Virtual and Augmented Reality in Neurosurgery: The Evolution of its Application and Study Designs.

BACKGROUND: As the art of neurosurgery evolves in the 21st century, more emphasis is placed on minimally invasive techniques, which require technical precision. Simultaneously, the reduction on training hours continues, and teachers of neurosurgery faces double jeopardy -with harder skills to teach and less time to teach them. Mixed reality appears as the neurosurgical educators\u27 natural ally: Virtual reality facilitates the learning of spatial relationships and permits rehearsal of skills, while augmented reality can make procedures safer and more efficient. Little wonder then, that the body of literature on mixed reality in neurosurgery has grown exponentially. METHODS: Publications involving virtual and augmented reality in neurosurgery were examined. A total of 414 papers were included, and they were categorized according to study design and analyzed. RESULTS: Half of the papers were published within the last 3 years alone. Whereas in the earlier half, most of the publications involved experiments in virtual reality simulation and the efficacy of skills acquisition, many of the more recent publication are proof-of-concept studies. This attests to the evolution of mixed reality in neurosurgery. As the technology advances, neurosurgeons are finding more applications, both in training and clinical practice. CONCLUSIONS: With parallel advancement in Internet speed and artificial intelligence, the utilization of mixed reality will permeate neurosurgery. From solving staff problems in global neurosurgery, to mitigating the deleterious effect of duty-hour reductions, to improving individual operations, mixed reality will have a positive effect in many aspects of neurosurgery

Augmented-reality template guided transorbital approach for intradural tumors.

For minimally invasive approaches to a deep-lying skull base lesion, the bone opening must be precisely placed and adequately wide to accomplish the surgical goal. Surgical rehearsal in virtual reality (VR) can generate navigation-integrated augmented reality (AR) templates to ensure precise surgical openings. In this video, the authors used AR templates for the transpalpebral, transorbital approach for intradural tumors. VR renderings of patient-specific anatomy were used in surgical rehearsal. The optimal openings were saved and, at surgery, projected into the eyepiece of the navigation-tracked microscope. The template enhanced the planning of the incision and soft-tissue exposure and guided the drill toward the target. The video can be found here: https://stream.cadmore.media/r10.3171/2021.10.FOCVID21172

Emergency extra-intracranial bypass surgery in a patient with neurologic deficit after an accident in carotid occlusive test: A case report.

OBJECTIVE: BTO is the procedure performed to assess the collateral circulation within the Willis circle in a giant ICA aneurysm. An ICA occlusion after BTO is very rare. We present a case of an internal carotid artery occlusion as a complication of BTO that required urgent revascularization surgery. CASE PRESENTATION: A 56-year-old female with a history of transient ischemic attacks for one year was diagnosed with multiple aneurysms: a giant aneurysm of the left supra-clinoid ICA, two small ones on left MCA and right ophthalmic. A BTO was performed to assess collateral supply and determine whether bypass surgery should be necessary. During the procedure, the balloon was detached while insufflating, and the patient had a subsequent neurological decline consistent with an MCA syndrome. EC-IC bypass surgery was performed with an end-to-side anastomosis of STA-MCA by trapping the giant aneurysm and clipping the ipsilateral MCA aneurysm. The patient had a reversal of neurological symptoms and made an uneventful recovery. DISCUSSION: We discuss the epidemiology of giant ICA aneurysms, the indications for BTO, and its complication. Emergency intracranial and extracranial bypass surgery in case of acute ICA injury is also discussed. We also highlighted the attributable factors to treatment strategies under restrictive conditions in Vietnam. CONCLUSIONS: ICA occlusion due to insufflated balloon detachment is an unreported complication in literature. Emergency bypass surgery is a potential treatment choice for this unusual iatrogenic complication

The substellar population of the young cluster lambda Orionis

By collecting optical and infrared photometry and low resolution spectroscopy, we have identified a large number of low mass stars and brown dwarf candidates belonging to the young cluster (~5 Myr) associated with the binary star lambda Orionis. The lowest mass object found is a M8.5 with an estimated mass of 0.02 Msun (~0.01 Msun for objects without spectroscopic confirmation). For those objects with spectroscopy, the measured strength of the Halpha emission line follows a distribution similar to other clusters with the same age range, with larger equivalent widths for cooler spectral types. Three of the brown dwarfs have Halpha emission equivalent widths of order 100 \AA, suggestive that they may have accretion disks and thus are the substellar equivalent of Classical T Tauri stars. We have derived the Initial Mass Function for the cluster. For the substellar regime, the index of the mass spectrum is alpha=0.60$+-0.06, very similar to other young associations.Comment: Astrophysica Journal, accepted April 2, 200

PRE‐dialysis survey on anaemia management

Background. The PRE‐dialysis survey on anaemia management (PRESAM) was designed to assess the care given to pre‐dialysis patients in the 12 months before haemodialysis or peritoneal dialysis, with emphasis on anaemia management. Methods. For this epidemiological study, a retrospective chart review was conducted for patients who started haemodialysis or peritoneal dialysis between 1 August, 1999 and 6 April, 2000. All adult patients who entered one of the 779 participating centres in 21 European countries, Israel or South Africa were included, except for patients who underwent dialysis only during an acute episode. In addition to demographic characteristics, the study examined the prevalence of anaemia, anaemia management including the use of iron supplementation and epoetin, source of referral to the dialysis centre, comorbidities and major clinical events. Results. A total of 4333 new dialysis patients were included in the survey. At the first visit to the dialysis centre, 68% of the patients had a haemoglobin (Hb) concentration ≤11.0 g/dl; Hb concentration was positively correlated with creatinine clearance rate (r=0.43, P<0.01). Patients who received epoetin had a mean Hb concentration of 8.8 g/dl at the start of epoetin treatment, and 96% of these patients had an Hb concentration ≤11.0 g/dl. Only 26.5% of the patients received epoetin before dialysis. The length of time under the care of a nephrologist was associated with meeting the European Best Practice Guidelines (EBPG) target Hb concentration, as well as receiving epoetin. Conclusions. Few pre‐dialysis patients met the EBPG target for Hb concentration, despite regular nephrology car

Caracteristicas de las epidemias de dengue en la ciudad de Santa Cruz (2003-2007)

Se realizó un análisis retrospectivo de las fichas clínico-epidemiológicas y de los resultados serológicos de los casos de dengue de la ciudad de Santa Cruz de la Sierra, durante el período de enero 2003 a octubre 2007. El objetivo es de analizar la evolución temporal espacial de los casos de dengue entre 2003-2007 y determinar los factores de riesgos de tipo demográficos. Se observó que desde el año 2003 el dengue se instaló en la ciudad de Santa Cruz y circuló cada año durante todo el año, incluso en temperada seca. Del 2003 al 2007 la infección viral sube y la precisión del diagnóstico mejora, el porcentaje de muestras positivas pasa de un 25,5% a un 49,4%. El número de casos notificados y casos confirmados son significativamente más importantes para las mujeres que para los hombres(p-<0,0001) y menos importantes en el grupo etáreo inferior a 10 años. El dengue fue más frecuente en el centro de la ciudad dentro del cuarto anillo y en seis zonas que cada año tienen un número de casos superior al medio de la ciudad. La diferenca de distribución de los casos positivos puede ser consecuencia de una información más baja de los casos, más marcada en la zona periférica. (résumé d'auteur

Aging in a simple glassformer

Using molecular dynamics computer simulations we investigate the out-of-equilibrium dynamics of a Lennard-Jones system after a quench from a high temperature to one below the glass transition temperature. By studying the radial distribution function we give evidence that during the aging the system is very close to the critical surface of mode-coupling theory. Furthermore we show that two-time correlation functions show a strong dependence on the waiting time since the quench and that their shape is very different from the one in equilibrium. By investigating the temperature and time dependence of the frequency distribution of the normal modes we show that the energy of the inherent structures can be used to define an effective (time dependent) temperature of the aging system.Comment: Talk presented at ``Unifying Concepts in Glass Physics'', ICTP, Trieste 15 - 18 September 1999; 12 pages of Late

CyberKnife(® )radiosurgery in the treatment of complex skull base tumors: analysis of treatment planning parameters

BACKGROUND: Tumors of the skull base pose unique challenges to radiosurgical treatment because of their irregular shapes, proximity to critical structures and variable tumor volumes. In this study, we investigate whether acceptable treatment plans with excellent conformity and homogeneity can be generated for complex skull base tumors using the Cyberknife(® )radiosurgical system. METHODS: At Georgetown University Hospital from March 2002 through May 2005, the CyberKnife(® )was used to treat 80 patients with 82 base of skull lesions. Tumors were classified as simple or complex based on their proximity to adjacent critical structures. All planning and treatments were performed by the same radiosurgery team with the goal of minimizing dosage to adjacent critical structures and maximizing target coverage. Treatments were fractionated to allow for safer delivery of radiation to both large tumors and tumors in close proximity to critical structures. RESULTS: The CyberKnife(® )treatment planning system was capable of generating highly conformal and homogeneous plans for complex skull base tumors. The treatment planning parameters did not significantly vary between spherical and non-spherical target volumes. The treatment parameters obtained from the plans of the complex base of skull group, including new conformity index, homogeneity index and percentage tumor coverage, were not significantly different from those of the simple group. CONCLUSION: Our data indicate that CyberKnife(® )treatment plans with excellent homogeneity, conformity and percent target coverage can be obtained for complex skull base tumors. Longer follow-up will be required to determine the safety and efficacy of fractionated treatment of these lesions with this radiosurgical system