Neuronavigation and fluoroscopy-assisted subdural strip electrode positioning: a simple method to increase intraoperative accuracy of strip localization in epilepsy surgery

Abstract

For localization of the epileptogenic zone in cases of focal epilepsy, detailed clinical investigations, imaging studies, and electrophysiological methods are used. If the noninvasive presurgical evaluation provides insufficient data, intracranial electrodes are necessary. Computed tomography and MR imaging techniques are the gold standard for localization of the postoperative position of the implanted intracranial electrode contacts. If the electrode strips are inserted through a bur hole, however, the exact localization of the electrode contacts on the patient's brain remains uncertain for the surgeon during insertion. Therefore, the authors developed a simple method to visualize the electrodes during the procedure. In this method they combine neuronavigation and intraoperative fluoroscopy for parallel visualization of the cortex, electrodes, and the navigation probe. The target region is searched with neuronavigation, a bur hole is made over the optimal entry point, and using real-time fluoroscopy the strip electrode is slid to the tip of the navigation probe, which was kept over the area of interest. At the authors' institution 26 strips in 8 patients have been inserted with this technique, and none of the strips had to be repositioned. There were no complications with this procedure and the prolongation of surgery time is acceptable. Compared to previously published electrode placement methods, this one enhances the accuracy of electrode placement at occipital, parietal, frontal, or interhemispheric regions as well. Intraoperative visualization of the electrodes with fluoroscopy combined with neuronavigation during positioning through a bur hole gives the neurosurgeon the ability to control the real position of the electrode over the gyri during the procedure.

Use of intraoperative ultrasonography to monitor surgery for large acoustic neuromas: a pilot study

“…A large tumor usually deforms the anatomic structure, leading to the compression and extrusion of the brain stem, cerebellum hemisphere, and nerves [2]. Thus, CT/MRI scans are the gold standard to follow neurosurgical procedures [7,8]. The present data indicated that ultrasonic images recorded immediately after the operation detected fragments of a residual tumor, which was consistent with postoperative CT/MRI scans.…”

Evoked effective connectivity of the human neocortex

“…Following noninvasive presurgical evaluation, patients underwent subdural strip, grid and depth electrode implantation (NSLIJ: Integra Lifesciences Corp., Plainsboro, New Jersey, NIN: AD TECH Medical Instrument Corp., Racine, WI). Subdural electrodes (10 mm intercontact spacing) were implanted with the aid of neuronavigation and fluoroscopy to maximize accuracy [Eross et al, ] via craniotomy with targets defined by clinical grounds. Video‐EEG monitoring was performed using Xltek EMU 128 LTM System (San Carlos, CA) at NSLIJ and a Brain Quick System 98 (Micromed, Mogliano Veneto, Italy) at NIN.…”

Intraoperative computed tomography for intracranial electrode implantation surgery in medically refractory epilepsy

“…Moreover, fluoroscopy is limited in its ability to detect medial and/or lateral lead deviations, and radiographic studies do not easily fuse with preoperative neuronavigation plans developed from CT and MRI. 4,11 Intraoperative CTs (iCTs) can be obtained in standard operating rooms using the portable O-arm image acquisition system (Medtronic Inc.). This technique has been described in deep brain stimulation (DBS) surgery for confirming the accurate placement of electrodes into deep brain structures, 14 but its use in epilepsy surgery has not been investigated.…”