Rethinking Seizure Care Blog

Scalp EEG Findings Could Improve Prediction of Epilepsy Surgery Outcomes

Posted by RSC Diagnostics on Oct 1, 2021

Female doctor holding tablet with blue background and informative graphs and charts

A study published in August of 2020 in Epilepsia: Official Journal of the International League Against Epilepsy delves into the role of scale electroencephalography (EEG) to help predict the outcomes of epilepsy surgery. The data that was gathered helped the researchers to create a nomogram that could help to predict seizure freedom.

The Methods Used for The Study

This was a retrospective study that looked into the scalp EEG findings and clinical data of patients who had undergone surgery for their seizures. The information was gathered from three different epilepsy centers.

The researchers used clinical variables and EEG variables that they then categorized into six interaction terms and 13 isolated candidate predictors to create a “multivariable Cox proportional hazards model to predict seizure freedom two years after surgery.”

The team used Harrell’s step-down procedure to eliminate the variables that were deemed the least informative from the model “until the change in the concordance index with variable removal was less than 0.01.” They also created a separate model with only the clinical variables. “Discrimination of the two models was compared to evaluate the role of scalp EEG in seizure-freedom prediction.”

What Were The Results?

The researchers analyzed 470 patient records. After internal validation, the full clinical and EEG model “achieved an optimism-corrected c-index of 0.65.” The model that did not have the EEG data had a c-index of 0.59. They found that certain issues would predict a worse outcome. This includes the absence of hippocampal sclerosis, the presence of nonlocalizable seizures, high preoperative seizure frequency, and focal bilateral tonic-clonic seizures.

Interestingly, when there was a presence of focal bilateral tonic-clonic seizures, there was the biggest impact for predicting the outcome. They found that by analyzing the models’ interactions, the patients with unilateral interictal epileptiform discharges had a better outcome with temporal lobe surgery.

When there were bilateral interictal epileptiform discharges, abnormal MRIs would predict worse outcomes. When there were no interictal epileptiform discharges, patients with extratemporal epilepsy and abnormal MRI still had better outcomes.

What Does This Mean for The Future?

The study shows just how important scalp EEG can be when it comes to helping patients who have epilepsy. EEGs are used in a wide variety of ways today and using them to help predict surgical outcomes can be a major benefit. The nomogram can provide an individual prediction of the outcome after the operation. It gives doctors and patients a better idea of whether surgery is the right choice.

People Worry About Surgery Outcomes

Many people who have epilepsy and who are unable to receive relief through the use of anti-seizure medications consider surgery. Of course, surgery also makes many people nervous and they are unsure of whether it will provide them with the help and relief they need. Having a way to better predict the potential outcome of the surgical procedures can be helpful for the doctors and patients. They can determine whether it will be a good option for them or not.

More Research in The Field is Always Important

There is still so much that we do not understand when it comes to epilepsy and seizures. The research that was done by this team has helped to push things forward when it comes to the benefits of using basic scalp EEG findings to help with predicting surgical outcomes.

However, there still needs to be more research into epilepsy to get a better sense of how to best treat the condition for all patients, including those who may not be good candidates for getting surgery.




Topics: Epilepsy Studies