Endoscopic Endonasal Transclival Approach versus Dual Transorbital Port Technique for Clip Application to the Posterior Circulation: A Cadaveric Anatomical and Cerebral Circulation Simulation Study

Purpose  Simulation training offers a useful opportunity to appreciate vascular anatomy and develop the technical expertise required to clip intracranial aneurysms of the posterior circulation. Materials and Methods  In cadavers, a comparison was made between the endoscopic transclival approach (ETA) alone and a combined multiportal approach using the ETA and a transorbital precaruncular approach (TOPA) to evaluate degrees of freedom, angles of visualization, and ergonomics of aneurysm clip application to the posterior circulation depending on basilar apex position relative to the posterior clinoids. Results  ETA alone provided improved access to the posterior circulation when the basilar apex was high riding compared with the posterior clinoids. ETA + TOPA provided a significantly improved functional working area for instruments and visualization of the posterior circulation for a midlevel basilar apex. A single-shaft clip applier provided improved visualization and space for instruments. Proximal and distal vascular control and feasibility of aneurysmal clipping were demonstrated. Conclusions  TOPA is a medial orbital approach to the central skull base; a transorbital neuroendoscopic surgery approach. This anatomical simulation provides surgical teams an alternative to the ETA approach alone to address posterior circulation aneurysms, and a means to preoperatively prepare for intraoperative anatomical and surgical instrumentation challenges

Innovations in the Surgery of Cerebral Aneurysms: Enhanced Visualization, Perfusion, and Function Monitoring

Surgery of cerebral aneurysms has evolved over the years. Advances regard enhanced intraoperative visualization and monitoring of both function and perfusion. Technological assistance used in oncological or skull base surgery, such as intraoperative neurophysiological monitoring (IONM) or endoscopy, now adopt to vascular surgery. Intraoperative indocyanine green video angiography (ICG-VA) and techniques for its interpretation (squeezing maneuver; entrapment sign), endoscopes, and exoscopes increase visualization. Flow evaluation by microflow probe permits perfusion monitoring; IONM allows functional monitoring. Bypasses replace flow in complex aneurysm cases. Pre-, intra-, and postoperative imaging and flow measurement techniques help in donor selection and follow-up. Despite some progression in the aneurysm clips, the principle has not changed. Innovation and even change of principle in aneurysm exclusion might be desirable. Basic research in aneurysm wall and flow dynamics might in the future change the paradigms of cerebral aneurysm treatment

Sellar and Parasellar Imaging

The skull base is a complex anatomical region that harbors many important neurovascular structures in a relatively confined space. The pathology that can develop at this site is varied, and many disease processes may present with similar clinical and neuroimaging findings. While computed tomography maintains a role in the evaluation of many entities and can, for instance, delineate osseous erosion with great detail and characterize calcified tumor matrices, magnetic resonance imaging (MRI) is the mainstay in the neuroimaging assessment of most pathology occurring at the skull base. Various MRI sequences have proven to be robust tools for tissue characterization and can provide information on the presence of lipids, paramagnetic and diamagnetic elements, and tumor cellularity, among others. In addition, currently available MRI techniques are able to generate high spatial resolution images that allow visualization of cranial nerves and their involvement by adjacent pathology. The information obtained from such examinations may aid in the distinction of these disease processes and in the accurate delineation of their extent prior to biopsy or treatment planning

Maximum intensity projection technique in evaluation of Willis polygon aneurysms: a prospective, case series study

Introducere. În ultimele decenii, metodele de postprocesare au crescut proporţional în importanţă, inclusiv, în stabilirea diagnosticului primar. Cu toate acestea, existenţa numeroaselor tehnici de reformatare a imaginilor angiografiei cu scanare computer tomografică necesită estimarea influenţei lor asupra calităţii finale a examinării. Este necesară determinarea avantajelor și limitărilor diferitor tehnici de reformatare a imaginii AST. Material și metode. Incluși 140 de pacienţi consecutivi, în vârstă de 19-79 de ani, cu anevrisme cerebrale ale poligonului Willis. În vederea stabilirii diagnosticului și în scopul determinării oportunităţii indicaţiei pentru tratament neurochirurgical, pacienţii au fost investigaţi prin computer tomografie cerebrală nativă, angiografie cerebrală cu scanare computer tomografică (imaginile primare axiale) și următoarele procedee de reconstrucţie a angiografiei computer tomografică: proiecţie de intensitate maximă (PIM), reconfigurare volumetrică tridimensională (RV-3D). Rezultate. Tehnica PIM a constatat anevrism vizibil în 99,3% de cazuri și anevrism parţial vizibil în 0,7% cazuri. Marea majoritate a anevrismelor erau saculare (96,5%). Hemoragia intracraniană, cauzată de ruperea anevrismului, a fost depistată în 75,0% din cazuri, vazospasmul – în 59,3% din cazuri, calcificate parietale – în 3,6% din cazuri, artefacte tip „efect de volum parţial” – în 82,9% din cazuri, artefacte de la clipsul metalic – în 69,3% din cazuri și trombi în anevrism – în 6,4% din cazuri. În cadrul reconstrucţiei PIM, contactul osanevrism nu se vizualiza în 12,8% cazuri, se vizualiza slab – în 28,2% din cazuri și bine – în 59,0 din cazuri. Relaţia cu sinusul cavernos nu se vizualiza în 16,6% din cazuri, se vizualiza slab în 50% din cazuri, bine – în 33,4% din cazuri. Concluzii. Imaginile proiecţiei de intensitate maximă trebuie să fie tehnica de reconstrucţie primară și necesită a fi inclusă în protocolul de analiză standard a angiografiei prin tomografie computerizată pentru estimarea arterelor cervicocraniene.Introduction. In the past few decades, methods of post processing have evolved proportionally, their role in stabilizing the primary diagnosis as well. Nevertheless, existence of many techniques of image reconfiguration makes it necessary to estimate their influence on final examination results. It is mandatory to determine the advantages and limitations of different techniques of CTA reconfiguration. Material and methods. One hundred and forty consecutive patients were included, aged 19-79, diagnosed with aneurysms of Willis polygon. In order to determine the diagnose and the possible following surgical treatment, patients were investigated through methods of native cerebral computer tomography, cerebral angiography with CT scanning (CTA, primary axial images) and the following methods of reconstruction of CTAs: maximum intensity projection (MIP) and tridimensional volumetric reconfiguration (3D-VR). Results. MIP technique showed visible aneurysm in 99.3% of the cases and partial visible aneurysm in 0.7% of the cases. The big majority of the aneurysms were saccular (96.5%). Intracranial bleeding caused by aneurysm rupture was found in 75.0% of the cases, vasospasm – in 59.3% of the cases, parietal calcification – in 3.6% of the cases, “partial volume effect” artifacts – in 82.9% of the cases, metal clip artifact – in 69.3% of the cases and aneurysm cloths – in 6.4% of the cases. During MIP reconstruction, aneurysm-bone contact could not be visualized in 12.8% of the cases, was poorly visualized in 28.2% of the cases and was well visualized in 59.0% of the cases. The relation with the cavernous sinus could not be appreciated in 16.6% of the cases, was poorly visualized in 50% of the cases and was well visualized in 33.4% of the cases. Conclusions. Images of maximum intensity must be the primary technique for reconstruction and must be included in the protocol of standard analysis of CTA in order to estimate the cervical and cranial arteries

A comparison between magnetic resonance angiography at 3 teslas (time-of-flight and contrast-enhanced) and flat-panel digital subtraction angiography in the assessment of embolized brain aneurysms

PURPOSE: To compare the time-of-flight and contrast-enhanced- magnetic resonance angiography techniques in a 3 Tesla magnetic resonance unit with digital subtraction angiography with the latest flat-panel technology and 3D reconstruction in the evaluation of embolized cerebral aneurysms. INTRODUCTION: Many embolized aneurysms are subject to a recurrence of intra-aneurismal filling. Traditionally, imaging surveillance of coiled aneurysms has consisted of repeated digital subtraction angiography. However, this method has a small but significant risk of neurological complications, and many authors have advocated the use of noninvasive imaging methods for the surveillance of embolized aneurysms. METHODS: Forty-three aneurysms in 30 patients were studied consecutively between November 2009 and May 2010. Two interventional neuroradiologists rated the time-of-flight-magnetic resonance angiography, the contrast-enhanced-magnetic resonance angiography, and finally the digital subtraction angiography, first independently and then in consensus. The status of aneurysm occlusion was assessed according to the Raymond scale, which indicates the level of recanalization according to degrees: Class 1: excluded aneurysm; Class 2: persistence of a residual neck; Class 3: persistence of a residual aneurysm. The agreement among the analyses was assessed by applying the Kappa statistic. RESULTS: Inter-observer agreement was excellent for both methods (K = 0.93; 95 % CI: 0.84-1). Inter-technical agreement was almost perfect between time-of-flight-magnetic resonance angiography and digital subtraction angiography (K = 0.98; 95 % CI: 0.93-1) and between time-of-flight-magnetic resonance angiography and contrast-enhanced-magnetic resonance angiography (K = 0.98; 95% CI: 0.93-1). Disagreement occurred in only one case (2.3%), which was classified as Class I by time-of-flight-magnetic resonance angiography and Class II by digital subtraction angiography. The agreement between contrast-enhanced-magnetic resonance angiography and digital subtraction angiography was perfect (K = 1; 95% CI: 1-1). In three patients, in-stent stenosis was identified by magnetic resonance angiography but not confirmed by digital subtraction angiography. CONCLUSION: Digital subtraction angiography and both 3T magnetic resonance angiography techniques have excellent reproducibility for the assessment of aneurysms embolized exclusively with coils. In those cases also treated with stent remodeling, digital subtraction angiography may still be necessary to confirm eventual parent artery stenosis, as identified by magnetic resonance angiography

Neurovascular Surgery

This open access book presents the diagnosis, investigation and treatment of neurovascular diseases, and offers expert opinions and advice on avoiding complications in neurovascular surgery. It also covers complication management and post-operative follow-up care. The book is divided in to three parts; the first part discusses common approaches in neurovascular surgery, describing the steps, indications for and limitations of the approach, as well as the associated complications and how to avoid them. The second part addresses surgical treatment based on pathology, taking the different locations of lesions into consideration. The third part focuses on the technological developments that support neurovascular surgery, which may not be available everywhere, but have been included to help vascular surgeon understand the principles. This book is a guide for young neurosurgeons, neurosurgery residents and neurosurgery fellows, as well as for medical students and nurses who are interested in neurosurgery or are associated with this field in any way. It is also a useful teaching aid for senior neurosurgeons

Augmented Reality-Assisted Craniotomy for Parasagittal and Convexity En Plaque Meningiomas and Custom-Made Cranio-Plasty: A Preliminary Laboratory Report

Background: This report discusses the utility of a wearable augmented reality platform in neurosurgery for parasagittal and convexity en plaque meningiomas with bone flap removal and custom-made cranioplasty. Methods: A real patient with en plaque cranial vault meningioma with diffuse and extensive dural involvement, extracranial extension into the calvarium, and homogeneous contrast enhancement on gadolinium-enhanced T1-weighted MRI, was selected for this case study. A patient-specific manikin was designed starting with the segmentation of the patient’s preoperative MRI images to simulate a craniotomy procedure. Surgical planning was performed according to the segmented anatomy, and customized bone flaps were designed accordingly. During the surgical simulation stage, the VOSTARS head-mounted display was used to accurately display the planned craniotomy trajectory over the manikin skull. The precision of the craniotomy was assessed based on the evaluation of previously prepared custom-made bone flaps. Results: A bone flap with a radius 0.5 mm smaller than the radius of an ideal craniotomy fitted perfectly over the performed craniotomy, demonstrating an error of less than ±1 mm in the task execution. The results of this laboratory-based experiment suggest that the proposed augmented reality platform helps in simulating convexity en plaque meningioma resection and custom-made cranioplasty, as carefully planned in the preoperative phase. Conclusions: Augmented reality head-mounted displays have the potential to be a useful adjunct in tumor surgical resection, cranial vault lesion craniotomy and also skull base surgery, but more study with large series is needed