Dysembryoplastic neuroepithelial tumors and gangliogliomas: clinical results of 52 patients

Seizure outcome in surgically treated pediatric gangliogliomas and dysembryoplastic neuroepitheliomas according to imaging and resection strategies

PURPOSE

Imaging and resection strategies for pediatric gangliogliomas (GG) and dysembryoplastic neuroepitheliomas (DNET) presenting with epilepsy were retrospectively analyzed in a consecutive institutional series of surgically treated patients.

METHODS

Twenty-two children (median 8 years, 3-18 years) presented with seizures for 30 months median (14-55.2 months) due to a histologically verified GG/DNET.

RESULTS

There were 20 GG and 2 DNT, 68 % located temporal, 32 % extra-temporal. Seizure history was significantly longer in temporal cases (38 versus 14 months median, p < 0.01). MRI contrast enhancement was present in 50 % and methionine (MET) positron emission tomography (PET) uptake in 70 % (standard uptake values (SUVs) 2.92 mean, from 1.6 to 6.4). 27 % had glucose PET hypometabolism. Primarily, in temporal GG, ECoG (electrocorticography) -guided lesionectomies were performed in 87 % and antero-mesial temporal lobe resections (AMTLR) in 13 %, whereas in extra-temporal GG/DNETs, lesionectomies were performed in 100 %. ILAE Class 1 seizure outcome was primarily achieved in 73 % of the temporal cases, and was increased to 93 % by performing six repeat surgeries using AMTLR. Extratemporal patients experienced ILAE Class 1 seizure outcomes in 86 % without additional surgeries, although harboring significantly more residual tumor (p < 0.005, mean follow-up 28 months).

CONCLUSION

In children, MET PET imaging for suspected GG is proposed preoperatively showing a high diagnostic sensitivity and an option to delineate the lesions for navigated resection, whereas MRI contrast behavior was of no differential diagnostic use. As a surgical strategy we propose primarily lesionectomies for extratemporal but AMTLR for temporal GG respecting eloquent brain areas.

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.

MR-Guided Focused Ultrasound for Refractory Epilepsy: Where Are We Now?

Epilepsy is one of the most common neurological diseases in both adults and children. Despite improvements in medical care, 20 to 30% of patients are still resistant to the best medical treatment. The quality of life, neurologic morbidity, and even mortality of patients are significantly impacted by medically intractable epilepsy. Nowadays, conservative therapeutic approaches consist of increasing medication dosage, changing to a different anti-seizure drug as monotherapy, and combining different antiseizure drugs using an add-on strategy. However, such measures may not be sufficient to efficiently control seizure recurrence. Resective surgery, ablative procedures and non-resective neuromodulatory (deep-brain stimulation, vagus nerve stimulation) treatments are the available treatments for these kinds of patients. However, invasive procedures may involve lengthy inpatient stays for the patients, risks of long-term neurological impairment, general anesthesia, and other possible surgery-related complications (i.e., hemorrhage or infection). In the last few years, MR-guided focused ultrasound (MRgFUS) has been proposed as an emerging treatment for neurological diseases because of technological advancements and the goal of minimally invasive neurosurgery. By outlining the current knowledge obtained from both preclinical and clinical studies and discussing the technical opportunities of this therapy for particular epileptic phenotypes, in this perspective review, we explore the various mechanisms and potential applications (thermoablation, blood-brain barrier opening for drug delivery, neuromodulation) of high- and low-intensity ultrasound, highlighting possible novel strategies to treat drug-resistant epileptic patients who are not eligible or do not accept currently established surgical approaches. Taken together, the available studies support a possible role for lesional treatment over the anterior thalamus with high-intensity ultrasound and neuromodulation of the hippocampus via low-intensity ultrasound in refractory epilepsy. However, more studies, likely conceiving epilepsy as a network disorder and bridging together different scales and modalities, are required to make ultrasound delivery strategies meaningful, effective, and safe.

Glioneuronal and Neuronal Tumors of the Central Nervous System

Glioneuronal and neuronal tumors (GNTs) are rare neoplasms composed of neural and glial elements frequently located in the temporal lobe. Epilepsy is the main symptom and diagnosis mostly occurs before adulthood. The great majority of GNTs are WHO grade I tumors, but anaplastic transformations and forms exist. Their common association with focal cortical dysplasia is well recognized and should be taken into consideration during neurophysiological presurgical and surgical planning since the aim of surgery should be the removal of the tumor and of the entire epileptogenic zone according to anatomo-electrophysiological findings. Surgery still remains the cornerstone of symptomatic GNT, while radiotherapy, chemotherapy, and new target therapies are generally reserved for anaplastic, unresectable, or evolving tumors. Furthermore, since many GNTs show overlapping clinical and neuroradiological features, the definition of specific histopathological, genetic, and molecular characteristics is crucial. Epileptological, oncological, neurosurgical, and pathological issues of these tumors make a multidisciplinary management mandatory.

The long-term surgical outcomes of low-grade epilepsy-associated neuroepithelial tumors

OBJECTIVE

This study aimed to evaluate the surgical outcomes and relevant prognostic factors in patients with low-grade epilepsy-associated neuroepithelial tumors (LEAT) and, especially, to develop a scoring system to predict postoperative seizure outcomes.

METHODS

The clinical data of patients who underwent epilepsy surgery for LEAT were retrospectively studied. The surgical outcomes of seizure and neurological statuses in patients were evaluated using Engel classification and modified Rankin Scale (mRS) scoring, respectively. A scoring system of seizure outcomes was constructed based on the weight of the β-coefficient estimate of each predictor in the final multivariate predicting model of seizure outcomes.

RESULTS

Of the 287 patients (106 female) enrolled, the median age was 19 years at surgery and 10 years at seizure onset, with a median duration of epilepsy of 60 months. Among 258 patients who were followed up for at least 12 months, 215 (83.3%) patients had a favorable seizure outcome (Engel class I) after surgery, and 43 (16.7%) patients had an unfavorable seizure outcome; longer duration of epilepsy, discordant magnetoencephalography (MEG) findings, and acute postoperative seizures were significantly included in the scoring system to predict unfavorable seizure outcomes, and in the scoring system, accumulated scoring of 0-19 scores was recorded, which were finally grouped into three risk levels: low risk (risk < 30%), medium risk (30% ≤ risk < 70%), and high risk (risk ≥ 70%). In addition, favorable neurological outcomes (mRS score 0-1) were recorded in 187 (72.5%) patients, while unfavorable neurological outcomes were recorded in 71 (27.5%) patients, which were significantly related to poor seizure control, older age at surgery, and longer duration of epilepsy and hospitalization time.

SIGNIFICANCE

The long-term surgical outcomes of LEAT after surgery were satisfactory. A scoring system for predicting unfavorable seizure outcomes with different risk levels was developed, which could partly guide clinical treatments of LEAT.

Seizure outcomes and prognostic factors in patients with gangliogliomas associated with epilepsy

Introduction

Ganglioglioma (GG) patients often present with seizures. Although most patients can be seizure-free after tumor resection, some still experience seizures. The present study aimed to analyze a group of GGs patients associated with epilepsy and evaluate the seizure outcomes and prognostic factors.

Methods

This retrospective study involved clinical data collected from medical records of patients diagnosed with GG pathologically and underwent surgical resection in Sanbo Brain Hospital, Capital Medical University. The seizure outcomes were evaluated based on the International League Against Epilepsy (ILAE) seizure outcome classification. The prognostic factors were identified according to univariate and multivariate analysis.

Results

A total of 222 patients were included, with a mean age at surgery of 19.19 ± 10.93 years. All patients were followed up at least for one year with a mean follow-up duration of 6.28 ± 3.17 years. At the final follow-up, 174 (78.4%) patients achieved ILAE Class 1 or 2. Univariate and multivariate analyses revealed that the short duration of seizures and gross total resection were significant positive factors for seizure-free. Bilateral interictal or ictal epileptiform discharges in preoperative video-electroencephalogram (VEEG) were related to poor seizure outcomes.

Conclusion

Surgical resection is an effective treatment for patients with epilepsy associated with GGs. The analysis of predictive factors could effectively guide clinical practice and evaluate the prognosis of epilepsy with GG.

Dysembryoplastic neuroepithelial tumours: clinical, radiological, pathological features and outcome

OBJECT

To analyse the clinical, imaging and histopathological data of patients who were diagnosed to have Dysembrioplastic Neuroepithelial Tumour (DNET) and underwent surgery between 1995-2015.

MATERIALS AND METHODS

Age at seizure onset, age at surgery, gender, disease duration, seizure outcome of 44 patients were analysed together with Magnetic Resonance Imaging (MRI) of 21 patients. MRI types were classified as type 1 (cystic/polycystic-like, well-delineated, strongly hypointense T1), type 2 (nodularlike,heterogeneous), type 3 (dysplastic-like, iso/hyposignal T1, poor delineation, gray-white matter blurring).

RESULTS

Histopathological classification revealed simple form in 19, complex in 14 and non-specific in 11 patients. Lobar distribution of the lesions was as follows: 21 Temporal (47.7%), 12 parietal (27.3%), 8 frontal (18.2%) and 3 occipital (6.8%). Type 1 MRI was observed in 10, type 2 was in 7, and type 3 in 4 patients on radiological evaluation. All cases with type 1 MRI corresponded to either simple or complex forms and all cases with type 3 MRI corresponded to nonspecific form. The histopathological distribution of cases with type 2 MRI was 4 as non-specific, 2 as simple, 1 as complex. There was no significant difference in the age of onset, age at operation and duration of epilepsy between the patients with different MRI subtypes. The majority of patients (N:36) had Engel I outcome (81,8%). In groups with Engel II and III outcome, duration of epilepsy was significantly higher (p:0,014) and simple form of DNET has significantly higher seizure freedom after surgery compared to complex and nonspecific forms of DNET (p:0,002).

CONCLUSION

Patients with DNET constitute a group with favorable outcomes after epilepsy surgery especially with early referral to surgery. Longer duration of epilepsy was associated with worse seizure outcome for DNET patients. There was significant correlation between radiological and histopathological types of DNET especially in type 1 and 3.

Glioneuronal tumors of cerebral hemisphere in children: correlation of surgical resection with seizure outcomes and tumor recurrences

OBJECT

Glioneuronal tumors are common neoplasms among the cerebral hemisphere during childhood. They consist of several histological types, of which gangliogliomas (GGs) and dysembryoplastic neuroepithelial tumors (DNTs) are most common and often present with seizures. A great majority of glioneuronal tumors are benign. However, there are conflict reports regarding postoperative tumor recurrence rates and seizure control. The authors analyzed and compared these tumors for their locations and histology and the tumor and seizure control following resection.

METHODS

The authors conducted a retrospective analysis of patients with pediatric glioneuronal tumors in the cerebral hemisphere. All histology reports and neuroimaging are reviewed. Seizure group and non-seizure group were compared with their tumor types and locations. The extent of tumor resections were divided into gross total resection (GTR) and subtotal resection (STR). Postoperative tumor recurrence-free survival (RFS) and seizure-free survival for patients who had the initial surgery done at our institution were calculated using Kaplan-Meier method.

RESULTS

There were 90 glioneuronal tumors including 58 GGs, 22 DNTs, 3 papillary glioneuronal tumor, 3 desmoplastic infantile gangliogliomas, 3 anaplastic GGs, and 1 central neurocytoma. Seventy-one patients (seizure group) presented with seizures. The temporal lobe is the most common location, 50 % in this series. GTR was attained in 79 patients and STR in 11. All of the patients with GTR had lesionectomy, and only six of them had extended corticectomy or partial lobectomy. Postoperative seizure outcome showed that 64 (90 %) of seizure group had Engel's class I, but five patients subsequently developed recurrent seizures. Patients with DNTs had a higher seizure recurrence rate. Tumor RFS was 87 % at 5 years and 75.5 % at 10 years. There are no significant difference in tumor recurrences between GGs and DNTs (p = 0.876). Comparison between GRT (67) and STR (9) showed that in spite of the better 5-year tumor RFSs among GRT group (94 %) than STR group (66 %), the 10-year RFSs showed no significant difference between GRT and STR groups (p = 0.719). Recurrent seizures are often related to recurrent tumor.

CONCLUSION

Lesionectomy alone often provides a high-rate seizure freedom. GGs and DNTs are benign tumor, but recurrences of GGs and DNTs are not uncommon. They may show late recurrences in spite of GTR. These patients need longer follow-up for 10 years. Recurrent seizures are often related to a tumor recurrence.

Rare glial tumors

This chapter describes the epidemiology, pathology, molecular characteristics, clinical and neuroimaging features, treatment, outcome, and prognostic factors of the rare glial tumors. This category includes subependymal giant cell astrocytoma, pleomorphic xanthoastrocytoma, astroblastoma, chordoid glioma of the third ventricle, angiocentric glioma, ganglioglioma, desmoplastic infantile astrocytoma and ganglioma, dysembryoplastic neuroepithelial tumor, papillary glioneuronal tumor, and rosette-forming glioneuronal tumor of the fourth ventricle. Many of these tumors, in particular glioneuronal tumors, prevail in children and young adults, are characterized by pharmacoresistant seizures, and have an indolent course, and long survival following surgical resection. Radiotherapy and chemotherapy are reserved for recurrent and/or aggressive forms. New molecular alterations are increasingly recognized.

Review of seizure outcomes after surgical resection of dysembryoplastic neuroepithelial tumors

Dysembryoplastic neuroepithelial tumors (DNETs) are rare tumors that present with seizures in the majority of cases. We report the results of a review of seizure freedom rates following resection of these benign lesions. We searched the English literature using PubMed for articles presenting seizure freedom rates for DNETs as a unique entity. Patient demographics, tumor characteristics, and operative variables were assessed across selected studies. Twenty-nine articles were included in the analysis. The mean age at surgery across studies was a median of 18 years (interquartile range 11-25 years). The mean duration of epilepsy pre-operatively was a median 7 years (interquartile range 3-11 years). Median reported gross-total resection rate across studies was 79% (interquartile range 62-92%). Authors variously chose lesionectomy or extended lesionectomy operations within and across studies. The median seizure freedom rate was 86% (interquartile range 77-93%) with only one study reporting fewer than 60% of patients seizure free. Seizure outcomes were either reported at 1 year of follow-up or at last follow-up, which occurred at a median of 4 years (interquartile range 3-7 years). The number of seizure-free patients who discontinued anti-epileptic drugs varied widely from zero to all patients. Greater extent of resection was associated with seizure freedom in four studies.

Seizure Freedom Rates and Prognostic Indicators After Resection of Gangliogliomas: A Review

Gangliogliomas are rare tumors that comprise up to 40% of lesional epilepsy. Seizure control represents an important quality-of-life determinant in patients with these tumors. Here we present results of a literature review addressing rates of seizure freedom in in patients with gangliogliomas. Across studies, seizure freedom occurred in 63%-100% of patients. Many studies included follow-up times of greater than 5 years, suggesting that the responses are durable. We discuss potential prognostic factors associated with seizure freedom, including the duration of epilepsy, patient age, frequency and semiology of seizures, tumor location, extent of surgical resection, and operative strategy, including surgical approach and use of invasive monitoring. Although significant differences in study populations and treatments preclude meta-analysis, we discuss prognostic factors identified in individual studies. Increased extent of resection, lesser duration of epilepsy, and younger age at surgery have been associated with increased seizure freedom rates in at least 2 studies each. Although all studies were retrospective in nature and are consequently limited by the weaknesses inherent to such investigations, the literature suggests that surgery is able to relieve most ganglioglioma patients--regardless of patient demographics, tumor characteristics, and operative variables--of seizures.

Epilepsy associated tumors: Review article

Long-term epilepsy associated tumors (LEAT) represent a well known cause of focal epilepsies. Glioneuronal tumors are the most frequent histological type consisting of a mixture of glial and neuronal elements and most commonly arising in the temporal lobe. Cortical dysplasia or other neuronal migration abnormalities often coexist. Epilepsy associated with LEAT is generally poorly controlled by antiepileptic drugs while, on the other hand, it is high responsive to surgical treatment. However the best management strategy of tumor-related focal epilepsies remains controversial representing a contemporary issues in epilepsy surgery. Temporo-mesial LEAT have a widespread epileptic network with complex epileptogenic mechanisms. By using an epilepsy surgery oriented strategy LEAT may have an excellent seizure outcome therefore surgical treatment should be offered early, irrespective of pharmacoresistance, avoiding both the consequences of uncontrolled seizures as well as the side effects of prolonged pharmacological therapy and the rare risk of malignant transformation.

BRAF V600E mutations are frequent in dysembryoplastic neuroepithelial tumors and subependymal giant cell astrocytomas

BACKGROUND

BRAF mutation has received a great deal of attention in neuro-oncology field, recently. This study aimed to investigate the incidence and the clinical significance of BRAF(V600E) in low-grade glial tumors.

METHODS

An institutional cohort of 105 brain tumors (51 dysembryoplastic neuroepithelial tumors (DNTs), 14 subependymal giant cell astrocytomas (SEGAs), 12 glioblastoma with neuronal marker expression (GBM-N), and 28 pleomorphic xanthoastrocytomas (PXAs)) from 100 patients were investigated for the presence of BRAF(V600E) by direct sequencing.

RESULTS

We found frequent BRAF(V600E) in DNTs (26/51, 51%), SEGAs (6/14, 42.9%), and PXAs (14/28, 50%). In DNTs, BRAF(V600E) was more commonly detected in tumors with extra-temporal location (68.2% vs. 37.9%; P = 0.032). The diagnostic subgroups of tuberous sclerosis complex were not correlated with BRAF(V600E) in patients with SEGA (P = 0.533). One PXA case revealed a unique duplication mutation (p.Thr599dup) of codon 599. All GMB-N cases did not carry BRAF mutation.

CONCLUSIONS

Our data indicate that BRAF(V600E) is a common genetic alteration in low-grade glial tumors with neuronal component or differentiation. High frequency of BRAF(V600E) in DNTs and SEGAs would be useful in the differential diagnosis, and also offers a potential specific treatment targeting BRAF(V600E) .

Invasive EEG studies in tumor-related epilepsy: when are they indicated and with what kind of electrodes?

Patients with tumor-related epilepsy (TRE) represent an important proportion of epilepsy surgery cases. Recently established independent negative predictors of postoperative seizure outcome are long duration of epilepsy, presence of generalized tonic-clonic seizures, and incomplete tumor resection. In temporal lobe cases, additional hippocampectomy or corticectomy may further improve outcome. Invasive electroencephalography (EEG) recordings (IEEG) may be indicated to guide the resection by defining eloquent cortex (EC) or to determine the extent of potentially magnetic resonance imaging (MRI)-negative epileptogenic tissue. In fact, invasive recordings are reportedly used in up to 10% of patients who are undergoing epilepsy surgery for TRE. Following careful consideration of the concepts underlying epilepsy surgery, the current use of IEEG, and the predictors of outcome in extratemporal and temporal tumors in TRE, we postulate the following> (1) In patients with extratemporal TRE, IEEG is necessary only if the MRI lesion (and if feasible a rim around it) cannot be completely resected because of adjacent or overlapping EC. In these cases, EC should be mapped to determine its relationships to the lesion, the irritative, and seizure-onset zones in order to maximize the extent of the lesionectomy. (2) In patients with nondominant temporal TRE, data suggest that if epileptogenic tumors (ETs) are encroaching on mesial temporal structures, if epilepsy duration is long, and seizures are frequent and disabling, these structures should be included in the resection. (3) In patients with dominant temporal TRE, we suggest leaving the mesial structures in place if they are functionally and structurally intact and to consider resecting these structures only if they are structurally and functionally abnormal. There is insufficient evidence justifying the use of IEEG to define the extent of the epileptogenic zone in such cases. This should be reserved for cases where an initial lesionectomy has failed.

Efficacy of vagus nerve stimulation as a treatment for medically intractable epilepsy in brain tumor patients. A case-controlled study using the VNS therapy Patient Outcome Registry

PURPOSE

Vagus nerve stimulation (VNS) therapy is a procedure to control seizure frequency in patients with medically intractable epilepsy. However, there is no data on efficacy in the subset of these patients with brain tumors. The purpose of this study is to evaluate the efficacy of VNS therapy in patients with brain tumor-associated medically intractable epilepsy.

METHODS

Data from the VNS therapy Patient Outcome Registry, maintained by the manufacturer of the device, Cyberonics Inc. (Houston, TX, USA), was queried to characterize the response of patients in whom a brain tumor was listed as the etiology of epilepsy. A case-control analysis was implemented and patient outcome was measured by Engel classification, median seizure response and responder rate (≥50% seizure reduction) using t-tests and chi-squared tests.

RESULTS

In 107 patients with an epilepsy etiology related to a brain tumor, seizure reduction was 45% at 3 months and 79% at 24 months with a responder rate of 48% at 3 months and 79% at 24 months. There was no statistical difference in seizure reduction compared with 326 case-control patients from the registry without brain tumors. There was no significant difference in anti-epileptic drug (AED) usage from baseline to 24 months post implant in either group.

CONCLUSIONS

VNS therapy is equally effective in patients who suffer seizures secondary to brain tumors as in patients without history of a brain tumor. VNS therapy is a viable treatment option for patients with brain tumor associated medically intractable epilepsy, assuming cytoreductive and other adjuvant therapies have been fully explored.

Systematic review and case series of neuropsychological functioning after epilepsy surgery in children with dysembryoplastic neuroepithelial tumors (DNET)

RATIONALE

The purposes of this study were to 1) conduct a review of neuropsychological (NP) outcomes after epilepsy surgery for DNET and 2) present pre/post-surgical NP results from a series of children with DNET.

METHODS

First, a systematic literature review was conducted with specific inclusion criteria. Second, a review of DNET surgical patients seen at two tertiary-care hospitals using reliable change methods of NP functioning was conducted.

RESULTS

Of 300 citations retrieved, 7 studies met criteria. Studies reported low average to average pre-surgical IQ. Engel Class I outcome was approximately 85%.

CASE SERIES

Thirteen children completed pre/post-surgical NP assessments. Pre-surgically, children demonstrated low average to average functioning. Post-surgically, few patients showed reliable change. One-third of children demonstrated psychological improvement.

CONCLUSIONS

NP outcome following DNET has not been well-described. Children with DNET demonstrate low average to average NP functioning pre-surgically, good seizure outcome, and stable NP functioning post-surgically.

Epileptogenic brain lesions in children: the added-value of combined diffusion imaging and proton MR spectroscopy to the presurgical differential diagnosis

PURPOSE

Focal cortical dysplasia (FCD), dysembryoplastic neuroepithelial tumors (DNTs), and gangliogliomas (GGs) share many clinical features, and the presurgical differential diagnosis of these lesions using conventional magnetic resonance imaging (MRI) is challenging in some cases. The purpose of this work was thus to evaluate the capacity of diffusion-weighted imaging (DWI) and proton magnetic resonance spectroscopy (MRS) to distinguish each lesion from the others.

METHODS

Seventeen children (mean age 9.0 ± 4.7 years), who had been referred for epilepsy associated with a brain tumor and operated, were selected. Preoperative MRI examinations were performed on a 1.5 T system and included anatomical images [T2-weighted, fluid-attenuated inversion recovery (FLAIR) and T1 pre- and post-injection images] as well as DWI and MRS [echo time (TE) = 30 and 135 ms]. Apparent diffusion coefficient (ADC) values were calculated in the lesion and healthy control. MRS relative quantification consisted in normalizing each metabolite by the sum (S) of all metabolites (S(TE=135 ms) = NAA+Cr+Cho; S(TE=30 ms) = NAA+Cr+Cho+Glx+mI). Univariate and multivariate analyses were performed in order to determine which criteria could differentiate the different epileptogenic brain lesions.

RESULTS

When taken alone, none of the MRI parameters was able to distinguish each disease from the others. Conventional MRI failed classifying two patients. When adding ADC to the linear discriminant analysis (LDA), one patient was still misclassified. Complete separation of the three groups was possible when combining conventional MRI, diffusion, and MRS either at long or short TE.

CONCLUSION

This study shows the added-value of multimodal MRI and MRS in the presurgical diagnosis of epileptogenic brain lesions in children.

One hundred and one dysembryoplastic neuroepithelial tumors: an adult epilepsy series with immunohistochemical, molecular genetic, and clinical correlations and a review of the literature

Simple and complex forms of dysembryoplastic neuroepithelial tumors (DNTs) are readily recognizable but forms with diffuse growth pattern, and hybrid tumors, that is, mixed DNT and ganglioglioma (DNT/GG), are more contentious entities. Rare DNTs have shown aggressive behavior. We reviewed cortical growth patterns, immunophenotype (including CD34, nestin and calbindin), genetic profile, and outcome in 101 DNT in adults. Simple (n = 18), complex (n = 31), diffuse (n = 35) DNT, and mixed DNT/GG (n = 17) showed no difference in age of onset, associated seizure type, or outcome (67.5% free from seizure; mean follow-up, 6 years). CD34 was seen in 61%, calbindin in 57%, and nestin in 86% of all DNT types; these markers were less common in simple DNT. Peritumoral cortical changes (Layer I hypercellularity [61%], satellite nodules [51.6%]) were frequent, but dyslamination (cortical dysplasia) was not identified. Molecular genetic abnormalities identified in 17 cases were IDH1 mutation (n = 3), 1p/19q loss (n = 10), isolated loss 9q (n = 2), and PTEN loss (n = 3), which were not associated with tumor type or location, higher cell proliferation, or distinguishing clinical features (mean age of epilepsy onset, 9 years; age at surgery = 31 years; 69% free from seizure); none had progression on magnetic resonance imaging (mean follow-up, 6 years). No single feature was predictive of seizure-free outcome, but there was a trend for better outcome in CD34-positive tumors (p = 0.07). One case has shown transformation to a higher grade. This study supports the existence of a range of subtypes of DNT some with overlapping features with ganglioglioma; molecular genetic abnormalities were not predictive of atypical behavior.

Pediatric temporal low-grade glial tumors: epilepsy outcome following resection in 48 children

PURPOSE

This paper summarizes our experience with surgical treatment of pediatric low-grade glial temporal lobe tumors focusing on the long-term outcome of seizures and identifying factors associated with seizure control and failure.

METHODS

We reviewed all medical records of pediatric patients that underwent temporal lobe surgery due to seizures at our institution between 1997 and 2009. Only patients with temporal lobe tumors were included in this series. The files were retrospectively reviewed for seizure history. All children had undergone pre- and postoperative evaluation, neurological examination, EEG, and MRI.

RESULTS

The cohort includes 48 children with mean follow-up time of 5.15 years (1-12 years). The mean age at surgery was 8.2 years (1-18.1) and the mean seizure duration until surgery was 2.6 years. All lesions in the cohort were low-grade tumors; pilocytic astrocytoma was the most common (41%). Eighty-three percent of the patients were classified as Engel class I following surgery. There was no correlation between Engel score and the preoperative epilepsy duration, age of seizure onset or type of seizures, and pathology. The surgical complication rate was 4.1% (2/48).

CONCLUSIONS

Surgical treatment for seizure control in children and adolescents with low-grade temporal tumors provides excellent long-term results.