![]() 2, 10 To delineate the borders of the STN precisely, the insertion of 5 microelectrodes simultaneously has been advocated, 8 with repeated MER (making as many as 10 parallel passes) if more information is required. 6, 10, 11 With regard to the physiologic localization, intraoperative macrostimulation is enhanced in many centers by microelectrode recording (MER). 2, 5 Few centers use MR imaging alone to calculate anatomic targets. 5– 7 Some routinely perform ventriculography, 8, 9 whereas others use fusion of MR and CT images. ![]() 3, 4 The protocols vary significantly from center to center. Intraoperative microelectrode recordings confirmed these coordinates in all cases from the first microelectrode pass, thereby eliminating prolonged intraoperative electrophysiological STN searching and tissue disruption that may occur from multiple passes.ĬONCLUSION: 3T MR imaging appears to be an excellent tool for reliable and accurate direct visualization of the human STN, necessary for precise surgical targeting.Īs clinical experience with deep-brain stimulation (DBS) of the subthalamic nucleus (STN) in treatment of advanced Parkinson disease (PD) increases and the procedure becomes more accepted among neurologists, neurosurgeons, and patients, more attention is being paid to the accuracy of surgical targeting 1, 2 to decrease morbidity associated with this operative procedure. RESULTS: At 3T, the STN was visualized as a small, hypointense, almond-shaped structure in 3 planes located immediately lateral to the anterior edge of the red nucleus, medial to the internal capsule, about 5 mm inferior, 1–2 mm posterior, and 9–12 mm lateral to the midcommissural point. These coordinates are used for surgical targeting. The STN is identified in all 3 planes by cross-referencing in a 3-plane viewer. With the patient positioned within a standard Leksell type G stereotactic frame localizer, rapidly acquired scout images are used to prescribe volumes of contiguous high-resolution T2-weighted fast spin-echo images in the axial, sagittal, and coronal planes through the midbrain and basal ganglia. ![]() METHODS: We performed preoperative stereotactic MR imaging at 3T to visualize the STN in 13 patients undergoing deep-brain stimulation for PD. The STN is also difficult to visualize directly by using MR imaging at 1.5T. CT imaging is dependent on atlas coordinates, because the STN is not visualized. A combination of anatomic imaging with a stereotactic frame, atlas coordinates, and intraoperative neurophysiology is currently considered the most reliable approach for STN targeting. Although procedural details are well established, targeting STN remains problematic because of its variable location and relatively small size (20–30 mm 3). BACKGROUND AND PURPOSE: Electrical stimulation of the subthalamic nucleus (STN) is an accepted treatment for advanced Parkinson disease (PD).
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