Glioneuronal tumors (GNTs) are a set of tumors of the Central Nervous System (CNS) composed entirely or partially of cells with neuronal differentiation. The description applies to several tumors referred to in the Classification of the World Health Organization (WHO) as neuronal and mixed neuronal-glial tumors. Some of them arise tipically in the cerebral cortex and represent a common cause of drug-resistant focal epilepsies in children and young adults. Three groups of tumors are of considerable relevance: Ganglion cell tumors (GCTs), ganglioglioma (GG) being the typical example, dysembryoplastic neuroepithelial tumors (DNTs) and neurocytic tumors, namely extraventricular neurocytoma. GNTs commonly arise from a cortex housing developmental malformations, that are able to provoke seizures, such as focal cortical dysplasia (FCD) and, less frequently, hyppocampal sclerosis (HS). Management of patients with GNTs includes dealing with both tumor and epilepsy. From the neuro-oncological point of view, consistently with the long clinical history, these tumors are generally considered as low-grade gliomas (LGGs). They correspond to grades I or II of the WHO classification and their therapy relies mainly on surgery. However, tumor progression or transformation into higher grade tumors may occur. From the neurological point of view, it is noteworthy that seizures are likely to respond very well to surgical treatment. Despite the favorable seizure outcome, the best surgical strategy has not been fully established yet. Indeed, while some authors regard tumor resection (the so-called lesionectomy) alone as sufficient for complete seizure control, other investigators also recommend the additional resection of peritumoral epileptogenic zones to maximize the seizure outcome. Anyway, surgical treatment should be planned on the basis of anatomo-electro-clinical correlation defining the epileptogenic zone to be resected. To conclude, in patients with GNTs-related epilepsies, surgery should be proposed in order to obtain complete seizure control with freedom from antiepileptic drugs (AEDs), and to prevent tumor growth and risk of malignant transformation.
Glioneuronal tumors and epilepsy: Clinico-diagnostic features and surgical strategies
Morana G;
2015-01-01
Abstract
Glioneuronal tumors (GNTs) are a set of tumors of the Central Nervous System (CNS) composed entirely or partially of cells with neuronal differentiation. The description applies to several tumors referred to in the Classification of the World Health Organization (WHO) as neuronal and mixed neuronal-glial tumors. Some of them arise tipically in the cerebral cortex and represent a common cause of drug-resistant focal epilepsies in children and young adults. Three groups of tumors are of considerable relevance: Ganglion cell tumors (GCTs), ganglioglioma (GG) being the typical example, dysembryoplastic neuroepithelial tumors (DNTs) and neurocytic tumors, namely extraventricular neurocytoma. GNTs commonly arise from a cortex housing developmental malformations, that are able to provoke seizures, such as focal cortical dysplasia (FCD) and, less frequently, hyppocampal sclerosis (HS). Management of patients with GNTs includes dealing with both tumor and epilepsy. From the neuro-oncological point of view, consistently with the long clinical history, these tumors are generally considered as low-grade gliomas (LGGs). They correspond to grades I or II of the WHO classification and their therapy relies mainly on surgery. However, tumor progression or transformation into higher grade tumors may occur. From the neurological point of view, it is noteworthy that seizures are likely to respond very well to surgical treatment. Despite the favorable seizure outcome, the best surgical strategy has not been fully established yet. Indeed, while some authors regard tumor resection (the so-called lesionectomy) alone as sufficient for complete seizure control, other investigators also recommend the additional resection of peritumoral epileptogenic zones to maximize the seizure outcome. Anyway, surgical treatment should be planned on the basis of anatomo-electro-clinical correlation defining the epileptogenic zone to be resected. To conclude, in patients with GNTs-related epilepsies, surgery should be proposed in order to obtain complete seizure control with freedom from antiepileptic drugs (AEDs), and to prevent tumor growth and risk of malignant transformation.
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