A new type of laser therapy is safe and effective for children with drug-resistant epilepsy, new research suggests.
In a study of nearly 150 children, more than half of those who received MRI-guided laser interstitial thermal therapy (MRgLITT) were seizure-free at 1 year.
Results show that this “is a new and promising therapy” for children for whom drug therapy has failed, said study investigator Elysa Widjaja, MD, pediatric neuroradiologist at the Hospital for Sick Children and professor in the Department of Medical Imaging, University of Toronto, Toronto, Canada.
In addition, the procedure is less invasive and requires a shorter hospital stay than does open epilepsy surgery, Widjaja told Medscape Medical News.
The findings were presented at the American Epilepsy Society (AES) 74th Annual Meeting 2020, which was held online this year because of the COVID-19 pandemic.
To date, most published studies on the laser procedure have had a small number of participants from only a few centers, Widjaja noted.
“The aim of our registry is to collect data from multiple centers in both Canada and the US to try to get a better understanding of the outcomes following laser therapy and the complications associated with this treatment,” she said.
In the procedure, a surgeon drills a tiny hole through the skull and, guided by MRI, inserts a very thin laser fiber into the center of the lesion. Heat then ablates the affected brain region.
From the dedicated registry, researchers recruited 182 children who were treated with MRgLITT at seven pediatric centers in the United States and two centers in Canada.
The youngest patient was aged 14 months, and the oldest was aged 21 years (mean age, 11.2 years). Some pediatric hospitals treat patients up to age 21, Widjaja noted.
All of the study participants had focal epilepsy, “so the seizures are coming from a defined area of the brain,” she added. In addition, study participants’ conditions were drug-resistant, defined as conditions in which two antiseizure medications had previously failed.
The mean age at seizure onset was 5.4 years, and the mean number of antiepileptic drugs that were taken was 2.3.
Before receiving the therapy, children typically undergo extensive analyses, including MRI and video electroencephalography, to pinpoint where in the brain the seizures originate. Widjaja noted that the specific area of the brain that is affected varies widely from child to child.
The investigators collected baseline clinical characteristic and procedural data, including ablation site, type of lesion, length of stay, complications, number of MRgLITT procedures, and seizure outcome. To gather this information, they used a secure electronic platform designed to collect and store research data.
Among 137 patients for whom 1-year seizure outcomes were available, seizure freedom was reported for 74 patients (54%).
In a recent meta-analysis conducted by the investigators, the rate of seizure-free outcomes following epilepsy surgery was about 65%.
Although this rate is higher than with the laser therapy, Widjaja pointed out that the laser intervention is less invasive and the hospital stay of a mean of 3.3 days is shorter than the week or so needed after surgery. This, she said, makes the procedure cost-effective.
Unlike surgery, laser therapy is also “particularly good” at reaching lesions deep in the brain without damaging surrounding tissue, Widjaja said.
Although the researchers have not evaluated seizure outcomes with respect to age, Widjaja believes age is not a major factor in outcomes. “I suspect it’s the type of lesion and how big the lesion is that mainly influences the outcome, rather than actual age,” she said.
Complications related to the laser therapy, including infections and bleeding, occurred in 15% of patients. Neurologic deficits affected about 8% of patients; however, these tended to be transient, Widjaja noted.
There were two cases (1%) of permanent neurologic deficits, both of which involved weakness of arms or legs. This, said Widjaja, is less than the 5% rate of permanent neurologic deficits that occur following surgery, as reported in the literature.
There were no cases of major intracranial hemorrhage among the participants. At 30 days, there was one reported death.
Laser therapy is limited to relatively small lesions of no more than about 2 cm on average, Widjaja said. “We normally can’t treat huge lesions using laser therapy; they would need surgery.”
However, it is possible to treat the same area twice. In the current study, 20 patients (11%) underwent laser therapy on one region on two occasions. Of these participants, 12 (60%) achieved freedom from seizures.
Widjaja noted that two additional epilepsy centers will soon be providing laser therapy and will expand the registry. In addition, the investigators are building a surgery registry that will enable them to compare outcomes of laser treatment with surgery.
Currently, laser therapy is available only at specialized epilepsy centers that perform surgery.
“Very Important” Research
Commenting for Medscape Medical News, Daniel Goldenholz, MD, PhD, Division of Epilepsy, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, called this is “a very important study.”
Laser therapy “offers the opportunity for very rapid recovery from a minimally invasive, targeted technique while simultaneously offering promising outcomes,” said Goldenholz, who was not involved with the research.
He noted the importance of the investigators’ choosing freedom from seizures as the outcome of interest. In addition, the 54% seizure-freedom rate in the study is “substantially better” than rates from other interventions, he said.
“To put the results into perspective, other work has found that these same patients would have a less than 10% chance of seizure freedom if many different drug combinations were tried,” said Goldenholz.
He noted that the 1-year outcomes “are a good first time point” but that it is very important to assess longer-term outcomes. “Often, postsurgical outcomes are worse when looking at 2 or 5 years postoperatively,” he added.
These longer-term data will be important “to fully inform our patients about long-term prognosis,” Goldenholz said.
Still, given the overall favorable results so far, “I think more centers will be likely to explore this newer technology,” he said.
The study was funded by the Pediatric Epilepsy Research Foundation. The study authors and Goldenholz report no relevant financial relationships.
American Epilepsy Society (AES) 74th Annual Meeting 2020: Abstract 912227 (poster 372). Presented December 6, 2020.