Patients affected by glioma frequently suffer of epileptic discharges, however the causes of brain tumor-related epilepsy (BTRE) are still not completely understood. We investigated the mechanisms underlying BTRE by analyzing the effects of exosomes released by U87 glioma cells and by patient-derived glioma cells. Rat hippocampal neurons incubated for 24 h with these exosomes exhibited increased spontaneous firing, while their resting membrane potential shifted positively by 10-15 mV. Voltage clamp recordings demonstrated that the activation of the Na + current shifted towards more hyperpolarized voltages by 10-15 mV. To understand the factors inducing hyperexcitability we focused on exosomal cytokines. Western Blot and ELISA assays show that TNF-a is present inside glioma-derived exosomes.Remarkably, incubation with TNF-a fully mimicked the phenotype induced by exosomes, with neurons firing continuously, while their resting membrane potential shifted positively. RT-PCR revealed that both exosomes and TNF-a induced over-expression of the voltage-gated Na channel Nav1.6, a low-threshold Na + channel responsible for hyperexcitability. When neurons were preincubated with Infliximab, a specific TNF-a inhibitor, the hyperexcitability induced by exosomes and TNF-a were drastically reduced. We propose that Infliximab, an FDA approved drug to treat rheumatoid arthritis, could ameliorate the conditions of glioma patients suffering of BTRE.