A new study published in the journal Neurosurgery reveals that critical data for surgical planning can be obtained more efficiently from patients with drug resistant epilepsy with the help of an updated stereoelectroencephalography (SEEG) technique. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.
"SEEG is a safe and accurate procedure for invasive assessment of the epileptogenic zone," according to the new report by Dr. Francesco Cardinale of Niguarda Ca' Granda Hospital, Milan, and colleagues. Their "updated workflow" combines sophisticated imaging data reconstructions and robot-assisted surgery, "providing essential information in the most complex cases of drug-resistant epilepsy."
Stereo EEG Technique Updated and Simplified The researchers describe the development of and initial experience with an updated SEEG technique for planning epilepsy surgery. The concept of SEEG is not new. Originally developed by French researchers named Talairach and Bancaud, SEEG uses electrodes implanted in the brain to localize the epileptogenic zone—the area in which seizures originate. The traditional SEEG technique includes two surgical steps: 3-D imaging of the brain blood vessels (stereotactic angiography) followed by electrode implantation.
Over the last few years, Dr. Cardinale and colleagues have been working to develop an updated SEEG workflow allowing a one-step surgical technique. Before surgery, the patient undergoes 3-D magnetic resonance imaging and 3-D digital subtraction angiography. The digital imaging data then undergo processing for reconstruction, resulting in the creation of a detailed computerized model of the brain and of the vascular tree. A key part of the development process was creating a "homemade" computer script to automate the necessary series of data processing steps.
Using the software program from an image-guided neurosurgical robot, the reconstructed data are used to plan the surgical approach, or "trajectory." Robot-assisted surgery was then performed to implant the electrodes. Whether performed by the traditional or updated workflow, the goal of SEEG is to provide the surgeon with highly precise information on the location of the epileptogenic zone, used for planning epilepsy surgery.
The researchers report on the outcomes of 500 SEEG procedures performed between 1996 and 2011 in patients with drug-resistant epilepsy. Both techniques were highly successful in guiding electrode placement to localize the epileptogenic zone. Complications occurred in 12 cases, for a rate of 2.4 percent.
Detailed analysis in a subset of cases found improved accuracy with the new technique. Median error in localizing the implanted electrodes decreased by about 1 millimeter both at the entry point (the most risky zone) and at the deepest point. The authors believe their technique allows them to estimate a "safe entry region" for electrode placement with 99 percent accuracy.