John Spooner

Neuromodulation of the cingulum for neuropathic pain after spinal cord injury. Case report.

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 patients 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.

Intersurgeon Variability in the Selection of Anterior and Posterior Commissures and Its Potential Effects on Target Localization

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.

Automatic selection of DBS target points using multiple electrophysiological atlases

In this paper we study and evaluate the influence of the choice of a particular reference volume as the electrophysiological atlas on the accuracy of the automatic predictions of optimal points for deep brain stimulator (DBS) implants. We refer to an electrophysiological atlas as a spatial map of electrophysiological information such as micro electrode recordings (MER), stimulation parameters, final implants positions, etc., which are acquired for each patient and then mapped onto a single reference volume using registration algorithms. An atlas-based prediction of the optimal point for a DBS surgery is made by registering a patients image volume to that reference volume, that is, by computing a correct coordinate mapping between the two; and then by projecting the optimal point from the atlas to the patient using the transformation from the registration algorithm. Different atlases, as well as different parameterizations of the registration algorithm, lead to different and somewhat independent atlas-based predictions. We show how the use of multiple reference volumes can improve the accuracy of prediction by combining the predictions from the multiple reference volumes weighted by the accuracy of the non-rigid registration between each of the corresponding atlases and the patient volume.

The VU-DBS project: integrated and computer-assisted planning, intra-operative placement, and post-operative programming of deep-brain stimulators.

Movement disorders affect over 5,000,000 people in the United States. Contemporary treatment of these diseases involves high-frequency stimulation through deep brain stimulation (DBS). This form of therapy is offered to patients who have begun to see failure with standard medical therapy and also to patients for which medical therapy is poorly effective. A DBS procedure involves the surgical placement, with millimetric accuracy, of an electrode in the proximity of functional areas referred to as targets. Following the surgical procedure, the implant, which is a multi-contact electrode is programmed to alleviate symptoms while minimizing side effects. Surgical placement of the electrode is difficult because targets of interest are poorly visible in current imaging modalities. Consequently, the process of implantation of a DBS electrode is an iterative procedure. An approximate target position is determined pre-operatively from the position of adjacent structures that are visible in MR images. With the patient awake, this position is then adjusted intra-operatively, which is a lengthy process. The post-surgical programming of the stimulator is an equally challenging and time consuming task, with parameter setting combinations exceeding 4000. This paper reports on the status of the Vanderbilt University DBS Project, which involves the development and clinical evaluation of a system designed to facilitate the entire process from the time of planning to the time of programming.

Deformable physiological atlas-based programming of deep brain stimulators: a feasibility study

The postoperative neurological management of patients with deep brain stimulation (DBS) of the subthalamic nucleus (STN) for Parkinsons disease is a complex and dynamic process that involves optimizing the stimulation parameters and decreasing the anti-parkinsonian medication while assessing the interactions of both treatment modalities. Neurologists who manage patients undergoing DBS therapy must have expert knowledge of the electro-anatomy of the subthalamic area and be familiar with the medical treatment of motor and non-motor symptoms. In clinical practice, finding the optimal programming parameters can be a challenging and time-consuming process. We have developed a computerized system to facilitate one of the bottlenecks of DBS therapy: the IPG (Internal Pulse Generator) programming. This system consists of a deformable physiological atlas built on more than 300 intra-operative macro-stimulations acquired from 30 Parkinsons patients and of a non-rigid registration algorithm used to map these data into an atlas. By correlating the position of the quadripolar electrode implanted in the patient with the information contained in our atlas, we can determine which of four contacts has the highest probability to be the most clinically effective. Preliminary results presented in this study suggest that this approach facilitates the programming process by guiding the neurologist to the optimal contact. The system we propose was tested retrospectively on a total of 30 electrodes. In 19 of these cases, this system predicted the contact that was selected as the optimal one by the neurologist.

Automated selection of anterior and posterior commissures based on a deformable atlas and its evaluation based on manual selections by neurosurgeons

We are developing and evaluating a system that will facilitate the placement of deep brain stimulators (DBS) used to treat movement disorders including Parkinsons disease and essential tremor. Although our system does not rely on the common reference system used for functional neurosurgical procedures, which is based on the anterior and posterior commissure points (AC and PC), automatic and accurate localization of these points is necessary to communicate the positions of our targets. In this paper, we present an automated method for AC and PC selection that uses non-rigidly deformable atlases. To evaluate the accuracy of our multi-atlas based method, we compare it against the manual selection of the AC and PC points by 43 neurosurgeons (38 attendings and 5 residents) and show that its accuracy is submillimetric compared to the median of their selections. We also analyze the effect of AC-PC localization inaccuracy on the localization of common DBS targets.