Seizures Resulting From Brain Tumors

A seizure is often the earliest sign of this diagnosis

Not all people with a brain tumor experience abnormal electrical activity in their brain known as seizures. But for those who do, a seizure is often the first symptom of the disease—and what jump-starts the process that leads to tumor diagnosis. The type of brain tumor and its location factor into why some people are more vulnerable to experiencing related seizures than others.

MRI scanning procedure.
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Seizures can be frequent and continue throughout treatment for a brain tumor and can, among other things, compromise your independence and overall quality of life. In some cases, seizures can pose additional—and significant—health dangers.

Seizures are often the first clinical sign of a brain tumor. Headaches are common with brain tumors, but studies show that it is actually a seizure or other neurological symptom that usually appears first.

How Brain Tumors Cause Seizures

Seizures are sudden, abnormal electrical impulse activity in the brain.

Tumor-related seizures happen because of the excessive firing of the neurons in and around the tumor. While it is not known why certain tumors cause seizures, some factors might include the location, the type of tumor, genetic factors, and the integrity of the blood-brain barrier (a network of blood vessels and tissue that protects the brain from toxins, supplies nutrients to brain tissues, and filters harmful substances from the brain back into the bloodstream).

The frequency of seizures can depend on whether a brain tumor is primary (at the site where it originiated) or metastatic (having spread from a tumor elsewhere in the body). Seizures also are more common in people with low-grade gliomas (the most common type of brain tumor in adults) than in high-grade types. Where the tumor is located is another major factor. In general, brain tumors close to the brain's surface are more likely to cause seizures.

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Types of Brain Tumors and Seizures

Various characteristics of brain tumors can affect seizure type and frequency. One of these characteristics is the type of brain tumor it is. The types of tumors and their chances of causing seizures include:

  • Neurogliomas and gangliogliomas: 80% to 100%
  • Oligodendrogliomas: 70% to 90%
  • Diffuse low-grade gliomas: 60% to 85%
  • Glioblastomas (GBMs): 40% of people with GBMs present with epilepsy, and 20% develop seizures later

Seizures are common in low-grade gliomas, when cancer cells tend to look normal. They act as an early warning sign of the presence of a brain tumor and, because of this, prognosis (likely outcome) tends to be good.

Recognizing a Brain Tumor-Related Seizure

A tumor-related seizure can cause different symptoms in different people. Generally speaking, a seizure can cause physical changes such as:

  • Twitching and convulsions
  • Staring
  • Momentary loss of bowel control and incontinence
  • Loss of consciousness

Other symptoms of a brain-tumor related seizure can include:

  • Intense emotions
  • Numbness or tingling sensations
  • Strange smells or tastes
  • Muscle stiffness or twitching
  • Hallucinations
  • Wandering around
  • Smacking lips or chewing on them
  • Trouble speaking or understanding words
  • Crying out or laughing uncontrollably
  • The feeling of déjà vu

The severity of brain tumor symptoms is not related to how large a tumor is. Rather, location, tumor type, and grade are key factors in severity of symptoms.

This is especially true when it comes to seizures. Tumors in one part of the brain may cause a more severe type of seizure than in another part of the brain even though the tumor may be smaller and the cancer less advanced than a tumor in another location that's not causing seizures.

Partial seizures (i.e., those that affect only part of the brain) without loss of consciousness tend to be most common in cases in which seizures persist.

Seizures are very serious and should never be ignored or left unreported to a physician. If you suspect you have had a seizure and are uncertain, report it to your healthcare provider immediately.

Treating Brain Tumor-Related Seizures

Whether a person with a brain tumor has had one or 100 seizure episodes, controlling and preventing seizure activity is an essential part of their treatment.

In most cases, the seizures themselves do not pose a great health risk (unless they last for several minutes or more).

Medications

Tumor-related seizures may be controlled with anticonvulsants or antiepileptic medications. Due to the high rate of seizure activity with brain tumors, the use of these drugs usually is standard in people with certain types of brain tumors. Commonly prescribed medications include:

Not everyone requires medication to prevent or control seizures—only patients who meet certain criteria. And even in people who fit the criteria, seizures can be resistant to medication.

Treating the tumor by reducing its size or removing it is a more effective (and sometimes permanent) solution to controlling seizures.

Summary

Not everyone who has a brain tumor has seizures, but seizures can be one of the first signs of a brain tumor. The seizures that occur can vary in intensity, frequency, and characteristics, depending on the type of brain tumor and its location, among other things.

Treating, managing, and working to prevent seizures are cornerstones of brain cancer treatment. This can be done through medications or by surgery. You and your healthcare team can work together to find a treatment plan that is best for you, given the course of your disease, symptoms, and prognosis.

A Word From Verywell

Seizures don't always behave the way you think they might. If you notice occasions of abnormal, uncontrollable symptoms, such as twitching, experiencing hallucinations, or staring, see your healthcare provider. They can examine you and assess you for a brain tumor. Living with a brain tumor can feel uncertain, but your treatment team can be a source of information, reassurance, and connection.

Frequently Asked Questions

  • What types of brain tumors cause seizures?

    A variety of brain tumors can cause seizures, including neurogliomas, gangliogliomas, oligodendrogliomas, and glioblastomas.

  • Can brain tumor-related seizures go away over time?

    They typically don't go away over time, but they may be able to be managed through medication or surgery.

  • What tests are done to diagnose brain tumor-related seizures?

    Often times the seizure is the first symptom, and in order to find out why the seizures are occurring, imaging tests are done like a CT (computed tomography) scan or MRI (magnetic resonance imaging).

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Originally written by Lisa Fayed