Temporal lobe tumoral epilepsy: characteristics and predictors of surgical outcome

Low-grade glioma of the temporal lobe and tumor-related epilepsy in children

PURPOSE

Low-grade glioma is the most common brain tumor among children and adolescents. When these tumors arise in the temporal lobe, patients frequently present with seizures that are poorly controlled with antiepileptic drugs. Here we summarize the clinical features, pathophysiology, preoperative evaluation, surgical treatment, and outcomes of pediatric patients with low-grade gliomas in the temporal lobe.

METHODS

We reviewed the literature on pediatric low-grade gliomas in the temporal lobe, focusing on cohort studies and systematic reviews that described surgical treatment strategies and reported both oncologic and epilepsy outcomes.

RESULTS

The differential diagnoses of pediatric low-grade gliomas in the temporal lobe include ganglioglioma, dysembryoplastic neuroepithelial tumor, desmoplastic infantile ganglioglioma, papillary glioneuronal tumor, pilocytic astrocytoma, pleomorphic xanthoastrocytoma, angiocentric glioma, and polymorphous low-grade neuroepithelial tumor of the young. There is no consensus on the optimal surgical approach for these tumors: lesionectomy alone, or extended lesionectomy with anterior temporal lobectomy, with or without removal of mesial temporal structures. Gross total resection and shorter preoperative duration of epilepsy are strongly associated with favorable seizure outcomes, defined as Engel Class I or Class II, approaching 90% in most series. The risk of surgical complications ranges from 4 to 17%, outweighing the lifetime risks of medically refractory epilepsy.

CONCLUSION

Pediatric patients with temporal low-grade glioma and tumor-related epilepsy are best managed by a multidisciplinary epilepsy surgery team. Early and appropriate surgery leads to prolonged survival and a greater likelihood of seizure freedom, improving their overall quality of life.

Do we have to continue antiseizure medications post surgery in long-term epilepsy associated tumors (LEATs)?

OBJECTIVE

To identify the rate of successful antiseizure medication (ASM) withdrawal after resective surgery in patients with long-term epilepsy-associated tumors (LEATs).

METHODS

A retrospective analysis (from our prospectively archived data) on the post-operative ASM profile of 123 consecutive patients who completed a minimum of 2 years after resection of LEATs for ASM-resistant epilepsy. A comparison between recurred and non-recurred groups in terms of seizure recurrence was used to identify the potential predictors of seizure recurrence whose attributes were further analyzed using univariate and multiple logistic regression analysis. Kaplan-Meier survival curves were used to study the probability of ASM freedom following surgery.

RESULTS

We attempted ASM withdrawal in 102 (82.9 %) patients. Forty-eight (47.1 %) had seizure recurrence while reducing ASM, of which 22 (21.6 %) continued to have seizures even after ASM optimisation. On univariate analysis, presence of pre-operative secondary generalized seizure(s) was the only factor associated with seizure recurrence. At a mean follow-up of 6.1 years, 72 (58.5 %) patients were seizure-free and aura-free at terminal follow-up (53 patients were off any ASM). The cumulative probability of achieving complete ASM-free status was 29 % at fourth year, 42 % at sixth year, 55 % at eighth year, and 59 % at 10th year after surgery.

CONCLUSIONS

Following resective surgery for LEATs, ASM(s) could be successfully discontinued in half of the patients. About one-third of the patients may have recurrent seizures on follow-up. Presence of secondary generalized seizure(s) prior to surgery predicts seizure recurrence, whereas MRI defined completeness of resection will not. This information will help in rationalising decisions on ASM management post-resection.

Epilepsy treatment in neuro-oncology: A rationale for drug choice in common clinical scenarios

Epilepsy represents a challenge in the management of patients with brain tumors. Epileptic seizures are one of the most frequent comorbidities in neuro-oncology and may be the debut symptom of a brain tumor or a complication during its evolution. Epileptogenic mechanisms of brain tumors are not yet fully elucidated, although new factors related to the underlying pathophysiological process with possible treatment implications have been described. In recent years, the development of new anti-seizure medications (ASM), with better pharmacokinetic profiles and fewer side effects, has become a paradigm shift in many clinical scenarios in neuro-oncology, being able, for instance, to adapt epilepsy treatment to specific features of each patient. This is crucial in several situations, such as patients with cognitive/psychiatric comorbidity, pregnancy, or advanced age, among others. In this narrative review, we provide a rationale for decision-making in ASM choice for neuro-oncologic patients, highlighting the strengths and weaknesses of each drug. In addition, according to current literature evidence, we try to answer some of the most frequent questions that arise in daily clinical practice in patients with epilepsy related to brain tumors, such as, which patients are the best candidates for ASM and when to start it, what is the best treatment option for each patient, and what are the major pitfalls to be aware of during follow-up.

Early EEG hyperexcitability is associated with decreased survival in newly diagnosed IDH-wildtype glioma

PURPOSE

The relationship between peritumoral neuronal activity, early onset clinical seizures, and glioma survival outcomes remains poorly understood. Hyperexcitability on continuous EEG in the peri-operative period was studied as a prognostic biomarker in patients with newly diagnosed IDH-wildtype diffuse glioma.

METHODS

A retrospective observational cohort study was performed including adults with newly diagnosed diffuse glioma, absence of IDH1/2 mutations, and continuous EEG monitoring prior to chemoradiation and within 1 month of initial resection. EEG hyperexcitability was defined by the presence of lateralized periodic discharges and/or electrographic seizures. The primary outcome of overall survival was estimated using the Kaplan-Meier method and compared between groups using multivariate Cox proportional hazards model.

RESULTS

There were 424 patients without continuous EEG and 32 with continuous EEG, of whom lateralized periodic discharges and/or electrographic seizures were seen in 17 (53%). Peri-operative EEG hyperexcitability was associated with decreased overall survival in multivariate analysis [median 12.5 (95% CI 6.2-25.6] months with hyperexcitability versus median 19.9 [95% CI 8.9-53.5] months without hyperexcitability, p = 0.043). Compared to patients without continuous EEG, overall survival was decreased in patients with hyperexcitability (p < 0.0001) and similar in patients without hyperexcitability (p = 0.193). Patients with and without hyperexcitability had similar rates of exposure to anti-seizure medication at baseline, and in long-term follow-up had no difference in number of medications required for seizure control.

CONCLUSIONS

These findings indicate the potential prognostic value of a clinical EEG biomarker of glioma aggressiveness prior to the initiation of chemoradiation.

Prescription preferences of antiepileptic drugs in brain tumor patients: An international survey among EANO members

Background

This study aimed at investigating antiepileptic drug (AED) prescription preferences in patients with brain tumor-related epilepsy (BTRE) among the European neuro-oncology community, the considerations that play a role when initiating AED treatment, the organization of care, and practices with regard to AED withdrawal.

Methods

A digital survey containing 31 questions about prescription preferences of AEDs was set out among members of the European Association of Neuro-Oncology (EANO).

Results

A total of 198 respondents treating patients with BTRE participated of whom 179 completed the entire survey. Levetiracetam was the first choice in patients with BTRE for almost all respondents (90% [162/181]). Levetiracetam was considered the most effective AED in reducing seizure frequency (72% [131/181]) and having the least adverse effects (48% [87/181]). Common alternatives for levetiracetam as equivalent first choice included lacosamide (33% [59/181]), lamotrigine (22% [40/181]), and valproic acid (21% [38/181]). Most crucial factors to choose a specific AED were potential adverse effects (82% [148/181]) and interactions with antitumor treatments (76% [137/181]). In the majority of patients, neuro-oncologists were involved in the treatment of seizures (73% [132/181])). Other relevant findings were that a minority of respondents ever prescribe AEDs in brain tumor patients without epilepsy solely as prophylaxis (29% [53/181]), but a majority routinely considers complete AED withdrawal in BTRE patients who are seizure-free after antitumor treatment (79% [141/179]).

Conclusions

Our results show that among European professionals treating patients with BTRE levetiracetam is considered the first choice AED, with the presumed highest efficacy and least adverse effects.

Oligodendroglioma: A Review of Management and Pathways

Anaplastic oligodendrogliomas are a type of glioma that occurs primarily in adults but are also found in children. These tumors are genetically defined according to the mutations they harbor. Grade II and grade III tumors can be differentiated most of the times by the presence of anaplastic features. The earliest regimen used for the treatment of these tumors was procarbazine, lomustine, and vincristine. The treatment modalities have shifted over time, and recent studies are considering immunotherapy as an option as well. This review assesses the latest management modalities along with the pathways involved in the pathogenesis of this malignancies.

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.

Distinguishing Focal Cortical Dysplasia From Glioneuronal Tumors in Patients With Epilepsy by Machine Learning

Purpose: We are aiming to build a supervised machine learning-based classifier, in order to preoperatively distinguish focal cortical dysplasia (FCD) from glioneuronal tumors (GNTs) in patients with epilepsy. Methods: This retrospective study was comprised of 96 patients who underwent epilepsy surgery, with the final neuropathologic diagnosis of either an FCD or GNTs. Seven classical machine learning algorithms (i.e., Random Forest, SVM, Decision Tree, Logistic Regression, XGBoost, LightGBM, and CatBoost) were employed and trained by our dataset to get the classification model. Ten features [i.e., Gender, Past history, Age at seizure onset, Course of disease, Seizure type, Seizure frequency, Scalp EEG biomarkers, MRI features, Lesion location, Number of antiepileptic drug (AEDs)] were analyzed in our study. Results: We enrolled 56 patients with FCD and 40 patients with GNTs, which included 29 with gangliogliomas (GGs) and 11 with dysembryoplasic neuroepithelial tumors (DNTs). Our study demonstrated that the Random Forest-based machine learning model offered the best predictive performance on distinguishing the diagnosis of FCD from GNTs, with an F1-score of 0.9180 and AUC value of 0.9340. Furthermore, the most discriminative factor between FCD and GNTs was the feature "age at seizure onset" with the Chi-square value of 1,213.0, suggesting that patients who had a younger age at seizure onset were more likely to be diagnosed as FCD. Conclusion: The Random Forest-based machine learning classifier can accurately differentiate FCD from GNTs in patients with epilepsy before surgery. This might lead to improved clinician confidence in appropriate surgical planning and treatment outcomes.

[Clinical and neuropsychological studies of patients before and after insular glioma resection]

AIM

The study was aimed to investigate the insula function based on analysis and comparison of epileptic seizures (irritation symptoms) and cognitive impairment (memory loss) in patients with insular gliomas.

MATERIAL AND METHODS

Epileptic seizures and cognitive impairment were analyzed in 51 patients with insular gliomas before and after surgery. The tumor was located on the left in 21 patients and on the right - in 30. Patients were aged 9 to 67 years; most patients were diagnosed with grade II and grade III gliomas. Patients were examined before surgery and 4-6 days after tumor resection. Neuropsychological examination was carried out according to the A.R. Luria method, which enabled establishing a correlation between detected impairments and the topography of injury to different brain areas. To identify the seizure features, the study presents data from two additional groups of patients: with temporal and frontal lobe tumors, 50 patients each.

RESULTS

Epileptic seizures were detected in 45 (88.2%) of 51 patients in the main group and were similar to paroxysms associated with medial temporal lobe tumors, but quantitatively differed from them. Seizures in patients with frontal lobe tumors significantly differed from those with insular and temporal lobe tumors. Compared to temporal lobe epilepsy, symptomatic epilepsy in the setting of insular tumors was characterized by significantly less frequent losses of consciousness (84% versus 35.2%) but more frequent olfactory and taste hallucinations (16% versus 51%). Fear and anxiety attacks associated with these tumor localizations occurred at the same rate (in 17.6% of patients with insular tumors and in 14% patients with temporal tumors). The vegetative component of seizures did not differ in tumors of both localizations and different lateralization. Olfactory and taste hallucinations were qualitatively similar in tumors of the insula and temporal lobe: smell and taste were always unpleasant or corresponded to danger. Pleasant taste or smell was not developed in any case. Cognitive impairment before and after surgery directly depended on the tumor spread to the adjacent temporal or frontal lobes. Memory impairments were most frequent, and speech disorders were most frequent in the case left-sided lesions. Eight patients with total removal of the insula and without postoperative complications had no deterioration in speech and memory.

CONCLUSION

Epileptic seizures associated with insular tumors are characterized by both similarities and differences with medial-temporal seizures, which is due to the close relationships between the insula and the limbic system. The nature of taste and olfactory hallucinations associated with insular tumors reflects a significant role of the insula in the formation of 'protective behavior'. The absence of clear cognitive impairment in focal lesions of the insula restricts extended interpretation of the insula role in implementation of cognitive functions. This issue needs further investigation.

Acute Neurological Complications of Brain Tumors and Immune Therapies, a Guideline for the Neuro-hospitalist

PURPOSE OF REVIEW

Patients with brain tumors presenting to the emergency room with acute neurologic complications may warrant urgent investigations and emergent management. As the neuro-hospitalist will likely encounter this complex patient population, an understanding of the acute neurologic issues will have value.

RECENT FINDINGS

We discuss updated information and management regarding various acute neurologic complications among neuro-oncology patients and neurologic complications of immunotherapy. Understanding of the acute neurologic complications associated with central nervous system tumors and with common contemporary cancer treatments will facilitate the neuro-hospitalist management of these patient populations. While there are aspects analogous to the diagnosis and management in the non-oncologic population, a number of unique features discussed in this review should be considered.

One Seizure Please, Hold the Sprouts: The Role of Hippocampal Mossy Fiber Sprouting in Epilepsy

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Outcome of lesional epilepsy surgery: Report of the first comprehensive epilepsy program in Iran

Background

We investigated the utility of epilepsy surgery and postoperative outcome in patients with lesional epilepsy in Iran, a relatively resource-poor setting.

Methods

This prospective longitudinal study was conducted during 2007-2017 in Kashani Comprehensive Epilepsy Center, Isfahan, Iran. Patients with a diagnosis of intractable focal epilepsy, with MRI lesions, who underwent epilepsy surgery and were followed up ≥ 24 months, were included and evaluated for postoperative outcome.

Results

A total of 214 patients, with a mean age of 26.90 ± 9.82 years (59.8% men) were studied. Complex partial seizure was the most common type of seizure (85.9%), and 54.2% of the cases had auras. Temporal lobe lesions (75.2%) and mesial temporal sclerosis (48.1%) were the most frequent etiologies. With a mean follow-up of 62.17 ± 19.33 months, 81.8% of patients became seizure-free postoperatively. Anticonvulsants were reduced in 86% of the cases and discontinued in 40.7%. In keeping with previous studies, we found that seizure freedom rates were lower among patients with longer follow-up periods.

Conclusions

We found high rates of seizure freedom after surgery in lesional epilepsy patients despite limited facilities and infrastructure; antiepileptic medications were successfully tapered in almost half of the patients. Considering the favorable outcome of epilepsy surgery in our series, we believe that it is a major treatment option, even in less resource-intensive settings, and should be encouraged. Strategies to allow larger scale utility of epilepsy surgery in such settings in the developing world and dissemination of such knowledge may be considered an urgent clinical need, given the established mortality and morbidity in refractory epilepsy.

Clinical characteristics associated with postoperative seizure control in adult low-grade gliomas: a systematic review and meta-analysis

Background

Epilepsy is the most common symptom in patients with supratentorial low-grade gliomas (LGGs), which adversely affects the patient's quality of life. Poor seizure control with anti-epileptic therapy is an indication for surgery in these patients. Recent studies have sought to identify predictors of postoperative seizure control after surgical resection of LGG; gross total resection was shown to be a significant predictor in this respect. However, the prognostic value of other factors is not clear.

Methods

We performed a systematic review and meta-analysis of 23 studies with a combined study population of 2641 patients with LGG, in order to identify potential factors associated with favorable postoperative seizure control. Data were extracted on age and sex of patient, tumor location, tumor histology, type of seizure, seizure duration, extent of resection, and imaging characteristics.

Results

Patients ≥45 years of age achieved better postoperative seizure control (risk ratio [RR], 0.89; 95% CI, 0.81-0.99). Focal seizures were associated with poor seizure control (RR, 1.32; 95% CI, 1.18-1.49) compared with generalized seizures (RR, 0.77; 95% CI, 0.68-0.87). Prolonged history of seizures (≥1 y) had a negative impact on postoperative seizure control (RR, 1.22; 95% CI, 1.10-1.34). Gross total resection was superior to subtotal resection with respect to postoperative seizure control (RR, 0.68; 95% CI, 0.63-0.73).

Conclusions

This systematic review and meta-analysis identified predictors of postoperative seizure control in patients undergoing surgical resection of LGGs. Our results provide a reference for clinical treatment of LGG-related epilepsy.

Cognitive features and surgical outcome of patients with long-term epilepsy-associated tumors (LEATs) within the temporal lobe

OBJECTIVE

The objective of the study was to evaluate cognitive and epilepsy-related features in 166 surgically treated patients with epilepsy with long-term epilepsy-associated tumors (LEATs) located in the temporal lobe.

METHOD

Pre- and postsurgical cognitive as well as the one-year seizure outcome of adult patients with histopathologically confirmed LEATs (28 grade-I dysembryoplastic neuroepithelial tumors (DNET), 95 grade-I gangliogliomas (GG), 24 grade-I pilocytic astrocytomas (PA), 9 grade-II pleomorphic xanthoastrocytoma (PXA), 10 grade-II diffuse astrocytoma (DA)) who underwent epilepsy surgery in Bonn/Germany between 1988 and 2012 were evaluated.

RESULTS

At baseline, tumor groups differed in regard to age at epilepsy onset and location within the temporal lobe. Postoperative seizure freedom was achieved most frequently (>77.8%) in DNET, GG, and DA, less often in PXA (62.5%) and the least in PA (56.5%). Preoperative memory was impaired in 67.1% of all patients, executive functions in 44.7%, and language in 45.5%. Patients with PA displayed the poorest cognitive performance. Individual significant memory decline that was observed in 27.1% of all patients was predicted by left-sided surgery, a mesial pathology, and extended hippocampal resection. Executive functions depended on antiepileptic drug (AED) load and remained stable (72.0%) or even improved (21.6%) after surgery. Language functions were unchanged in 89.5% of patients.

CONCLUSION

Patients with LEATs in the temporal lobe frequently show cognitive impairments. Predictors for pre- and postoperative cognition mostly correspond to what is known for temporal lobe epilepsy and resections in general. However, different tumor types appear to be associated with different cognitive and seizure outcomes with astrocytoma as the least benefitted group.

Correlation between glioma location and preoperative seizures: a systematic review and meta-analysis

Epilepsy is a common manifestation of glioma patients and negatively impacts on quality of life and neurocognitive function. The risk of preoperative seizures in patients with glioma is currently under discussion. We aimed to evaluate the relationship between tumor locations in the cerebrum and preoperative seizures in patients with glioma. PubMed, EMBASE, Web of Science, China Biology Medicine, and the Cochrane Library were systematically searched from inception to July 15, 2017, for original studies including reports of preoperative seizures in patients with gliomas in different brain regions. The pooled odds ratio (OR) and 95% confidence interval (CI) of the meta-analysis for preoperative seizure risk stratified by cerebrum regions were calculated. The quality of evidence was assessed per outcome, using the approach of the Grades of Recommendation, Assessment, Development and Evaluation. Overall, 4323 participants in 16 population-based studies were included in this meta-analysis. The meta-analysis indicated that gliomas in the frontal lobe (OR = 1.51, 95% CI = 1.09-2.09, P = 0.013) were associated with a higher risk for preoperative seizure compared to occipital lobe involved (OR = 0.53, 95% CI = 0.32-0.88, P = 0.014). Regarding the other three lobe involved gliomas, no difference was found between the incidence of preoperative seizures and tumor location. Current limited data suggest that frontal gliomas were associated with a higher risk of preoperative seizures, while gliomas in the occipital lobe were associated with a lower seizure risk. Further RCT studies recruiting larger sample sizes are required to validate these results and guide clinical practice.

Surgical Treatment of Lesional Mesial Temporal Lobe Epilepsy

Lesional mesial temporal lobe epilepsy (mTLE) concerns a lesion other than mesial hippocampal sclerosis present in the mesial temporal lobe and causing seizures. The lesions are usually composed of focal cortical dysplasia (FCD) or are tumorous. These are good candidates for surgical treatment. Sometimes, it is difficult to distinguish between tumors and FCD and to determine the extent of required removal. ¹¹C-methionine positron emission tomography (PET) is helpful in differentiating lesions before surgery in lesional mTLE. In ¹¹C-methionine PET imaging, tumors show a hot uptake, whereas FCD does not. In case of tumorous conditions, the removal of only specific lesions may be considered because the seizure outcome is dependent on complete excision of the tumor. There are several ways to safely access mesial temporal structures. The transsylvian-transcisternal approach is a good way to access the mesial structures while preserving the lateral and basal temporal structures. Actual lesions associated with epileptogenesis in FCD may be larger than they appear on magnetic resonance imaging. For this reason, evaluations to locate sufficient epileptogenic foci, including invasive studies, should be completed for FCD, and epilepsy surgery should be performed according to these results. Regardless, the ultimate goal of all epilepsy surgeries is to maximize seizure control while maintaining neurological function. Therefore, a tailored approach based on the properties of the lesion is needed.

New-onset seizure during and after brain tumor excision: a risk assessment analysis

OBJECTIVE

Prophylactic use of antiepileptic drugs (AEDs) in seizure-naïve brain tumor patients remains a topic of debate. This study aimed to characterize a subset of patients at highest risk for new-onset perioperative seizures (i.e., intraoperative and postoperative seizures occurring within 30 days of surgery) who may benefit from prophylactic AEDs.

METHODS

The authors conducted a retrospective case-control study of all adults who had undergone tumor resection or biopsy at the authors’ institution between January 1, 2004, and June 31, 2015. All patients with a history of preoperative seizures, posterior fossa tumors, pituitary tumors, and parasellar tumors were excluded. A control group was matched to the seizure patients according to age (± 0 years). Demographic data, clinical status, operative data, and postoperative course data were collected and analyzed.

RESULTS

Among 1693 patients who underwent tumor resection or biopsy, 549 (32.4%) had never had a preoperative seizure. Of these 549 patients, 25 (4.6%) suffered a perioperative seizure (Group 1). A total of 524 patients (95.4%) who remained seizure free were matched to Group 1 according to age (± 0 years), resulting in 132 control patients (Group 2), at an approximate ratio of 1:5. There were no differences between the patient groups in terms of age, sex, race, relationship status, and neurological deficits on presentation. Histological subtype (infiltrating glioma vs meningioma vs other, p = 0.041), intradural tumor location (p < 0.001), intraoperative cortical stimulation (p = 0.004), and extent of resection (less than gross total, p = 0.002) were associated with the occurrence of perioperative seizures.

CONCLUSIONS

While most seizure-naïve brain tumor patients do not benefit from perioperative seizure prophylaxis, such treatment should be considered in high-risk patients with supratentorial intradural tumors, in patients undergoing intraoperative cortical stimulation, and in patients in whom subtotal resection is likely.

Predicting the likelihood of postoperative seizure status based on mRNA sequencing in low-grade gliomas

AIM

No comprehensive and objective methods yet exist for predicting postoperative seizure.

PATIENTS & METHODS

mRNA-seq data and corresponding postoperative seizure status of 109 low-grade glioma samples were obtained from Chinese Glioma Genome Atlas database and divided into two sets randomly. Logistic regression and receiver operating characteristic analysis with risk score method were used to develop a ten-gene prediction model.

RESULTS

Considering gene number and area under the curve of receiver operating characteristic, a ten-gene model was generated which showed an area under the curve of 0.9965 in training set. Patients with high-risk scores had higher probability of postoperative seizure compared with those with low-risk scores.

CONCLUSION

This is the first prediction model for postoperative seizures in gliomas, integrating multiple genes. Clinical application may help patients with postoperative seizure control.

Rates of Seizure Freedom After Surgical Resection of Diffuse Low-Grade Gliomas

OBJECTIVE

Patients with diffuse low-grade gliomas (DLGGs) typically present with seizures. We sought to review the neurosurgical literature for seizure outcome after resection of these tumors.

METHODS

Using PubMed, we identified surgical series reporting seizure freedom rates for grade II astrocytoma, oligoastrocytoma, and oligodendroglioma. Inclusion criteria included seizure outcomes reported specifically for DLGGs and at least 10 patients with follow-up data.

RESULTS

Twelve articles met the inclusion criteria. The median seizure-free rate after surgery in these patients was 71%, with an interquartile range of 64%-82%. In 10 studies, more than 60% of patients were seizure free. Studies used varying reporting times for seizure outcome determination. In the 6 studies that reported postoperative antiepileptic medication use, 5%-69% of seizure-free patients were weaned off these agents (median, 32%). The durability of seizure freedom has not been clearly studied to date. The most commonly reported prognostic factor for seizure freedom after resection was increasing extent of resection.

CONCLUSIONS

Among articles reporting seizure outcomes after resection of DLGG, the median seizure-free rate was 71% (interquartile range, 64%-82%). Seizure freedom is likely associated with extent of resection.

[Clinical characteristics of epileptic seizures in insular gliomas]

AIM

To study the characteristics of epileptic seizures in insular gliomas.

MATERIAL AND METHODS

Forty-five patients with insular gliomas were examined. The spread of a tumor was established by MRI results and intraoperational findings. A tumor within the insular only was found in 9 out of 45 patients (7 left-sided and 2 right-sided). In 36 patients, a tumor slightly spread into temporal lobe pole and medial-basal regions of the frontal lobe (27 left-sided and 18 right-sided). The control group consisted of 50 patients with tumors of temporal and frontal lobes.

RESULTS

Paroxysmal symptoms were similar in patients with tumors of the insular and patients with tumors of temporal lobes. Seizures in patients with frontal lobe tumors differed significantly from insular and temporal tumors, with the exception of a tumor localized in the opercula area. The following quantitative differences were identified: different forms of unconsciousness were significantly less frequent in symptomatic epilepsy in patients with insular tumor than in epilepsy caused by temporal lobe tumors (36% of patients vs 84% in temporal tumors (p<0.0001)). In patients with insular tumors, olfactory and taste hallucinations occur more often compared to temporal lobe tumors (51% vs 16% (p<0.003). The frequency of paroxysmal seizures of fear and anxiety in patients with those tumors was similar (20% with insular tumors and 14 with temporal tumors). An autonomic component of episeizures did not differ between tumors of both localizations. Olfactory and taste hallucinations were qualitatively similar in insular and temporal lobe tumors: smell and taste were unpleasant or associated with a danger: smell of burning, gas, something spoiled, sour, tart chemistry, taste of somethong metallic, chemical, sour. No pleasant smell or taste were reported.

CONCLUSION

Epileptic seizures in insular tumors had similarities and certain differences compared with temporal seizures that well reflect function of the insula and its links, in the first turn, with limbic system structures.

Predictors and mechanisms of epilepsy occurrence in cerebral gliomas: What to look for in clinicopathology

Gliomas, especially low-grade gliomas, are highly epileptogenic brain tumors. Histopathological information is valuable in evaluating the diagnosis and/or biologic behavior of various gliomas. Here we explored the clinical data and histopathological predictors of the occurrence of epilepsy in patients with gliomas. A retrospective study examined 310 consecutive patients who had undergone surgical treatment for gliomas in our institution from January 2013 to January 2015. Clinical data and pathological examination results were analyzed. Literatures regarding the predictors and etiology of glioma associated epileptic seizures in the period of 1995-2015 were also reviewed. A total of 234 (75.5%) astrocytic tumors and 76 (24.5%) oligodendrial tumors were included. At diagnosis, 33.6% of patients had epileptic seizures. Multivariate analysis revealed cortex involvement (OR=7.991, 95%CI=1.599-39.926), lower World Health Organization grade (OR=3.584, 95%CI=1.032-12.346) and topoisomerase II (TopoII) positivity (OR=0.943, 95%CI=0.903-0.982) were strong predictors for preoperative epileptic seizures. Gender, disease course, tumor classification, location or volume did not significantly affect epileptic seizure occurrence. Forty-three publications involved glioma-associated epilepsy were found in PubMed online database and key data were extracted and summarized. The present studies on glioma-related epilepsy are relatively limited and inconsistent. Low-grade gliomas, cortex involvement and TopoII positivity were independent predictors of a history of epileptic seizures at diagnosis. Further studies to examine the underlying mechanism of topoisomerase II as well as other molecules in epilepsy occurrence in brain gliomas are needed in the future.

Predictors of Postoperative Seizure Recurrence: A Longitudinal Study of Temporal and Extratemporal Resections

Objective. We investigated the longitudinal outcome of resective epilepsy surgery to identify the predictors of seizure recurrence. Materials and Methods. We retrospectively analyzed patients who underwent resections for intractable epilepsy over a period of 7 years. Multiple variables were investigated as potential predictors of seizure recurrence. The time to first postoperative seizure was evaluated using survival analysis and univariate analysis at annual intervals. Results. Among 70 patients, 54 (77%) had temporal and 16 (23%) had extratemporal resections. At last follow-up (mean 48 months; range 24–87 months), the outcome was Engel class I in 84% (n = 59) of patients. Seizure recurrence followed two patterns: recurrence was “early” (within 2 years) in 82% of patients, of whom 83% continued to have seizures despite optimum medical therapy; recurrence was “late” (after 2 years) in 18%, of whom 25% continued to have seizures subsequently. Among the variables of interest, only resection site and ictal EEG remained as independent predictors of seizure recurrence over the long term (p < 0.05). Extratemporal resection and discordance between ictal EEG and resection area were associated with 4.2-fold and 5.6-fold higher risk of seizure recurrence, respectively. Conclusions. Extratemporal epilepsy and uncertainty in ictal EEG localization are independent predictors of unfavorable outcome. Seizure recurrence within two years of surgery indicates poor long-term outcome.

Surgical outcomes in patients with intraoperative Electrocorticography (EcoG) guided epilepsy surgery-experiences of a tertiary care centre in India

INTRODUCTION

The Comprehensive Epilepsy Surgery Program was started in 2001 at K.E.M. Hospital, Mumbai with the aim of performing epilepsy surgeries at highly concessional rates. We have started using intraoperative Electrocorticography (EcoG) since 2009 in patients with tumors, Mesial Temporal Sclerosis (MTS) plus and focal cortical dysplasia (FCD). This study highlights our experience with EcoG and it's utility in epilepsy surgery.introduction METHODS: 51 patients with drug resistant epilepsy due to temporal and extra-temporal tumors, MTS plus and FCD underwent pre-surgical evaluation and ECoG guided epilepsy surgery through our program. The surgical procedures employed included intraoperative EcoG guided lesionectomy or a lesionectomy with Anterior Temporal Lobectomy (ATL). Postoperative MRI and EEG were done. Seizure freedom was categorized as per Engel's classification.

RESULTS

At a mean follow up of 33 months (range: 14-69 months), 43 out of 51(84.31%) patients were completely seizure free post-surgery (Engel's Class I). Among the patients who were not seizure free, 3 patients were in Engel's Class II and 5 patients were in Engel's Class III. Presence of a residual lesion on postoperative MRI (p < 0.001), abnormal postoperative EEG (p < 0.001) and persistent spikes on post-resection EcoG (p < 0.05) had a significant statistical association with poor seizure freedom post-surgery.

CONCLUSION

The success of epilepsy surgery depends upon accurate localization and complete resection of the epileptogenic tissue, both of which are aided by intraoperative EcoG.Thus, intraoperative EcoG is a useful adjunct in epilepsy surgery to achieve optimal seizure freedom in cases of MTS plus, focal cortical dysplasia and tumors. Even the patients who are not seizure free can achieve worthwhile improvement post surgery.

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.

Clinicopathological factors predictive of postoperative seizures in patients with gliomas

PURPOSE

Epilepsy is one of the most common manifestations in gliomas and has a severe effect on the life expectancy and quality of life of patients. The aim of our study was to assess the potential connections between clinicopathological factors and postoperative seizure.

METHOD

We retrospectively investigated a group of 147 Chinese high-grade glioma (HGG) patients with preoperative seizure to examine the correlation between postoperative seizure and clinicopathological factors and prognosis. Univariate analyses and multivariate logistic regression analyses were performed to identify factors associated with postoperative seizures. Survival function curves were calculated using the Kaplan-Meier method.

RESULTS

53 patients (36%) were completely seizure-free (Engel class I), and 94 (64%) experienced a postoperative seizure (Engel classes II, III, and IV). A Chi-squared analysis showed that anaplastic oligodendroglioma/anaplastic oligoastrocytoma (AO/AOA) (P=0.05), epidermal growth factor receptor (EGFR) expression (P=0.0004), O(6)-methylguanine DNA methyltransferase (MGMT) expression (P=0.011), and phosphatase and tensin homolog (PTEN) expression (P=0.045) were all significantly different. A logistic regression analysis showed that MGMT expression (P=0.05), EGFR expression (P=0.001), and AO/AOA (P=0.038) are independent factors of postoperative seizure. Patients with lower MGMT and EGFR expression and AO/AOA showed more frequent instances of postoperative seizure. Postoperative seizure showed no statistical significance on overall survival (OS) and progression-free survival (PFS).

CONCLUSION

Our study identified clinicopathological factors related to postoperative seizure in HGGs and found two predictive biomarkers of postoperative seizure: MGMT and EGFR. These findings provided insight treatment strategies aimed at prolonging survival and improving quality of life.

Seizures in oligodendroglial tumors

Epilepsy develops in more than 70-90% of oligodendroglial tumors and represents a favorable indicator for long-term survival if present as the first clinical sign. Presence of IDH1 mutation is frequently associated with seizures in oligodendrogliomas, next to alterations of glutamate and GABA metabolism in the origin of glioma-associated epilepsy. Treatment by surgery or radiotherapy results in seizure freedom in about two-thirds of patients, and chemotherapy to a seizure reduction in about 50%. Symptomatic anticonvulsive therapy with levetiracetam and valproic acid as monotherapy are both evidence-based drugs for the partial epilepsies, and their effective use in brain tumors is supported by a large amount of additional data. Pharmacoresistance against anticonvulsants is more prevalent among oligodendrogliomas, occurring in about 40% despite polytherapy with two anticonvulsants or more. Toxic signs of anticonvulsants in brain tumors involve cognition, bone marrow and skin. Previous neurosurgery, radiation therapy or chemotherapy add to the risks of cognitive dysfunction.

Cortical GABAergic excitation contributes to epileptic activities around human glioma

Brain gliomas are highly epileptogenic. Excitatory glutamatergic mechanisms are involved in the generation of epileptic activities in the neocortex surrounding gliomas. However, chloride homeostasis is known to be perturbed in glioma cells. Thus, the contribution of γ-aminobutyric acidergic (GABAergic) mechanisms that depend on intracellular chloride merits closer study. We studied the occurrence, networks, cells, and signaling basis of epileptic activities in neocortical slices from the peritumoral surgical margin resected around human brain gliomas. Postoperative glioma tissue from 69% of patients spontaneously generated interictal-like discharges, synchronized, with a high-frequency oscillation signature, in superficial layers of neocortex around areas of glioma infiltration. Interictal-like events depended both on glutamatergic AMPA receptor-mediated transmission and on depolarizing GABAergic signaling. GABA released by interneurons depolarized 65% of pyramidal cells, in which chloride homeostasis was perturbed because of changes in expression of neuronal chloride cotransporters: KCC2 (K-Cl cotransporter 2) was reduced by 42% and expression of NKCC1 (Na-K-2Cl cotransporter 1) increased by 144%. Ictal-like activities were initiated by convulsant stimuli exclusively in these epileptogenic areas. This study shows that epileptic activities are sustained by excitatory effects of GABA in human peritumoral neocortex, as reported in temporal lobe epilepsies, suggesting that both glutamate and GABA signaling and cellular chloride regulation processes, all also involved in oncogenesis as already shown, induce an imbalance between synaptic excitation and inhibition underlying epileptic discharges in glioma patients. Thus, the control of chloride in neurons and glioma cells may provide a therapeutic target for patients with epileptogenic gliomas.

Seizures in children with dysembryoplastic neuroepithelial tumors of the brain--A review of surgical outcomes across several studies

PURPOSE

In children and adolescents, dysembryoplastic neuroepithelial tumors (DNETs) of the brain present with seizures almost 100% of the time, potentially creating significant long-term morbidity and disability despite the generally indolent course of the lesion. These tumors also tend to be quite resistant to anti-epileptic drugs which, themselves, can be associated with long-term side effects and resultant disability. Many clinicians advocate early surgical resection of these lesions, but how effective this approach is, and how aggressive tumor removal should be, continues to be debated.

METHODS

We performed a systematic review of the relevant literature to identify all reports of DNET resections in pediatric patients published over the past 20 years. In all, over 3000 MEDLINE abstracts were reviewed, ultimately resulting in 13 studies with 185 pediatric DNET patients to review.

RESULTS

Surgical resection of the lesion was effective at improving seizures in over 98% of patients and at achieving long-term seizure freedom in 86%. Surgical resection of DNETs also appeared to be quite safe, with no reported perioperative deaths and an overall rate of postoperative complications of 12%; the vast majority of these complications were transient.

CONCLUSIONS

Total gross resection of the lesion was the only factor statistically correlated with long-term seizure freedom (r = 0.63, p = 0.03). However, data remain lacking regarding whether this translates into more extensive procedures-like brain mapping and partial lobectomies-being any more effective than simple lesionectomies alone. Further research is clearly needed to address this and other crucial questions.

Low-grade temporal gliomas: surgical strategy and long-term seizure outcome

Low-grade gliomas (LGGs) are generally located in temporal lobe and cause medically-intractable seizure so that surgical treatment becomes inevitable. This study includes a retrospective analysis of our patients with temporal LGGs retrieved from our epilepsy surgery data base and tries to present appropriate surgical approach and long-term seizure and anti-epileptic drug (AED) outcomes. Fifty-three patients including children and adults underwent surgery on temporal lobe LGGs and 35 patients were reached to report seizure and AED outcomes. On the non-dominant temporal lobe, anterior temporal resection with hippocampectomy whether mesial structure are involved or not is the appropriate approach. On the dominant temporal lobe mesial structures should be respected. However, total resection of the tumor should be the goal of surgery. Mean follow-up period was 8.3 years and favorable seizure outcome was found to be 91.4%. Surgery decreased AED usage and mean number of AED significantly decreased. Children also benefited from surgery as adults. Surgical treatment of tumor-related epilepsy from temporal lobe controls seizures, and total removal should be the main goal of surgery as neuropsychological testing permit.

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.

Long-term monitoring of brain tumors: when is it necessary?

Tumors, particularly low grade glioma and glioneuronal tumors, account for 25-35% of patients who are undergoing epilepsy surgery for intractable seizures. A comprehensive epilepsy evaluation including video-electroencephalography (EEG) monitoring is useful for most of these patients, to determine the optimal extent of resection for the achievement of seizure-free outcome without causing postoperative deficits. Video-EEG monitoring for patients with brain tumor should also be considered in specific situations, such as patients with new postoperative seizures or advanced tumors with unexplained mental status change.

Resection strategies in tumoral epilepsy: is a lesionectomy enough?

Resection strategies in patients with tumor-related epilepsy vary from lesionectomy to larger epilepsy operations with no consensus on optimal approaches. The objective of this study is to use our prior experience in the management of these patients, to derive optimal strategies for the surgical management of epilepsy related to brain tumors. A prospectively compiled database of epilepsy and tumor patients was used to identify patients who underwent surgical resection of a neoplasm but then developed epilepsy, or who presented with epilepsy and were found to harbor a brain tumor. Seizure frequency, histopathology, type of surgical resection, and outcomes were compiled. Of 235 epilepsy surgery patients and 75 low/intermediate grade glioma surgery patients, 13 (5.5%) and 21 (28%) patients, respectively, had tumoral epilepsy. Twenty-two patients were male and 18 tumors were in the left hemisphere. Tumoral epilepsy occurred predominantly in temporal (50%) and perirolandic (26.5%) locations. The etiology was WHO grade I tumors in 29%, grade II in 35%, and grade III in 33%. In the epilepsy group, following lesionectomy in three and tailored resections in the majority, seizure outcomes were Engel class I in all except one case. In the tumor group, after the initial operation seven additional resections were performed due to seizure recurrence. Outcomes in this group were Engel class 1A in 18 patients and 1B, 1C and IIA in 1 patient each. Drawing upon these data, we propose a classification of the likely reasons of failure in seizure control in patients with tumoral epilepsy. This review reiterates the concept that a complete resection of the lesion is the best approach for dealing with tumors presenting with epilepsy. Overall excellent outcomes can be accomplished following aggressive initial tumor resection, re-resection in the context of recurrence, and epilepsy style operations in selected patients with a longer history of seizures.

Rates and predictors of seizure freedom in resective epilepsy surgery: an update

Epilepsy is a debilitating neurological disorder affecting approximately 1 % of the world's population. Drug-resistant focal epilepsies are potentially surgically remediable. Although epilepsy surgery is dramatically underutilized among medically refractory patients, there is an expanding collection of evidence supporting its efficacy which may soon compel a paradigm shift. Of note is that a recent randomized controlled trial demonstrated that early resection leads to considerably better seizure outcomes than continued medical therapy in patients with pharmacoresistant temporal lobe epilepsy. In the present review, we provide a timely update of seizure freedom rates and predictors in resective epilepsy surgery, organized by the distinct pathological entities most commonly observed. Class I evidence, meta-analyses, and individual observational case series are considered, including the experiences of both our institution and others. Overall, resective epilepsy surgery leads to seizure freedom in approximately two thirds of patients with intractable temporal lobe epilepsy and about one half of individuals with focal neocortical epilepsy, although only the former observation is supported by class I evidence. Two common modifiable predictors of postoperative seizure freedom are early operative intervention and, in the case of a discrete lesion, gross total resection. Evidence-based practice guidelines recommend that epilepsy patients who continue to have seizures after trialing two or more medication regimens should be referred to a comprehensive epilepsy center for multidisciplinary evaluation, including surgical consideration.

Seizure outcomes of lesionectomy in pediatric lesional epilepsy with brain tumor -- single institute experience

PURPOSE

To determine the clinical characteristics, surgical strategy, and outcome in pediatric lesional epilepsy patients younger than 5years of age undergoing surgery in a single institute.

METHOD

Retrospective data were collected and analyzed on patients younger than 5years of age who underwent lesionectomy for lesional epilepsy at single institute from January 2001 to August 2010. Fourteen pediatric lesional epilepsy patients were enrolled in this study. Engel classification was used to classify seizure outcome.

RESULTS

Median preoperative seizure period was 1month (range, 1-21). Median post-operative follow up period was 35months (range 13-84). Ten patients who underwent gross total resection of tumor showed Engel class Ia seizure outcome without any antiepileptic drug (AED). Subtotal resection was performed in four patients to avoid eloquent area injury. Two of these four patients with subtotal removal became seizure-free (Engel class Ia) without AED, while two were in Engel class Ib with AED medication. There was no significant surgical morbidity or mortality.

CONCLUSION

Lesionectomy in children younger than 5years of age is relatively safe and effective in controlling seizures. Short preoperative seizure periods and total removal of tumor might be associated with good outcome. Therefore, early and complete lesionectomy alone may help allow for seizure freedom and optimal brain development in pediatric patients.

Chronic epilepsy due to low grade temporal lobe tumors and due to hippocampal sclerosis: do they differ in post-surgical outcome?

Chronic seizures as a presenting feature of low grade temporal lobe gliomas and hippocampal sclerosis (HS) are reported to have similar outcomes although the prognostic indicators may not be the same. This study seeks to identify the variables that are associated with poor surgical outcome in both conditions. A retrospective analysis from our epilepsy data base was performed. All low-grade temporal lobe gliomas were selected and relevant variables were compared to the same variables in HS patients. There were 34 tumors (out of 233 cases of chronic temporal lobe epilepsy = 14.6 %) with a mean age of onset of 19 years, and the preoperative duration was 12.3 years. When compared to 120 HS patients both of these factors were significantly different (p < 0.001). Age at the time of surgery for tumors was 31.08 (p = 0.5). Tumors were left sided in 20 patients. In tumor cases amygdala resection was complete in 75 %, for hippocampus 24 % were complete and 39 % partial. Astrocytoma, ganglioglioma and oligodendroglioma constituted 80 % of tumor cases. Good outcome (Engel's Class I) was achieved in 88.2 % of tumor cases and 71 % of HS cases while poor outcome (Class III + IV) was seen in 5.9 and 16.7 % respectively. The follow up period for the two groups was not significantly different. In multivariate logistic regression analysis, the groups differed significantly in preoperative delay (between diagnosis and surgery) and in epilepsy outcome. Chronic temporal lobe epilepsy due to low-grade tumors had significantly better surgical outcome with considerably less preoperative delay. The age of onset of seizures was younger in HS patients but a delay in surgical treatment was significantly longer. Given that the diagnosis of treatment-resistant TLE secondary to HS can be established after two failed AED trials at optimal doses, shortening the interval between diagnosis and surgery may improve epilepsy outcome.

Seizure control following radiotherapy in patients with diffuse gliomas: a retrospective study

BACKGROUND

Little information is available regarding the effect of conventional radiotherapy on glioma-related seizures.

METHODS

In this retrospective study, we analyzed the seizure response and outcome following conventional radiotherapy in a cohort of 43 patients with glioma (33 grade II, 10 grade III) and medically intractable epilepsy.

RESULTS

At 3 months after radiotherapy, seizure reduction was significant (≥ 50% reduction of frequency compared with baseline) in 31/43 patients (72%) of the whole series and in 25/33 patients (76%) with grade II gliomas, whereas at 12 months seizure reduction was significant in 26/34 (76%) and in 19/25 (76%) patients, respectively. Seizure reduction was observed more often among patients displaying an objective tumor response on MRI, but patients with no change on MRI also had a significant seizure reduction. Seizure freedom (Engel class I) was achieved at 12 months in 32% of all patients and in 38% of patients with grade II tumors. Timing of radiotherapy and duration of seizures prior to radiotherapy were significantly associated with seizure reduction.

CONCLUSIONS

This study showed that a high proportion of patients with medically intractable epilepsy from diffuse gliomas derive a significant and durable benefit from radiotherapy in terms of epilepsy control and that this positive effect is not strictly associated with tumor shrinkage as shown on MRI. Radiotherapy at tumor progression seems as effective as early radiotherapy after surgery. Prospective studies must confirm and better characterize the response to radiotherapy.

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.

Seizure outcome in surgically treated drug-resistant mesial temporal lobe epilepsy based on the recent histopathological classifications

OBJECT

The study was performed to investigate the relation between seizure outcome after surgical treatment of mesial temporal lobe epilepsy (MTLE) and pathological findings, classified according to the recently proposed classifications of mesial temporal sclerosis (MTS), granule cell pathology (GCP), focal cortical dysplasia (FCD) and epilepsy-associated low-grade tumors (ELGT).

METHODS

The authors analyzed data obtained in 120 consecutive cases involving patients presenting with drug-resistant MTLE, who underwent tailored anteromesial temporal lobe resection, and correlated seizure outcome with pathological findings. They identified 5 histopathological groups: Group 1-ELGT, alone or associated with other lesions (30 cases); Group 2-isolated FCD (17 cases); Group 3-MTS, with or without GCP (28 cases); Group 4-MTS associated with FCD, with or without GCP (37 cases); Group 5-other lesions (8 cases).

RESULTS

Engel Class I outcome was observed in 83% of patients with ELGT (Class IA in 63%); in 59% of patients with isolated FCD, with FCD Type II showing a better prognosis than FCD Type I; in 82% of patients with isolated MTS (Class IA in 50%), with MTS Type 1a and MTS Type 1b showing a better prognosis than MTS Type 2 and patients with MTS and GCP having better postsurgical results than those with MTS without GCP. Engel Class I outcome was also achieved in 84% of patients with FCD associated with MTS (Engel Class IA in 62%); also in this group MTS 1a and MTS 1b associated with FCD showed a better prognosis than FCD associated with MTS 2. Finally, Engel Class I was also achieved in 2 patients with vascular malformation and in 1 with a temporal pole encephalocele.

CONCLUSIONS

Patients with MTLE and ELGT, MTS, or MTS associated with FCD showed the best postsurgical seizure outcome (Engel Class I in more than 80% of cases), whereas only 63% of patients with isolated FCD achieved the same type of outcome. Interestingly, the analysis of seizure outcome in histopathological subtypes of FCD and of MTS showed different prognoses in the different pathological subgroups, with worse outcomes for atypical MTS, absence of GCP, and isolated FCD Type I.

Clinical value of the first dedicated, commercially available automatic injector for ictal brain SPECT in presurgical evaluation of pediatric epilepsy: comparison with manual injection

The most challenging technical problem in ictal brain SPECT for localization of an epileptogenic focus is obtaining a timely injection of a radiopharmaceutical. In our institution, the first dedicated commercially available, remotely controlled automatic injector has been used in the pediatric epilepsy unit in conjunction with 24-h video and electroencephalogram monitoring. The goal of this study was to demonstrate the improved success rate of ictal injection by use of the automatic injector in the pediatric population.

METHODS

Eighty-four pediatric patients and eighty-four (99m)Tc-ethylcysteinate dimer ((99m)Tc-ECD) ictal brain SPECT studies were retrospectively analyzed in a masked manner. The group with manual injection consisted of 45 studies performed from 2004 to 2010 before the introduction of the automatic injector. The group with automatic injection consisted of 39 studies performed from 2010 to 2011 after the introduction of the automatic injector. The 2 groups were comparable in the total duration of seizure, injected dose, and time from the injection to the image acquisition. The latency time from the seizure onset to the initiation time of injection, the ratio of latency time to total duration of seizure (L/T), the number of patients with repeated studies, the number of days of additional hospitalization for each study, and the localization rate for identifying a single focus in each study were compared between the groups.

RESULTS

The median latency time in the group with automatic injection (8 s) was significantly lower than that of the group with manual injection (18 s) (P < 0.05). Also there was a statistically significant decrease in the number of patients with repeated studies in the group with automatic injection (2/39 [5%]), compared with the group with manual injection (14/45 [31%]) (P < 0.05). The median number of days of additional hospitalization in the group with manual injection (range, 0-7) was statistically significantly different, compared with the group with automatic injection (range, 0-1) (P < 0.05). In the group with automatic injection, 31 of 39 scans demonstrated a single localizing focus, compared to 22 of 45 scans from the manual-injection group, a significant difference (P < 0.05). The radiation exposure rate to nursing staff during the periods with automatic injection was lower than during the periods with manual injection.

CONCLUSION

The automatic injector combined with 24-h video and electroencephalogram monitoring demonstrated significant clinical value by decreasing latency time, the number of patients with repeated studies, and the number of days of additional hospitalization while increasing the number of studies with a single localizing focus.

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.