At least half of a small group of children and adolescents with difficult-to-localize refractory focal epilepsy was rendered seizure-free or much improved with stereoelectroencephalography (SEEG) methods, new research shows.
The procedure is also associated with minimal blood loss and significantly less morbidity than are older mapping techniques.
“The patients we studied are not the usual group of patients with seizures that are easy to localize and chances of them becoming seizure-free are over 80%,” Jorge Gonzalez-Martinez, MD, Epilepsy Center, Cleveland Clinic Cleveland, Ohio, told Medscape Medical News.
“We are talking about patients whose seizures are really difficult to localize, they have failed medication and even surgery so they are really a difficult group of patients. Even with this, we managed to get 50% to 60% of them seizure-free where before there was no hope — they were going to have seizures the rest of their lives,” he said.
“And while we still would have liked an optimal effect in all patients, this is still a good beginning.”
The study was published in the September issue of Neurosurgery.
The analysis is based on 30 children and adolescents with medically refractory focal epilepsy who were treated at the Cleveland Clinic Epilepsy Center between August 2009 and March 2012.
Patients underwent extraoperative invasive monitoring using SEEG methods. None of the patients studied with SEEG had a single clear focal epileptogenic lesion that could be targeted for resection on the basis of results of noninvasive testing, investigators observe.
Furthermore, equivocal or complex MRI abnormalities were observed in 40% of the group overall.
In total, 402 depth electrodes were implanted in all lobes during the SEEG procedure, for an average of 13 electrodes per patient. As the authors note, implantations were bilateral in 11 patients, right hemispheric in 10 patients, and left hemispheric in 9 patients.
Using the SEEG approach, investigators could localize the epileptogenic zone in 26 of the 30 patients (86.6% of the group). Among these patients, 18 patients (69.2%) underwent resection.
As the authors note, the reasons the other 12 patients did not undergo resection included failure to localize the epileptogenic zone in 4 patients; the presence of a multifocal epileptogenic zone in another 4 patients; and the fact that the epileptogenic zone was located in the eloquent cortex, which prevented resection in 3 patients.
Interestingly, seizures improved after the implantation of electrodes during SEEG in 1 patient who thus did not require resection.
At a mean follow-up of 25.9 months, 10 patients or 55.5% of the group who underwent resection during SEEG became seizure-free.
Seizures improved in another 5 patients (about 28%) to a level of Engel class II or III. Regrettably, as the authors note, 3 patients (about 17%) had no improvement in seizures after resection.
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