Autoimmune causes of seizures and epilepsy

A seizure is a sudden change in behaviour, movement, and/or consciousness due to abnormal electrical activity in the brain.

While 1 in 10 people will have a seizure during their lifetime, only around 1 in 100-200 will develop epilepsy, which means having repeated seizures over time.

There are many causes of seizures and epilepsy. However, it is only relatively recently that it has been found that the body’s own defence system can be a cause.

Discovering autoimmune encephalitis (AE)

Sometimes the body’s immune system mistakenly attacks its own brain, causing it to become inflamed.

This condition is called autoimmune encephalitis (AE) and was first understood by scientists in the late 2000s, when they found special proteins called antibodies in young women who had both encephalitis and a rare type of tumour.

In 2017, the International League Against Epilepsy (ILAE) officially added autoimmune conditions as a possible cause for seizures in some patients.

While it is uncertain how many people with regular epilepsy have an autoimmune cause, we do know that around 75% of people with AE will have at least one seizure during their illness.

Methods of treatment

The main approach to treatment for seizures due to AE is to calm down the immune system by immunotherapy. If a tumour is found, it needs to be removed.

Doctors also prescribe regular anti-seizure medications to help control seizures while the immune system treatment takes effect.

Advances in treatment

Recent years have seen significant progress in identifying and treating patients with seizures secondary to AE.

• Scientists have found several antibodies that can attack the brain.
• Doctors can test for antibodies when AE is suspected.
• Specific brain wave patterns have been identified using electroencephalography (EEG).
• Risk factors for epilepsy have been identified such as longer delays to immunotherapy.
• Certain anti-seizure medications have been identified as ore efficacious in specific subtypes of AE.

A brighter future

Scientists are currently running at least two major studies to understand how different immunotherapies work for the two most common types of AE. These studies are important because immunotherapy remains the backbone of treating seizures caused by AE.

Overall, we have made remarkable progress in understanding and treating seizures caused by autoimmune conditions. The goal now is to continue this momentum and make even more discoveries to improve patient outcomes. This includes improving ways to diagnose the condition and developing more effective treatments.

By Julien Hébert, MDCM, MSc, FRCPC
Assistant Professor of Medicine (Neurology), University of Toronto

For more information on seizures and encephalitis, click here.