PALLIDOTOMY LESION LOCATIONS - SIGNIFICANCE OF MICROELECTRODE REFINEMENT

OBJECTIVE: To determine whether stereotactic pallidotomy requires refi nement using microelectrode recording to ensure proper lesion placemen t. METHODS: The experiment approach was based on retrospective compari sons of microelectrode-refined radiofrequency lesion locations with hy pothetical unrefined lesion positions. Actual and hypothetical pallido tomy lesions were classified based on their lesion center (thermocoagu lative zone) locations and their total lesion areas (surrounding edema tous zone) relative to the pallidal target. Assessments were made usin g postoperative T2-weighted magnetic resonance axial images, which sho wed both the lesion and globus pallidus (CP). The magnitude of microel ectrode refinement from an initial preoperative starting point determi ned by computed tomography was calculated using stereotactic coordinat es and included corrections for the lesioning tract trajectory angle. RESULTS: In all 25 patients, the center of the actual pallidotomy lesi on was within the GP. Without microelectrode refinement, 13 of 25 hypo thetical lesion positions would have been localized such that the lesi on center would not have remained in the GP. In eight cases, microelec trode refinement resulted in no significant change in lesion location, but in one case, microelectrode refinement resulted in lesion center placement away from the CP. CONCLUSION: Kinesthetically driven microel ectrode refinement in pallidotomy lesioning seems to be required to en sure proper lesion location within the CP.