Why are seizures a symptom of gliomas?

Brain damage.: Gliomas are tumors of the brain. They arise from glial cells, which are part of the support structure of the brain. As the tumors enlarge, they press on and irritate brain cells. That can make the normal brain cells give off electical impulses, and if there is too much activity, involving too many cells, a seizure will occur.

Gliomas: Gliomas are tumors of the support cells for neurons. Neurons rely on these support cells for metabolism of the neurotransmitters. We do not fully understand the development of seizures in brain tumors, but it is likely that these seizures are caused by dysfunction of neurons due to the metabolic derangements of these tumors.