Evaluation of a Wearable AR Platform for Guiding Complex Craniotomies in Neurosurgery.

Today, neuronavigation is widely used in daily clinical routine to perform safe and efficient surgery. Augmented reality (AR) interfaces can provide anatomical models and preoperative planning contextually blended with the real surgical scenario, overcoming the limitations of traditional neuronavigators. This study aims to demonstrate the reliability of a new-concept AR headset in navigating complex craniotomies. Moreover, we aim to prove the efficacy of a patient-specific template-based methodology for fast, non-invasive, and fully automatic planning-to-patient registration. The AR platform navigation performance was assessed with an in-vitro study whose goal was twofold: to measure the real-to-virtual 3D target visualization error (TVE), and assess the navigation accuracy through a user study involving 10 subjects in tracing a complex craniotomy. The feasibility of the template-based registration was preliminarily tested on a volunteer. The TVE mean and standard deviation were 1.3 and 0.6 mm. The results of the user study, over 30 traced craniotomies, showed that 97% of the trajectory length was traced within an error margin of 1.5 mm, and 92% within a margin of 1 mm. The in-vivo test confirmed the feasibility and reliability of the patient-specific template for registration. The proposed AR headset allows ergonomic and intuitive fruition of preoperative planning, and it can represent a valid option to support neurosurgical tasks.

Eponyms of Cranial Neurosurgical Instruments: An International Collaboration to Optimize the Field of Neurosurgery.

The basic set of a cranial instrument tray is filled with eponyms of surgical instruments named after surgeons and physicians from all corners of the medical world. These include pioneers like Castroviejo, Doyen, Frazier, Gigli, Mayfield, Raney, Weitlaner, and Yasargil. These innovators have always strived to enhance and simplify procedures, ultimately shaping the way we perform surgery today. It was a process, which took several generations of surgeons and trials of instruments before its current form could be established. In this paper, the authors provide background information through a historical perspective on the pioneering surgeons and physicians, after whom the instruments were named. Data were collected by searching PubMed, Google Scholar/Books, Google, and the HathiTrust Digital Library. Additional information was obtained via personal contact with American and European medical institutions, libraries, museums, as well as with the surgeons' family members and their perspective foundations. Remembering the life stories of the inventors behind commonly used eponyms in the operating theater reminds us of the long history of even the most rudimentary neurosurgical tool. This unrelenting strive for perfection reminds us, as surgeons, of our duty to continuously assess and improve our surgical tools and processes for the benefit of our patients.

Patient-specific prediction of SEEG electrode bending for stereotactic neurosurgical planning.

PURPOSE : Electrode bending observed after stereotactic interventions is typically not accounted for in either computer-assisted planning algorithms, where straight trajectories are assumed, or in quality assessment, where only metrics related to entry and target points are reported. Our aim is to provide a fully automated and validated pipeline for the prediction of stereo-electroencephalography (SEEG) electrode bending. METHODS : We transform electrodes of 86 cases into a common space and compare features-based and image-based neural networks on their ability to regress local displacement ([Formula: see text]) or electrode bending ([Formula: see text]). Electrodes were stratified into six groups based on brain structures at the entry and target point. Models, both with and without Monte Carlo (MC) dropout, were trained and validated using tenfold cross-validation. RESULTS : mage-based models outperformed features-based models for all groups, and models that predicted [Formula: see text] performed better than for [Formula: see text]. Image-based model prediction with MC dropout resulted in lower mean squared error (MSE) with improvements up to 12.9% ([Formula: see text]) and 39.9% ([Formula: see text]), compared to no dropout. Using an image of brain tissue types (cortex, white and deep grey matter) resulted in similar, and sometimes better performance, compared to using a T1-weighted MRI when predicting [Formula: see text]. When inferring trajectories of image-based models (brain tissue types), 86.9% of trajectories had an MSE[Formula: see text] mm. CONCLUSION : An image-based approach regressing local displacement with an image of brain tissue types resulted in more accurate electrode bending predictions compared to other approaches, inputs, and outputs. Future work will investigate the integration of electrode bending into planning and quality assessment algorithms.

Development and clinical evaluation of a contactless operating interface for three-dimensional image-guided navigation for endovascular neurosurgery.

PURPOSE: In endovascular neurosurgery, the operator often acquires three-dimensional (3D) images of the cerebral vessels. Although workstation reoperation is required in some situations during treatment, it leads to time loss because a sterile condition cannot be maintained and treatment must be temporarily interrupted. Therefore, a workstation reoperating system is required while maintaining the desired sterility. METHODS: A contactless operating interface using Kinect to control 3D images was developed via gesture recognition for endovascular neurosurgery and was applied to a 3D volume rendering technique (VRT) image reconstructed at the workstation. The left-hand movement determines the assigned functions, whereas the right-hand movement is used like a computer mouse to pan and zoom in/out. In addition to the interface, voice commands were used and assigned to digital operations, such as image view changes and mode signal changes. RESULTS: This system was used for the actual endovascular treatment of cerebral aneurysms and cerebral arteriovenous malformations. The operator and gesture were recognized without any problems. Using voice operation, it was possible to expeditiously set the VRT image back to the reference angle. Furthermore, it was possible to finely adjust gesture operations, including mouse operation, and treatment was completed while maintaining sterile conditions. CONCLUSION: A contactless operating interface was developed by combining the existing workstation system with Kinect and voice recognition software, allowing surgeons to perform a series of operations, which are normally performed in a console room, while maintaining sterile conditions.

Tribute to Theodor Kocher: Far Beyond an Anatomical Reference

We know Kocher's name as an anatomical reference in neurosurgery. In fact, Theodor Kocher was a Swiss general surgeon, and his contributions were such that Kocher was honored in 1909 with the Nobel Prize in Medicine and Physiology, and he was the first surgeon to receive this honor. Kocher participated in the initial scientific phase of medicine, livingwith names that are in history, as well as him; Langenbeck and Virchow, Lucke, Billroth, Horsley, Lister, Halstedt, Pasteur, Osler, Lawson Tait, Verneuil, and a long list and other icons of the time. The present account rescues the many important facets and contributions of the Swiss surgeonTheodor Kocher, and his relationship with several of them. Kocher's memory, surgical instruments and literary production are preserved in a small wing of the University of Bern. The present article highlights how intense Kocher's dedication to the medical field was.

Adaptive self-healing electronic epineurium for chronic bidirectional neural interfaces.

Realizing a clinical-grade electronic medicine for peripheral nerve disorders is challenging owing to the lack of rational material design that mimics the dynamic mechanical nature of peripheral nerves. Electronic medicine should be soft and stretchable, to feasibly allow autonomous mechanical nerve adaptation. Herein, we report a new type of neural interface platform, an adaptive self-healing electronic epineurium (A-SEE), which can form compressive stress-free and strain-insensitive electronics-nerve interfaces and enable facile biofluid-resistant self-locking owing to dynamic stress relaxation and water-proof self-bonding properties of intrinsically stretchable and self-healable insulating/conducting materials, respectively. Specifically, the A-SEE does not need to be sutured or glued when implanted, thereby significantly reducing complexity and the operation time of microneurosurgery. In addition, the autonomous mechanical adaptability of the A-SEE to peripheral nerves can significantly reduce the mechanical mismatch at electronics-nerve interfaces, which minimizes nerve compression-induced immune responses and device failure. Though a small amount of Ag leaked from the A-SEE is observed in vivo (17.03 ppm after 32 weeks of implantation), we successfully achieved a bidirectional neural signal recording and stimulation in a rat sciatic nerve model for 14 weeks. In view of our materials strategy and in vivo feasibility, the mechanically adaptive self-healing neural interface would be considered a new implantable platform for a wide range application of electronic medicine for neurological disorders in the human nervous system.

Tumour collection chamber for space-occupying lesions in neurosurgery.

Collection of tissue sample is one of the most important step in neurosurgery while removing intracranial or intraspinal space occupying lesions (SOL). It is required for tissue diagnosis, further treatment planning and prognostication. There is no mention of any tool except taking pieces using various biopsy/holding forceps or curettes. Author has designed a prototype of a tumour collection chamber (TCC), which is connected to the suction tubing for collection of solid tumours during surgical removal by suction by selectively allowing the suction flow through the TCC. It is easy to use as and when the tumour is being removed and suction flow can be bypassed by the surgeon or the assistant once tumour removal is done or otherwise.

Three-Dimensional Printed Ergonomically Improved Microforceps for Microneurosurgery.

OBJECTIVE: The aim of this study was to develop and validate an ergonomically improved microforceps, which is a neurosurgical instrument used in microscopic procedures. The distance between tips of microforceps becomes large at high magnification of the operating microscope. This results in tips moving out of view and causes ergonomic discomfort. METHODS: The design criteria for ergonomic microforceps were defined, which primarily involved a reduction in the distance between tips and applied force. Computer models of the existing and modified microforceps were created and fabricated using direct metal laser sintering. Ten neurosurgeons validated the developed instrument and provided feedback. In objective validation, video feed of the operating microscope was marked and analyzed by an expert neurosurgeon. RESULTS: In subjective validation, most of the neurosurgeons endorsed the ergonomic improvements. The parameters, including microforceps tips moving out of view (P = 0.0005), suture holding attempts (P = 0.001), and needle holding attempts (P = 0.03), were found to be statistically improved (Mann-Whitney U test), whereas the average time taken to tie 1 knot was not statistically improved (P = 0.06). The ergonomic modification also resulted in a reduction of applied force by 47.5%. CONCLUSIONS: Validation results show that the developed instrument provides several ergonomic benefits for the microsuturing task under high magnification of the operating microscope.

Tribute to Milton D. Heifetz (1921-2015): The Man Behind the Heifetz Aneurysm Clip.

Milton Dave Heifetz (1921-2013) was a pioneer American neurosurgeon who spent the majority of his career at Cedars-Sinai Hospital in California. Heifetz greatly influenced the field of neurosurgery as an innovator, leader, and academic neurosurgeon. His redesign of the aneurysm clip addressed the long-standing issue of a fatiguing spring. Heifetz's innovation allowed the spring to maintain adequate closing force despite repetitive opening and closing. This clip was recognized as one of the most effective aneurysm clips for approximately 15 yr. While he was best known for this eponymous aneurysm clip, Heifetz also developed other various microsurgical instruments and tools for stereotactic approaches. Beyond neurosurgery, he was an influential figure and well-published author in fields such as medical ethics, philosophy, astronomy, and poetry. In 1975, he published The Right to Die: A Neurosurgeon Speaks of Death With Candor, a book which played a major role in our modern-day advanced directives. Throughout his life, Heifetz was an inspirational individual who consistently worked towards solutions to surgical and ethical problems. We present a historical vignette on his life, career, and contributions to neurosurgery.

Historical Aspects of Stereotactic Radiosurgery: Concepts, People, and Devices.

Stereotactic radiosurgery is a modern discipline that emerged after World War II. It represents a synthesis of an approach to patient care that was not immediately embraced by either neurosurgeons or radiation oncologists, but which has been shown, time and again, to be advantageous for the treatment of intracranial pathology. Indeed, stereotactic radiosurgical techniques are now being rapidly adapted and adopted for the treatment of extracranial malignant and benign disease. Any examination of the individuals, devices, and technological advances that permitted stereotactic radiosurgery to become a preferred approach for patient care cannot be absolutely comprehensive but can provide insights into the evolution of the specialty and potential future prospects for further improvements in patient care. As Shakespeare wrote in The Tempest, "What's past is prologue."

Near Infrared Spectroscopy Based Clinical Algorithm Applicability During Spinal Neurosurgery and Postoperative Cognitive Disturbances.

Background and Objectives: Postoperative cognitive disturbances (POCD) can significantly alter postoperative recovery. Inadequate intraoperative cerebral oxygen supply is one of the inciting causes of POCD. Near-infrared spectroscopy (NIRS) devices monitor cerebral oxygen saturation continuously and can help to guide intraoperative patient management. The aim of the study was to evaluate the applicability of the NIRS-based clinical algorithm during spinal neurosurgery and to find out whether it can influence postoperative cognitive performance. Materials and Methods: Thirty four patients scheduled for spinal neurosurgery were randomized into a study group (n = 23) and a control group (n = 11). We monitored regional cerebral oxygen saturation (rScO2) throughout surgery, using a NIRS device (INVOS 4100). If rScO2 dropped bilaterally or unilaterally by more than 20% from baseline values, or under an absolute value of 50%, the NIRS-based algorithm was initiated in the study group. In the control group, rScO2 was monitored blindly. To evaluate cognitive function, Montreal-Cognitive Assessment (MoCA) scale was used in both groups before and after the surgery. Results: In the study group, rScO2 dropped below the threshold in three patients and the NIRS-based algorithm was activated. Firstly, we verified correct positioning of the head; secondly, we increased mean systemic arterial pressure in the three patients by injecting repeated intravenous bolus doses of Ephedrine, ultimately resulting in an rScO2 increase above the approved threshold level. None of the three patients showed POCD. In the control group, one patient showed a drop in rScO2 of 34% from baseline and presented with a POCD. RScO2 drop occurred with other stable intraoperative measurements. Conclusions: A significant rScO2 drop may occur during spinal surgery in prone position despite other intraoperative measurements remaining stable, allowing it to stay otherwise unrecognized. Use of the NIRS-based clinical algorithm can help to avoid POCD in patients after spinal surgery.

Targeting inaccuracy caused by mechanical distortion of the Leksell stereotactic frame during fixation.

BACKGROUND: The stereotactic frame represents the mainstay of accuracy for targeting in stereotactic procedures. Any distortion of the frame may induce a significant source of error for the stereotactic coordinates. OBJECTIVE: To analyze the sources of distortion of the Leksell frame G induced by fixation to the patient's head and to evaluate the clinical impact of frame distortion on the accuracy of targeting in stereotactic procedures. METHODS: We analyzed the torques exerted on the fixation screws after frame placement in a series of patients treated stereotactically by an experienced team. We studied the risk for frame bending in an experimental model of stereotactic frame fixation, with increasing torque of fixation screws in a homogeneous and heterogeneous distribution of torques between the four screws. We assessed the impact of expanding dimensions of bending of the Leksell frame both on surgeries utilizing the stereotactic frame, and on radiosurgical procedures with the Gamma Knife. RESULTS: Frames were fixed clinically at a range of torques of 0.147-0.522 Nm (mean = 0.348 Nm). The torques did not vary significantly with time. Heterogeneity between the two opposite pairs of screws is often limited, but can reach 96.3%. Distortion of the frame may occur even at minimal levels of torque. Heterogeneity between the two opposite pairs of screws will significantly raise the amount of frame distortion. We found a direct correlation between measures of the frame distortion and extend of the deviation from the stereotactic target in clinical models of stereotactic procedures. CONCLUSION: Stereotactic frames were subjected to distortion due to the torque used for frame fixation. The risk of distortion increased with the torque used and the heterogeneity between the torques of the fixation screws. Distortion of the frame was a significant source of inaccuracy of targeting for stereotactic procedures in clinical practice.

Low-Cost Stereoscopic Recordings of Neurologic Surgery Operative Microscopy for Anatomic Laboratory Training.

OBJECTIVE: Stereoscopic video recordings of operative microscopy during neuroanatomic dissections are an important component of surgical training and research in well-financed medical schools and teaching hospitals. However, the high cost of the latest operative microscopes with integrated video recording equipment can be a limiting factor in their worldwide use. The aim of the present work is to provide a simple low-cost 3-dimensional (3D) stereoscopic operative microscope recording system that can be used even in economically and resource-limited locations. This is achieved by using readily available smartphones, smartphone accessories, and computer software. METHODS: Stereoscopic recording is accomplished by attaching and aligning matched or similar smartphones to the eyepieces of an operative microscope using readily available smartphone mounting connectors. Video recordings from the smartphones are then transferred to a personal computer and processed with a video-editing software to generate stereoscopic movies that are viewed on a smartphone using virtual-reality glasses. RESULTS: The setup time to mount and align the smartphone cameras typically requires 15-30 minutes. Video image quality and 3D depth presentation is more than sufficient for surgical training and research purposes. The implementation cost ranges from $1,315-$7,066, or much less if smartphones and a computer are already available. CONCLUSIONS: The 3D video system demonstrated herein can be implemented on any type of operative microscope, including older units for which commercial stereo recording systems are not available. The system and method presented herein can be readily and affordably implemented in low-budget environments for clinical training and research.

A Virtual Repository of Neurosurgical Instrumentation for Neuroengineering Research and Collaboration.

BACKGROUND: Advancements in microscopy and more recently in neuroendoscopy have revolutionized the field of neurosurgery. Handheld neurosurgical instruments are integral components of these procedures. However, these instruments have many limitations, such as poor ergonomics, constrained maneuverability, and limited degrees of freedom. A need for developing better instruments is commonly felt by neurosurgeons. Also, the focus of modern neurosurgical training is shifting toward simulation models. The baseline data of surgical instruments play a vital role in the development of virtual and physical simulators. A primary factor impeding development of novel instruments and simulators is lack of a comprehensive surgical instrument database. The aim of this study was to develop and validate a virtual repository of microscopic and neuroendoscopic instruments. METHODS: Standard neurosurgical instrument sets were scanned, reverse engineered, and stored in various file formats at the file transfer protocol server. The developed database was validated by 4 groups of experts by creating different neurosurgery applications. RESULTS: Four groups of experts used the repository content to create novel ergonomic instrument designs, e-learning material, computer vision-based surgical skills evaluation and virtual reality and validated the contents. The validation results showed that quality of content (75%), usefulness of content (85.6%), and time saving using content (88.1%) received high scores, and the effectiveness of the virtual repository contents was appreciated. CONCLUSIONS: The virtual database is an efficient starting aid to foster research collaborations related to neurosurgical instruments and surgical simulation platforms.

State of the art of fluorescence guided techniques in neurosurgery.

Achieving a safe and extensive neoplasm resection can be considered the main goal of brain tumor surgery. This paper is first aimed at providing an overview of the evolution of those tools serving the purpose. From the dawn of neurosurgery to the present days, major innovations have followed one another. However, those techniques may frequently lack of an instant biological feedback on the true extension and the infiltration of the tumor. Intraoperative fluorescence modalities could indeed fill this gap. Fluorescence guided surgery will be therefore introduced and discussed in this context. Our focus will be on the most common fluorescence techniques used in neurosurgery, namely 5-aminolevulinic acid, sodium fluorescein and in indocyanine green. Mode of action, strengths and weaknesses and level of evidence of each modality will be discussed.

The Siberian Lancet: One More Possible Innovative Example of Scalpel's Contribution to the Evolution of Surgical Anatomy and Neurosurgery.

BACKGROUND: Several primitive scalpels were used since the eve of surgical procedures. Numerous bronze knifes discovered in the Altai mountains region from the Xiongnu-Xianbei-Rouran period mold a hypotheses for a possible medical use. METHODS: On-sight archaeologic excavation brought into light the tools in question. RESULTS: Knifes, similar to modern lancets, were unearthed alongside with a series of skulls demonstrating signs of trepanation. CONCLUSIONS: Strong indications imply that those cutting tools, except for domestic usage, were one more example of scalpel's contribution to the evolution of surgical anatomy and neurosurgery.

[Point-of-care Coagulation Testing in Neurosurgery]. / Point-of-Care-Gerinnungsdiagnostik in der Neurochirurgie.

Disorders of the coagulation system can seriously impact the clinical course and outcome of neurosurgical patients. Due to the anatomical location of the central nervous system within the closed skull, bleeding complications can lead to devastating consequences such as an increase in intracranial pressure or enlargement of intracranial hematoma. Point-of-care (POC) devices for the testing of haemostatic parameters have been implemented in various fields of medicine. Major advantages of these devices are that results are available quickly and that analysis can be performed at the bedside, directly affecting patient management. POC devices allow identification of increased bleeding tendencies and therefore may enable an assessment of hemorrhagic risks in neurosurgical patients. Although data regarding the use of POC testing in neurosurgical patients are limited, they suggest that coagulation testing and hemostatic therapy using POC devices might have beneficial effects in this patient population. This article provides an overview of the application of point-of-care coagulation testing in clinical practice in neurosurgical patients.

Cerebrovascular Neurosurgery in Canada: An Historical Review.

Canadian contributions to cerebrovascular neurosurgery have been disproportionately large and, with some exceptions, relatively unrecognized. In this review, some of the efforts in the advancement of cerebrovascular neurosurgery by Canadian neurologists and neurosurgeons are described.