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  • Author or Editor: William D. Hutchison x
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Aviva Abosch, William D. Hutchison, Jean A. Saint-Cyr, Jonathan O. Dostrovsky and Andres M. Lozano

Object. The subthalamic nucleus (STN) is a target in the surgical treatment of Parkinson disease (PD). Little is known about the neurons within the human STN that modulate movement. The authors' goal was to examine the distribution of movement-related neurons within the STN of humans by using microelectrode recording to identify neuronal receptive fields.

Methods. Data were retrospectively collected from microelectrode recordings that had been obtained in 38 patients with PD during surgery for placement of STN deep brain stimulation electrodes. The recordings had been obtained in awake, nonsedated patients. Antiparkinsonian medications were withheld the night before surgery. Neuronal discharges were amplified, filtered, and displayed on an oscilloscope and fed to an audio monitor. The receptive fields were identified by the presence of reproducible, audible changes in the firing rate that were time-locked to the movement of specific joint(s).

The median number of electrode tracks per patient was six (range two–nine). The receptive fields were identified in 278 (55%) of 510 STN neurons studied. One hundred one tracks yielded receptive field data. Fourteen percent of 64 cells tested positive for face receptive fields, 32% of 687 cells tested positive for upper-extremity receptive fields, and 21% of 242 cells tested positive for lower-extremity receptive fields. Sixty-eight cells (24%) demonstrated multiple-joint receptive fields. Ninety-three cells (65%) with movement-related receptive fields were located in the dorsal half of the STN, and 96.8% of these were located in the rostral two thirds of the STN. Analysis of receptive field locations from pooled data and along individual electrode tracks failed to reveal a consistent somatotopic organization.

Conclusions. Data from this study demonstrate a regional compartmentalization of neurons with movement-related receptive fields within the STN, supporting the existence of specific motor territories within the STN in patients suffering from PD.

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Jean A. Saint-Cyr, Tasnuva Hoque, Luiz C. M. Pereira, Jonathan O. Dostrovsky, William D. Hutchison, David J. Mikulis, Aviva Abosch, Elspeth Sime, Anthony E. Lang and Andres M. Lozano

Object. The authors sought to determine the location of deep brain stimulation (DBS) electrodes that were most effective in treating Parkinson disease (PD).

Methods. Fifty-four DBS electrodes were localized in and adjacent to the subthalamic nucleus (STN) postoperatively by using magnetic resonance (MR) imaging in a series of 29 patients in whom electrodes were implanted for the treatment of medically refractory PD, and for whom quantitative clinical assessments were available both pre- and postoperatively. A novel MR imaging sequence was developed that optimized visualization of the STN. The coordinates of the tips of these electrodes were calculated three dimensionally and the results were normalized and corrected for individual differences by using intraoperative neurophysiological data (mean 5.13 mm caudal to the midcommissural point [MCP], 8.46 mm inferior to the anterior commissure—posterior commissure [AC—PC], and 10.2 mm lateral to the midline).

Despite reported concerns about distortion on the MR image, reconstructions provided consistent data for the localization of electrodes. The neurosurgical procedures used, which were guided by combined neuroimaging and neurophysiological methods, resulted in the consistent placement of DBS electrodes in the subthalamus and mesencephalon such that the electrode contacts passed through the STN and dorsally adjacent fields of Forel (FF) and zona incerta (ZI). The mean location of the clinically effective contacts was in the anterodorsal STN (mean 1.62 mm posterior to the MCP, 2.47 mm inferior to the AC—PC, and 11.72 mm lateral to the midline). Clinically effective stimulation was most commonly directed at the anterodorsal STN, with the current spreading into the dorsally adjacent FF and ZI.

Conclusions. The anatomical localization of clinically effective electrode contacts provided in this study yields useful information for the postoperative programming of DBS electrodes.

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Robert E. Gross, Wendy J. Lombardi, William D. Hutchison, Soni Narula, Jean A. Saint-Cyr, Jonathan O. Dostrovsky, Ronald R. Tasker, Anthony E. Lang and Andres M. Lozano

Object. To understand the factors that determine the distribution of lesions after microelectrode-guided pallidotomy for Parkinson's disease, the authors quantitatively characterized lesion location in a cohort of patients who were prospectively followed to determine the effects of pallidotomy on clinical outcome.

Methods. Thirty-three patients underwent volumetric magnetic resonance (MR) imaging after surgery to allow quantitative lesion localization in relation to conventional intraventricular landmarks and, alternatively, more anatomically relevant landmarks. The validity of the method was verified in a cohort of postpallidotomy patients who underwent concurrent volumetric and stereotactic MR imaging in an external head frame. Lesions were distributed over a considerable distance in the anteroposterior (8.8 mm) and mediolateral (8.7 mm) dimensions in relation to the anterior commissure and wall of the third ventricle, respectively. Less variation was seen in lesion location in the dorsoventral dimension (4.8 mm) in relation to the intercommissural plane.

Conclusions. Lesion distribution was not random: lesion locations in the anteroposterior and mediolateral dimensions were highly correlated, such that lesions were distributed from anteromedial to posterolateral, parallel to the border of the globus pallidus internus with the obliquely oriented internal capsule. The factors that led to variability in lesion location were variation in third ventricle width and the oblique anteromedial-to-posterolateral course of the internal capsule. This demonstration of variability of lesion location in a cohort of patients who experienced excellent clinical benefits and minimal postoperative complications emphasizes the importance of anatomical variations in determining lesion position and the need for physiological corroboration for correct lesion placement.