Search

Background Cerebrospinal fluid-venous fistulas (CVFs) are one of the less common etiologic causes of spontaneous intracranial hypotension. CVFs are most commonly treated with open surgical ligation and have reportedly not responded well to percutaneous treatments. Purpose To study treatment outcomes of CT-guided fibrin glue occlusion for CVFs. Materials and Methods Retrospective review of medical records from two institutions was performed for all patients with CVFs who underwent CT-guided percutaneous fibrin glue occlusion from March to October 2020. CVFs were assessed for resolution or persistence at posttreatment decubitus CT myelography (CTM). Pre- and posttreatment brain MRI scans were reviewed for principal signs of spontaneous intracranial hypotension. Clinical symptoms were documented before and immediately after therapy, and the current symptoms to date after fibrin glue occlusion were documented. Results CT-guided fibrin glue occlusion was performed in 13 patients (mean age, 62 years ± 14 [standard deviation]; eight women) with CVFs. Ten of 10 patients who underwent final posttreatment decubitus CTM examinations showed CVF resolution. All 13 patients showed improvement on posttreatment brain MRI scans. All 13 patients are currently asymptomatic, although three patients were asymptomatic before fibrin glue occlusion. Conclusion CT-guided fibrin glue occlusion is an effective treatment for patients with cerebrospinal fluid-venous fistulas (CVFs). Direct fibrin glue administration within the CVF may be one of the key factors for success. Further studies are needed to determine the long-term efficacy of this treatment. © RSNA, 2021.

Objective Spontaneous spinal cerebrospinal fluid (CSF) leaks are rare and challenging to diagnose and treat. Patients may present to a variety of physicians, and many patients are often referred to a specialized center with a dedicated spinal CSF leak program and expertise in this condition. To our knowledge, there are no reported publications on how to create such a program. Conclusion In this article, we describe the specific steps we took to develop a spinal CSF leak program, which we have implemented over a multihospital network.

Frame-based stereotactic localization generally assumes that all required fiducials are present in a single-slice image which can then be used to form targeting coordinates. Previously, we have published the use of novel localizers and mathematics that can improve stereotactic localization. As stereotactic procedures include numerous imaging slices, we sought to investigate, develop, and test techniques that utilize multiple slices for stereotactic localization and provide a solution for a parallel bipanel N-localizer. Several multi-slice equations were tested. Specifically, multi-slice stereotactic matrices (ms-SM) and multi-slice normal to parallel planes (ms-nPP) were of particular interest. Bipanel (2N) and tripanel (3N) localizer images were explored to test approaches for stereotactic localization. In addition, combination approaches using single-slice stereotactic matrices (ss-SM) and multi-slice methods were tested. Modification of ss-SM to form ms-SM was feasible. Likewise, a method to determine ms-nPP was developed. For the special case of the parallel bipanel N-localizer, single-slice and multi-slice methods fail, but a novel non-linear solution is a robust solution for ms-nPP. Several methods for single-slice and multi-slice stereotactic localization are described and can be adapted for nearly any stereotactic system. It is feasible to determine ms-SM and ms-nPP. In particular, these methods provide an overdetermined means to calculate the vertical z, which is determined for a tripanel system using single-slice methods. In addition, the multi-slice methods can be used for extrapolation outside of the localizer space. Importantly, a novel non-linear solution can be used for parallel bipanel N-localizer systems, where other methods fail. Finally, multi-slice stereotactic localization assumes strict patient and imaging system stability, which should be carefully assessed for each case.

Background Efficacy in deep brain stimulation (DBS) is dependent on precise positioning of electrodes within the brain. Intraoperative fluoroscopy, computed tomography (CT), or magnetic resonance imaging are used for stereotactic intraoperative localization (StIL), but the utility of biplanar X-ray has not been evaluated in detail. Objective To determine if analysis of orthogonal biplanar X-rays using graphical analysis (GA), ray tracing (RT), and/or perspective projection (PP) can be utilized for StIL. Methods A review of electrode tip positions comparing postoperative CT to X-ray methods was performed for DBS operations containing orthogonal biplanar X-ray with referential spheres and pins. Results Euclidean (Re) errors for final DBS electrode position on intraoperative X-rays vs postoperative CT using GA, RT, and PP methods averaged 1.58 mm (±0.75), 0.74 mm (±0.45), and 1.07 mm (±0.64), respectively (n = 56). GA was more accurate with a ventriculogram. RT and PP predicted positions that correlated with third ventricular structures on ventriculogram cases. RT was the most stable but required knowledge of the geometric setup. PP was more flexible than RT but required well-distributed reference points. A single case using the O-arm demonstrated Re errors of 0.43 mm and 0.28 mm for RT and PP, respectively. In addition, these techniques could also be used to calculate directional electrode rotation. Conclusion GA, RT, and PP can be employed for precise StIL during DBS using orthogonal biplanar X-ray. These methods may be generalized to other stereotactic procedures or instances of biplanar imaging such as angiograms, radiosurgery, or injection therapeutics.

Image-guidance for frame-based stereotaxis is facilitated by incorporating three to four N-localizers or Sturm-Pastyr localizers into a stereotactic frame. An extant frame that incorporates only two N-localizers violates the fundamental principle of the N-localizer, which requires three non-colinear points to define a plane in three-dimensional space. Hence, this two N-localizer configuration is susceptible to error. The present article proposes the V-localizer that comprises multiple diagonal bars to provide four or more non-colinear points to minimize error.

Obsessive-compulsive disorder (OCD), a leading cause of disability, affects ~1-2% of the population, and can be distressing and disabling. About 1/3 of individuals demonstrate poor responsiveness to conventional treatments. A small proportion of these individuals may be deep brain stimulation (DBS) candidates. Candidacy is assessed through a multidisciplinary process including assessment of illness severity, chronicity, and functional impact. Optimization failure, despite multiple treatments, is critical during screening. Few patients nationwide are eligible for OCD DBS and thus a multi-center approach was necessary to obtain adequate sample size. The study was conducted over a six-year period and was a NIH-funded, eight-center sham-controlled trial of DBS targeting the ventral capsule/ventral striatum (VC/VS) region. There were 269 individuals who initially contacted the sites, in order to achieve 27 participants enrolled. Study enrollment required extensive review for eligibility, which was overseen by an independent advisory board. Disabling OCD had to be persistent for ≥5 years despite exhaustive medication and behavioral treatment. The final cohort was derived from a detailed consent process that included consent monitoring. Mean illness duration was 27.2 years. OCD symptom subtypes and psychiatric comorbidities varied, but all had severe disability with impaired quality of life and functioning. Participants were randomized to receive sham or active DBS for three months. Following this period, all participants received active DBS. Treatment assignment was masked to participants and raters and assessments were blinded. The final sample was consistent in demographic characteristics and clinical features when compared to other contemporary published prospective studies of OCD DBS. We report the clinical trial design, methods, and general demographics of this OCD DBS sample.

Introduction: The N-localizer is generally utilized in a 3-panel or, more rarely, a 4-panel system for computing stereotactic positions. However, a stereotactic frame that incorporates a 2-panel (bipanel) N-localizer system with panels affixed to only the left and right sides of the frame offers several advantages: improved ergonomics to attach the panels, reduced claustrophobia for the patient, mitigation of posterior panel contact with imaging systems, and reduced complexity. A bipanel system that comprises two standard N-localizer panels yields only two three-dimensional (3D) coordinates, which are insufficient to solve for the stereotactic matrix without further information. While additional information to determine the stereotactic positions could include scalar distances from Digital Imaging and Communications in Medicine (DICOM) metadata or 3D regression across the imaging volume, both have risks related to noise and error propagation. Therefore, we sought to develop new stereotactic localizers that comprise only lateral fiducials (bipanel) that leave the front and back regions of the patient accessible but that contain enough information to solve for the stereotactic matrix using each image independently. Methods: To solve the stereotactic matrix, we assumed the need to compute three or more 3D points from a single image. Several localizer options were studied using Monte Carlo simulations to understand the effect of errors on the computed target location. The simulations included millions of possible combinations for computing the stereotactic matrix in the presence of random errors of 1mm magnitude. The matrix then transformed coordinates for a target that was placed 50mm anterior, 50mm posterior, 50mm lateral, or 50mm anterior and 50mm lateral to the centre of the image. Simulated cross-sectional axial images of the novel localizer systems were created and converted into DICOM images representing computed tomography (CT) images. Results: Three novel models include the M-localizer, F-localizer, and Z-localizer. For each of these localizer systems, optimized results were obtained using an overdetermined system of equations made possible by more than three diagonal bars. In each case, the diagonal bar position was computed using standard N-localizer mathematics. Additionally, the M-localizer allowed adding a computation using the Sturm-Pastyr method. Monte Carlo simulation demonstrated that the Z-localizer provided optimal results. Conclusion: The three proposed novel models meet our design objectives. Of the three, the Z-localizer produced the least propagation of error. The M-localizer was simpler and had slightly more error than the Z-localizer. The F-localizer produced more error than either the Z-localizer or M-localizer. Further study is needed to determine optimizations using these novel models.

Introduction: Frame-based stereotaxis has been widely utilized for precise neurosurgical procedures throughout the world for nearly 40 years. The N-localizer is an integral component of most of the extant systems. Analysis of targeting errors related to the N-localizer has not been carried out in sufficient detail. We highlight these potential errors and develop methods to reduce them. Methods: N-localizer systems comprising three and four N-localizers of various geometries were analyzed using Monte Carlo (MC) simulations. The simulations included native and altered geometric dimensions (Width [W] x Height [H]). Errors were computed using the MC simulations that included the x- and y-axes of vertically oriented rods, that altered the W/H ratio, and that added a fourth N-localizer to a three N-localizer system. Results: The inclusion of an overdetermined system of equations and the geometries of the N-localizer systems had significant effects on target errors. Root Mean Square Errors (RMS-e) computed via millions of MC iterations for each study demonstrated that errors were reduced by (1) inclusion of the x- and y-coordinates of the vertically oriented rods, (2) a greater triangular area enclosed by the diagonal fiducials of the N-localizer system (stereotactic triangle), (3) a larger W/H ratio, and (4) an N-localizer system that comprised four N-localizers. Conclusion: Monte Carlo simulations of Root Mean Square error (RMS-e) is a useful technique to understand targeting while using N-localizer systems in stereotactic neurosurgery. The application of vertical rod positions enhances computational accuracy and can be performed on any N-localizer system. Keeping the target point within the stereotactic triangle enclosed by the diagonal rods can also reduce errors. Additional optimizations of N-localizer geometry may also reduce potential targeting errors. Further analysis is needed to confirm these findings which may have clinical importance.

All stereotactic neurosurgical procedures utilize coordinate systems to allow navigation through the brain to a target. During the surgical planning, indirect and direct targeting determines the planned target point and trajectory. This targeting allows a surgeon to precisely reach points along the trajectory while minimizing risks to critical structures. Oftentimes, once a target point and a trajectory are determined, a frame-based coordinate system is used for the actual procedure. Considerations include the use of various coordinate spaces such as the anatomical (\begin{document}{X}\end{document}), the frame (\begin{document}{X'}\end{document}), the head-stage (\begin{document}{X''}\end{document}), and an atlas. Therefore, the relationships between these coordinate systems are integral to the planning and implementation of the neurosurgical procedure. Although coordinate transformations are handled in planning via stereotactic software, critical understanding of the mathematics is required as it has implications during surgery. Further, intraoperative applications of these coordinate conversions, such as for surgical navigation from the head-stage, are not readily available in real-time. Herein, we discuss how to navigate these coordinate systems and provide implementations of the techniques with samples.

Ray tracing (RT) and perspective projection (PP) using fiducial-based registration can be used to determine points of interest in biplanar X-ray imaging. We sought to investigate the implementation of these techniques as they pertain to X-ray imaging geometry. The mathematical solutions are presented and then implemented in a phantom and actual case with numerical tables and imaging. The X-ray imaging is treated like a Cartesian system in millimeters (mm) with a standard frame-based stereotactic system. In this space, the point source is the X-ray emitter (focal spot), the plane is the X-ray detector, and fiducials are in between the source and plane. In a phantom case, RT was able to predict locations of fiducials after moving the point source. Also, a scaled PP matrix could be used to determine imaging geometry, which could then be used in RT. Automated identification of spherical fiducials in 3D was possible using a center of mass computation with average Euclidean error relative to manual measurement of 0.23 mm. For PP, RT projection or a combinatorial approach could be used to facilitate matching 3D to 2D points. Despite being used herein for deep brain stimulation (DBS), utilization of this kind of imaging analysis has wide medical and non-medical applications.

Deep brain stimulation (DBS) of the subthalamic nucleus is an established therapeutic option for managing motor symptoms of Parkinson's disease. We conducted a double-blind, sham-controlled, randomised controlled trial to assess subthalamic nucleus DBS, with a novel multiple independent contact current-controlled (MICC) device, in patients with Parkinson's disease.This trial took place at 23 implanting centres in the USA. Key inclusion criteria were age between 22 and 75 years, a diagnosis of idiopathic Parkinson's disease with over 5 years of motor symptoms, and stable use of anti-parkinsonian medications for 28 days before consent. Patients who passed screening criteria were implanted with the DBS device bilaterally in the subthalamic nucleus. Patients were randomly assigned in a 3:1 ratio to receive either active therapeutic stimulation settings (active group) or subtherapeutic stimulation settings (control group) for the 3-month blinded period. Randomisation took place with a computer-generated data capture system using a pre-generated randomisation table, stratified by site with random permuted blocks. During the 3-month blinded period, both patients and the assessors were masked to the treatment group while the unmasked programmer was responsible for programming and optimisation of device settings. The primary outcome was the difference in mean change from baseline visit to 3 months post-randomisation between the active and control groups in the mean number of waking hours per day with good symptom control and no troublesome dyskinesias, with no increase in anti-parkinsonian medications. Upon completion of the blinded phase, all patients received active treatment in the open-label period for up to 5 years. Primary and secondary outcomes were analysed by intention to treat. All patients who provided informed consent were included in the safety analysis. The open-label phase is ongoing with no new enrolment, and current findings are based on the prespecified interim analysis of the first 160 randomly assigned patients. The study is registered with ClinicalTrials.gov, NCT01839396.Between May 17, 2013, and Nov 30, 2017, 313 patients were enrolled across 23 sites. Of these 313 patients, 196 (63%) received the DBS implant and 191 (61%) were randomly assigned. Of the 160 patients included in the interim analysis, 121 (76%) were randomly assigned to the active group and 39 (24%) to the control group. The difference in mean change from the baseline visit (post-implant) to 3 months post-randomisation in increased ON time without troublesome dyskinesias between the active and control groups was 3·03 h (SD 4·52, 95% CI 1·3-4·7; p0·0001). 26 serious adverse events in 20 (13%) patients occurred during the 3-month blinded period. Of these, 18 events were reported in the active group and 8 in the control group. One death was reported among the 196 patients before randomisation, which was unrelated to the procedure, device, or stimulation.This double-blind, sham-controlled, randomised controlled trial provides class I evidence of the safety and clinical efficacy of subthalamic nucleus DBS with a novel MICC device for the treatment of motor symptoms of Parkinson's disease. Future trials are needed to investigate potential benefits of producing a more defined current field using MICC technology, and its effect on clinical outcomes.Boston Scientific.

Objective The WHISPER randomized controlled trial (RCT) evaluates safety and clinical effectiveness of subperception spinal cord stimulation (SCS) at ≤1.2 kHz in subjects previously implanted with an SCS system for treatment of chronic, neuropathic pain. Methods WHISPER is a prospective, multicenter RCT with a crossover design sponsored by Boston Scientific, Marlborough, MA (ClinicalTrials.gov: NCT02314000). Eligible subjects were randomized (N = 140) to receive subperception or supraperception for three months and then crossed over to receive the alternative. Upon completion of crossover period, subjects who preferred subperception were followed up to one year. Overall pain, quality-of-life, and other outcomes were collected in the study. The primary endpoint was the overall pain responder rate (≥50% improvement from baseline) with no increase in medications. Secondary endpoints consisted of pain scores, physical disability, quality of life, and treatment preference. Results The study met its primary endpoint and demonstrated noninferiority between supraperception and subperception in a prespecified cohort of 70 randomized subjects (Interim Analysis). Thirty-nine percent of subjects with subperception settings and 29% with supraperception settings had a greater than or equal to 50% reduction in their overall pain scores with no increase in average daily medication at three-months post-activation as compared with baseline. Further assessment of all participating study subjects (N = 140) revealed similar results. Subjects were previously implanted 3.8 ± 2 years and had a disability score (Oswestry Disability Index) of 70.2 ± 11.4 at study start. Of the randomized subjects that completed the End of Period 2 Visit, 93 (66%) preferred subperception SCS and their mean overall pain reduced from 7.3 ± 1.1 (N = 89) at baseline to 4.0 ± 2.1 (N = 80) at 12-months post-activation. Post hoc analysis also demonstrated that multiple options provide superior outcomes, as supported by a 74% increase in the responder rate when subjects could choose their most effective option (47%) compared with supraperception alone (27%). Discussion Subperception SCS at ≤1.2 kHz is safe and effective in subjects with extreme physical disability and previously implanted for chronic pain. Further, by providing study participants with different waveform options, increased pain relief was achieved.

Facial pain is often debilitating and can be characterized by a sharp, stabbing, burning, aching, and dysesthetic sensation. Specifically, trigeminal neuropathic pain (TNP), anesthesia dolorosa, and persistent idiopathic facial pain (PIFP) are difficult diseases to treat, can be quite debilitating and an effective, enduring treatment remains elusive. We retrospectively reviewed our early experience with stimulation involving the trigeminal and sphenopalatine ganglion stimulation for TNP, anesthesia dolorosa, and PIFP between 2010–2014 to assess the feasibility of implanting at these ganglionic sites. Seven patients received either trigeminal and/or sphenopalatine ganglion stimulation with or without peripheral nerve stimulation, having failed multiple alternative modalities of treatment. The treatments were tailored on the physical location of pain to ensure regional coverage with the stimulation. Fluoroscopy or frameless stereotaxy was utilized to place the sphenopalatine and/or trigeminal ganglion stimulator. All patients were initially trialed before implantation. Trial leads implanted in the pterygopalatine fossa near the sphenopalatine ganglion were implanted via transpterygoid (lateral-medial, infrazygomatic) approach. Trial leads were implanted in the trigeminal ganglion via percutaneous Hartel approach, all of which resulted in masseter contraction. Patients who developed clinically significant pain improvement underwent implantation. The trigeminal ganglion stimulation permanent implants involved placing a grid electrode over Meckel’s cave via subtemporal craniotomy, which offered a greater ability to stimulate subdivisions of the trigeminal nerve, without muscular (V3) side effects. Two of the seven overall patients did not respond well to the trial and were not implanted. Five patients reported pain relief with up to 24-month follow-up. Several of the sphenopalatine ganglion stimulation patients had pain relief without any paresthesias. There were no electrode migrations or post-surgical complications. Refractory facial pain may respond positively to ganglionic forms of stimulation. It appears safe and durable to implant electrodes in the pterygopalatine fossa via a lateral transpterygoid approach. Also, implantation of an electrode grid overlying Meckel’s cave appears to be a feasible alternative to the Hartel approach. Further investigation is needed to evaluate the usefulness of these approaches for various facial pain conditions.

Urban Slums represent a chronic problem to Egypt. According to official statistics, there are 1,221 urban slum inhabited by 17 million people in Egypt. These urban slums suffer from deterioration in infrastructure; this includes lack of access to proper sanitation, inadequate water distribution networks and congested street networks. These issues in infrastructure systems are reflected on the social aspect and the quality of life in these areas with problems such as high crime rates, health problems and spread of epidemics.

OBJECTIVEStereotactic laser ablation and neurostimulator placement represent an evolution in staged surgical intervention for epilepsy. As this practice evolves, optimal targeting will require standardized outcome measures that compare electrode lead or laser source with postprocedural changes in seizure frequency. The authors propose and present a novel stereotactic coordinate system based on mesial temporal anatomical landmarks to facilitate the planning and delineation of outcomes based on extent of ablation or region of stimulation within mesial temporal structures.METHODSThe body of the hippocampus contains a natural axis, approximated by the interface of cornu ammonis area 4 and the dentate gyrus. The uncal recess of the lateral ventricle acts as a landmark to characterize the anterior-posterior extent of this axis. Several volumetric rotations are quantified for alignment with the mesial temporal coordinate system. First, the brain volume is rotated to align with standard anterior commissure–posterior commissure (AC-PC) space. Then, it is rotated through the axial and sagittal angles that the hippocampal axis makes with the AC-PC line.RESULTSUsing this coordinate system, customized MATLAB software was developed to allow for intuitive standardization of targeting and interpretation. The angle between the AC-PC line and the hippocampal axis was found to be approximately 20°–30° when viewed sagittally and approximately 5°–10° when viewed axially. Implanted electrodes can then be identified from CT in this space, and laser tip position and burn geometry can be calculated based on the intraoperative and postoperative MRI.CONCLUSIONSWith the advent of stereotactic surgery for mesial temporal targets, a mesial temporal stereotactic system is introduced that may facilitate operative planning, improve surgical outcomes, and standardize outcome assessment.

The safe and reversible nature of deep brain stimulation (DBS) has allowed movement disorder neurosurgery to become commonplace throughout the world. Fundamental understanding of individual patient's anatomy is critical for optimizing the effects and side effects of DBS surgery. Three patients undergoing stereotactic surgery for movement disorders, at the institution's intraoperative magnetic resonance imaging operating suite, were studied with fiber tractography. Stereotactic targets and fiber tractography were determined on preoperative magnetic resonance imagings using the Schaltenbrand-Wahren atlas for definition in the BrainLab iPlan software (BrainLAB Inc., Feldkirchen, Germany). Subthalamic nucleus, globus pallidus interna, and ventral intermediate nucleus targets were studied. Diffusion tensor imaging parameters used ranged from 2 to 8 mm for volume of interest in the x/y/z planes, fiber length was kept constant at 30 mm, and fractional anisotropy threshold varied from 0.20 to 0.45. Diffusion tensor imaging tractography allowed reliable and reproducible visualization and correlation between frontal eye field, premotor, primary motor, and primary sensory cortices via corticospinal tracts and corticopontocerebellar tracts. There is an apparent increase in the number of cortical regions targeted by the fiber tracts as the region of interest is enlarged. This represents a possible mechanism of the increased effects and side effects observed with higher stimulation voltages. Currently available diffusion tensor imaging techniques allow potential methods to characterize the effects and side effects of DBS. This technology has the potential of being a powerful tool to optimize DBS neurosurgery.

Background and Purpose— We analyzed the impact of detailed anatomic characteristics on the results of endovascular coil embolization for anterior communicating artery (AcoA) aneurysms and developed a predictive model estimating the probability of successful endovascular treatment. Methods— One hundred eighty-one AcoA aneurysms were treated with endovascular coil embolization between August 1991 and November 2005. Morphological characteristics that were analyzed included direction of the dome, location of the neck, association with hypoplasia or aplasia of AcoA complex vessels, sac, and neck size. Immediate clinical and anatomic results, long-term morbidity/mortality, recanalization rate, and delayed aneurysm thrombosis were analyzed. ORs were calculated for each anatomic and clinical result and logistic regression was used in formulating a predictive model. Results— There were 115 females and 66 males. Age range was 9 to 86 years (mean 57). Factors significantly associated with complete embolization included small aneurysms (10 mm, neck location on the AcoA, posterior dome orientation, and incomplete original embolization. Globally, the majority of patients remained neurologically intact or unchanged after the procedure (92.8%). Mortality was significantly influenced by the preoperative condition of the patient. The predictive model successfully represented the likely outcomes based on morphological features. Conclusions— AcoA aneurysm coil embolization can be safely performed with acceptable rates of morbidity. Dome and neck orientation, sack and neck size, sac-to-neck ratio, and associated anomalies should be considered to accurately assess the probability of successful treatment for AcoA aneurysms.

A good working knowledge of surgical anatomy has helped surgeons for centuries to choreograph operations, anticipate dangers, formulate appropriate surgical corridors, and create exit strategy. This paper reiterates the development of the topographical location of the central gyrus, the methodologies and their contributors throughout the last two centuries, and the accuracy of their methods.

Deep brain stimulation is a rapidly expanding therapy initially designed for the treatment of movement disorders and pain syndromes. The therapy includes implantation of electrodes in specific targets of the brain, delivering programmable small and safe electric impulses, like a pacemaker, that modulates both local and broad neurologic networks. The effects are thought to primarily involve a focus in the brain, probably inhibitory, which then restores a network of neural circuitry. Psychiatric diseases can be refractory and severe, leading to high medical costs, significant morbidity, and even death. Whereas surgery for psychiatric disease used to include destructive procedures, deep brain stimulation allows safe, reversible, and adjustable treatment that can be tailored for each patient. Deep brain stimulation offers new hope for these unfortunate patients, and the preliminary results are promising.

A case report is presented detailing the successful use of awake intraoperative memory testing while using white matter stimulation in order to isolate the fornix tracks involved in memory function. The identification of the white matter tracks of the fornix that were involved in memory function was used to tailor the neurosurgical resection of a third ventricle tumor that was impinging on the fornix in order to successfully preserve memory functioning in the patient.

Background The ventralis intermedius (VIM) nucleus of the thalamus is the primary surgical target for treatment of tremor. Most centers rely on indirect targeting based on atlas-defined coordinates rather than patient-specific anatomy, making intraoperative physiological mapping critical. Detailed identification of this target based on patient-specific anatomic features can help optimize the surgical treatment of tremor. Objective To study colored fractional anisotropic images and diffusion tensor imaging (DTI) tractography to identify characteristic magnetic resonance appearances of the VIM nucleus. Methods Four patients undergoing stereotactic surgery for essential tremor (ET) were retrospectively studied with analysis of magnetic resonance imaging-based colored fractional anisotropy (FA) images and fiber tractography. All were scanned with a 1.5-T magnetic resonance imaging unit, and all sequences were obtained before frame placement. Because the goal of this study was to identify the DTI characteristics of physiologically defined VIM nucleus, we selected and studied patients who had undergone DTI and had efficacious tremor control with intraoperative microlesioning effect and tremor reduction with less than 2.0-V stimulation. Results Analysis of color FA maps, which graphically illustrate fiber directionality, revealed consistent anatomic patterns. The region of the VIM nucleus can be seen as an intermediate region where there is a characteristic transition of color. Presumptive VIM nucleus interconnectivity with sensorimotor cortex and cerebellum was identified via the internal capsule and the superior cerebellar peduncle, respectively. FA maps could also be used to distinguish segments of gray matter, white matter, and gray-white matter boundaries. Conclusion Analysis of DTI and FA maps on widely available 1.5-T magnetic resonance imaging yields clear identification of various structures key to neurosurgical targeting. Prospective evaluation of integrating DTI into neurosurgical planning may be warranted.

Early diagnosis and disease prevention, thorough visualization and understanding of disease and societal affordability, are the focus of medicine in the years to come. The goals in treatments are precision, accuracy, non-invasive techniques, efficacy of treatment and no side effects. Radiosurgery’s impact on the field of radiotherapy has imposed these goals over the last 60 years. The ingredients for the evolution of medicine hinges on our increasing ability to non-invasively see the intricacies of the human body, initially only bones, then soft-tissues, inside of organs, and now at the cellular and molecular level. Are we ready in the life science field for what society asks of us, to decrease suffering and enhance human life? There has been much progress in the last several decades in the technology and applicability of radiation and its uses in medicine. Since the first description of radiosurgery by Lars Leksell, the field has blossomed to include the treatment of tumors, vascular lesions, and various functional disorders (Leksell 1951). There is no doubt that the application of this technology has impacted the field of medicine and neurosurgery more than any other single modality. However, until now radiation has largely been used as an ablative technique, and its ability to modify cellular function at the genetic level continues in early stages of development.

Introduction The subthalamic nucleus (STN) and the globus pallidus internus (GPi) are the most common surgical targets for the treatment of Parkinson’s disease. We studied directionally colored fractional anisotropy (FA) and diffusion tensor imaging (DTI) sequences to better target these anatomical regions. Methods Four patients undergoing stereotactic surgery for movement disorders were studied. Stereotactic targets and fiber tractography were determined on MRIs using the Schaltenbrand–Wahren atlas for definition in the iPlan software. In addition, post-operative imaging was fused to preoperative FA sequences for end-result identification. Axial, sagittal, and coronal images of the FA sequence were studied. DTI parameters used ranged from 2 to 4 mm for voxel size in the x/y/z planes, fiber length was kept constant at 15 mm and FA threshold of 0.25. Results Colored FA maps resulted in a key signature in and around the STN and GPi. Regions identified include, but were not limited to: the internal capsule, nigral projections, the thalamic fasciculus, Forel’s fields H1 and H2, zona incerta, suthalamic fasciculus, tegmental tracts, and cerebello-rubro-thalamic tract. Conclusions Colored FA maps allow a potential method to identify the STN and GPi accurately. DTI has proven to be a powerful tool that can be used to augment identification of the STN nucleus and GPi used for stereotactic surgery.

Lower-limb sensory loss as a result of peripheral neuropathy or amputation results in sub-optimal movement and an increased incidence of injury. While the adoption of lower-limb prostheses and therapeutic footwear can reduce tissue injury and support movement, the fundamental problem of sensory loss continues to exist. A prototype haptic feedback system has been developed to aid in the recovery of lower-limb sensation due to these causes. Thin-film force sensors placed at the critical points for gait and balance functions collect essential force data, which is delivered to the user via pneumatically controlled balloon inflation. It is postulated that the use of this system will increase the tactile awareness of a patient's lower-limb or prosthesis, and when used in concert with modern rehabilitation techniques will create a method that will reduce the duration and improve the quality of lower-limb rehabilitation, especially in gait and balance functions.

Introduction The reversible nature of deep brain stimulation (DBS) brought renewed interest on surgery to medically intractable mental illnesses. The explosion of anatomical and functional imaging has allowed the development of new potential targets and the understanding of historical targets.

Fluorescence spectroscopy of the endogenous emission of brain tumors has been researched as a potentiallyimportant method for the intraoperative localization of brain tumor margins. In this study, we investigate theuse of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) for demarcation of primary braintumors by studying the time-resolved spectra of gliomas of different histologic grades. Time-resolvedfluorescence (3 ns, 337 nm excitation) from excised human brain tumor show differences between the time-resolved emission of malignant glioma and normal brain tissue (gray and white matter). Our findings suggestthat brain tumors can be differentiated from normal brain tissue based upon unique time-resolvedfluorescence signature. Keywords: Time-Resolved Laser Induced Fluorescence, brain tumor, glioma, spectroscopy.1. INTRODUCTIONDespite aggressive treatment including surgical resection, irradiation and chemotherapy, the median survivalof patients diagnosed with malignant gliomas is less than 12 months [1,2]. Surgical resection alone offers asurvival benefit, particularly when a complete resection can be achieved. Considerable evidence suggeststhat both survival and quality of life depend on the amount of tumor removed at surgery; a better prognosisoccurs when maximal surgical resection is achieved.The degree to which a complete resection can be carried out is limited in the brain by a number of factorsunique to the central nervous system. Primary brain tumors are infiltrating in nature, and the margins of thetumor are often indistinct. The goal at surgery is to remove as much of the tumor as safely possible withoutextending the resection into the normal adjacent brain [3]. Current imaging technologies to detect cancer inthe central nervous system fails to accurately detect the extent of infiltrating glial tumor [4,5]. Because

Object The goal of this study was to evaluate the definition of treatment-resistant depression (TRD), review the literature regarding deep brain stimulation (DBS) for TRD, and identify potential anatomical and functional targets for future widespread clinical application. Methods A comprehensive literature review was performed to determine the current status of DBS for TRD, with an emphasis on the scientific support for various implantation sites. Results The definition of TRD is presented, as is its management scheme. The rationale behind using DBS for depression is reviewed. Five potential targets have been identified in the literature: ventral striatum/nucleus accumbens, subgenual cingulate cortex (area 25), inferior thalamic peduncle, rostral cingulate cortex (area 24a), and lateral habenula. Deep brain stimulation electrodes thus far have been implanted and activated in only the first 3 of these structures in humans. These targets have proven to be safe and effective, albeit in a small number of cases. Conclusions Surgical intervention for TRD in the form of DBS is emerging as a viable treatment alternative to existing modalities. Although the studies reported thus far have small sample sizes, the results appear to be promising. Various surgical targets, such as the subgenual cingulate cortex, inferior thalamic peduncle, and nucleus accumbens, have been shown to be safe and to lead to beneficial effects with various stimulation parameters. Further studies with larger patient groups are required to adequately assess the safety and efficacy of these targets, as well as the optimal stimulation parameters and long-term effects.