Do Seizures Mean Brain Tumors?

Yes, a small percentage of seizures are caused by brain tumors. However, these brain-tumor-related seizures are different from the regular seizures that you get due to other causes of epilepsy.

Epilepsy has a predictable trajectory, for the most part going in one line, and then it improves with treatment. On the contrary, the trajectory of brain-tumor-related epilepsy is very volatile and is changing constantly.

Brain tumors can be divided into three main groups:

• Benign
• Malignant
• Secondary deposits

Benign brain tumors grow slowly while malignant brain tumors proliferate more aggressively. Secondary deposits are the result of cancer elsewhere which has seeded the bloodstream and deposited in the brain which is also called metastasis.

How do Brain Tumors Cause Seizures?

Firstly, as the tumor is growing in the brain it can cause physical irritation to the surrounding brain tissue. This irritation can cause abnormal brain activity which leads to seizures.

Secondly, the brain tumor produces and releases various chemicals which can cause chemical irritation to the brain and cause seizures.

Further, and more interestingly, when scientists researched the genetics of these tumors they found that mutations in a gene called Isocitrate Dehydrogenase (IDH) cause the release of an enzyme that causes seizures.

What do Brain-Tumor-Related Seizures Look Like?

The nature of brain-tumor-related seizures varies greatly depending on the site of the brain they affect. 

For example, if they affect the motor region of the brain you will get seizures with shaking of arms and legs which are called tonic-clonic seizures.

If they affect the sensory area of the brain, they will get altered sensations. If the tumor is growing in the area of the brain that governs vision, you will get visual symptoms like seeing stars.

Do We Need Anti-Seizure Medication to Prevent these Seizures?

The answer to this is no. This is a heavily researched question, and many authorities and guidelines recommend not using medication prophylactically, meaning to prevent seizures from happening in brain tumors. Tumor-related seizures cannot be prevented by giving anti-seizure medications, but they can be used to treat the seizure if it occurs or in special instances like around surgery for a short period of time, likely for a week. 

What is the Course of Tumor-Related Epilepsy?

Tumor-related seizures have a very dynamic nature. Usually, at the beginning of tumor genesis, there will be many seizure attacks due to the constant physical irritation of the brain tissue by the growing tumor.

When surgery is done the surrounding tissue is also damaged and it starts to heal. The healing process involves inflammation which causes irritation and further fitting. Then it gradually reduces.

After some time, surgery is augmented with further chemo- and radiotherapy to kill off any residual cancer cells.

Chemo- and radiotherapy will kill cancer cells and release various toxic substances into the brain environment which will cause seizures. This is treated with anti-seizure medication and the condition will improve.

Brain tumors, especially the aggressive types, are almost impossible to get rid of completely. Some number of cells is left behind despite the surgeon’s best efforts. This little amount can regrow and cause seizures again. 

The reappearance of seizures after some time in a diagnosed brain tumor patient can be an early sign of tumor regrowth. 

The more advanced the brain tumor is the harder it is to control the seizure. Nonetheless, the more advanced the tumor the more sensitive it is to antiseizure medications. Therefore, tumor-related seizures follow a very volatile course.

How Do We Treat Brain-Tumor-Related Seizures?

Our first focus is the quality of life of the patient, and we take a holistic approach. We consider how the seizures affect the patient’s life and how the medication affects the patient’s life and proceed accordingly.

If we plan any surgeries if there are no seizures associated with the brain tumor, we only remove the tumor seen in our scans. However, if the patient does have associated seizures, we extend beyond the tumor margins and remove that tissue as well as it is also affected.

Due to the dynamic nature of the tumor and associated seizures, our treatment plan must be dynamic as well. We must change our medication according to the seizure control and medications’ side effects.

We can increase or reduce the dose, add on drugs or switch the drugs to a different form. It is important to use drugs with different mechanisms of action when using multiple drugs to control seizures.

We must also be mindful of other drugs the patient is receiving and whether there are any associated interactions between them and the anti-epileptic drugs.

Chemotherapy drugs are degraded by the liver. Some anti-seizure drugs (e.g.: carbamazepine) can induce the liver enzymes leading to rapid degradation of chemotherapy drugs and some (e.g.: valproate) retard the function of the liver enzymes. 

Drugs like levetiracetam, topiramate, lamotrigine, lacosamide, pregabalin and zonisamide affect the liver minimally.

It is also important to consider the background of the patient before prescribing anti-epileptic medication. For example, levetiracetam (Keppra) causes changes in mood, depressive states, anxiety and anger as side effects. 

We must be mindful not to prescribe these drugs to patients with a psychiatric history or even to those with frontal lobe tumors who can have similar symptoms. Another similar drug which has many psychiatric side effects is perampanel.

A recently discovered effective drug is cenobamate, about which we have discussed in another article.