Abstracts

Rationale: Invasive monitoring techniques for the localization of an epileptogenic focus in partial epilepsy are well-described. While subdural grid and strip recording electrodes provide a means of localizing foci on the cortical surface, the placement of depth recording electrodes is often necessary to obtain accurate localization to deeper brain structures such as the amygdala and hippocampus. The use of a miniature stereotactic frame, the StarFix microTargeting Platform (510(K), Number: K003776, 2/23/01, FHC Inc; Bowdoin Me., USA) for implantation of deep brain stimulators has been previously reported, and the accuracy of this novel platform shown to compare favorably to traditional stereotactic frame systems. We describe the first reported use of this system for successful implantation of bilateral depth electrodes for epilepsy monitoring. Methods: Three skull fiducials were placed one week prior to surgery using a platform template. A brain MRI and a CT were subsequently obtained to facilitate planning for electrode implantation using the FHC software. All planning was done pre-operatively in the office using personal computers. No further adjustments or workstation planning was necessary on the day of the operation. The FHC platform was secured to the previously implanted 4 skull fiducials and the platform was used to identify the area of entry for the depth electrodes on the right and left sides. Two 12-contact depth electrodes were then advanced to the depth of the targets without difficulty. There was no significant bleeding associated with the placement of the depth electrode. A temporal craniotomy was then performed for placement of subdural electrodes. The patient tolerated the procedure well and there were no intraoperative complications.Results: MRI, CT and plain films of the skull were obtained post-operatively. The positioning of the electrode was satisfactory in all modalities. There were no neurological complications associated with either electrode implantation or prolonged monitoring. The depth electrodes demonstrated symmetric, robust coverage of each hippocampus, with epileptiform discharges observed bilaterally. Conclusions: The use of the FHC platform system for placement of depth electrodes for epilepsy monitoring has not been previously reported. We demonstrate here that it is both safe and efficacious, and may be preferable to existing methods of depth electrode implantation.