Dysembryoplastic neuroepithelial tumour (DNT). Is the mechanism of seizures related to glutamate? An immunohistochemical study.

Dysembryoplastic neuroepithelial tumour (DNT) is a rare low-grade, mixed neuronal and glial tumour, usually associated with pharmacologically intractable, complex partial or generalised seizures which date from childhood. The prognosis after surgery is favourable. We present a classic case of DNT occurring in an 18-year-old male, who presented simple partial seizures without signs of raised intracranial pressure. CT and MR demonstrated focal mass located in the right temporal lobe. Histologically there were found the features of a typical DNT architecture with mixed cellular composition. The response to surgery was excellent. The tumour has not recurred, and the control of seizures remained good. Immunostaining for glutamate receptor GluR-2 showed stronger immunopositivity in neurones dispersed within the tumour and especially in margins of lesion as compared with apparently normal cerebral cortex. The expression of both excitatoryamino acid transporterproteins EAAT1 and EAAT2 was weaker then in normal cortex and uneven. This perhaps may explain the mechanism of seizures (elevated glutaminergic stimulation), and may suggest the excitotoxic damage of neurones.

[Pathomechanism and clinical presentation of neurobehavioral disturbances in a patient with MELAS syndrome]. / Patomechanizm i obraz kliniczny zaburzen neurobehawioralnych u pacjentki z zespolem MELAS.

The authors present the results of a longitudinal study of the neurobehavioral disturbances seen in K.S., a 22-year-old female patient with a mitochondrial cytopathy (MELAS) caused by the novel mutation C8293T. K.S. became ill in 1994 at the age of 16. She was referred for diagnosis to several different clinics. Four years after onset, the clinical diagnosis was established in the Department of Medical Rehabilitation at the Cracow Rehabilitation Center; the diagnosis was not confirmed until six years after onset, following the discovery of the mutation in the patient's mtDNA at Columbia University. Since 1996 the patient has presented with progressive dementia and periodic stroke-like episodes that produced fluctuating neurological symptoms. The essential pathomechanism of the neurobehavioral disturbances consists in the fragmentation of complex cerebral processes into their constituent elements; individual functions are frequently correctly executed on a lower level of cerebral organization, but the patient is unable to combine them into a sensible whole. The authors discuss the theoretical and clinical significance of the results presented here.