Carlo Schaller’s research while affiliated with Hôpitaux Universitaires de Genève and other places

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Publications (149)


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

August 2017

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19 Reads

Journal of Neurological Surgery. Part A: Central European Neurosurgery

Jeremy Brodard

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Carlo Schaller

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.


Fig. 1. Input photograph, MRI graph surface  
Fig. 2. Moment-based classification and the creases are the sulci on the cortical surface. We aim for a moment based analysis of the (cortical) surface C := ∂B and define the zero moment shift of the implicit surface C as follows M 0 [B](x) = 1 |B(x)| B(x) d(y)(y − x)dy which returns larger values in flat regions of C than in edge regions and even smaller near corners (cf. [7] for a related moment based classification on explicit surfaces). We define the scalar classification C(x) = g β M 0 [B](x)// 2 , where g β (t) = 1 1+βt 2. Fig. 2 illustrates the behavior of the classifier C on three simple shapes and a
Fig. 5. Both for the test data (top row) and the pair of a true photograph and an MRI extracted cortical surface (bottom row) we show (from left to right) the input image with marked sulci (computed image and real photograph respectively), the sulci classification on the 3D cortical surface segmented from MRI data, the initial misfit of the sulci marking on the 2D image projected on the cortical surface overlaying the cortical surface itself, and the final registration result.
Cortical Surface Co-Registration based on MRI Images and Photos
  • Article
  • Full-text available

March 2013

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62 Reads

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Carlo Schaller

Brain shift, i.e. 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 pre-operative MRI 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 with known ground truth deformation and on real data of a neuro clinical patient.

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

March 2013

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25 Reads

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3 Citations

Brain shift, i.e. 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 pre-operative MRI 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 with known ground truth deformation and on real data of a neuro clinical patient.


Fibrillary Structure is Key for Hemostasis: A Similar Effect of Collagen Fleece and Oxidized Cellulose on Experimental Hemorrhagic Brain Injury

March 2012

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57 Reads

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4 Citations

Journal of Neurological Surgery. Part A: Central European Neurosurgery

The choice of the ideal hemostatic agent for intraoperative cerebral bleeding is under continuous debate. Our aim was to assess the influence of such materials on bleeding time in hemorrhagic cerebral contusions. We compared oxidized regenerated cellulose in fibrillar form (ORC) to microfibrillar collagen fleece (CF) in an experimental study. N=50 Sprague Dawley rats underwent a bilateral craniectomy. 3 separate standardized superficial cortical impacts were inflicted using a high-speed drill. Immediately after lesion placement, each of the 3 lesions was covered with (a) nothing (control), (b) ORC, or (c) CF. We observed the 3 lesions with a surgical microscope. The bleeding times were recorded for each cerebral lesion and compared using ANOVA test. All traumatic lesions produced significant bleeding. The statistical analysis showed a clear reduction in bleeding time for groups treated with either ORC or CF compared to the control group. Lesions covered with ORC and CF showed no significant difference with regard to bleeding time. ORC and CF significantly reduce blood loss from hemorrhagic contusions. Our data suggest that they effectively reduce bleeding time. We advocate the use of hemostatic material for limiting bleeding from superficial cortical lesions.



Figure 1. Four typical digital photographs of the exposed human cortex (top row) and the sulci regions of the cortex manually marked by an expert (bottom row). 
Figure 3. Discriminative dictionary pairs with patch size of 12 × 12 (left pair) and 20 × 20 (right pair) learned from three frames of an intra-operative video. 
Figure 4. Two cortex images (first column), manual segmentation of the sulci by an expert (second column) and segmentation obtained using the dictionaries from Figure 3 of patch size 12 × 12 (third column) and 20 × 20 (forth column). Note that the manual marking from the top row was used during the dictionary learning but the one from the bottom row was not. 
Sulci Detection in Photos of the Human Cortex Based on Learned Discriminative Dictionaries

May 2011

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88 Reads

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2 Citations

Lecture Notes in Computer Science

The use of discriminative dictionaries is exploited for the segmentation of sulci in digital photos of the human cortex. Manual segmentation of the geometry of sulci by an experienced physician on training data is taken into account to build pairs of such dictionaries. It is demonstrated that this approach allows a robust segmentation of these brain structures on photos of the brain as long as the training data contains sufficiently similar images. Concerning the methodology an improved minimization algorithm for the underlying variational approach is presented taking into account recent advances in orthogonal matching pursuit. Furthermore, the method is stable since it ensures an energy decay in the dictionary update.


Role of Macrophage Migration Inhibitory Factor in Primary Glioblastoma Multiforme Cells

May 2011

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110 Reads

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44 Citations

Journal of Neuroscience Research

Macrophage migration inhibitory factor (MIF) is a protein that is overexpressed in many tumors, such as colon and prostate cancer, melanoma, and glioblastoma multiforme (GBM). In its function as a cytokine, MIF induces angiogenesis, promotes cell cycle progression, and inhibits apoptosis. Recently, the molecular signal transduction has been specified: MIF has been found to be a ligand to the CD74/CD44-receptor complex and to activate the ERK1/2 MAPK cascade. In addition MIF binds to the chemokine receptors CXCR2 and CXCR4. This effects an integrin-dependent leukocyte arrest and mediates leukocyte chemotaxis. Recent work has described a clearer role of MIF in GBM tumor cell lines. The current study used human primary GBM cells. We show that inhibition of MIF with ISO-1, an inhibitor of the D-dopachrome tautomerase site of MIF, reduced the growth rate of primary GBM cells in a dose-dependent manner, and in addition ISO-1 increased protein expression of MIF and its receptors CD74, CXCR2, and CXCR4 in vitro but decreased expression of CD44. Furthermore, hypoxia as cell stressor increases the protein expression of MIF in primary GBM cells. These results underscore the importance of MIF in GBM and show that MIF and its receptors may be a promising target for the treatment of malignant gliomas.


Table 1 Data from arterial blood gas analyses and mean arterial blood pressure (MABP) 
Dynamic Autoregulation Testing Does Not Indicate Changes of Cerebral Blood Flow Before and After Resection of Small- and Medium-Sized Cerebral AVM

March 2011

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53 Reads

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3 Citations

Translational Stroke Research

This study tested the hypothesis that dynamic cerebral autoregulation (AR) remains intact before and after the excision of human arteriovenous malformations (AVM). In 12 patients (six female and six male; mean age, 34 years) harboring cerebral AVMs (AVM group), and 15 patients (nine female/six male; mean age, 49 years) with deep-seated lesions (e.g., small frontobasal meningiomas) approached by transsylvian dissection (control group), we continuously assessed cerebral blood flow (CBF) using a thermo-diffusion technique, and mean arterial blood pressure (MABP). AR was estimated post-hoc using correlation-coefficient autoregulatory-index (Mx) analysis. Measurements were compared according to groups (AVM/control) and times (pre/post), referred to as conditions before and after AVM resection and transsylvian dissection, respectively. All values are given as mean ± SD. The correlation index Mx was without significant difference among the study groups, indicating unimpaired autoregulatory function. Intragroup comparisons related to AVM nidus size (small- (≤3 cm) and medium-sized (3-6 cm)) did not show significant influence on autoregulation. The study shows that in patients harboring small- and medium-sized AVMs, dynamic autoregulatory function as estimated by correlation-coefficient index analysis seems to be intact in the surrounding cerebrovascular bed perioperatively.


Fig. 1 Bar graph of cortical interstitial NE microdialysate concentrations of the key fistula groups before (pre) and after (post) occlusion of the AVF (dsp, scgx, and ds). Cortical interstitial NE microdialysate concentrations of these fistula animals show significant differences. According to treatment (extent of SNS inhibition), animals are labeled as dsp (inhibition of the central component by DSP-4), scgx (inhibition of the peripheral component by bilateral superior cervical ganglionectomy), and ds (inhibition of both components). Error bars , SD. *: against all other groups, P <0.001; #: against all other preocclusive groups, P <0.001; §: against fistula scgx pre, P <0.001; † : against fistula scgx post, P <0.001; ‡ : against fistula scgx pre, P =0.001 
Table 1 Mean values of regional cerebral blood flow and regional cortical oxygen saturation, mean interstitial microdialysate concentrations of NE, and serum levels of NE
Fig. 2 Bar graph showing mean values (±SD) of cortical oxygen saturation (%SO 2 ) over the right frontal cortex in dsp-, scgx-, and ds- labeled rats that underwent creation of an AV fistula 12 weeks prior to 
Fig. 3 Bar graph showing mean values (±SD) of the LDF measurements to approximate rCBF via a cranial window over the right ipsilateral frontal cortex 3 months after creation of an AV fistula (fistula). The groups are characterized according to the extent of SNS inhibition, as in Figs. 1 and 2. Regional CBF (in LDU) was significantly lower in all sham groups compared to the animals with altered cerebral perfusion, but there were no significant differences among the sham rats (P<0.001) (data not shown). Regional CBF levels were lowest at measurement under a situation with a completely inhibited SNS before occlusion of the fistula and reached statistical significance compared to all other fistula groups (P<0.001). Regional CBF increase following fistula occlusion only occurred in the peripherally inhibited animals and showed no significant difference. Significant differences were detected in fistula control (P<0.001), dsp (P=0.004), and ds (P<0.001). *: compared to all other groups; §: compared to all other fistula groups; #: compared to the situation before fistula occlusion (same group)
Evidence for a Predominant Intrinsic Sympathetic Control of Cerebral Blood Flow Alterations in an Animal Model of Cerebral Arteriovenous Malformation

September 2010

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96 Reads

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2 Citations

Translational Stroke Research

In terms of neurogenic cerebral blood flow (CBF) control, the activity of the sympathetic nervous system (SNS) has a regulating effect. The impact of a manipulation of both the peripheral (via the perivascular sympathetic net) and central components (via the intracortical noradrenergic terminals originating from the locus coeruleus) on CBF-and especially on hyperperfusion syndromes-is unclear. To test the specific patterns following such alterations, cortical oxygen saturation (rSO2), regional CBF (rCBF), and cortical interstitial norepinephrine (NE) concentrations were measured. Twelve weeks after either the creation of an extracranial AV fistula or sham operation, 80 male Sprague-Dawley rats underwent one of the following procedures: (1) no SNS manipulation, (2) peripheral SNS inhibition via bilateral sympathectomy, (3) central SNS inhibition via the neurotoxin DSP-4, or (4) complete SNS inhibition. Norepinephrine concentrations were lowest after complete inhibition (NE [nmol]: pre, 1.8 ± 1.2; post, 2.4 ± 1.8) and highest following peripheral inhibition (NE [nmol]: pre, 3.6 ± 1.9; post, 6.6 ± 4.4). Following fistula occlusion, rCBF (laser Doppler unit [LDU]) and rSO2 (%SO2) increases were highest after complete inhibition (pre: 204 ± 14 LDU, 34 ± 3%SO2; post: 228 ± 18 LDU, 39 ± 3%SO2) and lowest after peripheral inhibition (pre: 221 ± 18 LDU, 41 ± 2%SO2; post: 226 ± 14 LDU, 47 ± 2%SO2). Thus, a complete inhibition down-regulates SNS activity and provokes a cortical hyperperfusion condition. With this, the hitherto unknown predominant role of the intrinsic component could be demonstrated for the first time in vivo.


Prediction of traveling front behavior in a lattice-gas cellular automaton model for tumor invasion

April 2010

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79 Reads

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62 Citations

Computers & Mathematics with Applications

Cancer invasion is the process of cells detaching from a primary tumor and infiltrating the healthy tissue. Cancer invasion has been recognized as a complex system, since a tumor’s invasive behavior emerges from the combined effect of tumor cell proliferation, tumor cell migration and cell–microenvironment interactions. Cellular automata (CA) provide simple models of self-organizing complex systems in which collective behavior can emerge out of an ensemble of many interacting “simple” components. Here, we introduce a lattice-gas cellular automaton (LGCA) model of tumor cell proliferation, necrosis and tumor cell migration. The impact of the tumor environment on tumor cells has been investigated in a previous study. Our analysis aims at predicting the velocity of the traveling invasion front, which depends upon fluctuations that arise from the motion of the discrete cells at the front. We find an excellent agreement between the velocities measured in simulations of the LGCA and an analytical estimate derived in the cut-off mean-field approximation via the discrete Lattice Boltzmann equation and its linearization. In particular, we predict the front velocity to scale with the square root of the product of probabilities for mitosis and the migration coefficient. Finally, we calculate the width of the traveling front which is found to be proportional to the front velocity.


Citations (73)


... As derived from animal experiments (1,2,17,20,26), the general profile it exhibits for neurogenic cerebral blood flow (CBF) regulation under pathophysiological conditions fits well into the specific scenario with AVMs. These assumptions were substantiated by animal experiments using AVM models (13). ...

Reference:

Norepinephrine and Cerebral Blood Flow Regulation in Patients With Arteriovenous Malformations
Norepinephrine in the Rat Cortex before and after Occlusion of Chronic Arteriovenous Fistulae: A Microdialysis Study in an Animal Model of Cerebral Arteriovenous Malformations
  • Citing Article
  • September 2002

Neurosurgery

... VBH and image co-registration Patients with intractable focal epilepsy undergo structural and functional imaging to detect a possible epileptogenic lesion, to define the functional deficit zone and to indicate the seizure onset zone [9,10,19,23,42,43]. Various co-registration techniques permit the fusion of different MRI techniques [25], MRI and PET [6,50], MRI /CT and SPECT [17], interictal and ictal SPECT [55], MRI and ictal SPECT (SISCOM) [12,20,21,33,49], PET and SPECT [5], and SPECT and MRI (SATSCOM) [48]. Functional data might be included in the preoperative dataset, making the implantation of electrodes or intraoperative cortical stimulation superfluous [6,18,28,40,41,54]. ...

FLAIR-/T1-/T2-CO-REGISTRATION FOR IMAGE-GUIDED DIAGNOSTIC AND RESECTIVE EPILEPSY SURGERY
  • Citing Article
  • February 2008

Neurosurgery

... -Normal perfusion pressure breakthrough [14,15] -Occlusive hyperemia [16] -Venous engorgement [17][18][19] The Normal perfusion pressure breakthrough theory is a term coined by Spetzler in 1978. He used it to indicate a postoperative hyperemia responsible for hemorrhagic infarction. ...

Role of Venous Drainage in Cerebral Arteriovenous Malformation Surgery, as Related to the Development of Postoperative Hyperperfusion Injury
  • Citing Article
  • October 2002

Neurosurgery

... It can be applied either intraoperatively prior to resection or extraoperatively via chronically implanted subdural electrode arrays ( " grid mapping " ) [23]. The latter method yields particularly reliable mapping results due to the almost deliberate amount of time which can be devoted to cross-checking and replication and has been preferred in our epilepsy surgery program [12, 41] . Conversely, intraoperative mapping may lack reliability because only limited testing is possible during a surgical procedure but allows for identification of subcortical pathways [2]. ...

Epilepsy surgery: Arguments for the extraoperative rather than intraoperative invasive presurgical work-up
  • Citing Conference Paper
  • January 2007

Epilepsia

... Once bronchoscope reached the target area, the needle was advanced and inserted into the target lymph node puncturing the tracheobronchial wall perpendicularly [5]. The exact sites of aspiration for TBNA [2,[4][5][6] were determined by endobronchial abnormality (endobronchial lesions, bulge because of extrinsic compression and widening of carina). In cases where there was no endobronchial abnormality, site of aspiration was determined by CT scan results. ...

Epilepsy-Surgery and Invasive Diagnostic Procedures
  • Citing Article
  • June 2004

The Neuroradiology Journal

... Traditionally, the brain retractors were used to maintain the surgical corridor and during the sylvian fissure dissection. 2,[4][5][6]9,19 The position of the retractors was traditionally placed outside the sylvian fissure, especially on the frontal lobe. [8][9][10] The blunt dissection technique by bipolar tip spreading was frequently used by most neurosurgeons. ...

The Transsylvian Approach Is “Minimally Invasive” but Not “Atraumatic”
  • Citing Article
  • October 2002

Neurosurgery

... The outcome may depend on the local collateral circulation. 2,28 In this study, 1 cerebral infarct that caused disability was thought to be due to the occlusion of the feeding artery with Onyx. Trivelato et al 11 and Mendes et al 21 reported 2 cases each of postprocedural parenchymal edema thought to be related to venous outflow obstruction, one of which caused a disability. ...

Evidence for a Predominant Intrinsic Sympathetic Control of Cerebral Blood Flow Alterations in an Animal Model of Cerebral Arteriovenous Malformation

Translational Stroke Research

... It is recognized that the AVM size and such lesions are an acceptable contender for microsurgical management. Stüer and colleagues have shown that complex autoregulator y work is by all accounts, unblemished in the perioperative cerebrovascular bed in patients with small and medium-sized AVMs [16]. Also, larger AVMs are bound to have all the more depleting veins that have been shown to place a patient at risk for complications of postoperative progression. ...

Dynamic Autoregulation Testing Does Not Indicate Changes of Cerebral Blood Flow Before and After Resection of Small- and Medium-Sized Cerebral AVM

Translational Stroke Research

... Previous studies have used both manual and semi-automated methods to co-register fMRI and DCS results in heterogeneous patient cohorts, demonstrating relatively high measures of sensitivity, and specificity without explicitly correcting for brain shift (FitzGerald et al., 1997; Lehéricy et al., 2000; Roux et al., 2003; Kuchcinski et al., 2015). Although brain shift correction methods improve co-registration further, especially in cases of large tumor volumes, the most pressing need in the present context involves development of real-time brain shift corrections to enhance intra-operative usage of preoperative fMRI data, to improve guidance of the DCS probe during stimulation (Berkels et al., 2014; Reinertsen et al., 2014). Irrespective of such future developments, the conventional DCS mapping procedure involves photographing surgical chips that represent areas of functional significance on the brain surface. ...

Co-Registration of Intra-Operative Photographs and Pre-Operative MR Images
  • Citing Conference Paper
  • March 2013

... Intraventricular hemorrhage (IVH), and resultant post-hemorrhagic hydrocephalus (PHH), are among the most common, severe neurological complications of preterm birth, and infants frequently require CSF sampling for diagnostic or therapeutic purposes [5,6]. Growing evidence suggests that the antecedent IVH and PHH are associated with host-immune responses that can alter the CSF profile [7][8][9][10][11][12], potentially prompting empiric antimicrobial therapy on suspicion of infection or delaying time-sensitive surgical care [13,14]. ...

Neonatal high pressure hydrocephalus is associated with elevation of pro-inflammatory cytokines IL18 and IFNγ in cerebrospinal fluid

Cerebrospinal Fluid Research