Methods for microelectrode-guided posteroventral pallidotomy (original) (raw)
Related papers
Neurosurgery, 1999
OBJECTIVE: The reintroduction of pallidotomy for the treatment of Parkinson's disease (PD) has generated various opinions regarding the ideal anatomic or physiological location of the target within the globus pallidus. The role of microelectrode recording guidance in pallidotomy for the treatment of advanced PD is presently under debate. The purpose of this study was twofold. The first goal was to determine the degree of accuracy in the targeting of the globus pallidus internus (GPi) with magnetic resonance imaging (MRI), by comparing these results with the final placement of the thermolytic lesions (as defined by electrophysiological assessment). The second goal was to ascertain the somatotopic arrangement of the GPi in PD. METHODS: The analysis involved 50 patients with PD who underwent microrecording-guided pallidotomy. The theoretical coordinates for lesioning were calculated after definition of the intercommissural line by MRI. The actual placement of the lesions was determined after mapping of the GPi by microrecording, using stimulation to identify the sensorimotor region and its somatotopic organization. RESULTS: In most cases, the lesions were placed posterior and lateral to the targets chosen by MRI. Mapping by microrecording revealed differences of 2.3 ؎ 1.55 mm and 3 ؎ 1.9 mm in the mediolateral and anteroposterior coordinates, respectively. The actual lesion overlapped the theoretical target for only 45% of the patients. The somatotopic organization of the GPi was analyzed. Most of the units with sensorimotor activity or tremor-related activity were in the lateral portion of the nucleus. Upper limb and axial units were in the most lateral region and mainly in the ventral one-third of the nucleus. Lower limb responses were recorded mainly in the dorsal one-third of the nucleus. Tremor-related cells were found throughout the sensorimotor region of the nucleus. CONCLUSION: These results indicate that lesion targeting based on MRI alone is not sufficiently accurate to guarantee placement of the lesion in the sensorimotor region of the GPi.
Neurophysiologie Clinique/Clinical Neurophysiology, 2001
Stereotactic neurosurgery aims at placing therapeutic lesions or chronic stimulating electrodes at very precise locations within the brain. Microelectrode recording and macrostimulation are used in addition to anatomoradiological techniques to optimize targeting. Recently, the usefulness of electrophysiological procedures has been questioned. Based on more than 500 therapeutic stereotactic lesions in the last 10 years at the thalamic and subthalamic levels, we evaluate here retrospectively the utility of the two electrophysiological procedures. In two of the three stereotactic targets considered in this study, intraoperative electrophysiological confirmation is mandatory because of the target size with respect to interindividual anatomical variations and of the more or less close vicinity of eloquent structures. © 2001 Éditions scientifiques et médicales Elsevier SAS macrostimulation / microelectrode recording / neurosurgery / stereotaxy / thalamus Résumé -Enregistrements par microélectrodes et stimulation électrique en neurochirurgie stéréotaxique guidée par des IRM thalamique et sub-thalamique. La neurochirurgie stéréotaxique vise à placer des lésions thérapeutiques ou des électrodes de stimulation chronique à des endroits bien définis dans le cerveau. Compte tenu de la précision relative des techniques radiologiques utilisées pour déterminer les coordonnées de l'endroit à atteindre, on utilise l'enregistrement par microélectrode et/ou la stimulation électrique afin d'améliorer la localisation finale de la cible désirée. Récemment, la nécessité de ces deux techniques électrophysiologiques a été remise en question. En se basant sur plus de 500 lésions thérapeutiques effectuées au niveau thalamique et sub-thalamique ces dix dernières années, nous avons évalué rétrospectivement l'utilité de ces deux procédures. Seules deux des trois cibles stéréotaxiques considérées dans cette étude requièrent l'usage de ces deux techniques électrophysiologiques. Leur nécessité dépend en fait de la taille de la lésion thérapeutique envisagée par rapport aux variations anatomiques interindividuelles et de son voisinage plus ou moins étroit avec des structures dont la lésion entraînerait des effets secondaires importants.
MR Imaging of Ventral Thalamic Nuclei
American Journal of Neuroradiology, 2010
BACKGROUND AND PURPOSE: The Vim and VPL are important target regions of the thalamus for DBS. Our aim was to clarify the anatomic locations of the ventral thalamic nuclei, including the Vim and VPL, on MR imaging. MATERIALS AND METHODS: Ten healthy adult volunteers underwent MR imaging by using a 1.5T whole-body scanner. The subjects included 5 men and 5 women, ranging in age from 23 to 38 years, with a mean age of 28 years. The subjects were imaged with STIR sequences (TR/TE/TI ϭ 3200 ms/15 ms/120 ms) and DTI with a single-shot echo-planar imaging technique (TR/TE ϭ 6000 ms/88 ms, b-value ϭ 2000 s/mm 2). Tractography of the CTC and spinothalamic pathway was used to identify the thalamic nuclei. Tractography of the PT was used as a reference, and the results were superimposed on the STIR image, FA map, and color-coded vector map. RESULTS: The Vim, VPL, and PT were all in close contact at the level through the ventral thalamus. The Vim was bounded laterally by the PT and medially by the IML. The VPL was bounded anteriorly by the Vim, laterally by the internal capsule, and medially by the IML. The posterior boundary of the VPL was defined by a band of low FA that divided the VPL from the pulvinar. CONCLUSIONS: The ventral thalamic nuclei can be identified on MR imaging by using reference structures such as the PT and the IML. ABBREVIATIONS: AC ϭ anterior commissure; C ϭ caudate nucleus; CTC ϭ cerebellothalamocortical tract; DBS ϭ deep brain stimulation; DTI ϭ diffusion tensor imaging; FA ϭ fractional anisotropy; fMRI ϭ functional MR imaging; IML ϭ internal medullary lamina; P ϭ putamen; PC ϭ posterior commissure; PT ϭ pyramidal tract; Pulv ϭ pulvinar; RN ϭ red nucleus; ROI ϭ region of interest; ST ϭ sensory tract; STIR ϭ short tau inversion recovery; Th ϭ thalamus; VPL ϭ ventroposterolateral nuclei; Vim ϭ ventrointermediate nuclei
Chronic thalamic stimulation with three-dimensional MR stereotactic guidance
AJNR. American journal of neuroradiology
To report a method of electrode implantation in the ventralis intermedius nucleus of the thalamus for the treatment of tremor using a 3-D stereotactic MR imaging technique. Five patients (three men and two women; mean age, 59 years) with medically refractory tremor had intrathalamic implantation of a stimulating electrode. Stereotactic MR imaging was performed on a 1.5-T unit equipped with an MR-compatible Leksell G stereotactic frame fixed to the patient's head. Calculation of the coordinates of the theoretical target was based on the coordinates of the anterior commissure, the posterior commissure, and the midline sagittal plane as determined via stereotactic MR imaging. During the surgical procedure, the best position for the stimulating electrode was determined by electrophysiological and clinical studies. Postoperative MR control studies were done in all cases to verify the position of the electrode. Stereotactic MR imaging allowed precise implantation of the stimulating el...
Comparison of 3T and 7T MRI for the visualization of globus pallidus sub-segments
Scientific Reports
The success of deep brain stimulation (DBS) targeting the internal globus pallidus (GPi) depends on the accuracy of electrode localization inside the GPi. In this study, we sought to compare visualization of the medial medullary lamina (MML) and accessory medullary lamina (AML) between proton density-weighted (PDW) and T2-weighted (T2W) sequences on 3T and 7T MRI scanners. Eleven healthy participants (five men and six women; age, 19–28 years; mean, 21.5) and one 61-year-old man were scanned using two-dimensional turbo spin-echo PDW and T2W sequences on 3T and 7T MRI scanners with a 32-channel receiver head coil and a single-channel transmission coil. Profiles of signal intensity were obtained from the pixel values of straight lines over the GP regions crossing the MML and AML. Contrast ratios (CRs) for GPe/MML, GPie/MML, GPie/AML, and GPii/AML were calculated. Qualitatively, 7T visualized both the MML and AML, whereas 3T visualized the MML less clearly and hardly depicted the AML. T...
Optimal MRI methods for direct stereotactic targeting of the subthalamic nucleus and globus pallidus
2011
Objective Reliable identification of the subthalamic nucleus (STN) and globus pallidus interna (GPi) is critical for deep brain stimulation (DBS) of these structures. The purpose of this study was to compare the visibility of the STN and GPi with various MRI techniques and to assess the suitability of each technique for direct stereotactic targeting. Methods MR images were acquired from nine volunteers with T2-and proton density-weighted (PD-W) fast spin echo, susceptibility-weighted imaging (SWI), phase-sensitive inversion recovery and quantitative T1, T2 and T2* mapping sequences. Contrast-tonoise ratios (CNR) for the STN and GPi were calculated for all sequences. Targeting errors on SWI were evaluated on magnetic susceptibility maps. The sequences demonstrating the best conspicuity of DBS target structures (SWI and T2*) were then applied to ten patients with movement disorders, and the CNRs for these techniques were assessed.
Accessing the Anterior Mesencephalic Zone: Orbitozygomatic Versus Subtemporal Approach
World neurosurgery, 2018
Despite the latest developments in microsurgery, electrophysiological monitoring, and neuroimaging, the surgical management of intrinsic brainstem lesions remains challenging. Several safe entry points have been described to access the different surfaces of the brainstem. Knowledge of this entry zone anatomy is critical to performing a safe and less morbid approach. To access the anterior midbrain surface, a well-known entry point is the anterior mesencephalic (AM) zone. Our aim was to quantify surgical AM zone exposure through the orbitozygomatic (OZ) and subtemporal (ST) approaches. We also analyzed the angular exposure along the horizontal and vertical axis angles for the AM zone. Ten cadaveric heads were dissected using the OZ and ST approaches for anterior midbrain surface exposure. A neuronavigation system was used to determine the 3-dimensional coordinates. The area of surgical exposure, angular exposure, and anatomical limits of each craniotomy were evaluated and determined ...
Appearance of Normal Cranial Nerves on Steady-State Free Precession MR Images
RadioGraphics, 2009
Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights. nerve (white arrow) within the CSF-filled olfactory groove and the optic nerve (black arrow in b) ringed by highsignal-intensity CSF within the dural sheath. (2) Coronal 1.0-mm-thick SSFP MR image shows the cisternal segment of the olfactory nerve (arrow), which is located inferior to and between the gyrus rectus (r) and the medial orbital gyrus (o).
Magnetic resonance image evaluation of pallidotomy lesions: a volumetric and shape analysis
Neurosurgical FOCUS, 1997
Determination of acute pallidotomy-produced lesion volumes, pre- and postpallidotomy globus pallidus (GP) volumes, and assessment of lesion shape using magnetic resonance (MR) imaging-based computerized segmentation (contouring) and three-dimensional rendering was made in 19 patients. Magnetic resonance image slice thickness (1.5 mm or 6 mm) was not found to be a significant factor influencing contour-based pallidotomy lesion volume estimates. Previously reported lesion volumes produced by pallidotomy have often been estimated using the ellipsoid volume formula. Using 1.5-mm-thick MR sections, contour-based pallidotomy-produced lesion volumes were significantly different from those volumes estimated by the ellipsoid formula. Globus pallidus volumes, estimated by contouring T2-weighted MR images, were bilaterally similar (2.4 ± 0.37 ml [right]; 2.2 ± 0.45 ml [left]). Postoperative GP volumes were found on the contralateral, unlesioned side to be 2 ± 0.45 ml and on the lesioned side t...