Article In Brief
Robotic steroelectroencephalography, a minimally invasive procedure to determine whether patients with drug-resistant epilepsy are candidates for brain surgery, was reported to be safer and more efficient—leading to better outcomes—than the use of standard implanted subdural grid electrodes.
Patients with intractable epilepsy who had been evaluated using robot-assisted stereoelectroencephalography (SEEG) had significantly better outcomes compared with those who were assessed with standard implanted subdural grid electrodes (SDE), according to a comparative analysis of the two techniques by researchers at Memorial Hermann Texas Medical Center in Houston.
The retrospective, single institute study reported that nearly twice as many patients who were not found to have lesions on SEEG remained seizure-free or had fewer episodes at one-year than those evaluated with SDE: 69.2 percent versus 34.6 percent (p=.006), respectively. Among patients who then underwent resection or laser ablation for lesions, 76 percent of those assessed first with SEEG compared with 54.6 percent of patients who had undergone SDE had favorable epilepsy outcomes, that is, they were free of disabling or rare disabling seizures (p=.003) after one year.
The study was published online March 4 in JAMA Neurology.
SEEG is a presurgical evaluation procedure in which electrodes are surgically implanted into brain tissue in order to identify seizure foci in parts of the brain that are difficult to reach surgically or are inaccessible to traditional subdural grid technology. These are typically patients with more deeply rooted lesions, those who cannot tolerate craniotomy, those requiring bilateral implants or repeat operations, or those with insula, cingulate or supplementary motor area-suspected seizure etiology. The robot helps the surgeon place electrodes more accurately and efficiently, reducing the time it takes to complete an SEEG procedure.
Robot-guided SEEG uses smart technology and high precision image guidance to enable surgeons to insert multiple recording electrodes deep into the brain. (For more information, see “The Science Explained: Stereoelectroencephalography.”)
SEEG eliminates the need for before-and-after craniotomies required for SDEs while reducing both surgical and recovery times and associated risks, the authors of the current study said. It also allows more complete delineation of the neural network and access to deeper structures, less time under general anesthesia, and less discomfort afterwards.
The investigators found robotic SEEG implantation took considerably less time, was less painful, and resulted in fewer complications than SDE procedures. Moreover, despite being less likely to have evidence of lesions on MRI, patients evaluated by SEEG who underwent targeted procedures had better one-year outcomes.
SEEG patients also needed fewer blood products and fewer days taking narcotics for pain management, although fewer patients required resection compared with the SDE group.
The findings “should influence decision-making and lower the barrier to candidacy for resection or ablation among patients with intractable epilepsy,” said the lead study author Nitin Tandon, MD, professor of neurosurgery at McGovern Medical School at The University of Texas Health Science Center at Houston.
“The number of centers doing SEEG has grown exponentially in the past four years and is likely to continue to grow till most centers doing large volumes of epilepsy surgery have access to this technology. By my estimate, around 65 centers in the United States have robots available for SEEG,” he told Neurology Today.
SEEG does not constrain where electrodes can be implanted, enabling the study of brain networks in a much more comprehensive manner to pinpoint the seizure source, he added.
“The absence of time pressure, and the fact that no craniotomy has been done, allows us to pick out patients likely to do well, fully consider various options, and implement the most optimal plan.”
Study Methodology, Findings
The randomized, retrospective study included 239 patients who underwent 260 consecutive electroencephalographic intracranial procedures from November 2004 to June 2017. Patients either underwent standard SDE implantation or SEEG using a stereotactic robot, followed by resection or laser ablation of the seizure focus. The investigators then evaluated and compared length of surgical procedure, surgical complications, opiate use, and seizure outcomes.
Patients were similar in age, gender, numbers with failed anticonvulsant use, and duration of their epilepsy. More SDE than SEEG cases were lesional (99 percent versus 43.8 percent), and there were seven symptomatic hemorrhagic sequelae, including one that resulted in permanent neurological deficit. There were three infections in SDE patients but no clinically relevant complications in the SEEG group.
More SDE cases resulted in resection or ablation compared with SEEG cases— 91.4 percent versus 74.4 percent (p<.001), and favorable outcomes (seizure-free or rare episodes) were documented in 76 percent of these SEEG patients versus 54.6 percent in the SDE group (p=.003).
One-year analysis of only those patients without lesions showed 27 of 39 SEEG patients, or 69.2 percent, had good outcomes compared with nine of 26 SDE cases, 34.6 percent (p=.006). In all patients who underwent evaluation, not just those undergoing definitive procedures, favorable one-year outcomes were similar in both groups, at 47.1 percent in SEEG patients versus compared with 42.4 percent of those who had been assessed with SDE.
Dr. Tandon noted that SEEG requires a team with technical and cognitive expertise in managing refractory epilepsy. “Intracranial evaluations need to be carefully thought through to maximize the possibility of good outcomes with minimal impact on cognitive and neurological functions, while minimizing the numbers of evaluations that ultimately result in seizure freedom,” he told Neurology Today.
Adriana Bermeo-Ovalle, MD, associate professor of neurological sciences and director of the Laboratory of Electroencephalography at Rush University Medical Center in Chicago, said that the evolution of the technology matches the evolving understanding of the mechanisms of epileptic activity generation, propagation, and symptomatic expression.
“The technique has been used in Europe for decades, and recently has become more familiar and accessible to US doctors and patients, but it is important to note that not all patients are candidates for different invasive procedures,” she told Neurology Today.
“Often the multidisciplinary team makes specific recommendations regarding which diagnostic technique, and in which specific arrangement, would best answer the questions at hand for every specific patient,” she said.
“The key point in conducting an invasive EEG evaluation, regardless of the technology, is always to consider all of the information we have about each case and build a strong hypothesis for localization and propagation, as well as an alternative hypothesis. Once these are clear to the team, we spend a lot of time planning the localization and coverage to best answer the questions at hand. This is a very personalized and case to case planning enterprise.”
She said the risks with SEEG, as with any surgical procedure, include bleeding, infection, and vascular complications such as stroke. But unlike other procedures, the main risk of invasive EEG evaluations is to miss the target and failing to get sufficient or satisfactory information to make a decision or treatment recommendation.
Stephan Schuele MD, MPH, FAAN, chief of neurophysiology and epilepsy at Northwestern University, told Neurology Today that SEEG as a minimally invasive epilepsy surgery option has become much more appealing to patients and referring providers.
“The major benefit of robotic surgery versus frame-based implantation is probably efficiency for the surgeon. According to one study, robotic SEEG takes about two hours compared with six hours for electrode placement. Accuracy is actually fairly similar; however, patients perceive robotic surgery as something more accurate or state-of-the-art. We have had patients who waited several months until we got the robot with their surgery.”
He said SEEG adds some additional costs since it requires a third hospitalization for the actual procedure (noninvasive monitoring, invasive monitoring with SEEG, and then surgery or laser).
“The outcome in extratemporal lobe surgery with SEEG appears to be better, and we are able to tackle patients we could not assess properly before.”
Drs. Tandon, Bermeo-Ovalle, and Shuele reported no competing interests.