Seizure disorders in patients with brain tumors

Establishment of a Prediction Model Based on Preoperative MRI Radiomics for Diffuse Astrocytic Glioma, IDH-Wildtype, with Molecular Features of Glioblastoma

PURPOSE

In 2021, the WHO central nervous system (CNS) tumor classification criteria added the diagnosis of diffuse astrocytic glioma, IDH wild-type, with molecular features of glioblastoma, WHO grade 4 (DAG-G). DAG-G may exhibit the aggressiveness and malignancy of glioblastoma (GBM) despite the lower histological grade, and thus a precise preoperative diagnosis can help neurosurgeons develop more refined individualized treatment plans. This study aimed to establish a predictive model for the non-invasive identification of DAG-G based on preoperative MRI radiomics.

PATIENTS AND METHODS

Patients with pathologically confirmed glioma in Huashan Hospital, Fudan University, between September 2019 and July 2021 were retrospectively analyzed. Furthermore, two external validation datasets from Wuhan Union Hospital and Xuzhou Cancer Hospital were also utilized to verify the reliability and accuracy of the prediction model. Two regions of interest (ROI) were delineated on the preoperative MRI images of the patients using the semi-automatic tool ITK-SNAP (version 4.0.0), which were named the maximum anomaly region (ROI1) and the tumor region (ROI2), and Pyradiomics 3.0 was applied for feature extraction. Feature selection was performed using a least absolute shrinkage and selection operator (LASSO) filter and a Spearman correlation coefficient. Six classifiers, including Gauss naive Bayes (GNB), K-nearest neighbors (KNN), Random forest (RF), Adaptive boosting (AB), and Support vector machine (SVM) with linear kernel and multilayer perceptron (MLP), were used to build the prediction models, and the prediction performance of the six classifiers was evaluated by fivefold cross-validation. Moreover, the performance of prediction models was evaluated using area under the curve (AUC), precision (PRE), and other metrics.

RESULTS

According to the inclusion and exclusion criteria, 172 patients with grade 2-3 astrocytoma were finally included in the study, and a total of 44 patients met the diagnosis of DAG-G. In the prediction task of DAG-G, the average AUC of GNB classifier was 0.74 ± 0.07, that of KNN classifier was 0.89 ± 0.04, that of RF classifier was 0.96 ± 0.03, that of AB classifier was 0.97 ± 0.02, that of SVM classifier was 0.88 ± 0.05, and that of MLP classifier was 0.91 ± 0.03, among which, AB classifier achieved the best prediction performance. In addition, the AB classifier achieved AUCs of 0.91 and 0.89 in two external validation datasets obtained from Wuhan Union Hospital and Xuzhou Cancer Hospital, respectively.

CONCLUSIONS

The prediction model constructed based on preoperative MRI radiomics established in this study can basically realize the prospective, non-invasive, and accurate diagnosis of DAG-G, which is of great significance to help further optimize treatment plans for such patients, including expanding the extent of surgery and actively administering radiotherapy, targeted therapy, or other treatments after surgery, to fundamentally maximize the prognosis of patients.

Clinical and radiographic characteristics of diffuse astrocytic glioma, IDH-wildtype, with molecular features of glioblastoma: a single institution review

PURPOSE

Genetic analyses of gliomas have identified key molecular features that impact treatment paradigms beyond conventional histomorphology. Despite at-times lower grade histopathologic appearances, IDH-wildtype infiltrating gliomas expressing certain molecular markers behave like higher-grade tumors. For IDH-wildtype infiltrating gliomas lacking traditional features of glioblastoma, these markers form the basis for the novel diagnosis of diffuse astrocytic glioma, IDH-wildtype (wt), with molecular features of glioblastoma (GBM), WHO grade-IV (DAG-G). However, given the novelty of this approach to diagnosis, literature detailing the exact clinical, radiographic, and histopathologic findings associated with these tumors remain in development.

METHODS

Data for 25 patients matching the DAG-G diagnosis were obtained from our institution's retrospective database. Information regarding patient demographics, treatment regimens, radiographic imaging, and genetic pathology were analyzed to determine association with clinical outcomes.

RESULTS

The initial radiographic findings, histopathology, and symptomatology of patients with DAG-G were similar to lower-grade astrocytomas (WHO grade 2/3). Overall survival (OS) and progression free survival (PFS) associated with our cohort, however, were similar to that of IDH-wt GBM, indicating a more severe clinical course than expected from other associated features (15.1 and 5.39 months respectively).

CONCLUSION

Despite multiple features similar to lower-grade gliomas, patients with DAG-G experience clinical courses similar to GBM. Such findings reinforce the need for biopsy and subsequent analysis of molecular features associated with any astrocytoma regardless of presenting characteristics.

Efficacy of antiepileptic drugs in glioma patients with epilepsy: a systematic review

Background

Comprehensive data on the efficacy and tolerability of antiepileptic drugs (AED) treatment in glioma patients with epilepsy are currently lacking. In this systematic review, we specifically assessed the efficacy of AEDs in patients with a grade II-IV glioma.

Methods

Electronic databases PubMed/MEDLINE, EMBASE, Web of Science, and Cochrane Library were searched up to June 2020. Three different outcomes for both mono- and polytherapy were extracted from all eligible articles: (i) seizure freedom; (ii) ≥50% reduction in seizure frequency; and (iii) treatment failure. Weighted averages (WA) were calculated for outcomes at 6 and 12 months.

Results

A total of 66 studies were included. Regarding the individual outcomes on the efficacy of monotherapy, the highest seizure freedom rate at 6 months was with phenytoin (WA = 72%) while at 12-month pregabalin (WA = 75%) and levetiracetam (WA = 74%) showed highest efficacy. Concerning ≥50% seizure reduction rates, levetiracetam showed highest efficacy at 6 and 12 months (WAs of 82% and 97%, respectively). However, treatment failure rates at 12 months were highest for phenytoin (WA = 34%) and pregabalin (41%). When comparing the described polytherapy combinations with follow-up of ≥6 months, levetiracetam combined with phenytoin was most effective followed by levetiracetam combined with valproic acid.

Conclusion

Given the heterogeneous patient populations and the low scientific quality across the different studies, seizure rates need to be interpreted with caution. Based on the current limited evidence, with the ranking of AEDs being confined to the AEDs studied, levetiracetam, phenytoin, and pregabalin seem to be most effective as AED monotherapy in glioma patients with epilepsy, with levetiracetam showing the lowest treatment failure rate, compared to the other AEDs studied.

Brain tumor-related epilepsy and risk factors for metastatic brain tumors: analysis of 601 consecutive cases providing real-world data

OBJECTIVE

It is necessary to accurately characterize the epidemiology and trends of brain tumor-related epilepsy (BTE) in patients with metastatic brain tumors. This study aimed to determine the incidence of BTE associated with metastatic brain tumors and retrospectively investigate the risk factors for BTE.

METHODS

This retrospective analysis included 601 of 631 consecutive patients with metastatic brain tumors who received treatment, including surgery, radiotherapy, and/or other treatments. BTE and the clinical course were examined retrospectively. Logistic regression multivariate analyses were performed to identify risk factors for BTE.

RESULTS

BTE was reported in 148 (24.6%) of 601 patients during the entire course. Of these 148 patients, 81 (54.7%) had first-onset epilepsy (13.5% of all patients). Of the 520 cases of nonepileptic onset, 53 were in the prophylactic antiepileptic drug (AED) group. However, 12 of these patients and 55 of the no-prophylactic AED group developed epilepsy during the course of the study. Including these 67 patients, 148 patients were examined as the group of all epilepsy cases during the entire course. In 3 patients, the seizure progressed to status epilepticus. In most patients, the BTE (n = 83, 56.1%) manifested as focal aware seizures. Logistic regression analysis identified young age (p = 0.037), male sex (p = 0.026), breast cancer (p = 0.001), eloquent area (p < 0.001), peritumoral edema (p < 0.001), dissemination (p = 0.013), and maximum tumor volume (p = 0.021) as significant risk factors for BTE. BTE was more common with tumor volumes greater than the cutoff value of 1.92 ml.

CONCLUSIONS

BTE appears to be more likely to occur in cases with young age, male sex, breast cancer, tumors involving eloquent areas, brain edema, dissemination, and giant tumors.

Topographic brain tumor anatomy drives seizure risk and enables machine learning based prediction

OBJECTIVE

The aim of this study was to identify relevant risk factors for epileptic seizures upon initial diagnosis of a brain tumor and to develop and validate a machine learning based prediction to allow for a tailored risk-based antiepileptic therapy.

METHODS

Clinical, electrophysiological and high-resolution imaging data was obtained from a consecutive cohort of 1051 patients with newly diagnosed brain tumors. Factor-associated seizure risk difference allowed to determine the relevance of specific topographic, demographic and histopathologic variables available at the time of diagnosis for seizure risk. The data was divided in a 70/30 ratio into a training and test set. Different machine learning based predictive models were evaluated before a generalized additive model (GAM) was selected considering its traceability while maintaining high performance. Based on a clinical stratification of the risk factors, three different GAM were trained and internally validated.

RESULTS

A total of 923 patients had full data and were included. Specific topographic anatomical patterns that drive seizure risk could be identified. The involvement of allopallial, mesopallial or primary motor/somatosensory neopallial structures by brain tumors results in a significant and clinically relevant increase in seizure risk. While topographic input was most relevant for the GAM, the best prediction was achieved by a combination of topographic, demographic and histopathologic information (Validation: AUC: 0.79, Accuracy: 0.72, Sensitivity: 0.81, Specificity: 0.66).

CONCLUSIONS

This study identifies specific phylogenetic anatomical patterns as epileptic drivers. A GAM allowed the prediction of seizure risk using topographic, demographic and histopathologic data achieving fair performance while maintaining transparency.

Effect of seizure timing on long-term survival in patients with brain tumor

OBJECTIVE

Seizures often occur in patients with primary brain tumor (BT). The aim of this study was to determine if there is an association between the time of occurrence of seizures during the course of BT and survival of these patients.

METHODS

This retrospective cohort study at Henry Ford Hospital, an urban tertiary referral center, included all patients who were diagnosed with primary BTs at Henry Ford Health System between January 2006 and December 2014. Timing of seizure occurrence, if occurred at presentation or after the tumor diagnosis during follow-up period, in different grades of BTs, and survival of these patients were analyzed.

RESULTS

Of the 901 identified patients, 662 (53% male; mean age: 56 years) were included in final analysis, and seizures occurred in 283 patients (43%). Patients with World Health Organization (WHO) grade III BT with seizures as a presenting symptom only had better survival (adjusted hazard ratio (HR): 0.27; 95% confidence interval (CI), 0.11-0.67; P = 0.004). Seizures that occurred after tumor diagnosis only (adjusted HR: 2.11; 95% CI, 1.59-2.81; P < 0.001) in patients with WHO grade II tumors (adjusted HR: 3.41; 95% CI, 1.05-11.1; P = 0.041) and WHO grade IV tumors (adjusted HR: 2.14; 95% CI, 1.58-2.90; P < 0.001) had higher mortality. Seizures that occurred at presentation and after diagnosis also had higher mortality (adjusted HR: 1.34; 95% CI, 1.00-1.80; P = 0.049), in patients with meningioma (adjusted HR: 6.19; 95% CI, 1.30-29.4; P = 0.021) and grade III tumors (adjusted HR: 6.19; 95% CI, 2.56-15.0; P < 0.001).

CONCLUSION

Seizures occurred in almost half of the patients with BTs. The association between seizures in patients with BT and their survival depends on the time of occurrence of seizures, if occurring at presentation or after tumor diagnosis, and the type of tumor. Better survival was noted in patients with WHO grade III BTs who had seizures at presentation at the time of diagnosis, while higher mortality was noted in WHO grade II tumors who had seizure at presentation and after tumor diagnosis, and in grade IV tumors after tumor diagnosis.

Incidence of first seizures, epilepsy, and seizure mimics in a geographically defined area

OBJECTIVE

To determine the incidence of first seizures, epilepsy, and seizure mimics in a geographically defined area using the updated 2014 International League Against Epilepsy (ILAE) definition, which allows an epilepsy diagnosis after a single seizure when the risk of further seizures over the next 10 years is ≈60% or greater. This replaced the 1993 definition by which epilepsy was diagnosed when a person had ≥2 seizures separated by 24 hours.

METHODS

Using multiple overlapping methods of case ascertainment followed by individual case classification by an epileptologist, we identified all first seizures, new diagnosis of epilepsy, and seizure mimics occurring in a defined geographic area (population 542,868) from January 1, 2017, to December 31, 2017. Incidence was age standardized to the Standard European Population. We compared incidence rates using the 2014 and 1993 ILAE definitions.

RESULTS

When the 2014 ILAE definition of epilepsy was applied, the incidence of new diagnosis of epilepsy was 62 per 100,000 (age standardized 74) compared to 41 per 100,000 (age standardized 48) when the 1993 definition was applied, and the difference was more pronounced at older ages. The incidence of all first seizures and of seizure mimics was 102 per 100,000 (age standardized 123) and 94 per 100,000 (age standardized 111), respectively. The most frequently encountered seizure mimic was syncope.

CONCLUSION

Application of the 2014 ILAE definition of epilepsy resulted in a higher incidence of new diagnosis of epilepsy compared to the 1993 definition. The incidence of seizure mimics almost equals that of all first seizures. Seizures, epilepsy, and seizure mimics represent a significant burden to health care systems.

Epileptogenesis and oncogenesis: An antineoplastic role for antiepileptic drugs in brain tumours?

The first description of epileptic seizures due to brain tumours occurred in 19th century. Nevertheless, after over one hundred years, scientific literature is still lacking on how epilepsy and its treatment can affect tumour burden, progression and clinical outcomes. In patients with brain tumours, epilepsy dramatically impacts their quality of life (QoL). Even antiepileptic therapy seems to affect tumor lesion development. Numerous studies suggest that certain actors involved in epileptogenesis (inflammatory changes, glutamate and its ionotropic and metabotropic receptors, GABA-A and its GABA-AR receptor, as well as certain ligand- and voltage-gated ion channel) may also contribute to tumorigenesis. Although some antiepileptic drugs (AEDs) are known operating on such mechanisms underlying epilepsy and tumor development, few preclinical and clinical studies have tried to investigate them as targets of pharmacological tools acting to control both phenomena. The primary aim of this review is to summarize known determinants and pathophysiological mechanisms of seizures, as well as of cell growth and spread, in patients with brain tumors. Therefore, a special focus will be provided on the anticancer effects of commonly prescribed AEDs (including levetiracetam, valproic acid, oxcarbazepine and others), with an overview of both preclinical and clinical data. Potential clinical applications of this finding are discussed.

The risk of developing seizures before and after surgery for brain metastases

OBJECTIVE

Several risk factors have been shown to be associated with pre- and postoperative seizures in patients undergoing neurosurgical intervention for meningiomas and other primary brain tumors. This study aimed to identify risk factors associated with pre- and postoperative seizures in patients undergoing surgery for brain metastases (BM).

PATIENTS AND METHODS

286 patients who had undergone neurosurgical resection for brain metastases between 2007 and 2015 were included in this single-center retrospective cohort. Seizure incidence and patient characteristics were recorded. Univariate and multivariate logistic regression was performed for both pre- and postoperative seizures.

RESULTS

16.8 % of patients presented with seizures before surgical intervention, and a further 7.7 % of patients developed seizures within 3 months of surgical resection of BM. Patient age, cerebellar location, large tumor size, and headache were negatively correlated with pre-operative seizures, whereas parietal location was positively correlated. Surgery for recurrent tumor was positively correlated with newly developed seizures after surgery.

CONCLUSION

Age, cerebellar location, large tumor size, and headache were negatively correlated with development of seizures while parietal location was found to be a risk factor. Lower age and resection of recurrent tumors was correlated with an increased risk of developing postoperative seizures. There was no correlation between type of primary tumor and development of seizures.

Prediagnostic symptoms and signs of adult glioma: the patients' view

BACKGROUND

Little is known about the symptoms glioma patients experience in the year before diagnosis, either or not resulting in health care usage. This study aimed to determine the incidence of symptoms glioma patients experienced in the year prior to diagnosis, and subsequent visits to a general practitioner (GP).

METHODS

Glioma patients were asked to complete a 30-item study-specific questionnaire focusing on symptoms they experienced in the 12 months before diagnosis. For each indicated symptom, patients were asked whether they consulted the GP for this issue.

RESULTS

Fifty-nine patients completed the questionnaires, 54 (93%) with input of a proxy. The median time since diagnosis was 4 months (range 1-12). The median number of symptoms experienced in the year before diagnosis was similar between gliomas with favourable and poor prognosis, i.e. 6 (range 0-24), as were the five most frequently mentioned problems: fatigue (n = 34, 58%), mental tiredness (n = 30, 51%), sleeping disorder (n = 24, 41%), headache (n = 23, 39%) and stress (n = 20, 34%). Twenty-six (44%) patients visited the GP with at least one issue. Patients who did consult their GP reported significantly more often muscle weakness (11 vs 3, p = 0.003) than patients who did not, which remained significant after correction for multiple testing, which was not the case for paralysis in hand/leg (10 vs 4), focussing (11 vs 6) or a change in awareness (9 vs 4).

CONCLUSIONS

Glioma patients experience a range of non-specific problems in the year prior to diagnosis, but only patients who consult the GP report more often neurological problems.

Seizures in meningioma

More than one-third of patients with meningiomas will experience seizures at some point in their disease. Despite this, meningioma-associated epilepsy remains significantly understudied, as most investigations focus on tumor progression, extent of resection, and survival. Due to the impact of epilepsy on the patient's quality of life, identifying predictors of preoperative seizures and postoperative seizure freedom is critical. In this chapter, we review previously reported rates and predictors of seizures in meningioma and discuss surgical and medical treatment options. Preoperative epilepsy occurs in approximately 30% of meningioma patients with peritumoral edema on neuroimaging being one of the most significant predictor of seizures. Other associated factors include age <18, male gender, the absence of headache, and non-skull base tumor location. Following tumor resection, approximately 70% of individuals with preoperative epilepsy achieve seizure freedom. Variables associated with persistent seizures include a history of preoperative epilepsy, peritumoral edema, skull base tumor location, tumor progression, and epileptiform discharges on postoperative electroencephalogram. In addition, after surgery, approximately 10% of meningioma patients without preoperative epilepsy experience new seizures. Variables associated with new postoperative seizures include tumor progression, prior radiation exposure, and gross total tumor resection. Both pre- and postoperative meningioma-related seizures are often responsive to antiepileptic drugs (AEDs), although AED prophylaxis in the absence of seizures is not recommended. AED selection is based on current guidelines for treating focal seizures with additional considerations including efficacy in tumor-related epilepsy, toxicities, and potential drug-drug interactions. Continued investigation into medical and surgical strategies for preventing and alleviating epilepsy in meningioma is warranted.

Prediagnostic presentations of glioma in primary care: a case-control study

Aim:

This study aimed to assess the prevalence of symptoms glioma patients may present with to the general practitioner, and whether these can be distinguished from patients with other CNS disorders or any other condition.

Methods:

Glioma patients were matched to CNS patients and ‘other controls’ using anonymized general practitioner registries. Prevalences were evaluated in the 5 years prior to diagnosis.

Result:

CNS patients reported significantly more motor symptoms in the period 60–24 months, (p = 0.039). Moreover, <6 months before diagnosis CNS patients differed significantly in mood disorders/fear compared with ‘other controls’ (p = 0.012) but not glioma patients (p = 0.816).

Conclusion:

Glioma patients could not be distinguished from both control groups with respect to the number or type of prediagnostic symptoms.

Seizures in glioma patients: An overview of incidence, etiology, and therapies

Gliomas are fatal brain tumors, and even low-grade gliomas (LGGs) have an average survival of less than a decade. Seizures are a common presentation of gliomas, particularly LGGs, and substantially impact quality of life. Glioma-related seizures differ from other focal epilepsies in their pathogenesis and in the likelihood of refractory epilepsy. We review factors that predict seizure activity and response to treatment, optimal pharmacologic and surgical management of glioma-related epilepsy, and the benefit of using newer anti-seizure medications in patients with gliomas. As surgery is so often beneficial with seizure reduction, we discuss oncologic and epilepsy surgery perspectives. Treatment of gliomas has the potential to ameliorate seizures and increase rates of seizure freedom. Prospective, well-powered studies are needed to provide more definitive answers for practitioners taking care of glioma patients with seizures.

Predictive Factors for Seizures Accompanying Intracranial Meningiomas

OBJECTIVE

Seizures represent a common manifestation of intracranial meningiomas. Their predictive factors before and after excision merit studying.

MATERIALS AND METHODS

Patients having intracranial meningioma were prospectively studied. There were two groups; Group "A" with seizures and Group "B" with no preoperative epilepsy.

RESULTS

This study included 40 patients. Their ages ranged from 40 to 60 years old, and female-to-male ratio was 2.3:1 in both groups. In Group A, partial seizures were the most common pattern (60%). Manifestations other than fits included headache in most patients (97.5%), symptoms of increased intracranial pressure were found in 50% in Group A and 20% in Group B patients, peritumoral edema was present in 14 (70%) patients of Group A, compared to 6 (25%) patients of Group "B." There was a statistically significant relation between peritumoral edema and presentation with fits (P < 0.1). Complication after surgery included nonsurgical hematoma in three patients and contusion in 7 patients. Following surgery for Group "A", 8 (40%) patients had good seizure control. While, in Group "B" 3 (15%), patients developed new-onset seizures. Good seizure control in 7 (53%) patients with frontal, frontotemporal tumors than in other locations. In addition, better control was obtained in left sided, small tumors, and no peritumoral edema. Postoperative complication was significantly associated with new-onset epilepsy and poor seizure control (P < 0.05). Neither tumor size nor location had a significant relation to either pre or postoperative epilepsy.

CONCLUSION

Predictive factors for epilepsy accompanying intracranial meningioma included males, elderly patients and patients with small lesions, frontal and left-sided locations but were statistically insignificant predictors. Peritumoral edema and postoperative complications are the most significant predictors.

Anatomical features of primary brain tumors affect seizure risk and semiology

Objective

An epileptic seizure is the most common clinical manifestation of a primary brain tumor. Due to modern neuroimaging, detailed anatomical information on a brain tumor is available early in the diagnostic process and therefore carries considerable potential in clinical decision making. The goal of this study was to gain a better understanding of the relevance of anatomical tumor characteristics on seizure prevalence and semiology.

Methods

We reviewed prospectively collected clinical and imaging data of all patients operated on a supratentorial intraparenchymal primary brain tumor at our department between January 2009 and December 2016. The effect of tumor histology, anatomical location and white matter infiltration on seizure prevalence and semiology were assessed using uni- and multivariate analyses.

Results

Of 678 included patients, 311 (45.9%) presented with epileptic seizures. Tumor location within the central lobe was associated with higher seizure prevalence (OR 4.67, 95% CI: 1.90–13.3, p = .002), especially within the precentral gyrus or paracentral lobule (100%). Bilateral extension, location within subcortical structures and invasion of deeper white matter sectors were associated with a lower risk (OR 0.45, 95% CI: 0.25–0.78; OR 0.10, 95% CI: 0.04–0.21 and OR 0.39, 95% CI: 0.14–0.96, respectively). Multivariate analysis revealed the impact of a location within the central lobe on seizure risk to be highly significant and more relevant than histopathology (OR: 4.79, 95% CI: 1.82–14.52, p = .003). Seizures due to tumors within the central lobe differed from those of other locations by lower risk of secondary generalization (p < .001).

Conclusions

Topographical lobar and gyral location, as well as extent of white matter infiltration impact seizure risk and semiology. This finding may have a high therapeutic potential, for example regarding the use of prophylactic antiepileptic therapy.

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Brain tumor location affects seizure prevalence and semiology.

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Central lobe location is the strongest independent pro-epileptogenic factor.

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The precentral gyrus and paracentral lobule are most epileptogenic.

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Central lobe tumors rarely cause bilateral tonic-clonic seizures.

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Tumor location and white matter infiltration may guide antiepileptic therapy.

Tumor-related epilepsy: epidemiology, pathogenesis and management

INTRODUCTION

Seizure is a common comorbidity in patients with brain tumor. It may be the presenting symptom or develop after the tumor diagnosis. The underlying pathophysiology of brain tumor-related epilepsy remains poorly understood.

METHODS

A comprehensive literature review of Pubmed English articles from 1980-2017 was performed to summarize current knowledge and treatment options of brain tumor-related epilepsy.

RESULTS

Multiple factors have been found to contribute to tumor-related epilepsy, including tumor type, speed of tumor growth, location, and tumor burden. The underlying pathogenesis of epilepsy is not clear but perturbations in the peri-tumoral regions, both structural and cellular communications, have been implicated.

CONCLUSIONS

Surgical and medical treatments of tumor-related epilepsy remain challenging as additional factors such as the extent of surgical resection, interactions with tumor-related oncological treatments and anti-epileptic medication related side effects need to be considered.

Prevalence, Characteristics, and Long-Term Prognosis of Epilepsy Associated with Pediatric Brain Tumors

OBJECTIVE

We investigated the prevalence, onset, characteristics, and long-term course of epilepsy disease in children who underwent surgical intervention for diagnosed brain tumors.

METHODS

We reviewed the medical records of children with diagnosed brain tumors who underwent surgery during 2004-2014 at the Hadassah Medical Center. All patients with epilepsy were invited to a clinical visit that included a neurologic examination. The primary outcome measures were neurologic status according to the Glasgow outcome score (GOS) and postoperative seizure outcome according to the Engel system. We compared clinical characteristics according to the timing of epilepsy onset.

RESULTS

The mean follow-up was 49 months. Of 128 patients included in the study, 44 (34%) had seizures; 23 (18%) developed epilepsy after surgery. Of the 30 patients with epilepsy who survived, 21 (70%) are in Engel class I and 13% Engel are in class II. Forty-five percent of the children are classified as GOS 5. Children who developed epilepsy after surgery were more likely to be in GOS 1-2 than were those who had seizures before surgery (P = 0.0173). Children with seizures were more likely to have cortical tumors and less likely to have tumors of the posterior fossa (P < 0.001). Children who underwent gross total resection were less likely to have epilepsy (P < 0.001).

CONCLUSIONS

We show a high incidence of epilepsy in the late course of pediatric brain tumor disease. In the long term, seizure outcome was excellent. However, postsurgical onset of epilepsy was associated with a less favorable neurologic outcome.

Incidence of seizure in adult patients with intracranial metastatic disease

Seizures have considerable impact on a patient's quality of life. While guidelines have been articulated to direct clinicians in their management of patients with IMD who suffer from seizure, there have been few attempts to identify the seizure rate in IMD and to determine which primary cancers may be associated with an increased seizure incidence. To determine the incidence of seizure in patients with IMD. A systematic review on seizure incidence in patients with IMD from the magnetic resonance imaging (MRI) era was performed. Articles published between January 2000 and July 2014 with thirty or more consecutive adult patients were included in this study. Seizure rate was calculated using a pooled data analysis. Differences between observed and expected seizure rates between primary tumour sites were examined using the Chi square statistic and adjusted standardized residuals. The systematic search produced 18 relevant studies, with a total study population of 2012 patients. 14.6% (n = 294) had seizures. There was a significant association between primary tumour site and seizure rates. The seizure rate in patients with primary melanoma tumours was significantly greater than expected (z = 2.7; p = .006). The seizure rate in patients with primary prostate tumours was significantly lower than expected (z = -2.6; p = .008). Patients with intracranial metastasis are at significant risk for developing seizure, though at a significantly lower incidence than was estimated by studies performed during the CT era. Seizure rates appear to be greater in certain primary tumours, such as melanoma.

The effect of pregnancy on survival in a low-grade glioma cohort

OBJECTIVE

The impact of pregnancy on survival in female patients with low-grade glioma (LGG) is unknown and controversial. The authors designed a retrospective cohort study on prospectively collected registry data to assess the influence of pregnancy and child delivery on the survival of female patients with LGG.

METHODS

In Norway, the reporting of all births and cancer diagnoses to the Medical Birth Registry of Norway (MBRN) and the Cancer Registry of Norway (CRN), respectively, is compulsory by law. Furthermore, every individual has a unique 11-digit identification number. The CRN was searched to identify all female patients with a histologically confirmed diagnosis of World Health Organization (WHO) Grade II astrocytoma, oligoastrocytoma, oligodendroglioma, or pilocytic astrocytoma who were 16–40 years of age at the time of diagnosis during the period from January 1, 1970, to December 31, 2008. Obstetrical information was obtained from the MBRN for each patient. The effect of pregnancy on survival was evaluated using a Cox model with parity as a time-dependent variable.

RESULTS

The authors identified 65 patients who gave birth to 95 children after an LGG diagnosis. They also identified 281 patients who did not give birth after an LGG diagnosis. The median survival was 14.3 years (95% CI 11.7–20.6 years) for the entire study population. The effect of pregnancy was insignificant in the multivariate model (HR 0.71, 95% CI 0.35–1.42).

CONCLUSIONS

Pregnancy does not seem to have an impact on the survival of female patients with LGG.

Epilepsy and brain tumors

Seizures are common in patients with brain tumors, and epilepsy can significantly impact patient quality of life. Therefore, a thorough understanding of rates and predictors of seizures, and the likelihood of seizure freedom after resection, is critical in the treatment of brain tumors. Among all tumor types, seizures are most common with glioneuronal tumors (70-80%), particularly in patients with frontotemporal or insular lesions. Seizures are also common in individuals with glioma, with the highest rates of epilepsy (60-75%) observed in patients with low-grade gliomas located in superficial cortical or insular regions. Approximately 20-50% of patients with meningioma and 20-35% of those with brain metastases also suffer from seizures. After tumor resection, approximately 60-90% are rendered seizure-free, with most favorable seizure outcomes seen in individuals with glioneuronal tumors. Gross total resection, earlier surgical therapy, and a lack of generalized seizures are common predictors of a favorable seizure outcome. With regard to anticonvulsant medication selection, evidence-based guidelines for the treatment of focal epilepsy should be followed, and individual patient factors should also be considered, including patient age, sex, organ dysfunction, comorbidity, or cotherapy. As concomitant chemotherapy commonly forms an essential part of glioma treatment, enzyme-inducing anticonvulsants should be avoided when possible. Seizure freedom is the ultimate goal in the treatment of brain tumor patients with epilepsy, given the adverse effects of seizures on quality of life.

Principles of radiation therapy

Although resection remains the mainstay in the treatment of gliomas, microscopically complete resection of most central nervous system tumors remains challenging, and is, in fact, rarely accomplished. Considering their invasive nature, gross total resections to clearly negative margins often do or would require removal or transection of functional brain, with likely serious neurologic deficits. Consequently, radiotherapy has emerged as an indispensable component of therapy. It is delivered primarily by external-beam radiotherapy or brachytherapy techniques. Herein, we present the biologic principles, techniques, and applications of radiotherapy in glioma treatment today.

Gross-total resection of temporal low grade gliomas is a critically important factor in achieving seizure-freedom

OBJECTIVE

To present a surgical series of patients with low grade temporal gliomas causing intractable epilepsy, focusing on long-term seizure outcome.

METHOD

A retrospective study was conducted with patients with temporal low-grade gliomas (LGG).

RESULTS

Sixty five patients with were operated in our institution. Males were more affected than females and the mean age at surgery was 32.3 ± 8.4 (9-68 years). The mean age at seizure onset was 25.7 ± 9.2 (11-66 years). Seizure outcome was classified according with Engel classification. After one year of follow up, forty two patients (64.6%) were Engel I; seventeen (26.2%) Engel II; four (6.2%) Engel III and two (3.1%) Engel IV. Statistically significant difference in seizure outcome was obtained when comparing the extension of resection. Engel I was observed in 39 patients (69.6%) with total resection and in only 3 (33.3%) patients with partial resection.

CONCLUSION

Gross-total resection of temporal LGGs is a critically important factor in achieving seizure-freedom.

Risk of seizures in children with tectal gliomas

The objective of this study was to determine the prevalence of seizures in children with tectal gliomas and to determine if there are common clinical, electroencephalography (EEG), or radiologic findings that predict risk of seizures in these patients. We conducted a retrospective review of all patients with tectal gliomas over a 22-year period at a single institution. Data extraction included sex, age at presentation of tectal glioma and age of presentation with seizures, magnetic resonance imaging (MRI) findings, seizure frequency and semiology, and EEG findings. We identified 79 patients, 66 of whom had adequate imaging and clinical data for further analysis. Eight patients (12.1%) had a history of seizures. Three patients had a clear symptomatic cause of seizures. Three patients were diagnosed with a tectal glioma as an incidental finding after a first seizure. One patient had a history of febrile convulsions. One patient had a generalized seizure 5 years after presenting with macrocephaly. Although the risk of seizure in children with known tectal glioma was relatively high, we did not identify specific clinical, radiologic, EEG, or MRI features that are predictive of increased risk. Thus, in children with tectal gliomas who have seizures, alternative causes for the seizures must be sought.

Clinical Management of Seizures in Patients With Low-Grade Glioma

Seizures, transient disruptions of normal brain electrical activity, are common for patients with low-grade glioma (LGG) and significantly affect quality of life. Up to 75% of patients with a LGG will have seizures in the course of their disease (compared with 1%-2% of the general population). Depending on the type of abnormal electrical activity, the functional implications of seizure can impact any domain, including mental status, sensation or strength. In most cases, either the seizure or the medications used to treat the seizure may contribute to cognitive and psychosocial difficulties of various degrees of severity. Hence, effective management of seizures is a major priority for patients with LGG. Evidence-based guidelines suggest that levetiracetam is the best first-line agent for treatment of seizures in this population due to both its efficacy and tolerability. An important consideration in the field of neuro-oncology is that levetiracetam has very few drug interactions. Unfortunately, approximately one-third of patients with LGG have refractory epilepsy where additional agents such as valproic acid, or lacosamide, lamotrigine and nonpharmacologic therapies such as diet-based interventions, epilepsy surgery, and devices are considered.

Peritumoral epilepsy: relating form and function for surgical success

Seizures are a prominent symptom in patients with both primary and secondary brain tumors. Medical management of seizure control in this patient group is problematic as the mechanisms linking tumorigenesis and epileptogenesis are poorly understood. It is possible that several mechanisms contribute to tumor-associated epileptic zone formation. In this review, we discuss key candidates that may be implicated in peritumoral epileptogenesis and, in so doing, hope to highlight areas for future research. Furthermore, we summarize the current role of antiepileptic medications in this type of epilepsy and examine the changes in surgical practice which may lead to improved seizure rates after tumor surgery. Lastly, we speculate on possible future preoperative and intraoperative considerations for improving seizure control after tumor resection.

Tumor location and IDH1 mutation may predict intraoperative seizures during awake craniotomy

OBJECT

Intraoperative seizures during awake craniotomy may interfere with patients' ability to cooperate throughout the procedure, and it may affect their outcome. The authors have assessed the occurrence of intraoperative seizures during awake craniotomy in regard to tumor location and the isocitrate dehydrogenase 1 (IDH1) status of the tumor.

METHODS

Data were collected in 137 consecutive patients who underwent awake craniotomy for removal of a brain tumor. The authors performed a retrospective analysis of the incidence of seizures based on the tumor location and its IDH1 mutation status, and then compared the groups for clinical variables and surgical outcome parameters.

RESULTS

Tumor location was strongly associated with the occurrence of intraoperative seizures. Eleven patients (73%) with tumor located in the supplementary motor area (SMA) experienced intraoperative seizures, compared with 17 (13.9%) with tumors in the other three non-SMA brain regions (p < 0.0001). Interestingly, there was no significant association between history of seizures and tumor location (p = 0.44). Most of the patients (63.6%) with tumor in the SMA region harbored an IDH1 mutation compared with those who had tumors in non-SMA regions. Thirty-one of 52 patients (60%) with a preoperative history of seizures had an IDH1 mutation (p = 0.02), and 15 of 22 patients (68.2%) who experienced intraoperative seizures had an IDH1 mutation (p = 0.03). In a multivariate analysis, tumor location was found as a significant predictor of intraoperative seizures (p = 0.002), and a trend toward IDH1 mutation as such a predictor was found as well (p = 0.06). Intraoperative seizures were not associated with worse outcome.

CONCLUSIONS

Patients with tumors located in the SMA are more prone to develop intraoperative seizures during awake craniotomy compared with patients who have a tumor in non-SMA frontal areas and other brain regions. The IDH1 mutation was more common in SMA region tumors compared with other brain regions, and may be an additional risk factor for the occurrence of intraoperative seizures.

Localizing seizure-susceptible brain regions associated with low-grade gliomas using voxel-based lesion-symptom mapping

BACKGROUND

Patients afflicted with low-grade glioma (LGG) frequently suffer from seizures. The mechanisms of seizure initiation in these patients remain poorly understood. Tumor location has been correlated with seizure initiation. However, these correlative studies relied on dichotomized data analysis based on arbitrary lobe assignments. As a result, the lesion-symptom correlation may be incorrectly interpreted. Here, we present the first study that used a voxel-wise quantitative lesion analysis to investigate the spatial correlation between tumor location and seizure susceptibility.

METHODS

We collected the medical records and magnetic resonance images of 410 LGG patients. The dataset was divided into a discovery set and a validation set. A voxel-based lesion-symptom correlative analysis was performed to determine whether tumor location was associated with seizure risk and could be related to the specific type of seizure.

RESULTS

For all seizure types, increased seizure risks were identified for LGGs that involved the left premotor area. The LGGs that involved the posterior portion of the left inferior and middle frontal gyrus were associated with increased risk of simple partial seizures. LGGs that involved the right temporal-insular region were associated with an increased risk of complex partial seizures. LGGs that involved the left premotor area were more likely to be associated with seizures that generalize. These correlations were consistently observed in both the discovery and the validation datasets.

CONCLUSIONS

Our quantitative neuroimaging analyses support the concept that the anatomic location of an LGG is a contributing factor in tumor-related seizure.

Treatment of epileptic seizures in brain tumors: a critical review

Epileptic seizures represent a common signal of intracranial tumors, frequently the presenting symptom and the main factor influencing quality of life. Treatment of tumors concentrates on survival; antiepileptic drug (AED) treatment frequently is prescribed in a stereotyped way. A differentiated approach according to epileptic syndromes can improve seizure control and minimize unwarranted AED effects. Prophylactic use of AEDs is to be discouraged in patients without seizures. Acutely provoked seizures do not need long-term medication except for patients with high recurrence risk indicated by distinct EEG patterns, auras, and several other parameters. With chronically repeated seizures (epilepsies), long-term AED treatment is indicated. Non-enzyme-inducing AEDs might be preferred. Valproic acid exerts effects against progression of gliomatous tumors. In low-grade astrocytomas with epilepsy, a comprehensive presurgical epilepsy work-up including EEG-video monitoring is advisable; in static non-progressive tumors, it is mandatory. In these cases, the neurosurgical approach has to include the removal of the seizure-onset zone frequently located outside the lesion.

Tumor associated seizures in glioblastomas are influenced by survival gene expression in a region-specific manner: a gene expression imaging study

Tumor associated seizures (TAS) are common and cause significant morbidity. Both imaging and gene expression features play significant roles in determining TAS, with strong interactions between them. We describe gene expression imaging tools which allow mapping of brain regions where gene expression has significant influence on TAS, and apply these methods to study 77 patients who underwent surgical evaluation for supratentorial glioblastomas. Tumor size and location were measured from MRI scans. A 9-set gene expression profile predicting long-term survivors was obtained from RNA derived from formalin-fixed paraffin embedded tissue. A total of 32 patients (42%) experienced preoperative TAS. Tumor volume was smaller (31.1 vs. 58.8 cubic cm, p<0.001) and there was a trend toward median survival being higher (48.4 vs. 32.7 months, p=0.055) in patients with TAS. Although the expression of only OLIG2 was significantly lower in patients with TAS in a groupwise analysis, gene expression imaging analysis revealed regions with significantly lower expression of OLIG2 and RTN1 in patients with TAS. Gene expression imaging is a powerful technique that demonstrates that the influence of gene expression on TAS is highly region specific. Regional variability should be evaluated with any genomic or molecular markers of solid brain lesions.

The role of levetiracetam in treatment of seizures in brain tumor patients

Levetiracetam, trade name Keppra, is a new second generation antiepileptic drug that is being increasingly used in brain tumor patients. In patients suffering with brain tumors, seizures are one of the leading neurologic complications being seen in more than 30% of patients. Unlike other antiepileptic drugs, levetiracetam is proposed to bind to a synaptic vesicle protein inhibiting calcium release. Brain tumor patients are frequently on chemotherapy or other drugs that induce cytochrome P450, causing significant drug interactions. However, levetiracetam does not induce the P450 system and does not exhibit any relevant drug interactions. Intravenous delivery is as bioavailable as the oral medication allowing it to be used in emergency situations. Levetiracetam is an attractive option for brain tumor patients suffering from seizures, but also can be used prophylactically in patients with brain tumors, or patients undergoing neurological surgery. Emerging studies have also demonstrated that levetiracetam can increase the sensitivity of Glioblastoma tumors to the chemotherapy drug temozolomide. Levetiracetam is a safe alternative to conventional antiepileptic drugs and an emerging tool for brain tumor patients combating seizures.

Seizures in low-grade gliomas: natural history, pathogenesis, and outcome after treatments

Seizures represent a common symptom in low-grade gliomas; when uncontrolled, they significantly contribute to patient morbidity and negatively impact quality of life. Tumor location and histology influence the risk for epilepsy. The pathogenesis of tumor-related epilepsy is multifactorial and may differ among tumor histologies (glioneuronal tumors vs diffuse grade II gliomas). Gross total resection is the strongest predictor of seizure freedom in addition to clinical factors, such as preoperative seizure duration, type, and control with antiepileptic drugs (AEDs). Epilepsy surgery may improve seizure control. Radiotherapy and chemotherapy with alkylating agents (procarbazine + CCNU+ vincristine, temozolomide) are effective in reducing the frequency of seizures in patients with pharmacoresistant epilepsy. Newer AEDs (levetiracetam, topiramate, lacosamide) seem to be better tolerated than the old AEDs (phenobarbital, phenytoin, carbamazepine), but there is lack of evidence regarding their superiority in terms of efficacy.

Epilepsy in the end-of-life phase in patients with high-grade gliomas

Epilepsy is common in patients with brain tumors. Patients presenting seizures as the first sign of a malignant glioma are at increased risk of recurrent seizures despite treatment with antiepileptic drugs. However, little is known about the incidence of epilepsy in the last stage of disease and in the end-of-life phase of brain tumor patients. We retrospectively analyzed the incidence of seizures in the last months of life in a series of patients affected by high-grade gliomas who were assisted at home during the whole course of the disease until death. A total of 157 patients were available for analysis. Of these patients, 58 (36.9 %) presented seizures in the last month before death. The risk of seizures in the end-of-life phase is higher in patients presenting previous history of epilepsy, particularly in patients with late-onset epilepsy. Out of the 58 patients presenting seizures in the last month of life, 86.2 % had previously had seizures and 13.8 % were seizure free. Most patients may encounter swallowing difficulties in taking anticonvulsants orally due to dysphagia and disturbances of consciousness, thus anticonvulsant treatment needs to be modified in advance. Loss of seizure control in the end-of-life phase may influence the quality of life of patients and their caregivers.

[Glioma-associated epilepsy]

BACKGROUND

Epileptic seizures are a common symptom in patients with primary brain tumours of the glioma type. The paper presents a discussion of epileptogenesis, choice of medication and follow-up of these patients.

METHOD

The article is based on a search in PubMed and selection of articles based on the authors' discretionary judgement and clinical experience with this patient group.

RESULTS

Epileptic seizures are a common symptom of glioma, particularly the low-grade types. The background to glioma-associated epilepsy is multifactorial, and the molecular biological characteristics of the tumour probably play a central part in the epileptogenesis. Effective treatment of epileptic seizures is of great importance to the quality of life of the glioma patient. Seizure frequency and the effectiveness of anti-epileptic treatment vary, and some patients require treatment with several anti-epileptic drugs. Surgical and oncological treatment of the tumour will also often reduce the frequency of seizures.

CONCLUSION

As a general rule, antiepileptics without enzyme-inducing properties and with low protein-binding should be preferred for glioma patients. This will reduce the risk of interactions with chemotherapy or steroid therapy. Patients with brain tumours are particularly vulnerable to the effects on wakefulness, moods and cognition, and this should be borne in mind in the choice of medication and in follow-up. Haematological status should be monitored particularly closely when there is concomitant use of chemotherapy and antiepileptic drugs that may affect the bone marrow function.

Characteristics and treatment of seizures in patients with high-grade glioma: a review

High-grade gliomas (HGGs), including anaplastic astrocytoma and glioblastoma multiforme, are the most common primary brain tumors, and are often associated with seizures. Seizure control is a critical but often underappreciated goal in the treatment of patients harboring these malignant lesions. Patients with HGG who also have medically intractable seizures should be considered for a palliative resection guided by electrocorticography and functional mapping. Antiepileptic drugs remain the mainstay of seizure treatment in HGG, and antiepileptic medication should be started after a tumor-related seizure, but should not be used prophylactically in the absence of seizure activity.

Canine intracranial neoplasia: clinical risk factors for development of epileptic seizures

OBJECTIVES

To identify clinical risk factors for seizures in dogs with intracranial neoplasia.

METHODS

A cross-sectional retrospective study of 68 dogs with histopathologically confirmed primary or secondary intracranial neoplasia, complete clinical history and magnetic resonance imaging of the brain was conducted. Signalment and clinical history were retrieved from clinical records and magnetic resonance images of the brain were re-evaluated. Prevalence of findings was compared between dogs with and without seizures.

RESULTS

Forty-two dogs had tumour-related seizures, the remaining 26 were seizure-free. Tumour types included meningioma (23 dogs with and 5 without seizures), glioma (9 dogs with and 6 without seizures), choroid plexus tumour (2 dogs without seizures), neuroblastoma (1 dog with seizures) and metastatic/invasive tumours including lymphoma (9 dogs with and 13 without seizures). On the basis of multi-variable logistic regression analysis, risk factors for seizures associated with intracranial neoplasia were magnetic resonance imaging findings consistent with the presence of neoplastic tissue in frontal lobe [odds ratio (OR) 9·61; 95% confidence interval (CI) 2·59 to 35·61], marked gadolinium enhancement (OR 10·41; 95% CI 2·07 to 52·30) and magnetic resonance imaging findings of subfalcine and/or subtentorial herniation (OR 3·88; 95% CI 1·10 to 13·71).

CLINICAL SIGNIFICANCE

Dogs with primary or secondary intracranial neoplasia are at risk of seizures, particularly those with tumours that affect the frontal lobe, enhance markedly with gadolinium, or cause subfalcine and/or subtentorial herniation.

[Primary brain tumors and brain metastases. Symptomatic epilepsy and driving ability - systematic review and expert opinion]

PURPOSE

Primary brain tumors and metastases are common causes of symptomatic epilepsy. Seizures, neurological and neuropsychological deficits can interfere with driving ability. The present paper aims to systematically review the incidence of epileptic seizures in brain tumor patients and to discuss driving ability in the context of the current German guidelines and expert opinions.

METHODS

To evaluate the incidence of epileptic seizures which occur at the beginning and in the course of the disease, we performed a systematic literature research in PubMed from 1960 to 2007. Additionally on the basis of this data we performed a survey collecting expert opinions regarding the driving ability of brain tumor patients from members of the German working groups "Arbeitsgemeinschaft für prächirurgische Epilepsiediagnostik und operative Epilepsietherapie" (Working Group for Presurgical Epilepsy Diagnostics and Operative Epileptic Therapy) and "Neuroonkologische Arbeitsgemeinschaft" (Neuro-oncological Working Group).

RESULTS

The incidence of epileptic seizures depends on the entity, dignity and localization of the tumor. The driving ability of brain tumor patients is not explicitly regulated in Germany. Of the interviewed experts 72% judged the guidelines to be precise enough and 44% did not want to deprive the patients of their driving ability without a first seizure, independent of the individual risk.

DISCUSSION

The available studies are methodologically insufficient and show that a further evaluation is necessary to assess the driving ability. Possible restrictions of the driving ability in patients with a high risk of seizures in the course of the disease have to take into account the balance between individual rights and the interests of the general public.

Epilepsy in the cancer patient

PURPOSE

Epileptic seizures in patients with malignancies usually occur as a consequence of brain metastases from systemic cancer or the presence of a primary brain tumor. Other less-frequent causes include metabolic disorders such as electrolyte abnormalities, hypoglycemia, hypoxia and liver failure, paraneoplastic encephalitis, leptomeningeal carcinomatosis, side effects of certain chemotherapeutic agents, central nervous system infections, and pre-existing epilepsy.

METHODS

We reviewed all published literature in the English language regarding the use of antiepileptic drugs in patients with cancer.

RESULTS

In patients with brain metastases or primary brain tumors that had never experienced seizures, prophylactic anticonvulsant treatment is justified only for a period up to 6 months postoperatively after surgical excision of a cerebral tumor, since approximately half of the patients will never develop seizures and the anti-epileptic drugs may cause toxicity and interactions with antineoplastic therapies. For brief prophylaxis, newer antiepileptic drugs such as levetiracetam and oxcarbazepine are superior to older agents like phenytoin. In patients with a malignancy and seizures, certain antiepileptic drugs that express tumor inhibitory properties should be used such as valproic acid and levetiracetam, followed by oxcarbazepine and topiramate that exhibit good tolerance, efficient seizure control and absence of significant interactions with the chemotherapy.

CONCLUSIONS

Future clinical trials in patients with cancer and epilepsy should focus on combinations of chemotherapeutic interventions with antiepileptic drugs that demonstrate antineoplastic activities.

Epilepsy and brain tumors

PURPOSE OF REVIEW

To present an overview of the recent findings in pathophysiology and management of epileptic seizures in patients with brain tumors.

RECENT FINDINGS

Low-grade gliomas are the most epileptogenic brain tumors. Regarding pathophysiology, the role of peritumoral changes [hypoxia and acidosis, blood-brain barrier (BBB) disruption, increase or decrease of neurotransmitters and receptors] are of increasing importance. Tumor-associated epilepsy and tumor growth could have some common molecular pathways. Total/subtotal surgical resection (with or without epilepsy surgery) allows a seizure control in a high percentage of patients. Radiotherapy and chemotherapy as well have a role. New antiepileptic drugs are promising, both in terms of efficacy and tolerability. The resistance to antiepileptic drugs is still a major problem: new insights into pathogenesis are needed to develop strategies to manipulate the pharmakoresistance.

SUMMARY

Epileptic seizures in brain tumors have been definitely recognized as one of the major problems in patients with brain tumors, and need specific and multidisciplinary approaches.

Morphological characteristics of brain tumors causing seizures

OBJECTIVE

To quantify size and localization differences between tumors presenting with seizures vs nonseizure neurological symptoms.

DESIGN

Retrospective imaging survey. We performed magnetic resonance imaging-based morphometric analysis and nonparametric mapping in patients with brain tumors.

SETTING

University-affiliated teaching hospital.

PATIENTS OR OTHER PARTICIPANTS

One hundred twenty-four patients with newly diagnosed supratentorial glial tumors.

MAIN OUTCOME MEASURES

Volumetric and mapping methods were used to evaluate differences in size and location of the tumors in patients who presented with seizures as compared with patients who presented with other symptoms.

RESULTS

In high-grade gliomas, tumors presenting with seizures were smaller than tumors presenting with other neurological symptoms, whereas in low-grade gliomas, tumors presenting with seizures were larger. Tumor location maps revealed that in high-grade gliomas, deep-seated tumors in the pericallosal regions were more likely to present with nonseizure neurological symptoms. In low-grade gliomas, tumors of the temporal lobe as well as the insular region were more likely to present with seizures.

CONCLUSIONS

The influence of size and location of the tumors on their propensity to cause seizures varies with the grade of the tumor. In high-grade gliomas, rapidly growing tumors, particularly those situated in deeper structures, present with non-seizure-related symptoms. In low-grade gliomas, lesions in the temporal lobe or the insula grow large without other symptoms and eventually cause seizures. Quantitative image analysis allows for the mapping of regions in each group that are more or less susceptible to seizures.

Genetic markers in oligodendroglial tumours

BACKGROUND

Oliogodendrogliomas are brain tumours composed of the cells resembling oligodendrocytes. They represent the third most common glial tumour, comprising 2.5% of all primary brain tumours and 5-20% of all gliomas.

CONCLUSIONS

Oligodendroglial tumours with 1p and 19q loss demonstrate a better overall prognosis due to more indolent clinical behaviour and higher sensitivity to treatment. Additionally, 1p and 19q loss is a marker of clinical utility, helping to assess tumour sensitivity to chemotherapy and harbouring the potential for improving the diagnosis and survival of oligodendroglioma patients as well as future clinical practice.

Seizures in patients with low-grade gliomas--incidence, pathogenesis, surgical management, and pharmacotherapy

Seizures complicate the clinical course of > 80% of patients with low-grade gliomas. Patients with some tumor variants almost always have epilepsy. Diffuse low-grade gliomas (LGG) are believed to cause epilepsy through partial deafferentiation of nearby brain cortex (denervation hypersensitivity). Glioneural tumors may interfere with local neurotransmitter levels and are sometimes associated with structural abnormalities of the brain which may produce seizures. The severity of tumor associated epilepsy varies considerably between patients. Some cases may present with a first seizure. Others suffer from long-standing pharmacoresistant epilepsy. Seizure control rates of > 70-80% can be expected after complete tumor resections. Patients with drug-resistant epilepsy require a comprehensive preoperative epileptological work-up which may include the placement of subdural (and intraparenchymal) electrodes or intraoperative electrocorticography (ECoG) for the delineation of extratumoral seizure foci. Partial and subtotal tumor resections are helpful in selected cases, i.e. for gliomas involving the insula. In one series, 40% of patients presented for surgery with uncontrolled seizures, i.e. medical therapy alone often fails to control tumor-related epilepsy. Use of the newer (second generation) non-enzyme inducing antiepileptic drugs (non-EIAED) is encouraged since they seem to have lesser interactions with other medications (e.g. chemotherapy). Chemotherapy and irradiation may have some minor beneficial effects on the patients' seizure disorder. Overall 60-70% of patients may experience recurrent epilepsy during long-term follow-up. Recurrent seizures (not infrequently heralding tumor recurrence) after surgery continue to pose significant clinical problems.

Neurologic sequelae of brain tumors in children

Neurologic signs and symptoms are often the initial presenting features of a primary brain tumor and may also emerge during the course of therapy or as late effects of the tumor and its treatment. Variables that influence the development of such neurologic complications include the type, size, and location of the tumor, the patient's age at diagnosis, and the treatment modalities used. Heightened surveillance and improved neuroimaging modalities have been instrumental in detecting and addressing such complications, which are often not appreciated until many years after completion of therapy. As current brain tumor therapies are continually refined and newer targeted therapies are developed, it will be important for future cooperative group studies to include systematic assessments to determine the incidence of neurologic complications and to provide a framework for the development of novel strategies for prevention and intervention.