By: Mohammad Hassan Bagheri, MD Candidate, Vahid Kermani, MD, Amir Bahador Boroumand, MD, and Milad Shafizadeh, MD
Photo Credit: The Defeating Epilepsy Foundation
Mohammad Hassan Bagheri is an MD Candidate at Tehran University of Medical Sciences (TUMS) and a neurological researcher at Shariati Hospital and Iman Khomeini Hospital Complex (IKHC). Vahid Kermani, MD, is a neurosurgeon. Amir Bahador Boroumand, MD, is an Assistant Professor of Emergency Medicine at Isfahan University of Medical Sciences and the Head of the Emergency Department at Al-Zahra Hospital. Milad Shafizadeh, MD, is an Assistant Professor of Neurosurgery at Shariati Hospital and Tehran University of Medical Sciences. The Defeating Epilepsy Foundation thanks Mohammad, Dr. Kermani, Dr. Boroumand, and Dr. Shafizadeh for their expertise and the valuable information they provide to our community.
A seizure can sometimes be the first sign of a brain tumor. For people who already have a brain tumor, seizures may also develop during the course of the illness.
Not everyone with a brain tumor will have seizures. The risk varies depending on the type of tumor, where it is located, its biological characteristics, and other factors. A 2025 review found that the reported frequency of seizures varies widely among different types of brain tumors, ranging from about 10% to more than 80%.
For patients and families, understanding why seizures happen and how they are managed can make an already difficult diagnosis easier to navigate.
Why can a brain tumor cause seizures?
A seizure occurs when there is a sudden burst of abnormal electrical activity in the brain. A tumor can make nearby brain tissue more likely to produce this abnormal activity.
There is no single reason why this happens. Several processes may be involved, including pressure on surrounding brain tissue, changes in blood flow, inflammation, and changes in the chemicals that nerve cells use to communicate.
Inflammation appears to be an important part of this process. The area around a tumor can develop an inflammatory environment that makes nearby neurons more excitable. Changes in neurotransmitters, including increased excitatory signaling, may also contribute to seizure activity.
Tumor biology can matter as well. In gliomas, for example, mutations in the IDH1 and IDH2 genes have been associated with brain tumor-related epilepsy. Researchers are still working to understand how these molecular changes contribute to the development of seizures.
The underlying biology is complex, and not every mechanism has been fully established. Current research suggests that the relationship between the tumor and surrounding brain tissue can work in both directions, with tumor growth and abnormal neuronal activity influencing one another.
Does the type and location of the tumor matter?
Yes.
Seizures are particularly common in some gliomas and glioneuronal tumors. Tumor location is also important. Tumors involving the cerebral cortex are generally more likely to cause seizures than tumors located farther from the cortex.
The 2025 review reports that tumors involving the frontal and temporal lobes are more often associated with seizures, while tumors in the occipital lobe appear to have a lower seizure risk.
Location alone, however, cannot tell doctors whether an individual patient will have a seizure. It is one part of a much larger picture.
What factors can increase seizure risk?
Doctors consider several factors when assessing the likelihood of seizures.
Tumor location
Tumors involving or close to the brain’s cortex, particularly in areas such as the frontal and temporal lobes, are more likely to be associated with seizures.
Tumor type and molecular features
The likelihood of seizures differs among tumor types. In gliomas, certain molecular characteristics, including IDH mutations, have been associated with tumor-related epilepsy.
Tumor size
Tumor size may also play a role, although the relationship is not the same for every type of brain tumor. In some tumors, larger lesions have been associated with a higher seizure risk.
Swelling around the tumor
Peritumoral edema, or swelling in the brain tissue surrounding a tumor, can make the surrounding brain more susceptible to abnormal electrical activity. The review identifies edema as an important risk factor, particularly in some patients with meningioma.
Previous seizures
A history of seizures before brain tumor surgery is also associated with a greater likelihood of seizures afterward. Tumor progression and incomplete tumor removal can also affect seizure recurrence.
What might a seizure look like?
A seizure does not always involve falling down or shaking throughout the body.
Depending on where abnormal electrical activity begins, a person may experience changes in awareness, unusual movements, or other symptoms. Some seizures can be subtle and may look like a brief period of staring or unusual behavior.
If you notice a new or unexplained episode, tell the medical team. A family member or caregiver’s description can be particularly useful because a person may not remember everything that happened during a seizure.
The exact type of seizure matters because it can provide information about where in the brain the abnormal electrical activity may be starting.
Can treating the tumor help control seizures?
Sometimes.
When a tumor is contributing to seizures, treating the tumor may also improve seizure control. Surgery is an important example. For patients who are appropriate candidates, removing as much of the tumor as can safely be removed may improve both tumor control and seizure outcomes. The Society for Neuro-Oncology consensus review notes that gross total resection is favored when feasible from both an oncologic and epilepsy perspective.
The 2025 review reports that approximately 60% to 90% of patients who had seizures before brain tumor surgery may become seizure-free after surgery. This is a broad range, however, and outcomes vary according to tumor type, location, extent of resection, and other patient-specific factors. It should not be interpreted as a prediction for an individual patient.
Other cancer treatments can also affect seizure activity. The evidence regarding radiation and chemotherapy is not uniform across all tumor types. For example, the review describes more supportive evidence for seizure control after treatment in lower-grade gliomas, while findings in glioblastoma have been inconsistent.
Radiation can also occasionally contribute to seizures through treatment-related changes in brain tissue. This is one reason seizure symptoms need to be considered alongside the patient’s tumor status and treatment history.
What role do anti-seizure medications play?
If a person with a brain tumor has a seizure, an anti-seizure medication (ASM) is generally an important part of treatment.
Choosing the medication is not simply a matter of selecting the strongest drug. Doctors consider seizure type, other medical conditions, possible side effects, and interactions with cancer treatments. The Society for Neuro-Oncology emphasizes that drug-drug interactions are particularly important in people receiving treatment for brain tumors.
Medications that have fewer interactions with other drugs are often preferred in this setting. Levetiracetam, for example, is commonly used because of its relatively low potential for drug interactions, although it is not necessarily the best choice for every patient.
The goal is not only to stop seizures but also to find a treatment that the person can tolerate without adding unnecessary side effects or interfering with other aspects of cancer care.
Does everyone with a brain tumor need an anti-seizure medication?
No.
For people with a brain tumor who have never had a seizure, routine preventive treatment with an anti-seizure medication is generally not recommended. The available evidence has not shown a clear benefit from giving these medications simply because a person has a brain tumor or is undergoing brain tumor surgery.
The decision can be different for an individual patient when specific circumstances increase concern about seizure risk. Your treating team can explain why medication is or is not being recommended in your situation.
If you are already taking an anti-seizure medication, do not stop or change the dose without discussing it with your doctor.
What if seizures continue despite medication?
Some people continue to have seizures despite taking medication. This may be described as drug-resistant epilepsy.
In these situations, the treatment plan may need to be reassessed. Doctors may review the seizure history, brain imaging, tumor status, and current medications. They may also consider whether the tumor itself needs additional treatment or whether another epilepsy treatment could be appropriate.
For selected patients, particularly those with a clearly identifiable seizure-producing area, surgery or another procedure may be considered. The decision depends heavily on the tumor’s location, type, the patient’s overall health, and whether the area responsible for the seizures can be treated safely.
Because brain tumor-related epilepsy is not identical in every patient, current expert recommendations emphasize an individualized approach rather than a single treatment strategy for everyone.
What happens to seizures after brain tumor surgery?
Surgery can improve seizures, but it does not guarantee that they will stop.
The amount of tumor that can safely be removed, the tumor’s location, whether the tumor later progresses, and whether the patient had seizures before surgery can all affect seizure control afterward.
If seizures continue or a new seizure develops after surgery, it is important to tell your medical team. A change in seizure activity can sometimes provide useful information about the tumor or the surrounding brain tissue.
When should I contact my medical team?
Let your doctor know if you experience:
- A first seizure
- More frequent seizures than usual
- A change in what your usual seizures look or feel like
- New episodes of unexplained staring, confusion, or loss of awareness
- New movements or sensations that you cannot explain
- Seizures that continue despite taking your medication as prescribed
If a seizure is prolonged or repeated without the person returning to their usual level of awareness, emergency medical evaluation may be needed.
Your healthcare team can also help you and your family create a seizure action plan so that everyone knows what to do if a seizure occurs.
What should patients and families remember?
Having a brain tumor does not mean that a person will necessarily develop seizures. The risk depends on several factors, including the type and location of the tumor, its biological characteristics, swelling around the tumor, and whether seizures have occurred previously.
When seizures do occur, treatment usually involves addressing both problems: controlling the seizures and treating the underlying tumor. Anti-seizure medications are an important part of care for patients who have experienced seizures, while routine preventive medication is generally not recommended for people who have never had one.
The most important thing is to keep your medical team informed about changes in seizure activity. New or worsening seizures may require a review of medications, imaging, tumor status, or the overall treatment plan.
Brain tumor-related epilepsy can be complicated, but it can also be managed. Working with a team that understands both neuro-oncology and epilepsy can help ensure that seizure control, tumor treatment, side effects, and quality of life are considered together.
Sources
Avila EK, et al. Brain tumor-related epilepsy management: A Society for Neuro-oncology (SNO) consensus review on current management. Neuro-Oncology. 2024;26(1):7-24. doi:10.1093/neuonc/noad154.
Dantio CD, Fasoranti DO, Teng C, Li X. Seizures in brain tumors: pathogenesis, risk factors and management (Review). International Journal of Molecular Medicine. 2025;55(5):82. doi:10.3892/ijmm.2025.5523.
