Presurgical selection of the ideal aneurysm clip by the use of a three-dimensional planning system.

Aneurysm occlusion rate after clipping is higher than after endovascular treatment. However, a certain percentage of incompletely clipped aneurysms remains. Presurgical selection of the proper aneurysm clips could potentially reduce the rate of incomplete clippings caused by inadequate clip geometry. The aim of the present study was to assess whether preoperative 3D image-based simulation allows for preoperative selection of a proper aneurysm clip for complete occlusion in individual cases. Patients harboring ruptured or unruptured cerebral aneurysms prior to surgical clipping were analyzed. CT angiography images were transferred to a 3D surgical-planning station (Dextroscope®) with imported models of 58 aneurysm clips. Intracranial vessels and aneurysms were segmented and the virtual aneurysm clips were placed at the aneurysm neck. Operating surgeons had information about the selected aneurysm clip, and patients underwent clipping. Intraoperative clip selection was documented and aneurysm occlusion rate was assessed by postoperative digital subtraction angiography. Nineteen patients were available for final analysis. In all patients, the most proximal clip at the aneurysm neck was the preselected clip. All aneurysms except one were fully occluded, as assessed by catheter angiography. One aneurysm had a small neck remnant that did not require secondary surgery and was occluded 15 months after surgery. 3D image-based preselection of a proper aneurysm clip can be translated to the operating room and avoids intraoperative clip selection. The associated occlusion rate of aneurysms is high.

Lateral cervical approach for ventrally located upper cervical meningioma: experience of 14 cases with a narrative comparison with other surgical techniques.

BACKGROUND: Upper cervical meningioma represents a large portion of intradural extramedullary tumors that occur in the cervical spinal canal. Most of them are located ventrally or ventrolateral to the spinal cord. Reaching lesions at this location surgically is technically challenging. OBJECTIVES: The ideal approach to ventrally located upper cervical lesions continues to be controversial. The aim of this study was to discuss the advantage of the lateral cervical approach and compare it with other surgical routes. METHODS: This retrospective study was conducted on all cases of ventrally located upper cervical meningiomas (C1-C3) who have been operated on using the lateral cervical approach in a tertiary neurosurgery unit between 2006 and 2020. Demographic, clinical, surgical, and follow-up data were collected from hospital records. RESULTS: During the study period, fourteen patients (Nine females and five males, aged 42-73 years) were recruited. The follow-up period was 2-16 years. The most frequent presenting symptoms were neck pain, occipital headache, motor deficits, and sensory disturbances. Total excision was achieved in all patients. All patients who had preoperative motor deficits improved significantly postoperatively, and those who presented with sensory disturbance had partial recovery. There was neither mortality nor permanent neurological morbidity. CONCLUSION: A lateral cervical approach is a safe approach for ventrally located upper cervical lesions. In our series, it offered enough exposure for a safe dissection and total or extensive subtotal removal of the tumors. Retraction or rotation of the neuroaxis was avoided, and the incidence of complications (injury of neural or vascular structures, instability, infection) was very low.

sEVD-smartphone-navigated placement of external ventricular drains.

BACKGROUND: Currently, the trajectory for insertion of an external ventricular drain (EVD) is mainly determined using anatomical landmarks. However, non-assisted implantations frequently require multiple attempts and are associated with EVD malpositioning and complications. The authors evaluated the feasibility and accuracy of a novel smartphone-guided, angle-adjusted technique for assisted implantations of an EVD (sEVD) in both a human artificial head model and a cadaveric head. METHODS: After computed tomography (CT), optimal insertion angles and lengths of intracranial trajectories of the EVDs were determined. A smartphone was calibrated to the mid-cranial sagittal line. Twenty EVDs were placed using both the premeasured data and smartphone-adjusted insertion angles, targeting the center of the ipsilateral ventricular frontal horn. The EVD positions were verified with post-interventional CT. RESULTS: All 20 sEVDs (head model, 8/20; cadaveric head, 12/20) showed accurate placement in the ipsilateral ventricle. The sEVD tip locations showed a mean target deviation of 1.73° corresponding to 12 mm in the plastic head model, and 3.45° corresponding to 33 mm in the cadaveric head. The mean duration of preoperative measurements on CT data was 3 min, whereas sterile packing, smartphone calibration, drilling, and implantation required 9 min on average. CONCLUSIONS: By implementation of an innovative navigation technique, a conventional smartphone was used as a protractor for the insertion of EVDs. Our ex vivo data suggest that smartphone-guided EVD placement offers a precise, rapidly applicable, and patient-individualized freehand technique based on a standard procedure with a simple, cheap, and widely available multifunctional device.

The supraorbital keyhole approach: how I do it.

BACKGROUND: Improvements in image guidance, endoscopy, and instruments, have significantly advanced "keyhole" neurosurgery. We describe the concept and technique of the supraorbital keyhole approach. METHODS: The supraorbital keyhole approach is performed through an eyebrow skin incision. Image guidance may be used to define the optimal surgical trajectory. A limited supraorbital craniotomy is fashioned. The frontal lobe is mobilized and the central skull base approached, without the need for brain retractors. Endoscopy is used to enhance visualization, and tube-shaft instruments to improve manipulation through the narrow surgical corridor. CONCLUSIONS: The supraorbital keyhole approach provides a safe method to access selected skull base lesions.

Brainstem cavernoma surgery with the support of pre- and postoperative diffusion tensor imaging: initial experiences and clinical course of 23 patients.

The spatial complexity of highly vulnerable structures makes surgical resection of brainstem cavernomas (BSC) a challenging procedure. Diffusion tensor imaging (DTI) allows for the visualization of white matter tracts and enables a better understanding of the anatomical location of corticospinal and sensory tracts before and after surgery.We investigated the feasibility and clinical usefulness of DTI-based fiber tractography in patients with BSC.Pre- and postoperative DTI visualization of corticospinal and sensory tracts were retrospectively analyzed in 23 individuals with BSC. Preoperative and postoperative DTI-fiber accuracy were associated to the neurological findings. Preoperatively, the corticospinal tracts were visualized in 90 % of the cases and the sensory tracts were visualized in 74 % of the cases. Postoperatively, the corticospinal tracts were visualized in 97 % of the cases and the sensory tracts could be visualized in 80 % of the cases. In all cases, the BSC had caused displacement, thinning, or interruption of the fiber tracts to various degrees. Tract visualization was associated with pre- and postoperative neurological findings. Postoperative damage of the corticospinal tracts was observed in two patients. On follow-up, the Patzold Rating (PR) improved in 19 out of 23 patients (83 %, p = 0.0002).This study confirms that DTI tractography allows accurate and detailed white matter tract visualization in the brainstem, even when an intraaxial lesion affects this structure. Furthermore, visualizing the tracts adjacent to the lesion adds to our understanding of the distorted intrinsic brainstem anatomy and it may assists in planning the surgical approach in specific cases.

Virtual Reality Planning of Microvascular Decompression in Trigeminal Neuralgia: Technique and Clinical Outcome.

BACKGROUND: A neurovascular conflict (NVC) is considered the cause of trigeminal neuralgia (TN) in 75% of cases, and if so, a microvascular decompression (MVD) can lead to significant pain relief. A reliable preoperative detection of NVC is essential for clinical decision-making and surgical planning, making detailed neuroradiologic imaging an important component. We present our experiences and clinical outcomes with preoperative planning of the MVD procedure in a virtual reality (VR) environment, based on magnetic resonance imaging (MRI) including magnetic resonance angiography (MRA) and magnetic resonance venography (MRV) sequences. METHODS: We analyzed the data of 30 consecutive MVDs in patients treated for TN, in a retrospective single-surgeon (R.A. Kockro) study. Out of the 30 cases, 26 were included. Preoperatively, MRA/MRV and MRI series were fused and three dimensionally reconstructed in a VR environment. All critical structures such as the trigeminal nerve as well as the arteries and veins of the cerebellopontine angle, the brainstem, the neighboring cranial nerves, and the transverse and sigmoid sinus were segmented. The NVC was visualized and a simulation of a retrosigmoid approach, with varying trajectories, to the NVC was performed. The intraoperative findings were then compared with the data of the simulation. The clinical outcome was assessed by a detailed review of medical reports, and follow-up-interviews were conducted in all available patients (20/26). RESULTS: The VR planning was well integrated into the clinical workflow, and imaging processing time was 30 to 40 minutes. There was a sole arterial conflict in 13 patients, a venous conflict in 4 patients, and a combined arteriovenous conflict in 9 patients. The preoperative simulations provided a precise visualization of the anatomical relationships of the offending vessels and the trigeminal nerves as well as the surrounding structures. For each case, the approach along the most suitable surgical corridor was simulated and the exact steps of the decompression were planned. The NVC and the anatomy of the cerebellopontine angle as seen intraoperatively matched with the preoperative simulations in all cases and the MVC could be performed as planned. At follow-up, 92.3% (24/26) of patients were pain free and all the patients who completed the questionnaire would undergo the surgery again (20/20). The surgical complication rate was zero. CONCLUSION: Current imaging technology allows detailed preoperative visualization of the pathoanatomical spatial relationships in cases of TN. 3D interactive VR technology allows establishing a clear dissection and decompression strategy, resulting in safe vascular microsurgery and excellent clinical results.

Social Media for Global Neurosurgery. Benefits and limitations of a groundbreaking approach to communication and education.

Introduction: Social media have become ubiquitous and their role in medicine is quickly growing. They provide an open platform by which members share educational material, clinical experiences, and collaborate with educational equity. Research question: To characterize the role of social media in neurosurgery, we analyzed metrics of the largest neurosurgical group (Neurosurgery Cocktail), collected relevant data about activities, impact and risks of this groundbreaking technology. Material and methods: We extracted Facebook metrics from 60-day time sample, including users demographics and other platform-specific values such as active members and number of posts within 60 days. A quality assessment of the posted material (clinical case reports and second opinions) was obtained establishing four main quality-criteria: privacy violation; quality of imaging; clinical and follow up data. Results: By December 2022, the group included 29.524 members (79.8% male), most (29%) between 35 and 44 years of age. Over 100 countries were represented. A total of 787 posts were published in 60 days with an average of 12.7 per day. In 173 clinical cases presented through the platform, some issue with privacy was recorded in 50.9%. The imaging was considered insufficient in 39.3%, clinical data in 53.8%; follow up data were missing in 60.7%. Discussion and conclusion: The study provided a quantitative evaluation of impact, flaws and limitations of social medial for healthcare. Flaws were mostly data breach and insufficient quality of case reports. There are actions to correct these flaws that can be easily taken to provide a greater credibility and efficacy to the system.

Operative Anatomy of the Skull Base: 3D Exploration with a Highly Detailed Interactive Atlas.

Objective We evaluated the usefulness of a three-dimensional (3D) interactive atlas to illustrate and teach surgical skull base anatomy in a clinical setting. Study Design A highly detailed atlas of the adult human skull base was created from multiple high-resolution magnetic resonance imaging (MRI) and computed tomography (CT) scans of a healthy Caucasian male. It includes the parcellated and labeled bony skull base, intra- and extracranial vasculature, cranial nerves, cerebrum, cerebellum, and brainstem. We are reporting retrospectively on our experiences with employing the atlas for the simulation and teaching of neurosurgical approaches and concepts in a clinical setting. Setting The study was conducted at the University Hospital Mainz, Germany, and Hirslanden Hospital, Zürich, Switzerland. Participants Medical students and neurosurgical residents participated in this study. Results Handling the layered graphical user interface of the atlas requires some training; however, navigating the detailed 3D content from intraoperative perspectives led to quick comprehension of anatomical relationships that are otherwise difficult to perceive. Students and residents appreciated the collaborative learning effect when working with the atlas on large projected screens and markedly improved their anatomical knowledge after interacting with the software. Conclusion The skull base atlas provides an effective way to study essential surgical anatomy and to teach operative strategies in this complex region. Interactive 3D computer graphical environments are highly suitable for conveying complex anatomy and to train and review surgical concepts. They remain underutilized in clinical practice.

Advantages and limitations of intraoperative 3D ultrasound in neurosurgery. Technical note.

Three-dimensional ultrasound (US) technology is supposed to help combat some of the orientation difficulties inherent to two-dimensional US. Contemporary navigation solutions combine reconstructed 3D US images with common navigation images and support orientation. New real-time 3D US (without neuronavigation) is more time effective, but whether it further assists in orientation remains to be determined. An integrated US system (IGSonic, VectorVision, BrainLAB, Munich Germany) and a non-integrated system with real-time 3D US (iU22, Philips, Bothell, USA) were recently compared in neurosurgical procedures in our group. The reconstructed navigation view was time-consuming, but images were displayed in familiar planes (e.g., axial, sagittal, coronal). Further potential applications of US angiography and pure US navigation are possible. Real-time 3D images were displayed without the need for an additional acquisition and reconstruction process, but spatial orientation remained challenging in this preliminary testing phase. Reconstructed 3D US navigation appears to be superior with respect to spatial orientation, and the technique can be combined with other imaging data. However, the potential of real-time 3D US imaging is promising.

An alternative projection for fluoroscopic-guided needle insertion in the foramen ovale: technical note.

PURPOSE: Puncture of the ganglion Gasseri through the foramen ovale and subsequent thermocoagulation, balloon compression, or glycerin injection is a well-established technique to treat trigeminal neuralgia. However, direct puncture of the foramen is sometimes difficult. Here, the authors present a simple technique of improved biplane fluoroscopic control for insertion of the needle into the foramen ovale. METHODS: The authors evaluated an alternative oblique X-ray trajectory for the correct placement of a needle into the foramen ovale on cadaveric skull models. After determination of the ideal X-ray trajectory, 13 subsequent patients suffering from trigeminal neuralgia were subjected to intraforaminal needle placement with application of the alternative X-ray trajectory. RESULTS: An oblique projection with the X-ray tube (mean rotation 20.9° and angulations 28°) aligned coaxially to the inserted needle is proposed. On cadaver skull models, this oblique trajectory appeared to be ideal for visualization of the correct needle position. In the 13 patients, an immediate needle insertion into the foramen ovale was achieved under this direct oblique fluoroscopic control. No complications were observed. CONCLUSIONS: Experimentally and clinically, the new projection demonstrated three distinct advantages over the standard submental projection: Firstly, the foramen ovale can be better visualized independent of the patient's position. Secondly, needle correction or insertion can be performed much easier because of the direct fluoroscopic control. Thirdly, the correct needle position in the foramen ovale is more reliably determined than with the submental projection due to projection geometry. Further studies are needed to give evidence that the needle insertion into the foramen ovale is easier achieved with the coaxial projection than with the standard technique.

Translamina Terminalis Approach to the Hypothalamus Using Supraorbital Craniotomy: Technical Note and Comparison with Other Surgical Corridors.

OBJECTIVES: Approaches to the hypothalamus and anterior third ventricle are variable. We present a technical note on access of the hypothalamus using the trans-lamina terminalis approach by supraorbital craniotomy in a patient who had a hypothalamic cavernoma and presented to us with recurrent hemorrhage. PATIENTS AND METHODS: The trans-lamina terminalis approach, including anatomical landmarks and surgical steps through a supra-orbital craniotomy, is described and a comparison with other surgical corridors is discussed. RESULTS: The supraorbital trans lamina terminalis approach allowed an effective access to the hypothalamic lesions. This approach provided a safe and minimally invasive corridor for gross total resection of the lesion since trespass of viable brain tissue is avoided. One clinical case illustrates the feasibility of the approach allowing complete removal of a cavernoma without surgery related neurological of endocrinological deficits. CONCLUSIONS: The supra-orbital craniotomy for trans-lamina terminalis approach is a valid surgical choice for hypothalamic lesions. The major strengths of this approach include minimal brain retraction and direct end-on view; however, the long and narrow surgical corridor requires some technical familiarization. The clinical outcomes are comparable to other surgical corridors.

Surgical planning for microsurgical excision of cerebral arterio-venous malformations using virtual reality technology.

BACKGROUND: To evaluate the feasibility of surgical planning using a virtual reality platform workstation in the treatment of cerebral arterio-venous malformations (AVMs) METHODS: Patient-specific data of multiple imaging modalities were co-registered, fused and displayed as a 3D stereoscopic object on the Dextroscope, a virtual reality surgical planning platform. This system allows for manipulation of 3D data and for the user to evaluate and appreciate the angio-architecture of the nidus with regards to position and spatial relationships of critical feeders and draining veins. We evaluated the ability of the Dextroscope to influence surgical planning by providing a better understanding of the angio-architecture as well as its impact on the surgeon's pre- and intra-operative confidence and ability to tackle these lesions. FINDINGS: Twenty four patients were studied. The mean age was 29.65 years. Following pre-surgical planning on the Dextroscope, 23 patients underwent microsurgical resection after pre-surgical virtual reality planning, during which all had documented complete resection of the AVM. Planning on the virtual reality platform allowed for identification of critical feeders and draining vessels in all patients. The appreciation of the complex patient specific angio-architecture to establish a surgical plan was found to be invaluable in the conduct of the procedure and was found to enhance the surgeon's confidence significantly. CONCLUSION: Surgical planning of resection of an AVM with a virtual reality system allowed detailed and comprehensive analysis of 3D multi-modality imaging data and, in our experience, proved very helpful in establishing a good surgical strategy, enhancing intra-operative spatial orientation and increasing surgeon's confidence.

Surgical complications after endoscopic transsphenoidal pituitary surgery.

Between January 2004 and June 2007 we conducted a retrospective analysis to assess post-operative complications related to endoscopic pituitary surgery in a series of 150 patients. Patients were treated with an endoscopic endonasal transsphenoidal approach to the sellar region for removal of pathological sellar and suprasellar lesions. We analysed the complications in groups according to the anatomical structures of the approach and the functional systems of the pituitary gland (anterior and posterior endocrine systems), and compared them to a large historical series using the traditional microsurgical transsphenoidal approach. Overall, we observed a decreased incidence of complications with respect to the surgical trauma, the functionality of the pituitary gland and post-operative patient comfort. We believe that the reduction of the complication rate observed in this study was mainly due to the wide structural overview offered by the endoscope as well as the anatomically direct, and therefore minimally invasive, character of the procedure. Successful endoscopic pituitary surgery requires extensive training in the use of an endoscope and careful planning of the surgery. Furthermore, close cooperation between a multidisciplinary team consisting of endocrinologists, neurosurgeons, ear, nose and throat surgeons, radiologists, and radiation oncologists is of utmost importance.

A stereotactic device for rabbits based on mandibular and cranial landmarks: technical note.

The authors have developed a stereotactic device for use in rabbits that uses the plane at the base of the mandible combined with cranial sutures as an anatomical reference. The device was developed for a study designed to evaluate catheters for infection prophylaxis, and this required the implantation of silicone catheters along a reproducible trajectory through the lateral ventricle. Cadaver and atlas studies demonstrated consistent spatial relationships between intracranial structures and the surface plane on which the animals were resting during the surgery. This plane is formed by the 2 mandibular angles and the mandibular tip. The authors developed a stainless steel stereotactic device that uses this mandibular plane as well as the coronal and sagittal sutures as spatial references. Operations were performed in 60 animals using the stereotactic device, and postmortem dissections of the animals' brains demonstrated 78.6% accuracy of the trajectory within a tolerance of deviation of 5 degrees , and 94.6% accuracy within a tolerance of 10 degrees . The accuracy of the trajectory of the last 18 consecutively operated animals was constantly within a tolerance of 5 degrees . The device can be autoclaved and, since it is relatively simple and inexpensive to build, the authors manufactured 3 identical frames and used them alternately to operate under sterile conditions. The fast and pain-free head fixation minimized anesthesia-related risks. The authors' experiences suggest that the device is suitable for ventricular punctures and, dependant on the individual requirements of accuracy, other procedures that require "approximate" stereotactic guidance especially when a series of animals need to undergo operations quickly.

Virtual reality system for planning minimally invasive neurosurgery. Technical note.

OBJECT: The authors report on their experience with a 3D virtual reality system for planning minimally invasive neurosurgical procedures. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Aneurysm Surgery with Preoperative Three-Dimensional Planning in a Virtual Reality Environment: Technique and Outcome Analysis.

OBJECTIVE: Aneurysm surgery demands precise spatial understanding of the vascular anatomy and its surroundings. We report on a decade of experience planning clipping procedures preoperatively in a virtual reality (VR) workstation and present outcomes with respect to mortality, morbidity, and aneurysm occlusion rate. METHODS: Between 2006 and 2015, the clipping of 115 intracranial aneurysms in 105 patients was preoperatively planned with the Dextroscope, a stereoscopic, patient-specific VR environment. The outcome data for all cases, planned and performed in 3 institutions, were analyzed based on clinical charts and radiologic reports. RESULTS: Eighty-five incidental, unruptured aneurysms in 77 patients were electively planned and treated surgically. Mortality was 0% and morbidity (modified Rankin Scale score >2) was 2.6%. The rate of complete aneurysm obliteration on postoperative imaging was 91.8%. In addition, 30 aneurysms were treated in 28 patients with previous subarachnoid hemorrhage. Mortality in these cases was 3.6%, morbidity (modified Rankin Scale score >2) 7.1%, and the rate of complete aneurysm clipping was 90%. CONCLUSIONS: Meticulous three-dimensional surgical planning in a VR environment enhances the surgeon's spatial understanding of the individual vascular anatomy and allows clip preselection and positioning as well as anticipation of potential difficulties and complications. VR planning was associated, in this multi-institutional series, with excellent clinical outcomes and rates of complete aneurysm closure equivalent to benchmark cohorts.

Combining 5-Aminolevulinic Acid Fluorescence and Intraoperative Magnetic Resonance Imaging in Glioblastoma Surgery: A Histology-Based Evaluation.

BACKGROUND: Glioblastoma resection guided by 5-aminolevulinic acid (5-ALA) fluorescence and intraoperative magnetic resonance imaging (iMRI) may improve surgical results and prolong survival. OBJECTIVE: To evaluate 5-ALA fluorescence combined with subsequent low-field iMRI for resection control in glioblastoma surgery. METHODS: Fourteen patients with suspected glioblastoma suitable for complete resection of contrast-enhancing portions were enrolled. The surgery was carried out using 5-ALA-induced fluorescence and frameless navigation. Areas suspicious for tumor underwent biopsy. After complete resection of fluorescent tissue, low-field iMRI was performed. Areas suspicious for tumor remnant underwent biopsy under navigation guidance and were resected. The histological analysis was blinded. RESULTS: In 13 of 14 cases, the diagnosis was glioblastoma multiforme. One lymphoma and 1 case without fluorescence were excluded. In 11 of 12 operations, residual contrast enhancement on iMRI was found after complete resection of 5-ALA fluorescent tissue. In 1 case, the iMRI enhancement was in an eloquent area and did not undergo a biopsy. The 28 biopsies of areas suspicious for tumor on iMRI in the remaining 10 cases showed tumor in 39.3%, infiltration zone in 25%, reactive central nervous system tissue in 32.1%, and normal brain in 3.6%. Ninety-three fluorescent and 24 non-fluorescent tissue samples collected before iMRI contained tumor in 95.7% and 87.5%, respectively. CONCLUSION: 5-ALA fluorescence-guided resection may leave some glioblastoma tissue undetected. MRI might detect areas suspicious for tumor even after complete resection of all fluorescent tissue; however, due to the limited accuracy of iMRI in predicting tumor remnant (64.3%), resection of this tissue has to be considered with caution in eloquent regions.

Endoscopic fenestration of intraventricular cerebrospinal fluid cysts: the contralateral approach.

OBJECTIVE: The endoscopic fenestration of intraventricular CSF cysts has evolved into a well-accepted treatment modality. However, definition of the optimal trajectory for endoscopic fenestration may be difficult. Distorted ventricular anatomy and poor visibility within the cyst due to its contents can make endoscopic fenestration challenging if approached from the ipsilateral side. In addition, transcortical approaches can theoretically cause injury to eloquent cortex, particularly in patients with dominant-sided lesions. The aim of this study was to examine the value of the contralateral transcortical transventricular approach in patients with dominant-sided ventricular cysts. METHODS: During a 5-year period between 2007 and 2011, 31 patients with intraventricular CSF cysts underwent surgery by the senior author (R.R.). Fourteen of these patients had cysts located on the dominant side. An image-guided endoscopic cyst fenestration via the contralateral transcortical transventricular approach was performed in 11 patients. A retrospective chart review was performed in all these patients to extract data on clinical presentation, operative technique, and surgical outcome. RESULTS: The most common presenting symptom was headache, followed by memory deficits and cognitive deterioration. In all cases CSF cysts were space occupying, with associated obstructive hydrocephalus in 8 patients. Image-guided endoscopic fenestration was successfully performed in all cases, with septum pellucidotomy necessary in 6 cases, and endoscopic third ventriculostomy in 1 case for additional aqueductal occlusion. Postoperative clinical outcome was excellent, with no associated permanent neurological or neuropsychological morbidity. No recurrent cysts were observed over a mean follow-up period of 2 years and 3 months. CONCLUSIONS: The contralateral approach to ventricular cysts can achieve excellent surgical outcomes while minimizing approach-related trauma to the dominant hemisphere. Careful case selection is essential to ensure that the contralateral endoscopic trajectory is the best possible exposure for sufficient cyst fenestration and restoration of CSF circulation.

Stereoscopic neuroanatomy lectures using a three-dimensional virtual reality environment.

INTRODUCTION: Three-dimensional (3D) computer graphics are increasingly used to supplement the teaching of anatomy. While most systems consist of a program which produces 3D renderings on a workstation with a standard screen, the Dextrobeam virtual reality VR environment allows the presentation of spatial neuroanatomical models to larger groups of students through a stereoscopic projection system. MATERIALS AND METHODS: Second-year medical students (n=169) were randomly allocated to receive a standardised pre-recorded audio lecture detailing the anatomy of the third ventricle accompanied by either a two-dimensional (2D) PowerPoint presentation (n=80) or a 3D animated tour of the third ventricle with the DextroBeam. Students completed a 10-question multiple-choice exam based on the content learned and a subjective evaluation of the teaching method immediately after the lecture. RESULTS: Students in the 2D group achieved a mean score of 5.19 (±2.12) compared to 5.45 (±2.16) in the 3D group, with the results in the 3D group statistically non-inferior to those of the 2D group (p<0.0001). The students rated the 3D method superior to 2D teaching in four domains (spatial understanding, application in future anatomy classes, effectiveness, enjoyableness) (p<0.01). CONCLUSION: Stereoscopically enhanced 3D lectures are valid methods of imparting neuroanatomical knowledge and are well received by students. More research is required to define and develop the role of large-group VR systems in modern neuroanatomy curricula.

The DextroBeam: a stereoscopic presentation system for volumetric medical data.

This paper describes an interaction system called the DextroBeam designed for manipulating objects in 3D space while looking at a 3D stereoscopic display located in front of the user. Three-dimensional interaction is two-handed and is achieved by means of a stylus with a single button or switch. We have been planning several neurosurgical cases with the DextroBeam, including the separation of Nepalese Siamese twins in April 2001, and have conducted a course on surgery of the Temporal Bone (as part of the 9th ASEAN ORL Head and Neck Congress in Singapore, March 2001).