Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> The long term objective of our research is to develop a system that will automate as much as possible DBS implantation procedures. It is estimated that about 180,000 patients/year would benefit from DBS implantation. Yet, only 3000 procedures are performed annually. This is so because the combined expertise required to perform the procedure successfully is only available at a limited number of sites. Our goal is to transform this procedure into a procedure that can be performed by a general neurosurgeon at a community hospital. In this work we report on our current progress toward developing a system for the computer-assisted pre-operative selection of target points and for the intra-operative adjustment of these points. The system consists of a deformable atlas of optimal target points that can be used to select automatically the pre-operative target, of an electrophysiological atlas, and of an intra-operative interface. The atlas is deformed using a rigid then a non-rigid registration algorithm developed at our institution. Results we have obtained show that automatic prediction of target points is an achievable goal. Our results also indicate that electrophysiological information can be used to resolve structures not visible in anatomic images, thus improving both pre-operative and intra-operative guidance. Our intra-operative system has reached the stage of a working prototype that is clinically used at our institution. <s> BIB001 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> Abstract Background In the search for a better preoperative knowledge of the position of probes and electrodes, we assessed the feasibility and the usefulness of transcranial sonography during surgery for the implantation of stimulation electrodes into the subthalamic nucleus (STN) of patients with Parkinson's disease. Methods Transcranial sonography was carried out during stereotactic surgery in 8 patients with Parkinson's disease who had a suitable temporal bone window on the side receiving the electrode. Test stimulation parameters were 130 Hz, 0.1 ms, up to 0 to 4.5 V. Results The test probe with a diameter of 0.8 mm was visualized through the temporal preauricular window. The correct anatomic position of the electrode tip could be indirectly assessed thanks to the topographic relationship of the STN with the hyperechogenic substantia nigra and the nucleus ruber. The tip position of the final electrode was easily documented. A laterality of 10.5 to 11.5 mm, verified by teleradiographic ventriculography and plain films, was correlated with the best response of symptoms of Parkinson's disease to electrical impulses delivered to the STN. Conclusions Transcranial sonography is easily feasible during stereotactic surgery. In combination with the clinical effects of electrostimulation on the symptoms of Parkinson's disease and with stereotactic x-ray images, it enables the assessment and the documentation of the correct position of implanted STN electrodes in real time. <s> BIB002 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> BACKGROUND ::: Deep brain stimulation (DBS) is widely used to treat advanced Parkinson's disease, other movement and psychiatric disorders. DBS implantation requires application of a stereotactic frame throughout a lengthy procedure, making it uncomfortable and tiring. We designed a stereotactic cube to stage the operation, perform frameless microelectrode recording (MER) and fix the DBS. ::: ::: ::: METHODS ::: The 15-mm cube is implanted in a burr hole using bone cement. It contains 5 parallel trajectories (central + 4 around). It is aligned by stereotactic frame so that central trajectory reaches the target. Frameless MER is performed by attaching a micro-driver to the cube using 2-5 cannulae (4 cm). The DBS is fixed to the cube by a mini-plate and 1 screw. Ninety-six cubes were compared with 43 Bennet spheres (BS). ::: ::: ::: RESULTS ::: No cube moved compared to 2 (5%) BS (p < 0.05). The final trajectory was central in 64.4% of cubes compared to 47.5% of BS, and the final target was >2 mm out in no cubes compared to 12.5% of BS (p < 0.01). Infection and haemorrhage were observed in 2.5% and 3.3% of cubes, respectively, while 5% of BS developed infection, 5% haemorrhage and 7.5% skin erosion. ::: ::: ::: CONCLUSIONS ::: This method is simple and effective in staging DBS procedures, performing frameless MER and DBS implantation, fixation and revision. <s> BIB003 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> Numerous factors need to be taken into account when implanting deep brain stimulation (DBS) systems into patients with Parkinson's disease. The surgical procedure itself can be divided into immediate preoperative, intraoperative, and immediate postoperative phases. Preoperative considerations include medication withdrawal issues, stereotactic equipment choices, imaging modalities, and targeting strategy. Intraoperative considerations focus on methods for physiological confirmation of a given target for DBS electrode deployment. Terms such as microelectrode recording, microstimulation, and macrostimulation will be defined to clarify inconsistencies in the literature. Advantages and disadvantages of each technique will be addressed. Furthermore, operative decisions such as staging, choice of electrode and implantable pulse generator, and methods of device fixation will be outlined. Postoperative issues include imaging considerations, including magnetic resonance safety, device–device interactions, and immediate surgical complications pertaining to the DBS procedure. This report outlines answers to a series of questions developed to address all aspects of the DBS surgical procedure and decision-making with a systematic overview of the literature (until mid-2004) and by the expert opinion of the authors. This is a report from the Consensus on Deep Brain Stimulation for Parkinson's Disease, a project commissioned by the Congress of Neurological Surgeons and the Movement Disorder Society. It outlines answers to a series of questions developed to address all surgical aspects of deep brain stimulation. © 2006 Movement Disorder Society <s> BIB004 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> Magnetic resonance imaging (MRI) is a commonly used and important imaging modality to evaluate lead location and rule out complications after deep brain stimulation (DBS) surgery. Recent safety concerns have prompted new safety recommendations for the use of MRI in these patients, including a new recommendation to limit the specific absorption rate (SAR) of the MRI sequences used to less than 0.1 W/kg. Following SAR recommendations in real-world situations is problematic for a variety of reasons. We review our experience scanning patients with implanted DBS systems over a 7-year period using a variety of scanning techniques and four scanning platforms. 405 patients with 746 implanted DBS systems were imaged using 1.5-tesla MRI with an SAR of up to 3 W/kg. Many of the DBS systems were imaged multiple times, for a total of 1,071 MRI events in this group of patients with no adverse events. This series strongly suggests that the 0.1 W/kg recommendation for SAR may be unnecessarily low for the prevention of MRI-related adverse events. <s> BIB005 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> This study aimed to find out whether preoperative diffusion tensor imaging (DTI) and probabilistic tractography could help with surgical planning for deep brain stimulation in the periaqueductal/periventricular grey area (PAG/PVG) in a patient with lower leg stump pain. A preoperative DTI was obtained from the patient, who then received DBS surgery in the PAG/PVG area with good pain relief. The postoperative MRI scan showing electrode placement was used to calculate four seed areas to represent the contacts on the Medtronic 3387 electrode. Probabilistic tractography was then performed from the pre-operative DTI image. Tracts were seen to connect to many areas within the pain network from the four different contacts. These initial findings suggest that preoperative DTI scanning and probabilistic tractography may be able to assist surgical planning in the future. <s> BIB006 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> Traditional methods of deep brain stimulator (DBS) implantation utilize a rigid, head mounted stereotactic frame to deliver electrodes to the intended brain target. New surgical navigation systems have provided the substrate for the development of frameless DBS delivery techniques that now provide a viable alternative to frame-based implantations, and may have advantages for both the surgical team and the patient. Intraoperative MR imaging and purely image-guided implantation may represent the next generation of implantation strategies. <s> BIB007 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> OBJECT ::: Accurate localization of the subthalamic nucleus (STN) is important for proper placement of the electrodes in deep brain stimulation (DBS) surgery for patients with advanced Parkinson disease. The authors evaluated the accuracy of our modified composite targeting method and the value of using high-field MR imaging for targeting the STN. ::: ::: ::: METHODS ::: Thirteen patients with advanced Parkinson disease underwent bilateral STN DBS based on 3-T MR imaging, and 13 patients underwent surgery based on 1.5-T MR imaging. By sequentially referring to the postmammillary commissure, the red nucleus, the mammillothalamic tract, and the STN, the modified composite targeting method determined the stereotactic coordinates for targeting the STN. The accuracy and efficacy of the composite targeting method and 3-T MR imaging were evaluated by using the intraoperative microelectrode recording, the postoperative imaging study, and the postoperative clinical improvement. ::: ::: ::: RESULTS ::: The landmark structures for targeting the STN were visualized clearly with 3-T MR imaging. The mean (+/- SD) path length through the STN of the central track was 4.9 +/- 1.1 mm in the 3-T group and 3.1 +/- 2.0 mm in the 1.5-T group (p < 0.001). Twenty-one (81%) of 26 electrodes were placed in the central track in the 3-T group, whereas 8 (31%) of 26 electrodes were placed in the central track in the 1.5-T group (p = 0.006). The rest of the electrodes were placed in the noncentral optimum track for alleviating parkinsonian motor symptoms. The mean Unified Parkinson's Disease Rating Scale motor part score during off period was reduced by 53% in the 3-T group and by 41% in the 1.5-T group (p = 0.14). The mean reductions of levodopa equivalent daily doses were 48.6% in the 3-T group and 43.7% in the 1.5-T group (p = 0.61). ::: ::: ::: CONCLUSIONS ::: The use of the modified composite targeting method referring to the multiple landmarks with 3-T MR imaging offers reliable and clinically effective target for STN DBS surgery. <s> BIB008 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> Deep brain stimulation is increasingly being applied to movement disorders, and other novel applications are emerging. The therapy requires precise localization of the stimulation electrode at specific target sites in deep brain structures. Conventional means of implantation rely on stereotactic approaches, which lack sufficient targeting accuracy and therefore are supported by invasive physiological mapping. We review the use of interventional magnetic resonance image guidance for the implantation of deep brain stimulator electrodes in patients with moderate to advanced Parkinson disease. The methodologies used in this innovative surgical technique are presented, along with the potential benefits and limitations of such an approach. Targeting accuracies are shown to be within approximately 1 mm of the intended deep brain structure and are achieved with a single brain penetration in most cases. Preliminary evaluation of clinical outcomes indicates comparable results to that achieved with conventional implantation methods, and the technique holds promise for substantially reducing operative durations. <s> BIB009 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> The authors describe a method for placement of deep brain stimulator electrodes using interventional MRI in conjunction with a skull-mounted aiming device (Medtronic Nexframe). This approach adapts the procedure to a standard-configuration 1.5-T diagnostic MRI scanner in a radiology suite. Preoperative imaging, device implantation, and postimplantation MRI are integrated into a single procedure performed under general anesthesia, providing real-time, high-resolution magnetic resonance confirmation of electrode position. The method is conceptually simpler than the current standard technique for deep brain stimulator placement, as it eliminates the stereotactic frame, the subsequent requirement for registration of the brain in stereotactic space, physiologic testing, and the need for patient cooperation. With further technical refinement, the interventional MRI method should improve the accuracy, safety, and speed of deep brain stimulator electrode placement. <s> BIB010 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> Deep-brain-stimulation (DBS) surgery requires implanting stimulators at target positions with sub millimetric accuracy. Traditional stereotactic frames can provide such accuracy, but a recent innovation called the micro Targeting Platform (FHC, Inc.) replaces this large, universal frame with a single-use, miniature, and custom-designed platform. Both single-target and dual-target platforms are available for unilateral and bilateral procedures, respectively. In this paper, their targeting accuracies are evaluated in vitro. Our approach employs ldquovirtual targets,rdquo which eliminates the problem of collision of the implant with the target. We implement virtual targets by mounting fiducial markers, which are not used in platform targeting, on an artificial skull and defining targets relative to the skull via that fiducial system. The fiducial system is designed to surround the targets, thereby reducing the overall effect of fiducial localization inaccuracies on the evaluation. It also provides the geometrical transformation from image to physical space. Target selection is based on an atlas of stimulation targets from a set of 31 DBS patients. The measured targeting error is the displacement between the phantom implant and the virtual target. Our results show that the micro Targeting Platform exhibits sub millimetric in vitro accuracy with a mean of 0.42 mm and a 99.9% level of 0.90 mm. <s> BIB011 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> Background Deep brain stimulation (DBS) of the subcallosal cingulate white matter (SCCwm) or anterior limb of the internal capsule (ALIC) may be effective in treating depression. Connectivity patterns of these regions may inform on mechanisms of action for DBS of these targets. Methods Diffusion tensor imaging (DTI) and probabilistic tractography were performed in 13 nondepressed subjects to determine connectivity patterns of SCCwm and ALIC. Tract maps were generated for each target in each subject, and tract voxels were coded as being unique to either target or shared. Group level tract maps were generated by including only those voxels common to at least 10 of 13 (>75%) subjects. Results The two targets have distinct patterns of connectivity with regions of overlap. The SCCwm showed consistent ipsilateral connections to the medial frontal cortex, the full extent of the anterior and posterior cingulate, medial temporal lobe, dorsal medial thalamus, hypothalamus, nucleus accumbens, and the dorsal brainstem. The ALIC seed, in contrast, demonstrated widespread projections to frontal pole, medial temporal lobe, cerebellum, nucleus accumbens, thalamus, hypothalamus, and brainstem. Common to both targets, albeit through distinct white matter bundles, were connections to frontal pole, medial temporal lobe, nucleus accumbens, dorsal thalamus, and hypothalamus. Conclusions Connectivity patterns of these two DBS white matter targets suggest distinct neural networks with areas of overlap in regions implicated in depression and antidepressant response. <s> BIB012 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is an effective treatment in primary dystonia. Its success depends on the implantation accuracy of the DBS electrode into the targeted GPi. Discrepancies of up to 4 mm between the initial target, selected on preoperative MRI, and the final DBS lead location are caused mainly by caudal brain shift that occurs once the cranium is open. Nowadays, transcranial sonography (TCS) can display echogenic deep brain structures with higher image resolution compared to MRI under clinical conditions. Here, we demonstrate for the first time the use of a contemporary clinical high-end TCS system for intraoperative monitoring of DBS electrode position. Herewith, a high-resolution real-time imaging of closely located microelectrodes and of the DBS lead through the intact skull is feasible. Simultaneous color-coded sonographic imaging of arteries near the anatomical target allows further intraoperative refinement of DBS lead positioning, simultaneously preventing hemorrhages. <s> BIB013 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> Functional neurosurgery involves precise surgical targeting of anatomic structures to modulate neurologic function. The ultimate aim is to improve the symptoms and quality of life of patients suffering from chronic neurologic disorders; this demands minimal risk of inflicting morbidity and mortality. Well-established indications for functional neurosurgery include movement disorders such as Parkinson disease (PD), several forms of dystonia, essential tremor, and chronic pain. Other indications proposed in recent literature, either novel or revisited, are less well established but hold promise for patients with chronic debilitating conditions including cluster headache, Tourette syndrome, obsessive compulsive disorder, severe refractory depression, and epilepsy. This article focuses on the role of imaging in the surgical treatment of movement disorders. Imaging has played a central role in the practice of functional neurosurgery since its inception. The current situation and likely future directions are best appreciated by reviewing their parallel development. <s> BIB014 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> Object A challenge associated with deep brain stimulation (DBS) in treating advanced Parkinson disease (PD) is the direct visualization of brain nuclei, which often involves indirect approximations of stereotactic targets. In the present study, the authors compared T2*-weighted images obtained using 7-T MR imaging with those obtained using 1.5- and 3-T MR imaging to ascertain whether 7-T imaging enables better visualization of targets for DBS in PD. Methods The authors compared 1.5-, 3-, and 7-T MR images obtained in 11 healthy volunteers and 1 patient with PD. Results With 7-T imaging, distinct images of the brain were obtained, including the subthalamic nucleus (STN) and internal globus pallidus (GPi). Compared with the 1.5- and 3-T MR images of the STN and GPi, the 7-T MR images showed marked improvements in spatial resolution, tissue contrast, and signal-to-noise ratio. Conclusions Data in this study reveal the superiority of 7-T MR imaging for visualizing structures targeted for DBS in the management... <s> BIB015 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Neuroimaging and navigation <s> The objective of this study was to examine the experience with and safety of brain 1.5 Tesla (T) magnetic resonance imaging (MRI) in deep brain stimulation (DBS) patients. This was a retrospective review of brain MRI scanning performed on DBS patients at the University of Kansas Medical Center between January 1995 and December 2007. A total of 249 DBS patients underwent 445 brain 1.5 T MRI scan sessions encompassing 1,092 individual scans using a transmit-receive head coil, representing the cumulative scanning of 1,649 DBS leads. Patients with complete implanted DBS systems as well as those with externalized leads underwent brain imaging. For the majority of scans, specific absorption rates localized to the head (SAR(H)) were estimated and in all cases SAR(H) were higher than that specified in the present product labeling. There were no clinical or hardware related adverse events secondary to brain MRI scanning. Our data should not be extrapolated to encourage MRI scanning beyond the present labeling. Rather, our data may contribute to further defining safe MRI scanning parameters that might ultimately be adopted in future product labeling as more centers report in detail their experiences. <s> BIB016
During the last decade, biomedical imaging has gained more and more importance for surgical planning of deep brain stimulation surgery BIB014 . With the introduction of 3T MR scanners, it has become possible to further increase the image quality and resolution BIB008 , and 7T images may follow in the future BIB015 . Nevertheless, the choice of the imaging sequence still remains essential to visualise the different targets as illustrated in Sect. 3 of this article. In order to provide real-time image guidance, interventional MRI has recently been used in some centres performing DBS surgery. One approach is to use an open MRI, but due to low image quality of 0.2 T MRI scans, which are sub-optimal for anatomical localisation, image fusion with pre-operative higher quality scan is necessary [27] . Another approach is reported by Starr and colleagues BIB007 BIB009 BIB010 . They use a skull-mounted aiming device, the NeXframe system, in a standard configuration 1.5 T MR imaging unit, where also the entire surgical procedure is accomplished. In this way, surgical planning, guided implantation and final electrode position check is performed intraoperatively. Other alternatives to the traditional frames are the Eljamel-Tulley stereotactic cube BIB003 and the STarFix TM microtargeting Platform BIB011 BIB001 . The STarFix TM platform uses titanium anchors which are implanted into the patient's skull before imaging. Based on the results from high-resolution preoperative CT and MR images, a patient-and treatment-specific platform is constructed. During surgery, the platform is mounted on the anchors together with a guide tube which is used for insertion of the DBS electrode. Concerning postoperative MR scanning there has been a considerable debate about the safety in patients with DBS systems. Following manufacturer guidelines  , imaging is possible only with a 1.5 Tesla horizontal bore MRI, a transmit/receive head coil and when limiting the average head-specific absorption rate (SAR) to 0.1 W/kg or less even if this implicates a lower imaging quality. Otherwise heating, magnetic field interactions or induced stimulation for example can be the consequence BIB004 . Experiences from MRI of implanted deep brain stimulators on a large patient material have been presented by several groups BIB005 BIB016 . Diffusion tensor imaging (DTI) represents another possibility to obtain data using MRI. It is used to measure the water diffusion in multiple directions, which has been proposed to represent the electrical conductivity of the tissue, and can be used to visualise nerve bundles in the brain. For the moment, DTI is still in the state of evaluation, i.e. images are acquired preoperatively to deep brain stimulation, and they are analysed postoperatively concerning target position and interstructure connections BIB012 BIB006  . Transcranial sonography has started to be applied for the placement of DBS electrodes in dystonic BIB013 and Parkinsonian patients BIB002 . Transcranial sonography can display echogenic deep brain structures such as the GPi in dystonic patients and the substantia nigra. Also the STN has been identified considering its topographic relationship with the substantia nigra BIB002 . For the moment, highly echogenic imaging artefacts of the metal parts of the electrode do exist.