Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a clinically effective neurosurgical treatment for Parkinson disease. Tissue reaction to chronic DBS therapy and the definitive location of active stimulation contacts are best studied on a postmortem basis in patients who have undergone DBS. The authors report the postmortem analysis of STN DBS following 5 years and 11 months of effective chronic stimulation including the histologically verified location of the active contacts associated with bilateral implants. They also describe tissue response to intraoperative test passes with recording microelectrodes and stimulating semimacroelectrodes. The results indicated that 1) the neural tissue surrounding active and nonactive contacts responds similarly, with a thin glial capsule and foreign-body giant cell reaction surrounding the leads as well as piloid gliosis, hemosiderin-laden macrophages, scattered lymphocytes, and Rosenthal fibers; 2) there was evidence of separate tracts in the adjacent tissue for intraoperative microelectrode and semimacroelectrode passes together with reactive gliosis, microcystic degeneration, and scattered hemosiderin deposition; and 3) the active contacts used for approximately 6 years of effective bilateral DBS therapy lie in the zona incerta, just dorsal to the rostral STN. To the authors' knowledge, the period of STN DBS therapy herein described for Parkinson disease and subjected to postmortem analysis is the longest to date.
The authors present a case in which high-frequency electrical stimulation of the cingulum using standard deep brain stimulation (DBS) technology resulted in pain relief similar to that achieved with cingulotomy and superior to that achieved with periventricular gray matter (PVG) stimulation. This patient had a complete spinal cord injury at the C-4 level and suffered from medically refractory neuropathic pain. He underwent placement of bilateral cingulum and unilateral PVG DBS electrodes and a 1-week blinded stimulation trial prior to permanent implantation of a pulse generator. During the stimulation trial, the patient's pain level was assessed using a visual analog scale, and pain medication usage was recorded. During this period the patient was blinded to stimulation parameters. Stimulation of the cingulum provided better pain control than PVG stimulation or medication alone. The authors believe that cingulum stimulation can benefit patients with severe neuropathic pain that is refractory to other treatments. Advantages over cingulotomy include reversibility and the ability to adjust stimulation parameters for optimum efficacy.
Background: This study reports the intersurgeon variability in manual selection of the anterior and posterior commissures (AC and PC). The study also investigates the effect of this variability on the localization of targets like the subthalamic nucleus, ventralis intermedius nucleus and globus pallidus internus. The additional effect of variation in the selection of the mid-plane on target localization is also evaluated. Methods: 43 neurosurgeons (38 attendings, 5 residents/ fellows) were asked to select the AC and the PC points (as routinely used for stereotactic neurosurgical planning) on two MRI scans. The corresponding mid-commissural points (MCPs) and target coordinates were calculated. Results: The collected data show that the MCP is more reliable than either the AC or the PC points. These data also show that, even for experienced neurosurgeons, variations in selecting the AC and the PC point result in substantial variations at the target points: 1.15 ± 0.89 mm, 1.45 ± 1.25 mm, 1.21 ± 0.83 for the subthalamic nucleus, ventralis intermedius nucleus, and globus pallidus internus, respectively, for the first MRI volumeand 1.08 ± 1.37 mm, 1.35 ± 1.71 mm, 1.12 ± 1.17 mm for the same structures for the second volume. These variations are larger when residents/fellows are included in the data set. Conclusions: The data collected in this study highlight the difficulty in establishing a common reference system that can be used to communicate target location across sites. It indicates the need for the development and evaluation of alternative normalization methods that would permit specifying targets directly in image coordinates or the development of improved imaging techniques that would permit direct targeting.
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