What seizure-causing abnormalities can MRI show?
Tumors Overall, brain tumors are a relatively rare cause of new seizures. Tumors are found in about 4% of all such patients but they may be found in 10% or more of middle-aged people. Seizures are the first symptom of 33% to 38% of brain tumors and occur in over half of patients by the time the tumor is found. Many different types of tumors commonly cause seizures. They are labeled astrocytomas, oligodendrogliomas, mixed tumors (tumors with both astrocytic and oligodendroglial elements), gangliogliomas, harmartomas, and dysembryoplastic neuroepithelial tumors. On MRI, these tumors tend to be small and clearly limited, with little or no swelling or fluid around them. They are most often found in the frontal or temporal lobes, usually in the cortex (the outer layer, the “gray matter”). They may affect the inner layer of the bones of the cranium. Their appearance on MRI varies, and it is difficult to determine the precise type of tumor from an MRI scan alone. A biopsy or other surgical pr
