Biomedical subjects

Hugues Duffau

Publications and source records attributed to Hugues Duffau.

At least 37 records · Page 2Linked to original sources

PubMed2005

Direct evidence for a parietal-frontal pathway subserving spatial awareness in humans.

Intraoperative electrical stimulation, which temporarily inactivates restricted regions during brain surgery, can map cognitive functions in humans with spatiotemporal resolution unmatched by other methods. Using this technique, we found that stimulation of the right inferior parietal lobule or the caudal superior temporal gyrus, but not of its rostral portion, determined rightward deviations on line bisection. However, the strongest shifts occurred with subcortical stimulation. Fiber tracking identified the stimulated site as a section of the superior occipitofrontal fasciculus, a poorly known parietal-frontal pathway. These findings suggest that parietal-frontal communication is necessary for the symmetrical processing of the visual scene.

Adult↗

PubMed2005

Unruptured intracranial aneurysms treated by three-dimensional coil embolization: evaluation of the postoperative aneurysm occlusion volume.

Our purpose was to evaluate the postoperative aneurysm occlusion volume and clinical results of treating unruptured intracranial aneurysm using three-dimensional (3D) coils. Over a 2-year period 62 aneurysms (39 with a neck < or =4 mm, 23 with a neck >4 mm) in 62 patients in five participating centres were treated. The procedure consisted, firstly, of framing the aneurysm with one or more spherical 3D coils, and secondly, of filling it with two-dimensional (2D) helical coils. Anatomical and clinical results were evaluated by univariate analysis. Multivariate analysis was used to identify independent predictors of these results. For neck sizes < or =4 and >4 mm, angiographic occlusion was complete in 31 (79%) and 16 (70%) aneurysms, respectively; the mean percentage of occlusion volume was 31.4% and 29.5%, respectively, and postoperative morbidity was 3% and 4%, respectively, with no significant differences between the two groups. There were no deaths. However, occlusion volume correlated with sac size (P = 0.037) and sac-to-neck ratio <1.5 (P = 0.073), except when three or more 3D coils per aneurysm were used (P = 0.516 and P = 0.308, respectively). Occlusion volume correlated with the number of 3D coils per aneurysm (P < 0.001) and was an independent predictor of angiographic complete occlusion (P = 0.002). The use of the largest number of 3D coils per aneurysm was safe and may improve the postoperative volume and angiographic occlusion of aneurysms with a neck >4 mm, provided the sac-to-neck ratio is > or =1.5.

Adult↗

PubMed2005

New insights into the anatomo-functional connectivity of the semantic system: a study using cortico-subcortical electrostimulations.

Despite a better understanding of the organization of the cortical network underlying the semantic system, very few data are currently available regarding its anatomo-functional connectivity. Here, we report on a series of 17 patients operated on under local anaesthesia for a cerebral low-grade glioma located within the dominant hemisphere. Prior to and during resection, intraoperative electrical stimulation was used to map sensorimotor and language structures so that permanent neurological deficits could be avoided. In a number of cases, cortical and subcortical stimulation caused semantic paraphasias. Using postoperative MRI, we correlated these functional findings with the anatomical locations of the sites where semantic errors were elicited by stimulation, especially at the subcortical level, with the aim of studying the connectivity underlying the semantic system. In temporal gliomas, cortical sites involved in semantic processing were found around the posterior part of the superior temporal sulcus, with subcortical pathways reproducibly located under the depth of this sulcus. In insular gliomas, although stimulation elicited no semantic disturbances at the cortical level, such semantic paraphasias were generated at the level of the anterior floor of the external capsule. In frontal tumours, cortical regions implicated in semantics were detected in the lateral orbitofrontal region and dorsolateral prefrontal cortex, with subcortical fibres located under the inferior frontal sulcus. All these eloquent structures were systematically preserved, thereby avoiding permanent postoperative deficits. Our results provide arguments in favour of the existence of a main ventral subcortical pathway underlying the semantic system, within the dominant hemisphere, joining the two essential cortical epicentres of this network: the posterior and superior temporal areas, and the orbitofrontal and dorsolateral prefontal regions. Such a ventral stream might anatomically partly correspond to the inferior fronto-occipital fasciculus.

Adolescent↗

PubMed2005

Chromosome 1p loss: a favorable prognostic factor in low-grade gliomas.

Search for loss of heterozygosity on chromosomes 1p, 9p, 10q, and 19q, epidermal growth factor receptor (EGFR) gene amplification, and p53 expression was performed in a series of 131 low-grade gliomas. The profile of molecular changes, clinical findings, and histology were subsequently correlated with the course of the disease, mainly progression-free survival. When these parameters were considered as candidate variables in a multivariate analysis, only loss of heterozygosity on chromosome 1p was associated with increased progression-free survival (hazard ratio, 0.521), indicating a major favorable prognostic role of this genetic alteration in low-grade gliomas.

Adolescent↗

PubMed2005

Simulation of anisotropic growth of low-grade gliomas using diffusion tensor imaging.

A recent computational model of brain tumor growth, developed to better describe how gliomas invade through the adjacent brain parenchyma, is based on two major elements: cell proliferation and isotropic cell diffusion. On the basis of this model, glioma growth has been simulated in a virtual brain, provided by a 3D segmented MRI atlas. However, it is commonly accepted that glial cells preferentially migrate along the direction of fiber tracts. Therefore, in this paper, the model has been improved by including anisotropic extension of gliomas. The method is based on a cell diffusion tensor derived from water diffusion tensor (as given by MRI diffusion tensor imaging). Results of simulations have been compared with two clinical examples demonstrating typical growth patterns of low-grade gliomas centered around the insula. The shape and the kinetic evolution are better simulated with anisotropic rather than isotropic diffusion. The best fit is obtained when the anisotropy of the cell diffusion tensor is increased to greater anisotropy than the observed water diffusion tensor. The shape of the tumor is also influenced by the initial location of the tumor. Anisotropic brain tumor growth simulations provide a means to determine the initial location of a low-grade glioma as well as its cell diffusion tensor, both of which might reflect the biological characteristics of invasion.

Anisotropy↗

PubMed2005

Lessons from brain mapping in surgery for low-grade glioma: insights into associations between tumour and brain plasticity.

Surgical treatment of low-grade gliomas (LGGs) aims to maximise the amount of tumour tissue resected, while minimising the risk of functional sequelae. In this review I address the issue of how to reconcile these two conflicting goals. First, I review the natural history of LGG-growth, invasion, and anaplastic transformation. Second, I discuss the contribution of new techniques, such as functional mapping, to our understanding of brain reorganisation in response to progressive growth of LGG. Third, I consider the clinical implications of interactions between tumour progression and brain plasticity. In particular, I show how longitudinal studies (preoperative, intraoperative, and postoperative) could allow us to optimise the surgical risk-to-benefit ratios. I will also discuss controversial issues such as defining surgical indications for LGGs, predicting the risk of postoperative deficit, aspects of operative surgical neuro-oncology (eg, preoperative planning and preservation of functional areas and tracts), and postoperative functional recovery.

Brain↗

PubMed2005

Intraoperative cortico-subcortical stimulations in surgery of low-grade gliomas.

In order to increase the impact of surgery on the natural history of low-grade glioma, resection should be of maximum importance. Nevertheless, since low-grade gliomas are frequently located in eloquent structures, function needs to be preserved. Therefore, studying the functional organization of the brain is mandatory for each patient due to the inter-individual anatomofunctional variability, increased in tumors due to cerebral plasticity. This strategy enables performance of a resection according to functional boundaries. However, preoperative neurofunctional imaging only allows the study of the gray matter. Consequently, since low-grade glioma invades cortical and subcortical structures and shows an infiltrative progression along the fibers, the goal of this review is to focus on the techniques able to map both cortical and subcortical regions. In addition to diffusion tensor imaging, which gives only anatomical information and still needs to be validated, intraoperative direct cortico-subcortical electrostimulation is the sole current method allowing a reliable study of the individual anatomofunctional connectivity, concerning sensorimotor, language and other cognitive functions. Its actual contribution is detailed, both in clinical issues, especially the improvement of the benefit/risk ratio of low-grade glioma resection, and in fundamental applications--namely, a new door to the connectionism and cerebral plasticity.

Brain Mapping↗

PubMed2005

Incontinence after brain glioma surgery: new insights into the cortical control of micturition and continence. Case report.

Cortical control of micturition and continence remains poorly understood. The authors report two cases of patients who presented with prolonged urinary disturbances after resection of a brain glioma. Accurate anatomofunctional correlations determined using postoperative magnetic resonance imaging support the following: 1) the implication of the posterior portion of the right anterior cingulate gyms in the perception of bladder sensation and maintenance of continence; 2) the involvement of the right anterior insula in bladder relaxation; and 3) the role of the right inferior frontal cortex in the decision concerning whether to initiate a micturition. On the basis of these results, a preliminary model of a cortical network associated with micturition and continence is proposed.

Adult↗

PubMed2004

Preferential brain locations of low-grade gliomas.

BACKGROUND: The objectives of this study were to register the brain locations in a consecutive series of low-grade gliomas (LGGs) and compare these localizations with the locations of de novo glioblastomas (GBMs) that were collected during the same period in an effort to analyze whether LGGs are situated in preferential areas and to review the pathophysiologic hypothesis of such a phenomenon. METHODS: One hundred thirty-two patients with LGG and 102 patients with GBM who were followed consecutively between 1996 and 2003 by the authors were reviewed, whatever their treatment. Using anatomic, three-dimensional magnetic resonance imaging, the location of each tumor was analyzed accurately according to a classification system based on the proximity of eloquent areas previously reported by the authors. RESULTS: One hundred nine LGGs (82.6%), compared with 55 GBMs (53.9%), were situated within functional regions (P < 0.001). More specifically, 36 LGGs (27.3%), compared with 11 GBMs (10.8%), were localized in the region of the supplementary motor area (SMA) (P < 0.001); and 33 LGGs (25%), compared with 11 GBMs (10.8%), were located within the insula (P < 0.001). CONCLUSIONS: The current findings suggest that LGGs are located preferentially in "secondary" functional areas (immediately near the so-called primary eloquent regions), especially within the SMA and the insular lobe. This preferential localization may be explained by developmental, cytomyeloarchitectonic, neurochemical, metabolic, and functional reasons. A better knowledge of the pathophysiologic mechanisms underlying preferential LGGs locations may improve understanding of the genesis and natural history of these tumors and, subsequently, their management.

Adolescent↗

PubMed2004

Double dissociation between picture naming and comprehension: an electrostimulation study.

We performed a cortico-subcortical language electrical mapping, using a picture naming task and a semantic test of association, during resection of a left posterior temporal glioma in an awake patient. Two discrete naming sites were identified in the posterior part of the left superior temporal gyrus, plus a third distinct site between the two previous areas, inducing specific comprehension disorders without anomia when stimulated. After resection, white matter stimulation elicited anomia without comprehension disorder. We suggest the existence of distinct naming and comprehension systems, which can explain the possibility of a double dissociation aphasic syndrome: one with normal undertanding but naming error, reflecting post-semantic problems of access to the phonological form; the other with correct naming but without normal comprehension, testifying to a direct non-semantic pathway for naming.

Adult↗

PubMed2004

Surgical removal of corpus callosum infiltrated by low-grade glioma: functional outcome and oncological considerations.

OBJECT: Although still controversial, many authors currently advocate extensive resection in the treatment of low-grade gliomas (LGGs). Because these tumors usually migrate along white matter pathways, the corpus callosum is often invaded. Nevertheless, there is evidently no specific study featuring resection of the corpus callosum infiltrated by glioma, despite abundant literature concerning callosotomy in epilepsy surgery or transcallosal ventricular approaches. The aim of this paper was to analyze functional outcome following removal of corpus callosum invaded by LGG and to analyze the impact of this callosectomy on the quality of resection. METHODS: Between 1996 and 2002, a total of 32 patients harboring an LGG involving part of the corpus callosum and having no or only a mild preoperative deficit underwent surgery aided by intraoperative electrical mapping to preserve eloquent structures identified on stimulation and to perform the most extensive resection possible. Preoperatively, no clinical response was elicited on stimulation of the corpus callosum; thus, the part of this structure that was invaded by LGG was removed. Despite immediate postoperative neurological worsening, all patients but one recovered within 3 months and returned to a normal socioprofessional life. The additional callosectomy allowed for nine total resections, 18 subtotal resections, and five partial resections. Furthermore, only two cases of contralateral hemispherical migration occurred during a median follow up of 3 years. CONCLUSIONS: Resection of the corpus callosum infiltrated by glioma improves the quality of tumor removal without increasing the risk of sequelae.

Adult↗

PubMed2003

The articulatory loop: study of the subcortical connectivity by electrostimulation.

Although a cortical network involving Broca's area and the supramarginal gyrus (SMG) was widely studied using neurofunctional imaging, the functional connectivity underlying this so-called articulatory loop remains poorly documented. We describe a patient operated on for a glioma invading the left parietal operculum, using intraoperative electrical functional mapping under local anesthesia. Following the identification of cortical language sites within Broca's area and SMG, the subcortical pathways connecting these regions were detected and preserved during the resection. Postoperatively, the patient presented a slight dysarthria, then recovered. This is the first report of direct tracking of the subcortical connectivity underlying the fronto-parietal articulatory loop, allowing to better understand the pathophysiology of this network and the consequences of its damage.

Adult↗

PubMed2003

Continuous growth of mean tumor diameter in a subset of grade II gliomas.

Serial magnetic resonance images of 27 patients with untreated World Health Organization grade II oligodendrogliomas or mixed gliomas were reviewed retrospectively to study the kinetics of tumor growth before anaplastic transformation. Analysis of the mean tumor diameters over time showed constant growth. Linear regression, using a mixed model, found an average slope of 4.1mm per year (95% confidence interval, 3.8-4.4mm/year). Untreated low-grade oligodendrogliomas or mixed gliomas grow continuously during their premalignant phase, and their pattern of growth can be predicted within a relatively narrow range. These findings could be of interest to optimize patients management and follow-up.

Adult↗

PubMed2003

The role of dominant premotor cortex in language: a study using intraoperative functional mapping in awake patients.

Although the role of the premotor cortex (PMC) was widely studied in motor function, very few data are currently available about the participation of this structure in language. We report a series of 25 right-handed patients harboring a low-grade glioma near or within the left dominant PMC, operated on under local anesthesia with intraoperative real-time sensorimotor and language mappings using electrical stimulations all along the resection. Language tasks consisted of counting and picture naming (preceded by the reading of a short sentence). Stimulations of the left PMC induced transient speech disturbances in all patients, with disruption of both counting and reading/naming during stimulation of the ventral PMC--due to elicitation of an anarthria--while generating an anomia during stimulation of the dorsal PMC. Moreover, corresponding subcortical pathways generated the same language disorders as at the cortical level when stimulated. Eloquent structures were systematically preserved, allowing the avoidance of definitive postoperative deficit. These findings suggest first that the left dominant PMC seems to play a major role in language and second that this structure could have a well-ordered functional organization, namely with the ventral PMC, which might be involved in planification of articulation, and the dorsal PMC, which might be involved in the naming network.

Adult↗

PubMed2003

Transient Foix-Chavany-Marie syndrome after surgical resection of a right insulo-opercular low-grade glioma: case report.

OBJECTIVE AND IMPORTANCE: We describe an atypical case of transient Foix-Chavany-Marie syndrome, or faciopharyngoglossomasticatory diplegia with automatic voluntary dissociation, occurring after surgical resection of a right insulo-opercular glioma. CLINICAL PRESENTATION: A 26-year-old right-handed man experienced partial seizures that were poorly controlled by antiepileptic drugs during a 2-year period as a result of a right insulo-opercular low-grade glioma, leading to the proposal of surgical resection. In addition, 1 year before the operation, the patient experienced a severe brain injury that resulted in a coma. A computed tomographic scan revealed left opercular contusion. The patient recovered completely within 6 months. INTERVENTION: Intraoperative corticosubcortical electrical functional mapping was performed along the resection, allowing the identification and preservation of the facial and upper limb motor structures. A subtotal removal of the glioma was achieved. The patient had postoperative anarthria, with loss of voluntary muscular functions of the face and tongue, and he had trouble chewing and swallowing. All of these symptoms resolved within 3 months. CONCLUSION: These findings provide insight into the use of surgery to treat a right insulo-opercular tumor. First, surgeons must be particularly cautious in cases with a potential contralateral lesion (e.g., history of head injury), even if such a lesion is not visible on magnetic resonance imaging scans; preoperative metabolic imaging and electrophysiological investigations should be considered before an operative decision is made. Second, surgeons must perform intraoperative functional mapping to identify and to attempt to preserve the corticosubcortical facial motor structures. A procedure performed while the patient is awake should be discussed to detect the structures involved in chewing and swallowing in cases of suspected bilateral lesions. Third, the patient must be informed of this particular risk before surgery is performed.

Adult↗

PubMed2003

Usefulness of intraoperative electrical subcortical mapping during surgery for low-grade gliomas located within eloquent brain regions: functional results in a consecutive series of 103 patients.

OBJECT: Although a growing number of authors currently advocate surgery to treat low-grade gliomas, controversy still persists, especially because of the risk of inducing neurological sequelae when the tumor is located within eloquent brain areas. Many researchers performing preoperative neurofunctional imaging and intraoperative electrophysiological methods have recently reported on the usefulness of cortical functional mapping. Despite the frequent involvement of subcortical structures by these gliomas, very few investigators have specifically raised the subject of fiber tracking. The authors in this report describe the importance of mapping cortical and subcortical functional regions by using intraoperative real-time direct electrical stimulations during resection of low-grade gliomas. METHODS: Between 1996 and 2001, 103 patients harboring a corticosubcortical low-grade glioma in an eloquent area, with no or only mild deficit, had undergone surgery during which intraoperative electrical mapping of functional cortical sites and subcortical pathways was performed throughout the procedure. Both eloquent cortical areas and corresponding white fibers were systematically detected and preserved, thus defining the resection boundaries. Despite an 80% rate of immediate postoperative neurological worsening, 94% of patients recovered their preoperative status within 3 months--10% even improved--and then returned to a normal socioprofessional life. Eighty percent of resections were classified as total or subtotal based on control magnetic resonance images. CONCLUSIONS: The use of functional mapping of the white matter together with cortical mapping allowed the authors to optimize the benefit/risk ratio of surgery of low-grade glioma invading eloquent regions. Given that preoperative fiber tracking with the aid of neuroimaging is not yet validated, we used intraoperative real-time cortical and subcortical stimulations as a valuable adjunct to the other mapping methods.

Adolescent↗

PubMed2002

Intraoperative frontal eye field stimulation elicits ocular deviation and saccade suppression.

Cortical stimulation is a useful way of elucidating the cortical control of eye movements. The aim of this study was to determine the type of eye movements evoked in response to intraoperative electrical stimulation of the frontal eye field (FEF) region in a fully awake patient during surgery for a frontal lobe glioma. A train of low-intensity electrical pulses within an area in the precentral gyrus evoked contraversive smooth eye movements (SEM) recorded electro-oculographically. Stimulation of an anterior sub-region of this electrically determined FEF disclosed both SEM and suppression of self-paced saccades. However, electrical stimulation of this region evoked no saccades in agreement with pre-operative fMRI using a self-paced saccade paradigm, which did not show activation within the ipsilateral FEF. In humans, intraoperative FEF stimulation may elicit recordable contraversive SEM, and interfere with oculomotor behaviour, suppressing self-paced saccades.

Adult↗

PubMed2002

Modeling of pathophysiological coupling between brain electrical activation, energy metabolism and hemodynamics: insights for the interpretation of intracerebral tumor imaging.

Gliomas can display marked changes in the concentrations of energy metabolism molecules such as creatine (Cr), phosphocreatine (PCr) and lactate, as measured using magnetic resonance spectroscopy (MRS). Moreover, the BOLD (blood oxygen level dependent) contrast enhancement in functional magnetic resonance imaging (fMRI) can be reduced or missing within or near gliomas, while neural activity is not significantly reduced (so-called neurovascular decoupling), so that the location of functionally eloquent areas using fMRI can be erroneous. In this paper, we adapt a previously developed model of the coupling between neural activation, energy metabolism and hemodynamics, by including the venous dilatation "Balloon model" of Buxton and Frank. We show that decreasing the cerebral blood flow (CBF) baseline value, or the CBF increase fraction, results in a decrease of the BOLD signal and an increase of the lactate peak during a sustained activation. Baseline lactate and PCr levels are not significantly affected by CBF baseline reduction, but are altered even by a moderate decrease of mitochondrial respiration. Decreasing the total Cr and PCr concentration reduces the BOLD signal after the initial overshoot. In conclusion, we suggest that the coupled use of BOLD fMRI and MRS could contribute to a better understanding of the neurovascular and metabolic decoupling in gliomas.

Adenosine Triphosphate↗