Xavier Morandi

Nevoid basal cell carcinoma syndrome: relation with desmoplastic medulloblastoma in infancy. A population-based study and review of the literature.

Patients with nevoid basal cell carcinoma syndrome (NBCCS) are believed to be predisposed to develop early‐onset neoplasms including medulloblastomas (MB). The desmoplastic subtype of MB is associated most commonly with NBCCS. The goals of this study were to demonstrate the relation between desmoplastic MB and NBCCS and to evaluate the concomitant diagnosis of NBCCS and MB.

Dermal sinus and intramedullary spinal cord abscess Report of two cases and review of the literature

Abstract Intramedullary abscesses of the spinal cord are uncommon. Most of them occur in association with heart, pulmonary or urogenital infections. We report two cases of intramedullary spinal cord abscesses secondary to congenital dermal sinus. Only 14 cases of such an association have previously been reported. In our cases, dermal sinus was associated with an epidermoid tumour. The clinical presentation, pathogenesis, magnetic resonance imaging findings, surgical management and outcome are discussed.

Automatic non-linear MRI-ultrasound registration for the correction of intra-operative brain deformations

Objective: Movements of brain tissue during neurosurgical procedures reduce the effectiveness of using pre-operative images for intra-operative surgical guidance. In this paper, we explore the use of acquiring intra-operative ultrasound (US) images for the quantification of and correction for non-linear brain deformations. Materials and Methods: We will present a multi-modal registration strategy that automatically matches pre-operative images (e.g., MRI) to intra-operative US to correct for these deformations. The strategy involves using the predicted appearance of neuroanatomical structures in US images to build “pseudo ultrasound” images based on pre-operative segmented MRI. These images can then be non-linearly registered to intra-operative US using cross-correlation measurements within the ANIMAL package. The feasibility of the theory is demonstrated through its application to clinical patient data acquired during 12 neurosurgical procedures. Results: Results of applying the method to 12 surgical cases, including those with brain tumors and selective amygdalo-hippocampectomies, indicate that our strategy significantly recovers from non-linear brain deformations occurring during surgery. Quantitative results at tumor boundaries indicate up to 87% correction for brain shift. Conclusions: Qualitative and quantitative examination of the results indicate that the system is able to correct for non-linear brain deformations in clinical patient data.

Surgical models for computer-assisted neurosurgery

In this paper, we outline a way to improve computer-assisted neurosurgery using surgical models along with patient-specific models built from multimodal images. We propose a methodological framework for surgical models that include the definition of a surgical ontology, the development of software for describing surgical procedures based on this ontology and the analysis of these descriptions to generate knowledge about surgical practice. Knowledge generation is illustrated by two studies. One hundred fifty-nine patients who underwent brain tumor surgery were described from postoperative reports using the surgical ontology. First, from a subset of 106 surgical cases, we computed a decision tree using a prediction approach that gave probability in terms of operating room patient positioning percentages and according to tumor location within one or more lobes. Second, from the whole set of 159 surgical cases, we identified 6 clusters describing families of cases according to pathology-related parameters. Results from both studies showed possible prediction of parts of the surgical procedure from pathology-related characteristics of the patient. Surgical models enable surgical knowledge to be made explicit, facilitating the surgical decision-making process and surgical planning and improving the human-computer interface during surgery.

Acute nontraumatic spinal subdural hematomas in three patients.

Study Design. The clinical data, magnetic resonance imaging, intraoperative findings, and functional outcome were reviewed for three patients under anticoagulant therapy who experienced acute nontraumatic spinal subdural hematoma. Objectives. To draw attention to this rare complication of anticoagulant therapy and to assess the magnetic resonance findings and clinical outcome of patients with spinal subdural hematoma after surgical evacuation. Summary of Background Data. Among intraspinal hematomas, spinal subdural hematomas are by far the least common. Magnetic resonance findings have been demonstrated in only a few cases of spinal subdural hematomas. The timing of the operation and the anatomic location of the hematoma essentially determine the functional outcome. Methods. Three case reports of spinal subdural hematomas in patients receiving anticoagulant therapy are presented. Particular interest was given to the clinical and magnetic resonance data, the intraoperative findings, and the functional outcome. Results. The three patients each had a complete preoperative neurologic deficit. Sagittal T1- and T2-weighted magnetic resonance images of the spine proved to have high sensitivity for defining the type of bleeding and delineating the craniocaudal extension of the hematoma. Surgical evacuation was performed within 26 hours after the onset of symptoms. Intraoperative findings showed the hematoma to be confined between the dura and the arachnoid in two patients, and to be associated with rupture into the subarachnoid space in one patient. Postoperative recovery was incomplete in two patients, and did not improve in the remaining patient. Conclusions. Spinal subdural hematoma must be considered in patients under anticoagulant therapy with spontaneous signs of acute spinal cord or cauda equina compression. Magnetic resonance imaging with sagittal T1- and T2-weighted images were adequate and reliable for diagnosis of spinal subdural hematoma. On the basis of previous studies and the authors’ intraoperative findings, spinal subdural hematomas could be viewed as spinal dural border hematomas. The level of preoperative neurologic deficit seemed to be critical for recovery despite prompt surgical evacuation.

Anterior screw fixation of odontoid fractures

BACKGROUND Anterior screw fixation is the best treatment for odontoid fractures when the fracture line is horizontal or oblique downward and backward, as it preserves atlantoaxial mobility, especially axial rotation. Some details regarding patient positioning and operative technique need to be stressed to obtain the best results and avoid complications. METHODS Between 1989 and 1997, we treated 17 cases of odontoid fracture by anterior screw fixation. Only two patients presented with motor neurologic deficit. Fracture line was horizontal in 3 cases and oblique downward and backward in 14 cases. RESULTS Adequate reduction and fixation was obtained in all cases except one, where posterior displacement of the screw occurred without neurologic complications. Functional result was satisfactory in all cases except two, where we noted significant limitation of cervical rotation. CONCLUSION Successful anterior screw fixation gives the best anatomical and functional results for odontoid fractures. Correct installation is very important for operative success.

Time-of-flight MR angiography at 3 T versus digital subtraction angiography in the imaging follow-up of 51 intracranial aneurysms treated with coils

OBJECTIVE To compare 3D time-of-flight MR angiography (TOF-MRA) at 3 Tesla (3T) with digital subtraction angiography (DSA) for the evaluation of intracranial aneurysm occlusion after endovascular coiling. METHODS In a prospective study, 51 consecutive patients (25 females, 26 males; median age, 51 years) with 51 saccular aneurysms treated with endovascular coiling underwent simultaneous DSA and 3T TOF-MRA at follow-up. DSA and TOF-MRA images were analyzed independently by two senior neuroradiologists. Findings were assigned to 1 of 3 categories in the Raymond classification: complete obliteration, residual neck or residual aneurysm. Agreement between observers and techniques was evaluated using kappa statistics. RESULTS DSA images were not interpretable for one patient. Interobserver agreement was determined as excellent for DSA (kappa=0.86) and TOF-MRA (kappa=0.80). After reaching a consensus, DSA follow-up showed 26 (51%) complete obliterations, 20 (39%) residual necks and 4 (8%) residual aneurysms. TOF-MRA showed 23 (45%) complete obliterations, 22 (43%) residual necks and 6 (12%) residual aneurysms. Comparison between TOF-MRA and DSA showed excellent agreement between the techniques (kappa=0.86). In the four cases that were misclassified, TOF-MRA findings were assigned to a higher class than for DSA. CONCLUSION TOF-MRA at 3T is at least as efficient as DSA for the evaluation of intracranial aneurysm occlusion after endovascular treatment with detachable coils. We suggest that TOF-MRA at 3T might be used as the primary method for imaging follow-up of coiled intracranial aneurysms.

MRI of intramedullary spinal schwannomas: case report and review of the literature

Abstract Intramedullary spinal schwannomas are uncommon. We report a solitary cervical intramedullary schwannoma shown by MRI and treated surgically, and review 12 previous cases with MRI. MRI findings and pathogenesis are discussed.

A Data Fusion Environment for Multimodal and Multi-Informational Neuronavigation

OBJECTIVE Part of the planning and performance of neurosurgery consists of determining target areas, areas to be avoided, landmark areas, and trajectories, all of which are components of the surgical script. Nowadays, neurosurgeons have access to multimodal medical imaging to support the definition of the surgical script. The purpose of this paper is to present a software environment developed by the authors that allows full multimodal and multi-informational planning as well as neuronavigation for epilepsy and tumor surgery. MATERIALS AND METHODS We have developed a data fusion environment dedicated to neuronavigation around the Surgical Microscope Neuronavigator system (Carl Zeiss, Oberkochen, Germany). This environment includes registration, segmentation, 3D visualization, and interaction-applied tools. It provides the neuronavigation system with the multimodal information involved in the definition of the surgical script: lesional areas, sulci, ventricles segmented from magnetic resonance imaging (MRI), vessels segmented from magnetic resonance angiography (MRA), functional areas from magneto-encephalography (MEG), and functional magnetic resonance imaging (fMRI) for somatosensory, motor, or language activation. These data are considered to be relevant for the performance of the surgical procedure. The definition of each entity results from the same procedure: registration to the anatomical MRI data set (defined as the reference data set), segmentation, fused 3D display, selection of the relevant entities for the surgical step, encoding in 3D surface-based representation, and storage of the 3D surfaces in a file recognized by the neuronavigation software (STP 3.4, Leibinger; Freiburg, Germany). RESULTS Multimodal neuronavigation is illustrated with two clinical cases for which multimodal information was introduced into the neuronavigation system. Lesional areas were used to define and follow the surgical path, sulci and vessels helped identify the anatomical environment of the surgical field, and, finally, MEG and fMRI functional information helped determine the position of functional high-risk areas. CONCLUSION In this short evaluation, the ability to access preoperative multi-functional and anatomical data within the neuronavigation system was a valuable support for the surgical procedure.

The subthalamic nucleus is a key-structure of limbic basal ganglia functions

Among the basal ganglia nuclei, the subthalamic nucleus has a major function in the motor cortico-basal ganglia-thalamo-cortical circuit and is a target site for neurosurgical treatment such as parkinsonian patients with long-term motor fluctuations and dyskinesia. According to animal and human studies, the motor functions of the subthalamic nucleus have been well documented whereas its implication on limbic functions is still less well understood and is only partially explained by anatomical and functional theories of basal ganglia organisation. After chronic subthalamic nucleus stimulation in patients with Parkinsons disease, many studies showed executive impairments, apathy, depression, hypomania, and impairment of recognition of negative facial emotions. The medial tip of the subthalamic nucleus represents its limbic part. This part receives inputs from the anterior cingulate cortex, the medial prefrontal cortex, the limbic part of the striatum (nucleus accumbens), the ventral tegmental area and the limbic ventral pallidum. The medial tip of the subthalamic nucleus projects to the limbic part of the substantia nigra and the ventral tegmental area. We propose a new function scheme of the limbic system, establishing connections between limbic cortical structures (medial prefrontal cortex, amygdala and hippocampus) and the limbic part of the basal ganglia. This new circuit could be composed of a minor part based on the model of cortico-basal ganglia-thalamo-cortical loop, and of a major part linking the subthalamic nucleus with the mesolimbic dopaminergic pathway via the ventral tegmental area and the nucleus accumbens, and with limbic cortical structures. This scheme could explain limbic impairments after subthalamic nucleus stimulation by disruption of limbic information inside the subthalamic nucleus and the ventral tegmental area.