PHOENIX - Mayo Clinic researchers have detected measurable changes in the brain within 18 minutes of deep brain stimulation (DBS) in people with drug-resistant epilepsy, a finding that could eventually help clinicians personalize treatment without waiting months to determine whether stimulation settings are effective. The study was recently published in iScience.
DBS is approved by the Food and Drug Administration as a therapy for certain patients with drug-resistant epilepsy. Electrical pulses delivered through electrodes implanted in the brain can help reduce seizures. But finding the most effective stimulation settings can require months or even years of adjustments.
"One of the biggest questions we have when we stimulate the brain with therapeutic devices is: Are these the right settings for the person sitting across from me?" says Jonathon Parker, M.D., Ph.D., a Mayo Clinic neurosurgeon in Arizona and senior author of the study. "Right now, we may have to wait months to see whether a patient's seizures improve. We're trying to find a brain signal that could eventually give us that information much earlier."
Listening to the brain's response
The study included nine adults with drug-resistant focal epilepsy who were undergoing intracranial electroencephalogram (EEG) monitoring at Mayo Clinic as part of their clinical care. Researchers examined how communication between the thalamus and other areas of the brain changed before and after short periods of stimulation.
They compared two stimulation patterns, which Dr. Parker likens to the difference between two drummers. Conventional stimulation resembles a drumline playing a steady, predictable beat. Nonperiodic stimulation is more like a jazz drummer, with beats arriving at less predictable intervals.
Researchers found that the two stimulation patterns affected brain communication differently. Those changes were particularly evident in the connections between the thalamus and areas of the brain's frontal lobe.
"That was one of our aha moments," Dr. Parker says. "Different stimulation patterns can change the way the thalamus communicates with other areas of the brain. The brain is telling us something when we stimulate it. We're developing the tools to understand if that response can predict future reduction of seizures."
From months of waiting to measurable signals
For epilepsy, determining whether DBS is effective can be particularly challenging. Seizure reduction can take months to emerge, and seizures occur intermittently, making it difficult to assess treatment success soon after stimulation settings are changed.
The findings suggest that measurable changes in brain connectivity may provide an earlier, objective signal of how the brain is responding to stimulation.
Researchers say the next step is to determine whether the brain responses they measured are associated with long-term seizure reduction and clinical improvement.
The Mayo Clinic team has expanded this research beyond the nine participants in the published study and is investigating whether information gathered could eventually be captured using less invasive methods.
"The goal is to take what we can learn from these very highly precise recordings and determine the minimum amount of information we need to understand the brain's response to stimulation," Dr. Parker says. "Ultimately, we want to translate this measurement into something noninvasive and useful to clinicians and patients."
Researchers are also exploring how machine learning and artificial intelligence could help clinicians interpret brain signals and guide stimulation settings. Any predictive algorithms would require prospective validation before clinical use, Dr. Parker notes.
Patients make the research possible
Dr. Parker credits the patients with drug-resistant epilepsy who volunteered for the study while undergoing invasive brain monitoring.
"The patients are the true heroes," he says. "They're volunteering their time to be part of these studies and helping create a path toward better care for patients in the future."
The research was funded in part by funds from the Neurosurgery Research and Education Foundation (NREF).
For a complete list of authors, disclosures and funding, review the study.
