The study is one of the first to examine the responsive neurostimulation (RNS) system in children.
RNS has already been approved by the U.S. Food and Drug Administration for adult patients with drug-resistant epilepsy, but the research for safety and efficacy in children has been limited.
"As we expand use of RNS to children, it is critical to consider how to determine the lower age limit," said study author Dr. Yasunori Nagahama, director of pediatric epilepsy surgery at Rutgers Robert Wood Johnson Medical School in New Jersey.
"Considering this procedure involves removing a portion of the skull to implant the device, the benefits and potential harm based on the variable skull development in individual patients should be considered. Children experience rapid skull growth within the first two years and reach about 90% of adult skull volume by around age 8," Nagahama explained in a Rutgers news release.
"In this study, there were two patients under 7 years at the time RNS was implanted, including a 3-year-old, who was the youngest reported patient to undergo RNS implantation," he added.
Nagahama and his team looked at 35 children and young adults, ranging in age from 3 to 25, who were plagued by drug-resistant epilepsy and were treated with RNS. Afterwards, 84% of the patients saw a reduction in disabling seizures, including 18% who had a reduction of more than 90%, and 6% who achieved complete freedom from seizures.
RNS involves implanting a device (similar to a heart pacemaker) that sends electrical charges directly to the brain, stimulating it when needed to prevent seizures. This system is being increasingly used in pediatric centers to help control seizures.
Of those plagued by epileptic seizures, up to 40% don't respond to medication, the study authors noted.
As an alternative to medication, RNS works by monitoring brainwave activity to detect developing seizures or any unusual electrical activity that may trigger seizures. The implanted device then delivers small pulses of stimulation to help the brainwaves return to normal.
"The findings suggest that responsive neurostimulation is an effective off-label surgical treatment of drug-resistant epilepsy in carefully selected pediatric patients," Nagahama said. "However, more research on long-term efficacy and safety is needed to determine which patients will benefit most."
Among the 35 patients in the study, only three experienced complications that required additional surgery. Interestingly, these complications were noted only in the young adults, not the younger children.
The findings were published recently in the journal Neurosurgery.
Despite the positive findings, RNS does come with risk, according to two experts who were not involved with the study.
"The RNS device is implanted into the skull, and in very young children there may be a risk for complications related to ongoing skull growth," said Dr. Keith Starnes, a pediatric epileptologist with the Mayo Clinic in Rochester, Minn. "Variability in skull growth and thickness should be considered on a case-by-case basis, and the potential benefits of neuromodulation weighed against the possibility of complications for an individual patient."
Another caveat to consider for RNS is the battery life of the monitor, Starnes noted.
"The expected battery life for RNS is currently about five to nine years. For children who have longer expected remaining life spans than adults, this could mean several more skull surgeries for battery replacement," he explained. "It is possible that this concern may be obviated in the future by advances in battery life and other technologies, but for now this is an important consideration."
Still, the findings suggest RNS is an effective, safe and well-tolerated treatment that can reduce the number of disabling seizures in children with epilepsy. But pediatric specialists should carefully select patients, who can be as young as 3, to determine if the implant is a suitable treatment for their condition.
Dr. Aparna Polavarapu, a pediatric epilepsy specialist and assistant professor at Montefiore Health System in New York City, said, "RNS provides a new way to approach seizure treatment; without the use of daily medications that may need periodic blood tests, drug interactions to be aware of or systemic side effects to monitor."
Visit the U.S. Centers for Disease Control and Prevention for more on epilepsy.
SOURCES: Rutgers University, news release, Jan. 5, 2022; Keith Starnes, MD, member, Epilepsy Society, and pediatric epileptologist, Mayo Clinic, Rochester, Minn.; Aparna Polavarapu, MD, pediatric epilepsy specialist and assistant professor, Montefiore Health System, New York City; Neurosurgery, December 2021