcome. A total of 12 articles were included in the analysis. Five hundred and nine patients with epilepsy-associated brain tumors were screened for the BRAF V600E gene mutation. Among them, 193 patients had the BRAF V600E mutation (34.06%, 95% CI = 0.25 to 0.43). The subgroup analyses of BRAF V600E mutation showed positive frequency of 44.76% (95% CI = 0.36 to 0.54) in ganglioglioma, 24.75% (95% CI = 0.14 to 0.37) in gysembryoplastic neuroepithelial tumor, 2.15% (95% CI = 0 to 0.19) in angiocentric glioma, and 50.16% (95% CI = 0.33 to 0.68) in pleomorphic xanthoastrocytoma. Compared with the overall frequency, the BRAF V600E positive frequency in ganglioglioma was significantly higher (P = 0.0283). We also found that BRAF V600E gene mutation was significantly associated with age at seizure onset (MD = -2.37; 95% CI = -4.33 to -0.41; P = 0.02). There was no statistical difference between BRAF V600E mutations and wild type in gender, duration of epilepsy, tumor site, and Engel outcome comparison. In conclusion, our updated and comprehensive meta-analysis based on a large number of clinical data demonstrated that BRAF V600E mutation is a specific biomarker and could be a pharmacological target for ganglioglioma patients and an exclusion diagnostic criterion for angiocentric glioma. This meta-analysis suggested the critical role of BRAF V600E mutation in the occurrence and development of EATs. Our findings help to elucidate the progression mechanisms in EATs and develop future therapeutic strategies for EATs.

Seizure burden pre- and postresection of low-grade gliomas as a predictor of tumor progression in low-grade gliomas

Background

Low-grade gliomas (LGGs) are slow-growing, infiltrative tumors frequently associated with seizures. Predicting which patients will develop early tumor recurrence based on clinical indicators following initial surgical intervention remains a challenge. Seizure recurrence following surgery may be an early indicator of tumor recurrence, especially in patients presenting with increase in seizure frequency.

Methods

This study analyzed 148 patients meeting inclusion criteria (age >18 years, LGG diagnosis, at least 1 seizure event recorded before and after initial surgical intervention). All patients were treated at the Brain and Spine Center at The University of Texas MD Anderson Cancer Center from January 2000 to March 2013. Seizure frequency in a 6-month period before and after tumor resection was categorized as none, 1, few (2 to 3 seizures) or several (>3 seizures). Immediately postoperative seizures (up to 48 hours from surgery) were not included in the analysis.

Results

A total of 116 (78.4%) patients had seizures at initial presentation and most (95%) were started on antiepileptic drugs (AEDs). We found 2 clinical variables with a significant impact on progression-free survival (PFS): Higher seizure frequency during the 6-month postoperative period and seizure frequency increase between the 6-month pre- and the 6-month postoperative periods were both correlated to higher risk of early tumor recurrence (P = .007 and P = .004, respectively).

Conclusion

Seizure frequency following surgical resection of LGGs and the seizure frequency change between the 6-month preoperative and postoperative periods may serve as clinical predictors of early tumor recurrence in patients with LGGs who are also afflicted by seizures.

Brain tumor related-epilepsy

INTRODUCTION

Gliomas are commonly associated with the development of epilepsy; in some cases the two conditions share common pathogenic mechanisms and may influence each other. Brain tumor related-epilepsy (BTRE) complicates the clinical management of gliomas and can substantially affect daily life.

STATE OF THE ART

The incidence of seizures is high in patients with slow growing tumors located in the frontotemporal regions. However, recent studies suggest that epileptogenesis may be more associated with tumor molecular genetic markers than tumor grade or location. Although the exact mechanism of epileptogenesis in glioma is incompletely understood, glutamate-induced excitotoxicity and disruption of intracellular communication have garnered the most attention.

CLINICAL MANAGEMENT

Management of BTRE requires a multidisciplinary approach involving the use of antiepileptic drugs (AEDs), surgery aided by electrocorticography, and adjuvant chemoradiation.

FUTURE DIRECTIONS

Insight into the mechanisms of glioma growth and epileptogenesis is essential to identify new treatment targets and to develop effective treatment for both conditions. Selecting AEDs tailored to act against known tumor molecular markers involved in the epileptogenesis could enhance treatment value and help inform individualized medicine in BRTE.

FOXO4 expression is associated with the occurrence and outcome of seizures: An RNA-sequencing analysis of low-grade gliomas

PURPOSE

Epileptic seizures account for most of the initial symptoms in patients with low-grade gliomas (LGGs). Nevertheless, the molecular mechanisms of tumor-associated seizures remain unclear. This study investigated the genetic changes associated with the occurrence and outcome of seizures in patients with LGGs.

METHODS

The clinical characteristics and gene profile data of 86 patients with LGGs were collected from the Chinese Glioma Genome Atlas database. Gene expression was analyzed based on whole-genome RNA sequencing. The genes with significantly different expressions between patients with and without seizures were identified. Additionally, the Engel Epilepsy Surgery Outcome Scale was applied to evaluate the seizure outcomes at 6 months after tumor resection.

RESULTS

In patients with LGGs, the expression of Forkhead Box O4 (FOXO4) was significantly different between the seizure and non-seizure groups, and high FOXO4 expression was found to be associated with a low risk of seizure occurrences (p=0.026). This result was validated by using the clinical information and RNA sequence data from The Cancer Genome Atlas database (p=0.005). FOXO4 was additionally identified as a predictor of seizure outcomes in patients with LGGs at 6 months after tumor resection (p=0.018).

CONCLUSIONS

The results of our genomic analysis suggest that low FOXO4 expression is a significant risk factor for epileptic seizures in patients with LGGs and is associated with the seizure outcome. FOXO4 may be a potential therapeutic target for tumor-associated epilepsy.

Epilepsy in patients with primary brain tumors: The impact on mood, cognition, and HRQOL

BACKGROUND

A primary brain tumor (PBT) is often a fatal disease of the nervous system and has a serious impact on health-related quality of life (HRQOL). Presence of epilepsy and adverse reactions from tumor and epilepsy treatments may cause additional decline in HRQOL.

OBJECTIVES

We aimed to study the impact of epileptic seizures on cognition, mood, and HRQOL in patients with brain tumor-related epilepsy.

MATERIALS AND METHOD

Patients were grouped on an ordinal scale according to epilepsy burden from none to severe based on the presence of epileptic seizures and seizure frequency: L1, no epilepsy; L2, with epilepsy, seizure-free in the last 6 months with antiepileptic drugs; and L3, with epilepsy, at least one seizure in the last 6 months with AEDs. Health-related quality of life was measured by Functional Assessment of Cancer Therapy-Brain (FACT-Br) and Quality of Life in Epilepsy-31 (QOLIE-31) tools, cognition by the Montreal Cognitive Assessment (MoCA) tool and Frontal Assessment Battery (FAB), mood by the Hospital Anxiety and Depression Scale (HADS), activities of daily living (ADLs) by the Barthel Index (BI), and performance status by the Karnofsky Performance Status (KPS) scale in patients with primary brain tumors at least one month following neurosurgery with or without radiotherapy and chemotherapy.

RESULTS

Eighty-one patients with a diagnosis of primary brain tumors were recruited. Sixty-eight percent of patients were diagnosed with primary brain tumor-related epilepsy, 50.61% patients had cognitive impairment, 33% had abnormal scores in the anxiety scale, and 34% had abnormal scores in the depression scale. There were no statistically significant differences in these scores among L1, L2, and L3 groups. There were statistically significant differences in duration of disease and KPS and BI scores between L1 and L3 groups. The L3 group has significantly longer duration of disease and scored low in both the BI and KPS scale when compared to the L1 group. All patients with primary brain tumors scored significantly low in FACT-Br 'physical well-being' (PWB) and 'emotional well-being' (EWB) and high in 'social well-being' (SWB) when compared to healthy controls. When scores of each group were individually compared to healthy controls, the L3 group showed the lowest scores in PWB, EWB, and 'functional well-being'. In SWB, L1 and L2 groups showed statistically significantly high scores when compared to normative data. The QOLIE-31 applied to groups with epilepsy showed statistically significantly lower scores in the L3 group when compared to the L2 group in 'cognitive' and 'social functioning' domains. On multivariate analysis, both poor performance status and frequency of seizures were found to be independent risk factors for poor HRQOL when FACT-Br mean scores were compared. Level of seizures was found to be an independent risk factor for poor HRQOL when QOLIE-31 scores were compared between L2 and L3 groups.

DISCUSSION

Presence of brain tumors could be attributed to cognitive impairment irrespective of the presence of epilepsy in our cohort. High seizure burden is an independent risk factor for poor HRQOL in patients with primary brain tumors. The QOLIE-31 is a more sensitive tool than the FACT-Br because of the presence of a seizure-related questionnaire.

Repeat resective surgery in complex pediatric refractory epilepsy: lessons learned

OBJECT Resection can sometimes offer the best chance of meaningful seizure reduction in children with medically intractable epilepsy. However, when surgery fails to achieve the desired outcome, reoperation may be an option. The authors sought to investigate outcomes following resective reoperation in pediatric patients with refractory epilepsy, excluding tumoral epilepsies. Differences in preoperative workup between surgeries are analyzed to identify factors influencing outcomes and complications in this complex group. METHODS Medical records were reviewed for all pediatric patients undergoing a repeat resective surgery for refractory epilepsy at the authors' institution between 2005 and 2012. Tumor and vascular etiologies were excluded. Preoperative evaluation and outcomes were analyzed for each surgery and compared. RESULTS Ten patients met all inclusion criteria. The median age at seizure onset was 4.5 months. Preoperative MRI revealed no lesion in 30%. Nonspecific gliosis and cortical dysplasia were the most common pathologies. The majority of preoperative workups included MRI, video-electroencephalography (EEG), and SISCOM. Intracranial EEG was performed for 60% for the first presurgical evaluation and 70% for the second evaluation. The goal of surgery was palliative in 4 patients with widespread cortical dysplasia. The final Engel outcome was Class I in 50%. The rate of favorable outcome (Engel Class I-II) was 70%. The complication rate for the initial surgery was 10%. However, the rate increased to 50% with the second surgery, and 3 of these 5 complications were pseudomeningoceles requiring shunt placement (2 of the 3 patients underwent hemispherotomy). CONCLUSIONS Resective reoperation for pediatric refractory epilepsy has a high rate of favorable outcome and should be considered in appropriate candidates, even as a palliative measure. Intracranial EEG monitoring should be considered on initial workup in cases where the results of imaging or EEG studies are ambiguous or conflicting. Epilepsy secondary to cortical dysplasia, especially if the dysplasia is not seen clearly on MRI, can be difficult to cure surgically. Therefore, in these cases, as large a resection as can be safely accomplished should be done, particularly when the goal is palliative. The rate of complications, particularly pseudomeningocele ultimately requiring shunt placement, is much higher following reoperation, and patients should be counseled accordingly.

Animal models of tumour-associated epilepsy

Brain tumours cause a sizeable proportion of epilepsies in adulthood, and actually can be etiologically responsible also for childhood epilepsies. Conversely, seizures are often first clinical signs of a brain tumour. Nevertheless, several issues of brain-tumour associated seizures and epilepsies are far from understood, or clarified regarding clinical consensus. These include both the specific mechanisms of epileptogenesis related to different tumour types, the possible relationship between malignancy and seizure emergence, the interaction between tumour mass and surrounding neuronal networks, and - not least - the best treatment options depending on different tumour types. To investigate these issues, experimental models of tumour-induced epilepsies are necessary. This review concentrates on the description of currently used models, focusing on methodological aspects. It highlights advantages and shortcomings of these models, and identifies future experimental challenges.

Deficiency of very large G-protein-coupled receptor-1 is a risk factor of tumor-related epilepsy: a whole transcriptome sequencing analysis

The majority of patients with low-grade glioma (LGG) experience epileptic seizures as their initial symptom, while the underlying mechanisms of tumor-related seizures are still far from being fully understood. In addition to tumor type and location, genetic changes of LGGs are considered to be influential factors in causing epileptic seizures. Nevertheless, the molecular biomarkers associated with tumor-related epilepsy have rarely been identified. RNA sequence data from 80 patients with histologically confirmed LGG were collected from the Chinese glioma genome atlas database and significant differences in expression levels of 33 genes were found. One of the genes, Very large G-protein-coupled receptor-1 (VLGR1), had been previously associated with seizures. Therefore, we investigated the association between LGG-related epilepsy and VLGR1, which played a role in idiopathic epilepsy. The level of VLGR1 expression was compared between patients with epileptic seizures and those without using the reads per kilobase transcriptome per million method. To evaluate the prognostic role of VLGR1 gene expression, the progression-free survival was determined by the Kaplan-Meier method and a multivariate Cox model. We demonstrated that VLGR1 had a significantly lower expression level in patients with epileptic seizures compared to seizure-free patients (p = 0.003). Furthermore, VLGR1 was highly associated with the presence of seizures in a multivariate statistical model. However, VLGR1 could not serve as an independent prognostic factor to determine progression-free survival of LGG patients. Based on RNA sequence data analysis, our results suggest that low expression of VLGR1 is a significant risk factor of epileptic seizures in patients with LGG.

A neuropathology-based approach to epilepsy surgery in brain tumors and proposal for a new terminology use for long-term epilepsy-associated brain tumors

Every fourth patient submitted to epilepsy surgery suffers from a brain tumor. Microscopically, these neoplasms present with a wide-ranging spectrum of glial or glio-neuronal tumor subtypes. Gangliogliomas (GG) and dysembryoplastic neuroepithelial tumors (DNTs) are the most frequently recognized entities accounting for 65 % of 1,551 tumors collected at the European Epilepsy Brain Bank (n = 5,842 epilepsy surgery samples). These tumors often present with early seizure onset at a mean age of 16.5 years, with 77 % of neoplasms affecting the temporal lobe. Relapse and malignant progression are rare events in this particular group of brain tumors. Surgical resection should be regarded, therefore, also as important treatment strategy to prevent epilepsy progression as well as seizure- and medication-related comorbidities. The characteristic clinical presentation and broad histopathological spectrum of these highly epileptogenic brain tumors will herein be classified as “long-term epilepsy associated tumors—LEATs”. LEATs differ from most other brain tumors by early onset of spontaneous seizures, and conceptually are regarded as developmental tumors to explain their pleomorphic microscopic appearance and frequent association with Focal Cortical Dysplasia Type IIIb. However, the broad neuropathologic spectrum and lack of reliable histopathological signatures make these tumors difficult to classify using the WHO system of brain tumors. As another consequence from poor agreement in published LEAT series, molecular diagnostic data remain ambiguous. Availability of surgical tissue specimens from patients which have been well characterized during their presurgical evaluation should open the possibility to systematically address the origin and epileptogenicity of LEATs, and will be further discussed herein. As a conclusion, the authors propose a novel A–B–C terminology of epileptogenic brain tumors (“epileptomas”) which hopefully promote the discussion between neuropathologists, neurooncologists and epileptologists. It must be our future mission to achieve international consensus for the clinico-pathological classification of LEATs that would also involve World Health Organization (WHO) and the International League against Epilepsy (ILAE).