Invasive Neurosurgical Procedures Research Articles

Fiducial Optimization for Minimal Target Registration Error in Image-Guided Neurosurgery

This paper presents new methods for the optimal selection of anatomical landmarks and optimal placement of fiducial markers in image-guided neurosurgery. These methods allow the surgeon to optimally plan fiducial marker locations on routine diagnostic images before preoperative imaging and to intraoperatively select the set of fiducial markers and anatomical landmarks that minimize the expected target registration error (TRE). The optimization relies on a novel empirical simulation-based TRE estimation method built on actual fiducial localization error (FLE) data. Our methods take the guesswork out of the registration process and can reduce localization error without additional imaging and hardware. Our clinical experiments on five patients who underwent brain surgery with a navigation system show that optimizing one marker location and the anatomical landmarks configuration reduced the TRE. The average TRE values using the usual fiducials setup and using the suggested method were 4.7 mm and 3.2 mm, respectively. We observed a maximum improvement of 4 mm. Reducing the target registration error has the potential to support safer and more accurate minimally invasive neurosurgical procedures.

Occipital sulci of the human brain: variability and morphometry

The external morphology of the occipital lobe was investigated in 15 human post-mortem brains (30 hemispheres) fixed in formalin. We identified, described and measured the lengths of nine major human occipital sulci and five variable ones, comparing both types between individuals and hemispheres. Morphological variability of human occipital sulci is related to interindividual and interhemispheric differences in their presence, origin, type, segmentation, intersection and length. The major occipital sulci, particularly the parieto-occipital, the calcarine, the inferior lateral occipital and the anterior occipital sulci, as well as two points of their intersections (cuneal point and intersection of the transverse occipital and superior occipital sulcus) may be used as reliable anatomical landmarks for the location of architectonically and functionally defined human visual areas (V1, V2, V3, V3A, V5/MT+, LO1 and LO2) and during less invasive neurosurgical procedures in the cases of focal lesions within the occipital lobe. Two lateral occipital sulci (inferior and superior) were defined on the lateral surface of the occipital lobe. The variable lunate sulcus was studied and combining our results with those from histological and functional imaging studies, we suggest that the lunate sulci of human and nonhuman primates are not homologous.

Deep Brain Stimulation for Dejerine-Roussy Syndrome: Case Report

The term "central post-stroke pain" is more appropriate to describe neuropathic pain following a cerebrovascular accident. Most patients complain of burning and other symptoms like lacerating and shooting pain. Treatment options for central pain are limited in number and efficacy. This paper reports on a 47-year-old man with central post-stroke pain refractory to treatment. The patient underwent insertion of a deep brain stimulator utilizing the Leksell frame. The target was the left centromedian thalamic nuclei. He had a qualitative symptomatic improvement. Deep brain stimulation can be a useful tool when all other modalities have failed. It is a minimally invasive neurosurgical procedure that may improve the quality of life in carefully selected (often desperate) patients with central post-stroke pain.

Is deep brain stimulation a prospective "cure" for addiction?

Deep brain stimulation has been put forward as a potential “cure” for intractable drug addiction. This is largely based on preclinical studies in animal models of addiction and small case series of positive, but short-term, effects on addictive behaviour in highly selected individuals. The history of neurosurgical treatment for psychiatric disorders suggests that we should be cautious in prematurely advocating invasive neurosurgical procedures on the basis of such limited evidence. Further research is required in animal models of addiction and in people treated for other neurological or psychiatric disorders before trials in addicted populations can be justified.

Neurosurgical craniotomy localization using a virtual reality planning system versus intraoperative image–guided navigation

Accurate craniotomy placement is essential for frameless neuronavigation in minimally invasive neurosurgery. A craniotomy using virtual reality (VR) can be as accurate as neuronavigation. We prospectively enrolled 48 patients that underwent minimally invasive cranial procedures planned using VR, followed by neuronavigation. First, craniotomies were planned using VR derived measurements. Second, frameless neuronavigation was applied to define the craniotomy. The locations of these paired craniotomies were compared. A correctly placed craniotomy was defined as one that enabled the surgeon to totally remove the pathology without need to enlarge the craniotomy intraoperatively. Using VR, the size and the position of the craniotomy were measured correctly in 47 of 48 cases (98%). In 44 of 48 cases (92%), neuronavigation identified the craniotomy site correctly. In cases where neuronavigation failed, minimally invasive surgery was successfully completed using preoperative VR surgery planning. No statistically significant difference was found between craniotomy localization using VR surgery planning or standard frameless neuronavigation (p=0.36). The craniotomy for minimally invasive neurosurgical procedures can be identified accurately using VR surgery planning or neuronavigation. In cases of neuronavigation failure, VR surgery planning serves as an effective backup system to perform a minimally invasive operation.

The Role of Interventional Therapies in Cancer Pain Management

Cancer pain is complex and multifactorial. Most cancer pain can be effectively controlled using analgesics in accordance to the WHO analgesic ladder. However, in a small but significant percentage of cancer patients, systemic analgesics fail to provide adequate control of cancer pain. These cancer patients can also suffer from intolerable adverse effects of drug therapy or intractable cancer pain in advance disease. Though the prognosis of these cancer patients is often very limited, the pain relief, reduced medical costs and improvement in function and quality of life from a wide variety of available interventional procedures is extremely invaluable. These interventions can be used as sole agents or as useful adjuncts to supplement analgesics. This review will discuss interventional procedures such as epidural and intrathecal drug infusions, intrathecal neurolysis, sympathetic nervous system blockade, nerve blocks, vertebroplasty and the more invasive neurosurgical procedures. Intrathecal medications including opioids, local anaesthetics, clonidine, and ziconotide will also be discussed.

Quantitative Analysis of Surgical Exposure and Angle of Surgical Freedom Obtained by Endoscope and Microscope in Various Approaches to the Anterior Communicating Artery Complex Using CT-Based Frameless Stereotaxy

Introduction: Surgical treatment of aneurysms of the anterior communicating artery complex is challenging due to the intricate vascular anatomy. Endoscopy is a leading technique of minimally invasive neurosurgical procedures, and it could lend itself well to overcome some of the vascular visualization challenges associated with this procedure.

Venous Thromboembolism (VTE) in Patients with Cancer: Epidemiology and Risk Factors

Although cancer is recognized as a major risk factor for venous thromboembolism, the exact magnitude of the problem and specific risk factors most strongly associated with the development of VTE is not well defined. Several recent studies have shown that the incidence of VTE is highest in patients who present with metastatic cancer, particularly cancers associated with a high one-year mortality rate, such as pancreatic cancer. The incidence rate of VTE is highest in the first few months after the diagnosis of cancer, and it decreases over time thereafter. For most cancers, it is not clear to what extent undergoing major surgery adds to the already high risk of VTE associated with the presence of the cancer. However, patients with glioma clearly have a very high incidence of VTE soon after they undergo any invasive neurosurgical procedure. Active chemotherapy, the use of erythropoetin agents, and the use of certain anti-cancer therapies such as thalidomide, high-dose steroids, and anti-angiogenic therapy also increase the risk of thrombosis. Similar to patients without cancer, the risk of VTE is higher in patients with coexisting chronic medical illnesses. Development of VTE is clearly associated with decreased survival and this effect is greater among patients initially diagnosed with local or regional stage cancer compared to patients with metastatic cancer.

Virtual reality system for planning minimally invasive neurosurgery

The authors report on their experience with a 3D virtual reality system for planning minimally invasive neurosurgical procedures. Between October 2002 and April 2006, the authors used the Dextroscope (Volume Interactions, Ltd.) to plan neurosurgical procedures in 106 patients, including 100 with intracranial and 6 with spinal lesions. The planning was performed 1 to 3 days preoperatively, and in 12 cases, 3D prints of the planning procedure were taken into the operating room. A questionnaire was completed by the neurosurgeon after the planning procedure. After a short period of acclimatization, the system proved easy to operate and is currently used routinely for preoperative planning of difficult cases at the authors' institution. It was felt that working with a virtual reality multimodal model of the patient significantly improved surgical planning. The pathoanatomy in individual patients could easily be understood in great detail, enabling the authors to determine the surgical trajectory precisely and in the most minimally invasive way. The authors found the preoperative 3D model to be in high concordance with intraoperative conditions; the resulting intraoperative "déjà-vu" feeling enhanced surgical confidence. In all procedures planned with the Dextroscope, the chosen surgical strategy proved to be the correct choice. Three-dimensional virtual reality models of a patient allow quick and easy understanding of complex intracranial lesions.

FIXED DYSTONIA UNRESPONSIVE TO PALLIDAL STIMULATION IMPROVED BY MOTOR CORTEX STIMULATION

We read with interest the report by Romito et al. about a patient with fixed dystonia who responded to motor cortex stimulation.1 In our view, their conclusions are limited by uncertainties about the diagnosis and shortcomings in the evaluation of the therapeutic response. These aspects are important when an invasive neurosurgical procedure is proposed for consideration in similar cases. The diagnosis of psychogenic dystonia is excluded by the authors with the statement that “nothing indicated somatoform or psychogenic disorder.”1 This diagnosis should be suspected when patients have fixed and painful posturing of the neck or limbs, which renders them unable to carry out basic daily activities.2 Possible, probable, documented, and clinically established categories of certainty can be established by applying Fahn and Williams' criteria.3 Only 10% of the fixed dystonia cohort evaluated prospectively with a standardized neuropsychiatric protocol by Schrag et al. did not meet criteria for psychogenic dystonia.4 Furthermore, the posture exhibited by this patient is similar to …

Preconditioning with hyperbaric oxygen attenuates brain edema after experimental intracerebral hemorrhage

Preconditioning with hyperbaric oxygen (HBO2) reduces ischemic brain damage. Activation of p44/42 mitogen-activated protein kinases (p44/42 MAPK) has been associated with preconditioning-induced brain ischemic tolerance. This study investigated if preconditioning with HBO2 protects against intracerebral hemorrhage (ICH)-induced brain edema formation and examined the role of p44/42 MAPK in such protection. The study had three experimental groups. In Group 1, Sprague-Dawley rats received two, three, or five consecutive sessions of preconditioning with HBO2 (3 ata, 100% oxygen, 1 hour daily). Twenty-four hours after preconditioning with HBO2, rats received an infusion of autologous blood into the caudate. They were killed 1 or 3 days later for brain edema measurement. Rats in Group 2 received either five sessions of preconditioning with HBO2 or control pretreatment and were killed 24 hours later for Western blot and immunohistochemical analyses. In Group 3, rats received an intracaudate injection of PD098059 (an inhibitor of p44/42 MAPK activation) before the first of five sessions of preconditioning with HBO2. Twenty-four hours after the final preconditioning with HBO2, rats received an intracaudate blood infusion. Brain water content was measured 24 hours after ICH. Fewer than five sessions of preconditioning with HBO2 did not significantly attenuate brain edema after ICH. Five sessions of preconditioning with HBO2 reduced perihematomal edema 24 and 72 hours after ICH (p < 0.05). Strong p44/42 MAPK immunoreactivity was detected in the basal ganglia 24 hours after preconditioning with HBO2. Intracaudate infusion of PD098059 abolished HBO2 preconditioning-induced protection against ICH-induced brain edema formation. Preconditioning with HBO2 protects against brain edema formation following ICH. Activation of the p44/42 MAPK pathway contributes to that protection. Preconditioning with HBO2 may be a way of limiting brain injury during invasive neurosurgical procedures that cause bleeding.

Fixed dystonia unresponsive to pallidal stimulation improved by motor cortex stimulation

We read with interest the report by Romito et al. about a patient with fixed dystonia who responded to motor cortex stimulation.1 In our view, their conclusions are limited by uncertainties about the diagnosis and shortcomings in the evaluation of the therapeutic response. These aspects are important when an invasive neurosurgical procedure is proposed for consideration in similar cases. The diagnosis of psychogenic dystonia is excluded by the authors with the statement that “nothing indicated somatoform or psychogenic disorder.”1 This diagnosis should be suspected when patients have fixed and painful posturing of the neck or limbs, which renders them unable to carry out basic daily activities.2 Possible, probable, documented, and clinically established categories of certainty can be established by applying Fahn and Williams' criteria.3 Only 10% of the fixed dystonia cohort evaluated prospectively with a standardized neuropsychiatric protocol by Schrag et al. did not meet criteria for psychogenic dystonia.4 Furthermore, the posture exhibited by this patient is similar to …

Venous thromboembolism in 9,489 patients with glioma

1538 Background: Venous thromboembolic events (VTE) are a commonly reported complication of brain tumors. The objective of this study was to define the incidence, risk factors, and outcomes associated with VTE in a population-based cohort. Methods: This was a retrospective analysis of all glioma cases diagnosed in California between 1993–1995 and 1997–1999. Glioma cases in the California Cancer Registry were linked to the California Patient Discharge Database to identify incident VTE. Cox models were generated to analyze the association of pre-specified risk factors with VTE or death within one year of the cancer diagnosis. Results: There were 9489 cases: 76% were Caucasians and 56% were men. The 1-year cumulative incidence of VTE was 663 (7%) with an incidence rate during the first year of 11.1 events per 100 person-years. Sixty-six percent of all VTE diagnosed in the first year occurred within 3 months of the cancer diagnosis with a corresponding incidence rate of 21.6 events per 100 person-years. Of 663 first year VTE, 405 (61%) occurred &lt;2 months after an invasive neurosurgical procedure. Glioblastoma multiforme (GBM) was associated with an increased risk of VTE (HR=1.6, CI: 1.3–2.0) compared to other gliomas. The risk of VTE was strongly associated with the number of chronic co-morbidities (HR=4.0, CI: 3.1–5.0 for ≥3 chronic co-morbidities). Asian race was associated with significantly lower risk of VTE (HR=0.3, CI: 0.2–0.6) and female gender conferred a modestly lower risk (HR=0.8, CI: 0.7–0.9). A VTE in the first year was associated with slightly lower risk of death (HR = 0.8; CI: 0.8–0.9), whereas increasing age (HR=6.3, CI: 5.6–7.0 for age≥75), number of co-morbidities (HR=1.9, CI: 1.7–2.0 for ≥3 chronic co-morbidities), and GBM (HR=2.2, CI: 2.0–2.4) or anaplastic astrocytoma (HR=1.5, CI: 1.3–1.7) histology were associated with a higher risk of death within 1 year. Conclusions: In this large glioma cohort, the incidence of symptomatic VTE was very high. Two-thirds of all VTE occurred early after the diagnosis of glioma, and most of these occurred within 2 months of an invasive neurosurgical procedure. The presence of chronic medical co-morbidities and GBM histology were strong predictors of VTE. A diagnosis of VTE was not associated with an increased risk of death within 1 year. No significant financial relationships to disclose.

Anesthesia for Minimally Invasive Cranial and Spinal Surgery

The field of minimally invasive neurosurgery has evolved rapidly in its indications and applications over the last few years. New, less invasive techniques with low morbidity and virtually no mortality are replacing conventional neurosurgical procedures. Providing anesthesia for these procedures differs in many ways from conventional neurosurgical operations. Anesthesiologists are faced with the perioperative requirements and risks of newly developed procedures. This review calls attention to the anesthetic issues in various minimally invasive neurosurgical procedures for cranial and spinal indications. Among the procedures specifically discussed are endoscopic third ventriculostomy, endoscopic transsphenoidal hypophysectomy, endoscopic strip craniectomy, deep brain stimulation, video-assisted thorascopic surgery, vertebroplasty and kyphoplasty, cervical discectomy and foraminectomy, and laparoscopically assisted lumbar spine surgery.

Is There an Interaction Between Pravastatin and Clinical Events Other Than Vasospasm in Patients With Aneurysmal Subarachnoid Hemorrhage?

To the Editor: We would like to congratulate Tseng et al1 for the article titled “Effects of acute treatment with Pravastatin on cerebral vasospasm, autoregulation, and delayed ischemic deficits after aneurysmal subarachnoid hemorrhage: A phase II randomized placebo-controlled trial”. The authors hypothesized that statins might improve cerebral vasomotor activity through cholesterol-dependent and -independent mechanisms. They randomized aneurysmal subarachnoid hemorrhage patients (18 to 84 years of age) within 72 hours from the ictus to receive either oral pravastatin (40 mg) or placebo daily for up to 14 days. They were able to show a decrease in incidence of vasospasm, duration of severe vasospasm, duration of impaired autoregulation, incidence of vasospasm-related delayed ischemic deficits and mortality with pravastatin treatment impressively in this 80-patient study. The authors’ center …

Transcranial magnetic stimulation for central pain

Transcranial magnetic stimulation recently has emerged as a therapeutic tool in neurology and psychiatry, with contradictory results. Central pain, a major chronic pain syndrome affecting millions of people worldwide, has been the focus of a few studies. Although transcranial magnetic stimulation has no role in the chronic management of such pain, it has potential as a screening procedure for the much more effective extradural cortical stimulation, a minimally invasive neurosurgical procedure that has emerged as the technique of choice in treating these patients.

Delivery of recombinant gene product to canine brain with the use of microencapsulation

An alternative approach to somatic gene therapy is to deliver a therapeutic protein by implanting “universal” recombinant cells that are immunologically protected from graft rejection with alginate microcapsules. This strategy has proved successful in reversing pathologic conditions in several rodent models of human disease (dwarfism, lysosomal storage disease, hemophilia, cancer). In particular, neurologic disease and behavioral deficit in the mouse model of a neurodegenerative disease (mucopolysaccharidosis [MPS] VII) were significantly improved through the intraventricular implantation of the recombinant encapsulated cells. Here we report the feasibility of delivering recombinant gene products to the central nervous systems (CNSs) of dogs, first using human growth hormone as a marker for delivery in normal dogs and then using α-iduronidase as a therapeutic product for delivery in the MPS I dog that is genetically deficient in this lysosomal enzyme. Madin-Darby canine kidney cells were genetically modified to express either human growth hormone or canine α-iduronidase, then enclosed in alginate-poly- l-lysine-alginate microcapsules of about 500 μm in diameter. The encapsulated cells were implanted into the brain under steoreotaxic guidance. The brains were monitored with computed tomographic scans before and after surgery and examined biochemically and histologically. Delivery of gene products, as measured in the plasma and cerebrospinal fluid sampled periodically through 21 days or in various regions of the brain after death showed that the delivery of both gene products was extremely low but detectable. However, we noted extensive inflammatory reactions, both at the sites of implantation and in the immediate vicinity of the implanted microcapsules. Hence for this technology to be applicable to the CNSs of larger animals and human beings, a more accurate and less invasive neurosurgical procedure, more biocompatible microcapsule–recombinant cell combinations, and higher output of recombinant products must be developed.

Anaesthetic care during minimally invasive neurosurgical procedures in infants and children.

Pediatric AnesthesiaVolume 12, Issue 6 p. 478-488 Anaesthetic care during minimally invasive neurosurgical procedures in infants and children Joel O. Johnson MD, PHD, Joel O. Johnson MD, PHD Department of Anesthesiology, The University of Missouri, Columbia, Missouri, USA, Department of Pediatrics, The University of Missouri, Columbia, Missouri, USA,Search for more papers by this authorDavid F. Jimenez MD , David F. Jimenez MD Department of Pediatrics, The University of Missouri, Columbia, Missouri, USA, Department of Neurosurgery, The University of Missouri, Columbia, Missouri, USASearch for more papers by this authorJoseph D. Tobias MD , Joseph D. Tobias MD Department of Anesthesiology, The University of Missouri, Columbia, Missouri, USA, Department of Pediatrics, The University of Missouri, Columbia, Missouri, USA,Search for more papers by this author Joel O. Johnson MD, PHD, Joel O. Johnson MD, PHD Department of Anesthesiology, The University of Missouri, Columbia, Missouri, USA, Department of Pediatrics, The University of Missouri, Columbia, Missouri, USA,Search for more papers by this authorDavid F. Jimenez MD , David F. Jimenez MD Department of Pediatrics, The University of Missouri, Columbia, Missouri, USA, Department of Neurosurgery, The University of Missouri, Columbia, Missouri, USASearch for more papers by this authorJoseph D. Tobias MD , Joseph D. Tobias MD Department of Anesthesiology, The University of Missouri, Columbia, Missouri, USA, Department of Pediatrics, The University of Missouri, Columbia, Missouri, USA,Search for more papers by this author First published: 25 July 2002 https://doi.org/10.1046/j.1460-9592.2002.00821.xCitations: 20 Joel O. Johnson, The University of Missouri, Department of Anesthesiology, N314 HSC, One Hospital Drive, Columbia, Missouri 65212, USA. (e-mail: johnsonjo@missouri.edu) Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume12, Issue6July 2002Pages 478-488 RelatedInformation

Gamma knife radiosurgery for trigeminal neuralgia: the initial experience of the Barrow Neurological Institute

Purpose: To assess the efficacy and complications of Gamma Knife radiosurgery for trigeminal neuralgia. Methods and Materials: The Barrow Neurological Institute (BNI) Gamma Knife facility has been operational since March 17, 1997. A total of 557 patients have been treated, 89 for trigeminal neuralgia (TN). This report includes the first 54 TN patients with follow-up exceeding 3 months. Patients were treated with Gamma Knife stereotactic radiosurgery (RS) in uniform fashion according to two sequential protocols. The first 41 patients received 35 Gy prescribed to the 50% isodose via a single 4-mm isocenter targeting the ipsilateral trigeminal nerve adjacent to the pons. The dose was increased to 40 Gy for the remaining 13 patients; however, the other parameters were unvaried. Outcome was evaluated by each patient using a standardized questionnaire. Pain before and after RS was scored as level I–IV per our newly-developed BNI pain intensity scoring criteria (I: no pain; II: occasional pain, not requiring medication; III: some pain, controlled with medication; IV: some pain, not controlled with medication; V: severe pain/no pain relief). Complications, limited to mild facial numbness, were similarly graded by a BNI scoring system. Results: Among our 54 TN patients, 52 experienced pain relief, BNI score I in 19 (35%), II in 3 (6%), III in 26 (48%), and IV in 4 (7%). Two patients (4%) reported no relief (BNI score V). Median follow-up was 12 months (range 3–28). Median time to onset of pain relief was 15 days (range 0–192), and to maximal relief 63 days (range 0–253). Seventeen (31%) noted immediate improvement (≤ 24 h). Prior to RS, all patients were on pharmacologic therapy felt to be optimal or maximal. Twenty-two (41%) were able to stop medications entirely (BNI score I or II). Another 16 (30%), with BNI Score III relief, decreased medication intake by at least 50%. Patients with classical TN pain symptoms were more likely to stop medications than those with atypical features, 49% (21 of 43) versus 9% (1 of 11). This difference was significant at p = 0.040. Statistically, the finding most predictive for pain relief was new facial numbness following RS. Each of the 5 patients with new numbness after RS developed BNI score I relief, contrasting with 35% for the 49 patients with no new numbness ( p = 0.019). Complications have been limited to delayed, mild facial sensory loss. Before RS, 17 patients had numbness from prior invasive procedures, none of whom reported a worse numbness score after treatment. Thirty-seven patients had no facial numbness at the time of RS, of whom 5 developed facial hypesthesia. Each rated this as “mild, not bothersome.” There have been no other sequellae. Conclusion: RS is an effective treatment, and is the least invasive nonpharmacologic therapy for TN. It carries a small risk of mild facial hypesthesia, a side effect which, somewhat ironically, may be desirable, because it appears to correlate favorably with an excellent pain response. We currently include radiosurgery among the appropriate options for TN patients who have failed optimal medical management, with or without prior invasive neurosurgical procedures. We present here BNI scoring systems for pain intensity and facial numbness. These have proved simple and reliable, have facilitated data collection, rendered analysis more objective, and improved our ability to discuss results with patients and colleagues.

Virtual Endoscopy for Planning and Simulation of Minimally Invasive Neurosurgery

OBJECTIVE: This article demonstrates the usefulness and the problems of present-state software for virtual endoscopy as a tool for the planning and simulation of minimally invasive neurosurgical procedures. METHODS: The software Navigator (General Electric Medical Systems, Buc, France) was applied for virtual endoscopic visualization of three-dimensional magnetic resonance data sets of healthy volunteers and neurosurgical patients, using a clinical magnetic resonance scanner (1.5-T Signa Hispeed; General Electric Medical Systems). Classical approaches for minimally invasive procedures were simulated. RESULTS: Virtual endoscopy provided impressive three-dimensional views of intracranial and intracerebral cavities, with visualization of many anatomic details of the brain's inner and outer surfaces. The method proved to be especially suited for the simulation and planning of operations of intraventricular lesions, for which the technical limitations of the present state of development of this method have fewer implications. However, the present state of technology, as described in this article, has two major shortcomings: 1) the blood vessels cannot be visualized together with the brain tissue and cranial nerves; and 2) different tissue compartments cannot be stained in their original coloring, which would facilitate their recognition and thus orientation in space by anatomic landmarks. Another important disadvantage at this stage is time consumption for many single working steps. CONCLUSION: Virtual endoscopy is a promising tool for teaching and training in intracranial neuroanatomy as well as for planning and simulation of minimally invasive (e.g., endoscopic), mainly intraventricular, operations. Direct clinical application is, at this stage of development, limited by several technical shortcomings of visualization and quantification of distances and modeling of surfaces.