Ivan Cabrilo

Right insular damage decreases heartbeat awareness and alters cardio- visual effects on bodily self-consciousness

Recent evidence suggests that multisensory integration of bodily signals involving exteroceptive and interoceptive information modulates bodily aspects of self-consciousness such as self-identification and self-location. In the so-called Full Body Illusion subjects watch a virtual body being stroked while they perceive tactile stimulation on their own body inducing illusory self-identification with the virtual body and a change in self-location towards the virtual body. In a related illusion, it has recently been shown that similar changes in self-identification and self-location can be observed when an interoceptive signal is used in association with visual stimulation of the virtual body (i.e., participants observe a virtual body illuminated in synchrony with their heartbeat). Although brain imaging and neuropsychological evidence suggest that the insular cortex is a core region for interoceptive processing (such as cardiac perception and awareness) as well as for self-consciousness, it is currently not known whether the insula mediates cardio-visual modulation of self-consciousness. Here we tested the involvement of insular cortex in heartbeat awareness and cardio-visual manipulation of bodily self-consciousness in a patient before and after resection of a selective right neoplastic insular lesion. Cardio-visual stimulation induced an abnormally enhanced state of bodily self-consciousness; in addition, cardio-visual manipulation was associated with an experienced loss of the spatial unity of the self (illusory bi-location and duplication of his body), not observed in healthy subjects. Heartbeat awareness was found to decrease after insular resection. Based on these data we propose that the insula mediates interoceptive awareness as well as cardio-visual effects on bodily self-consciousness and that insular processing of interoceptive signals is an important mechanism for the experienced unity of the self.

Augmented reality in the surgery of cerebral arteriovenous malformations: technique assessment and considerations

BackgroundAugmented reality technology has been used for intraoperative image guidance through the overlay of virtual images, from preoperative imaging studies, onto the real-world surgical field. Although setups based on augmented reality have been used for various neurosurgical pathologies, very few cases have been reported for the surgery of arteriovenous malformations (AVM). We present our experience with AVM surgery using a system designed for image injection of virtual images into the operating microscope’s eyepiece, and discuss why augmented reality may be less appealing in this form of surgery.MethodsN = 5 patients underwent AVM resection assisted by augmented reality. Virtual three-dimensional models of patients’ heads, skulls, AVM nidi, and feeder and drainage vessels were selectively segmented and injected into the microscope’s eyepiece for intraoperative image guidance, and their usefulness was assessed in each case.ResultsAlthough the setup helped in performing tailored craniotomies, in guiding dissection and in localizing drainage veins, it did not provide the surgeon with useful information concerning feeder arteries, due to the complexity of AVM angioarchitecture.ConclusionThe difficulty in intraoperatively conveying useful information on feeder vessels may make augmented reality a less engaging tool in this form of surgery, and might explain its underrepresentation in the literature. Integrating an AVM’s hemodynamic characteristics into the augmented rendering could make it more suited to AVM surgery.

Augmented reality-assisted skull base surgery

Neuronavigation is widely considered as a valuable tool during skull base surgery. Advances in neuronavigation technology, with the integration of augmented reality, present advantages over traditional point-based neuronavigation. However, this development has not yet made its way into routine surgical practice, possibly due to a lack of acquaintance with these systems. In this report, we illustrate the usefulness and easy application of augmented reality-based neuronavigation through a case example of a patient with a clivus chordoma. We also demonstrate how augmented reality can help throughout all phases of a skull base procedure, from the verification of neuronavigation accuracy to intraoperative image-guidance.

Renal carcinoma relapse presenting as a peripheral nerve sheath tumor: A case report and brief review of the literature

We report a rare case of renal carcinoma metastasis involving a lumbar nerve root. Metastases to nerve roots are rare occurrences, and to our knowledge, only six cases have been reported so far in the literature. The patient in this report presented with weakness in the right lower limb and intractable pain irradiating along the L5 dermatome. MRI findings revealed a right-sided L5 nerve root mass, suggestive of a schwannoma, involving the spinal ganglion and its extraforaminal region. Complete macroscopic resection of this mass was performed, and histopathologic analysis confirmed the lesion to be a metastasis of a renal clear cell carcinoma. Local radiotherapy was given and tyrosine kinase inhibitors administered. At 5 months, the patient was pain-free and his right limb weakness had completely resolved. A tumoral recurrence could be observed on the control MRI 5 months after surgery. This report presents the first case of a patient with a renal clear cell carcinoma metastasis to a L5 nerve root, as well as a brief review of previous cases of metastases to peripheral nerve roots.

Co-Registration of Intra-Operative Photographs and Pre-Operative MR Images

Brain shift, the change in configuration of the brain after opening the dura mater, is a key problem in neuronavigation. We present an approach to co-register intra-operative microscope images with preoperative MRI data to adapt and optimize intra-operative neuronavigation. The tools are a robust classification of sulci on MRI extracted cortical surfaces, guided user marking of most prominent sulci on a microscope image, and the actual variational registration method with a fidelity energy for 3D deformations of the cortical surface combined with a higher order, linear elastica type prior energy. Furthermore, the actual registration is validated on an artificial testbed and on real data of a neuro clinical patient.

Improving workflows of neuro-interventional procedures with autostereoscopic 3D visualization of multi-modality imaging in hybrid interventional suites

PurposeRecent developments in interventional neuroradiology techniques, medical imaging modalities, endovascular stenting and embolization materials lead to an increasing number of patients with cerebral aneurysms and arteriovenous malformations that are eligible for endovascular treatment and have opened new perspectives for novel ways for patient treatment in general. In this paper, we describe a software tool for 3D image fusion of multi-modal acquisitions to assist endovascular treatment of cerebral malformations. The software and an autostereoscopic 3D display were implemented and tested in clinical applications in a hybrid interventional suite that is used for radio-interventional as well as neurosurgical procedures. Our hypothesis is that fusion of image data acquired prior to intervention procedures with images acquired during those procedures should allow better visualizing and navigating through complex cerebral vasculature. This should also improve workflows of neuro-interventional procedures.MethodsPreoperative and intra-operative acquisitions of vascular images of the brain were performed and transferred to a dedicated imaging workstation to be processed with our image fusion and visualization software tool. The tool was developed as a plugin extension to the open-source DICOM viewer OsiriX and is based on a modular and scalable architecture. Several processing modules were implemented to allow spatial co-registration and fusion of preoperative and intra-operative modalities. A special extension was also implemented for interactive autostereosopic, glass-free 3D visualization of fused results.ResultsThe software platform was validated and evaluated in nine in vivo procedures by expert users. All patient cases were related to interventional treatment of neuro-vascular diseases. The emphasis was laid on the added value of spatial co-registration and fusion of preoperative and intra-operative modalities, as well as the overall impact on workflow during the intervention. The co-registered and fused images were visualized on an autostereoscopic 3D monitor installed in hybrid interventional suite. All experiments were evaluated and scored by interventional physicians and technicians.ConclusionsDisplaying 3D–4D representations of brain vascular anomalies based on multi-modal acquisitions on a 3D autostereoscopic display is beneficial for the workflow and efficiency of interventional radiologists. The implemented software tool fulfills the premise of applicability of an open-source platform for more advanced, multi-modal visualization and processing of brain vascular structures for image-guided therapeutic interventions.

Cauda equina tumor surgery: how I do it

BackgroundTumors of the cauda equina usually require surgery due to their impingement on neighboring nerve roots, often resulting in pain and neurological deficits.MethodThe Authors first give a brief introduction on cauda equina tumors, followed by a description of the surgical anatomy, and then develop the microsurgical technique. In particular, tricks to avoid complications are presented, underlining the importance of intraoperative neuromonitoring.ConclusionBoth microsurgical technique and neuromonitoring are important in cauda equina tumor surgery, the goal of which is to achieve complete resection while at the same time preserving neurological function.

Intraoperative monitoring with visual evoked potentials for brain surgeries

In BriefMonitoring of the visual system was performed with flash visual evoked potentials (VEPs) during brain lesion resections (white LEDs, protected from lights of the operating room). The possible decreases in VEPs were analyzed relative to electroretinograms, triggering an alarm only if certain criteria were met. VEPs appear to be a reliable intraoperative tool to detect new deficits in visual fields that are more severe than a discrete quadrantanopia. Early changes in VEPs could trigger corrective surgical actions and contribute to preserving vision.

Intracranial Spider Aneurysm

From the Neurosurgery Division (I.C., K.S.), Department of Clinical Neurosciences, Geneva University Medical Center, Faculty of Medicine, Rue Gabrielle-Perret-Gentil 4, 1211 Geneva, Switzerland; and Neurosurgery Division (I.R.), Surgery Department, Faculty of Medicine, University of Toronto, Toronto Western Hospital, Toronto, Canada. Received March 7, 2015; revised March 22, 2015; accepted in final form March 23, 2015. Address correspondence to I.C.; E-mail: ivan.cabrilo@hcuge.ch A 30-year-old man presented with intense sudden-onset headaches. Computed tomography was performed, revealing a Fisher 4 subarachnoid hemorrhage and the presence of two aneurysms of the anterior communicating artery, forming a curious spider-shaped arrangement (circle in Fig 1) “dwelling” among the weblike trabeculae of the subarachnoid space. Digital subtraction angiography (Fig 2) showed an associated dominant left A1 segment and a ruptured, inferiorly located anterior communicating artery aneurysm (long arrow in Fig 2) and a smaller superiorly situated aneurysm (short arrow in Fig 2). Both lesions were successfully treated with coil embolization (arrows in Fig 3).

Jugular Foramen Meningioma with Transverse and Sigmoid Sinuses Invasion and Jugular Vein Extension

Abstract We present the case of a jugular foramen meningioma with predominantly intraluminal invasion of the transverse, sigmoid sinuses, jugular bulb, and internal jugular vein with venous occlusion in a 45‐year‐old woman. Magnetic resonance imaging (MRI) of the brain and conventional angiography were performed preoperatively and revealed a right‐sided extra‐axial dural‐based mass in the jugular foramen. The surgical approach was a high cervical approach with exposure of the internal carotid artery, jugular vein, and cranial nerves IX to XII as well as a combined posterior temporo‐basal and retrosigmoid craniotomy with mastoidectomy and posterior retrolabyrinthine petrosectomy. The transverse, sigmoid sinuses, jugular bulb, and superior internal jugular vein were removed en bloc, and the exophytic intradural tumor extension around cranial nerves IX, X, XI, and XII was resected subtotally. Postoperatively, the patient presented a transient right facial weakness (House‐Brackmann II). MRI showed partial resection. This is the first case report of a jugular foramen meningioma with transverse and sigmoid sinuses invasion and jugular vein extension in the adult population.