Neuropathological findings in intractable epilepsy: 435 Chinese cases

[Disseminated ependymal dysembryoplastic neuroepithelial tumor: a case report and literature review]

Dysembryoplastic neuroepithelial tumor (DNET) is a benign mixed neuronal-glial neoplasm (WHO grade 1). DNET is most often localized in temporal lobes and found in children and young people with epilepsy. There a few cases of DNET in ventricular system with dissemination along the ependyma in the world literature.

MATERIAL AND METHODS

We present a rare case of T1- and T2-negative ventricular system tumor. Only FIESTA imaging revealed dissemination with multiple focal lesions of the third ventricle, its bottom and lateral walls, anterior horns of lateral ventricles, cerebellar vermis, cervical and lumbar spinal cord.

RESULTS

The patient underwent transcortical endoscopic biopsy of the third ventricle tumor with simultaneous ventriculoperitoneal shunting. DNET was diagnosed, and radiotherapy was subsequently performed. Literature data on this issue were analyzed.

CONCLUSION

To date, disseminated forms of DNET are extremely rare. X-ray features and morphological results allow us to establish the correct diagnosis and determine further treatment strategy.

[Analysis of neural fragility in epileptic zone based on stereoelectroencephalography]

There are some limitations in the localization of epileptogenic zone commonly used by human eyes to identify abnormal discharges of intracranial electroencephalography in epilepsy. However, at present, the accuracy of the localization of epileptogenic zone by extracting intracranial electroencephalography features needs to be further improved. As a new method using dynamic network model, neural fragility has potential application value in the localization of epileptogenic zone. In this paper, the neural fragility analysis method was used to analyze the stereoelectroencephalography signals of 35 seizures in 20 patients, and then the epileptogenic zone electrodes were classified using the random forest model, and the classification results were compared with the time-frequency characteristics of six different frequency bands extracted by short-time Fourier transform. The results showed that the area under curve (AUC) of epileptic focus electrodes based on time-frequency analysis was 0.870 (delta) to 0.956 (high gamma), and its classification accuracy increased with the increase of frequency band, while the AUC by using neural fragility could reach 0.957. After fusing the neural fragility and the time-frequency characteristics of the γ and high γ band, the AUC could be further increased to 0.969, which was improved on the original basis. This paper verifies the effectiveness of neural fragility in identifying epileptogenic zone, and provides a theoretical reference for its further clinical application.

Anterior transtemporal endoscopic selective amygdalohippocampectomy: a virtual and cadaveric feasibility study

PURPOSE

Selective amygdalohippocampectomy (SelAH) is one of the most common surgical treatments for mesial temporal sclerosis. Microsurgical approaches are associated with the risk of cognitive and visual deficits due to damage to the cortex and white matter (WM) pathways. Our objective is to test the feasibility of an endoscopic approach through the anterior middle temporal gyrus (aMTG) to perform a SelAH.

METHODS

Virtual simulation with MRI scans of ten patients (20 hemispheres) was used to identify the endoscopic trajectory through the aMTG. A cadaveric study was performed on 22 specimens using a temporal craniotomy. The anterior part of the temporal horn was accessed using a tubular retractor through the aMTG after performing a 1.5 cm corticectomy at 1.5 cm posterior to the temporal pole. Then, an endoscope was introduced. SeIAH was performed in each specimen. The specimens underwent neuronavigation-assisted endoscopic SeIAH to confirm our surgical trajectory. WM dissection using Klingler's technique was performed on five specimens to assess WM integrity.

RESULTS

This approach allowed the identification of collateral eminence, lateral ventricular sulcus, choroid plexus, inferior choroidal point, amygdala, hippocampus, and fimbria. SelAH was successfully performed on all specimens, and CT neuronavigation confirmed the planned trajectory. WM dissection confirmed the integrity of language pathways and optic radiations.

CONCLUSIONS

Endoscopic SelAH through the aMTG can be successfully performed with a corticectomy of 15 mm, presenting a reduced risk of vascular injury and damage to WM pathways. This could potentially help to reduce cognitive and visual deficits associated with SelAH.

Case Report: Late-Onset Lennox-Gastaut Syndrome Treated With Stereotactic Electroencephalography-Guided Radiofrequency Thermocoagulation Before Craniotomy

The onset of Lennox-Gastaut syndrome (LGS), a severe epilepsy syndrome, is typically before 8 years of age. Late-onset LGS (with onset in adolescence and adulthood) is relatively rare clinically and has some differences from classical LGS. Herein, we describe the case of a patient with late-onset LGS and provide a literature review of such cases. The patient had focal epilepsy onset at 8 years of age. After a 9-year evolution, he suffered seizures of different types and had a diagnosis of late-onset LGS. Drug treatment was ineffective. Nothing was found on stereotactic electroencephalography (SEEG) and magnetic resonance imaging (MRI) during the course of the disease. After the second presurgical evaluation, we found a suspicious focus on high-resolution structural MRI which was verified by SEEG at last. After SEEG-guided radiofrequency thermocoagulation (RFTC), his seizures were controlled, and his cognitive function and quality of living clearly improved. However, his seizures recurred 2 years later, and he underwent left occipital resection. Thereafter, his seizures have been controlled until now. This case emphasizes the importance of high-resolution structural MRI in the treatment of LGS. Furthermore, it suggests that late-onset LGS may be caused by focal lesions and evolve from focal epilepsy. Thus, characterizing the clinical symptoms and performing individualized electroencephalographic follow-up are both very important. Additionally, the clinical outcome in this case implies the value and limitations of RFTC in patients with epilepsy and a clear focal lesion. Moreover, this case further supports differences between late-onset and classical LGS in terms of clinical manifestation, cognitive changes, prognosis, and treatment.

Integrated genotype-phenotype analysis of long-term epilepsy-associated ganglioglioma

The BRAF p.V600E mutation is the most common genetic alteration in ganglioglioma (GG). Herein, we collected a consecutive series of 30 GG specimens from Xuanwu Hospital in order to corroborate the genetic landscape and genotype–phenotype correlation of this enigmatic and often difficult‐to‐classify epilepsy‐associated brain tumor entity. All specimens with histopathologically confirmed lesions were submitted to targeted next‐generation sequencing using a panel of 131 genes. Genetic alterations in three cases with histologically distinct tumor components, that is, GG plus pleomorphic xanthoastrocytoma (PXA), dysembryoplastic neuroepithelial tumor (DNT), or an oligodendroglioma (ODG)‐like tumor component, were separately studied. A mean post‐surgical follow‐up time‐period of 23 months was available in 24 patients. Seventy seven percent of GG in our series can be explained by genetic alterations, with BRAF p.V600E mutations being most prevalent (n = 20). Three additional cases showed KRAS p.Q22R and KRAS p.G13R, IRS2 copy number gain (CNG) and a KIAA1549‐BRAF fusion. When genetically studying different histopathology patterns from the same tumor we identified composite features with BRAF p.V600E plus CDKN2A/B homozygous deletion in a GG with PXA features, IRS2 CNG in a GG with DNT features, and a BRAF p.V600E plus CNG of chromosome 7 in a GG with ODG‐like features. Follow‐up revealed no malignant tumor progression but nine patients had seizure recurrence. Eight of these nine GG were immunoreactive for CD34, six patients were male, five were BRAF wildtype, and atypical histopathology features were encountered in four patients, that is, ki‐67 proliferation index above 5% or with PXA component. Our results strongly point to activation of the MAP kinase pathway in the vast majority of GG and their molecular‐genetic differentiation from the cohort of low‐grade pediatric type diffuse glioma remains, however, to be further clarified. In addition, histopathologically distinct tumor components accumulated different genetic alterations suggesting collision or composite glio‐neuronal GG variants.

Our results strongly point to activation of the MAP kinase pathway in the vast majority of ganglioglioma (GG).

Composite genetic alterations were found in cases with histologically distinct tumor components firstly, i.e. GG plus pleomorphic xanthoastrocytoma (PXA), dysembryoplastic neuroepithelial tumor, or an oligodendroglioma‐like tumor.

Seizure recurrence is inclined to ganglioglioma with atypical histopathology features (i.e. GG containing a ki‐67 proliferation index above 5% or GG with PXA component).

Neuropathological spectrum of drug resistant epilepsy: 15-years-experience from a tertiary care centre

Neuropathology of drug resistant epilepsy (DRE) has direct bearing on the clinical outcome. Classification of the most common pathologies, hippocampal sclerosis (HS) and focal cortical dysplasia (FCD) have undergone several revisions and studies on the surgical pathology of DRE employing the updated ILAE classification are scarce. Here, we report the neuropathological spectrum of 482 surgically treated cases of DRE from a single institute using the latest ILAE classifications along with clinicoradiologic correlation. Majority of the cases (324, 67.2%) had temporal lobe epilepsy (TLE), with 158 (32.8%) having extratemporal seizure focus. Among TLE, HS was most common (n = 208, 64.2%), followed by neoplasms (42, 13%), FCD (26, 8%) and dual pathology (23, 7%). Less frequent were vascular malformations (cavernoma-3, arteriovenous malformation-1), mild malformation of cortical development (mMCD, 3), gliotic lesions (5), cysticercosis (2), double pathology (2) and polymicrogyria (1). Among extratemporal epilepsies, FCD was most common (46, 29.1%), followed by neoplasms (29, 18.3%), gliotic lesions (27, 17.1%), Rasmussen encephalitis (18, 11.4%), hypothalamic hamartoma (12, 7.6%), malformations of cortical development (10, 6.3%) and vascular malformations (6, 3.8%). Less frequent were double pathology (2, cysticercosis + FCD type IIb, DNET + FCD type IIb), mMCD (2), cysticercosis (1) and dual pathology (1). No underlying pathology was detected in 12 cases (2.5%). Radiopathological concordance was noted in 83%. In 36 cases (7.5%), histopathology detected an unsuspected second pathology that included FCD type III (n = 16) dual pathology (n = 18) and double pathology (n = 2). Further, in four MRI negative cases, histopathology was required for a conclusive diagnosis.

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.

Surgical histopathologic findings of 232 Chinese children cases with drug-resistant seizures

OBJECTIVES

The drug-resistant seizures are characterized by frequent and severe onset of seizures in childhood. There is only little literature had extensively explored the types of pathological brain damage in Chinese children cases. The present study aims to investigate the histopathologic findings and seizure outcomes of drug-resistant seizures in cases of 0-14-year-old children.

MATERIALS AND METHODS

About 232 children cases were retrospectively who underwent epilepsy surgery. The medical records, onset age, age of surgery, disease course, seizure type, pathological reports, and seizure outcomes of these patients were retrospectively analyzed.

RESULTS

The most common categories were malformations of cortical development (focal cortical dysplasia (FCD) was the most common type (94.36%, 67/71), found in 30.60% of the patients, tumors in 18.11%, glial scar in 12.50%, and encephalitis in 11.63%). It was found that the effective seizure outcome of FCD cases with shorter duration of epilepsy (<2 years, 87.23%) was better than that with longer duration (≥2 years, 60.00%) and the difference was statistically significant (χ²  = 4.76, p < .05). Patients with FCD I, FCD II, and tumor showed the relatively better postsurgical seizure outcome than patients with other pathological types.

CONCLUSION

The malformations of cortical development (MCD) (most FCD) were the most common pathological type for children cases in China with drug-resistant seizures. It was speculated further that the FCD patients with shorter duration of epilepsy before surgery seem to have a higher ratio of being seizure-free after surgery.

Use of an Automated Quantitative Analysis of Hippocampal Volume, Signal, and Glucose Metabolism to Detect Hippocampal Sclerosis

Purpose: Magnetic resonance imaging (MRI) and positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (¹⁸FDG) are valuable tools for evaluating hippocampal sclerosis (HS); however, bias may arise during visual analyses. The aim of this study was to evaluate and compare MRI and PET post-processing techniques, automated quantitative hippocampal volume (Q-volume), and fluid-attenuated inversion-recovery (FLAIR) signal (Q-FLAIR) and glucose metabolism (Q-PET) analyses in patients with HS.

Methods: We collected MRI and ¹⁸FDG-PET images from 54 patients with HS and 22 healthy controls and independently performed conventional visual analyses (CVA) of PET (CVA-PET) and MRI (CVA-MRI) images. During the subsequent quantitative analyses, the hippocampus was segmented from the 3D T1 image, and the mean volumetric, FLAIR intensity and standardized uptake value ratio (SUVR) values of the left and right hippocampus were assessed in each subject. Threshold confidence levels calculated from the mean volumetric, FLAIR intensity and SUVR values of the controls were used to identify healthy subjects or subjects with HS. The performance of the three methods was assessed using receiver operating characteristic (ROC) curves, and the detection rates of CVA-MRI, CVA-PET, Q-volume, Q-FLAIR, and Q-PET were statistically compared.

Results: The areas under the curves (AUCs) for the Q-volume, Q-FLAIR, and Q-PET ROC analyses were 0.88, 0.41, and 0.98, which suggested a diagnostic method with moderate, poor, and high accuracy, respectively. Although Q-PET had the highest detection rate among the two CVA methods and three quantitative methods, the difference between Q-volume and Q-PET did not reach statistical significance. Regarding the HS subtypes, CVA-MRI, CVA-PET, Q-volume, and Q-PET had similar detection rates for type 1 HS, and Q-PET was the most sensitive method for detecting types 2 and 3 HS.

Conclusions: In MRI or ¹⁸FDG-PET images that have been visually assessed by experts, the quantification of hippocampal volume or glucose uptake can increase the detection of HS and appear to be additional valuable diagnostic tools for evaluating patients with epilepsy who are suspected of having HS.

Intractable Epilepsy with Solitary Cerebral Calcification

Cerebral calcification is a common incidental finding upon brain imaging and its epileptogenicity is often underestimated. Here, we report a case of intractable epilepsy arising in conjunction with a solitary cerebral calcification. A 42-year-old male with intractable epilepsy was admitted to the epilepsy clinic for invasive epilepsy surgery. Brain magnetic resonance imaging revealed a slight high-intensity signal change in the right amygdala and a small, calcified lesion in the right lateral temporal region. The patient underwent invasive monitoring with subdural electrodes. He had five habitual seizures with automatisms and fast activity. These seizures initiated in the right lateral temporal area just above the solitary calcified lesion. Neuropathology of the calcified lesion showed no specific findings apart from a fibrocalcific nodule. Thus, although solitary cerebral calcifications may be an asymptomatic or coincidental finding in some patients, they may also have a highly epileptogenic focus.

Detection superiority of 7 T MRI protocol in patients with epilepsy and suspected focal cortical dysplasia

In 11 adult patients with suspicion of Focal cortical dysplasia (FCD) on 1.5 T (n = 1) or 3 T (n = 10) magnetic resonance imaging (MRI), 7 T MRI was performed. Visibility, extent, morphological features and delineation were independently rated and subsequently discussed by three observers. Additionally, head-to-head comparisons with corresponding 3 T images were made in the eight patients with a previous 3 T MRI and sustained suspicion of FCD. Comparison with histopathology was done in the five patients that underwent surgery. All lesions, seen at 1.5 and 3 T, were also recognized on 7 T. At 7 T FLAIR highlighted the FCD-like lesions best, whereas T2 and T2* were deemed better suited to review structure and extent of the lesion. Image quality with the used 7 T MRI setup was higher than the quality with the used 3 T MRI setup. In 2 out of 11 patients diagnosis changed, in one after re-evaluation of the images, and in the other based on histopathology. With the used 7 T MRI setup, FCD-like lesions can be detected with more confidence and detail as compared to lower field strength. However, concordance between radiologic diagnosis and final diagnosis seems to be lower than expected.

Dysembryoplastic Neuroepithelial Tumors

Dysembryoplastic neuroepithelial tumor (DNT) is a benign glioneuronal neoplasm that most commonly occurs in children and young adults and may present with medically intractable, chronic seizures. Radiologically, this tumor is characterized by a cortical topography and lack of mass effect or perilesional edema. Partial complex seizures are the most common presentation. Three histologic subtypes of DNTs have been described. Histologically, the recognition of a unique, specific glioneuronal element in brain tumor samples from patients with medically intractable, chronic epilepsy serves as a diagnostic feature for complex or simple DNT types. However, nonspecific DNT has diagnostic difficulty because its histology is indistinguishable from conventional gliomas and because a specific glioneuronal element and/or multinodularity are absent. This review will focus on the clinical, radiographic, histopathological, and immunohistochemical features as well as the molecular genetics of all three variants of DNTs. The histological and cytological differential diagnoses for this lesion, especially the nonspecific variant, will be discussed.

Expression Patterns of TRPC1 in Cortical Lesions from Patients with Focal Cortical Dysplasia

Focal cortical dysplasia (FCD) is known as a common cause of chronic refractory epilepsy, but the underlying mechanisms of the factors that lead to FCD-related epilepsy are unclear. Previous studies have shown that canonical transient receptor potential channels (TRPCs) might be involved in the process of epileptogenesis. Canonical transient receptor potential channel 1 (TRPC1), which is ubiquitously expressed in the brain, has been shown to be involved in epileptiform bust firing in knockout mice. In this study, we examined the expression of TRPC1 in FCD type Ia (FCDIa), FCD type IIa (FCDIIa), and FCD type IIb (FCDIIb) surgical specimens from patients and age-matched autopsy control samples. Real-time quantitative PCR and western blotting indicated that TRPC1 mRNA and protein levels were increased in FCDIa, FCDIIa, and FCDIIb samples compared to control samples. Immunohistochemistry results revealed that TRPC1 was mainly distributed in microcolumns, dysmorphic neurons, and balloon cells. Further double immunofluorescent staining showed that TRPC1 was co-localized with glutamatergic and GABAergic markers. Taken together, our results demonstrate that the overexpression and specific cellular location of TRPC1 might be related to the epileptogenesis of FCD.

Upregulation of RBFOX1 in the malformed cortex of patients with intractable epilepsy and in cultured rat neurons

Mutations in RNA-binding Fox 1 (RBFOX1) are known to be associated with neurodevelopmental disorders including epilepsy, mental retardation and autism spectrum disorder. The deletion of the Rbfox1 gene in mice has been shown to result in heightened susceptibility to seizures. However, other studies have revealed mutations or the downregulation of RBFOX1 in specimens obtained from patients with epilepsy or malformations of cortical development (MCD). Generally, the expression of RBFOX1 varies according to tissue type. In this study, we demonstrated the upregulation of RBFOX1 protein in the cortex of patients with MCD and intractable epilepsy. Electrophysiological recordings of cultured rat cortical neurons with increased Rbfox1 expression also revealed a significantly increased amplitude of action potential (AP) and Na⁺ current density. Some of these neurons (26.32%) even displayed spontaneous, recurrent, epileptiform discharges (SREDs). Additionally, certain Rbfox1 target transcripts associated with epilepsy, including glutamate receptor, ionotropic, N-methyl D-aspartate 1 [Grin1, also known as N-methyl-D-aspartate receptor subunit NR1 (NMDAR1)], synaptosomal-associated protein, 25 kDa (SNAP-25 or Snap25) and sodium channel, voltage gated, type VIII, alpha subunit (Scn8a, also known as Nav1.6) were identified to be upregulated in these cultured cortical neurons with an upregulated Rbfox1 expression. These data suggest that the upregulation of RBFOX1 contributes to neuronal hyperexcitation and seizures. The upregulation of NMDAR1 (Grin1), SNAP-25 (Snap25) and Scn8a may thus be involved in Rbfox1-related neuronal hyperexcitation.

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

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

Factors associated with preoperative and postoperative epileptic seizure in patients with cerebral ganglioglioma

OBJECTIVE

To explore the factors associated with preoperative epileptic seizure and surgical outcome in patients with cerebral gangliolioma (GG).

METHODS

A total of 31 consecutive patients with pathologically confirmed ganglioglioma and surgically treated from January 2003 to June 2011 in West China Hospital of Sichuan University were retrospectively reviewed. Clinical data, surgical procedure and follow-up information were collected and analyzed.

RESULTS

Nineteen patients presented with epileptic seizure, of which 63.2% were males. The mean age at epilepsy surgery and mean seizure duration were 25.6 years and 2.3 years respectively. Factors associated with preoperative epileptic seizure were supratentorial lesion and temporal lobe involvement (p=0.016 and 0.008). Intraoperative electrocorticography (ECoG) was applied in 8 out of 19 epilepsy patients. Eighteen achieved total tumor excision. After a mean follow up of 2.8 (1.3-6.3) years, 11 (68.8%, 11/16) achieved seizure free (Engel class I). Early surgery (seizure duration <3 years) was a significant predictor of favorable seizure outcome (p=0.013). None of the factors including seizure type, tumor location, neuroimaging characteristics and application of intraoperative ECoG or surgical strategy were found to be significantly associated with postoperative seizure outcome. Postoperative combination of AEDs was unnecessary for seizure control.

CONCLUSIONS

Ganglioglioma with temporal lobe involvement usually associated with intractable epilepsy. Early surgical resection is strongly suggested to achieve favorable outcome. Intraoperative ECoG is not inevitable and simple lesionectomy is sufficient for satisfactory seizure control. Early accurate diagnosis of ganglioglioma should be established on comprehensive consideration and plays an important role in dealing with these patients.

Recurrence and histological evolution of dysembryoplastic neuroepithelial tumor: A case report and review of the literature

Studies of recurrent dysembryoplastic neuroepithelial tumors (DNTs) are distinctly rare. The present study reports the case of a 15-year-old female with a temporal lobe DNT, which recurred and transformed into an astrocytoma (WHO grade II) five years after an initial gross total resection (GTR). Furthermore, all the previous studies on recurrent DNT are reviewed. Although the majority of DNT cases demonstrate benign behavior, recurrent DNTs have been observed following a GTR of the tumor. Patients do not appear to benefit from post-operative adjuvant therapy, and inappropriate radiotherapy or chemotherapy may result in tumor recurrence or malignant transformation. The prognosis is favorable if a GTR of the recurrent tumor is achieved. The use of regular imaging examinations and the maintenance of a long-term follow-up is of importance following a tumor resection.

Cortical dysplasia: a possible substrate for brain tumors

The similarities between brain tumor stem cells and neural stem cells suggest a possible stem cell origin of tumorigenesis. Recently, cells with features of stem cells have been observed in lesions of adult and pediatric cortical dysplasia (CD). Given the evidence for a close relationship between CD and certain brain tumors, together with the finding that CD neural stem cells/progenitors are abnormally developed, we propose that CD is a possible substrate for brain tumors. The neural stem cells/progenitors in CD have accumulating abnormalities, and these abnormal stem/progenitor cells may be the initiating, transformed cells of brain tumors, when subsequently exposed to a carcinogen.

Neuropathology of temporal lobe epilepsy

Pathologic findings in surgical resections from patients with temporal lobe epilepsy include a wide range of diagnostic possibilities that can be categorized into different groups on the basis of etiology. This paper outlines the various pathologic entities described in temporal lobe epilepsy, including some newly recognized epilepsy-associated tumors, and briefly touch on the recent classification of focal cortical dysplasia. This classification takes into account coexistent pathologic lesions in focal cortical dysplasia.

Stuttered swallowing: electric stimulation of the right insula interferes with water swallowing. A case report

Background

Various functional resonance imaging, magnetoencephalographic and lesion studies suggest the involvement of the insular cortex in the control of swallowing. However, the exact location of insular activation during swallowing and its functional significance remain unclear.

Case presentation

Invasive electroencephalographic monitoring was performed in a 24-year-old man with medically intractable stereotyped nocturnal hypermotor seizures due to a ganglioglioma. During stimulation of the right inferior posterior insular cortex with depth electrodes the patient spontaneously reported a perception of a "stutter in swallowing". Stimulation of the inferior posterior insular cortex at highest intensity (4 mA) was also associated with irregular and delayed swallows. Swallowing was not impaired during stimulation of the superior posterior insular cortex, regardless of stimulation intensity.

Conclusions

These results indicate that the right inferior posterior insular cortex is involved in the neural circuitry underlying the control of swallowing.