O. Levrier

Endovascular treatment of idiopathic intracranial hypertension: clinical and radiologic outcome of 10 consecutive patients.

Objective: To explore the relation between venous disease and idiopathic intracranial hypertension. Background: Optic nerve sheath fenestration and ventricular shunting are the classic methods when medical treatment has failed. Idiopathic intracranial hypertension is caused by venous sinus obstruction in an unknown percentage of cases. Recently, endoluminal venous sinus stenting was proposed as an alternative treatment. Methods: Ten consecutive patients with refractory idiopathic intracranial hypertension underwent examination with direct retrograde cerebral venography and manometry to characterize the morphologic features and venous pressures in their cerebral venous sinus. All patients demonstrated morphologic obstruction of the venous lateral sinuses. The CSF pressure was measured in all patients. The CSF pressure on lumbar puncture ranged from 27 to 45 mm Hg with normal composition. All patients had headache, and visual acuity loss was noted in eight patients. Funduscopic examination demonstrated papilledema for all patients. All patients had stenting of the venous sinuses. Intrasinus pressures were recorded before and after the procedure and correlated with clinical outcome. Results: Intrasinus pressures were invariably reduced by stenting. For headache, six patients were rendered asymptomatic, two were improved, and two were unchanged after venous sinus stenting for a mean (± SD) follow-up of 17 ± 10.1 months (range 6 to 36 months). Papilledema disappeared in all patients. In all cases, CSF pressure was normalized at 3-month follow-up. In all patients, direct retrograde cerebral venography or multidetector row CT angiography was performed at 6-month follow-up and demonstrated the absence of stent thrombosis. Conclusion: The importance of venous sinus disease in the etiology of idiopathic intracranial hypertension is probably underestimated. Patients with idiopathic intracranial hypertension in whom a venous sinus stenosis is demonstrated by a noninvasive radiologic workup should be evaluated with direct retrograde cerebral venography and manometry. In patients with a lesion of the venous sinuses who experienced medical treatment failure, endovascular stent placement seems to be an interesting alternative to classic surgical approaches.

MR imaging of fetal brain malformations

MethodsFrom the generally accepted data on the morphogenesis of the brain, the principles for the classification of brain malformations are given, and the salient features of each malformation which may be considered as independent from the developmental stage and therefore practical for MR imaging in the fetus after mid-gestation, are discussed.Results and discussionHowever, the correlation with the clinical results in 150 cases of malformations out of a series of more than 1,000 cases of MR fetal brain imaging, demonstrates that beside the main, well-defined malformative entities, a significant degree of uncertainty remains. As the indication of further imaging is mainly based on the ultrasonographic findings, cases that are not identified as abnormal by US are not submitted to MRI (partial commissural agenesis and malformations of cortical development). A striking discrepancy exists between the findings of US and those of MRI, in the specific instance of the disorders of the posterior fossa (cystic malformations versus mega cisterna magna versus cerebellar defects), which may be only partly corrected by the use of strict anatomic criteria. Similar difficulties are observed for the diagnosis of nondestructive microcephaly.ConclusionLong-term prospective longitudinal clinical-radiological studies of these groups of patients are needed.

Schizencephaly: correlation between the lobar topography of the cleft(s) and absence of the septum pellucidum

Abstract The bipolar defects observed in schizencephalies – clefts in the hemispheric mantle on the one hand, absent septum pellucidum on the other – without any anatomic or functional continuity suggest that there is some sort of common specific vulnerability of both structures. A study of the correlation between lobar location of the clefts and involvement of the septum pellucidum was undertaken, considering the hypothesis that the septum pellucidum is the portion of a ”medial medullary velum” that corresponds to the frontal lobe, while the psalterium would correspond to the parieto-occipital lobe and the fimbria corresponds to the temporal lobe. This retrospective study of 16 cases of schizencephaly properly investigated by MR discloses a perfect correlation, all cases with absent septum pellucidum having clefts into the frontal lobe, all cases with present septum pellucidum having clefts in the parietal, temporal, and occipital lobes, and only the few instances (3 cases) of overlapping findings being characterized by clefts in the central area, where the distinction between posterior frontal and anterior parietal lobes is uncertain because of the cortical dysplasia related to the clefts. Partial defects of the septum also proved to correlate closely, topographically, with the location of the clefts. Therefore, the facts confirm a segmental organization of the mantle and septal defects, suggesting a developmental rather than a destructive mechanism, which could at least be related to a segmental pattern of selective vulnerability.

Functional Cerebral Venous Outflow in Swine and Baboon: Feasibility of an Intracranial Venous Hypertension Model

Introduction: To evaluate the feasibility of performing a functional cerebral venous outflow blockage in two large animals species, the swine and the baboon, for elaboration of venous hypertension models. Method: Cerebral venous outflow pathways were identified on angiogram and venography of three swine and two baboons, and potential approaches to access these structures were assessed. Practicability of performing functional intracranial dural outflow blockage was tested. Results: The main cerebral venous outflow route was the internal jugular vein in baboons and the paraspinal venous network in swine. Both animals had an additional venous outflow structure, the petrosquamous sinus. Access to intracranial venous sinuses was achieved through a percutaneous retrograde approach in baboon but not in swine, due to the absence of a direct connection between the dural structures and the internal jugular vein. A transcranial approach allowed to access dural venous structures in swine. In both models, partial and progressive venous sinus occlusion increased intracranial pressure, while preserving the animals vital status. At 6 months, all animals are alive with no neurological deficits. Conclusion: Functional venous dural outflow blockage for elaboration of intracranial venous hypertension is feasible in both models. To be effective, the sinus blockage must be performed before the origin of the petrosquamous, an additional venous sinus seen in swine and baboon. The baboon has the greatest advantage of resembling human cerebral venous drainage, which enables an intracranial venous retrograde access. However, the transcranial approach remains a valuable option to access intracranial venous sinuses in swine.

Three-dimensional rotational angiography in the assessment of the angioarchitecture of brain arteriovenous malformations

BACKGROUND AND PURPOSE The angioarchitecture of brain arteriovenous malformations (BAVM) still remains a complex subject of study despite advances in medical imaging techniques. For this reason, the present study aimed to assess whether or not 3D rotational angiography (3DXA) might improve the assessment of BAVM. PATIENTS AND METHODS Included prospectively were 72 patients who had undergone conventional digital subtraction angiography (DSA) and 3DXA for pretherapeutic assessment of BAVM prior to radiosurgery. Dimensional criteria, arterial-feed patterns, venous drainage, points of weakness and vascular densities (VD) of the nidus and shunt zone were studied. RESULTS 3DXA detected all arteriovenous shunts by revealing abnormal venous enhancement. Post-processing tools similar to CT and MRI may also be used to make complex 3D reconstructions. In addition, the technique provided significant help for volumetric estimations, extraction of arterial feeders and origins of draining veins, and analysis of the 3D conformation of the nidus. Furthermore, 3DXA detected significantly more points of weakness, such as intranidus aneurysms and venous anomalies (P<0.005). In 65% of cases, a gradient of vascular enhancement intensity was found between the arteries and draining veins surrounding or comprising the nidus. VD, or the percentages of space occupied by the enhanced vascular elements, was evaluated in both the nidus and shunt zone. VD in the shunt zone was highest in untreated patients with no history of bleeding (P<0.005). CONCLUSION 3DXA offers a useful approach to BAVM exploration and can improve our knowledge of lesional angioarchitecture, necessary for the planning of therapeutic strategies.

Imagerie des tumeurs cérébrales de l’enfant

Few studies exist in the literature on pediatric brain tumors examined with advances MRI techniques. The aim of this review is to try to find out some specific tissular characteristics of the main cerebral tumors encountered in children, especially through diffusion imaging, perfusion imaging and proton magnetic resonance spectroscopy (MRS). However, hemispheric cerebral tumors are not as common as in the adult population.

Effectiveness of Endovascular Embolization with a Collagen-based Embolic Agent (Marsembol) in an Animal Model

PURPOSE To investigate in a porcine experimental model the effectiveness, tissue penetration, and histologic impact of renal artery embolization with a collagen-based nonadhesive embolic agent, marsembol. MATERIALS AND METHODS Fifteen pigs underwent embolization of one interlobular artery of the renal artery with collagen-resorcinol gel emulsified with Lipiodol and further polymerized with glutaraldehyde-formaldehyde mixture. Angiograms were obtained before, during, and after the procedure. Animals were euthanized at day 0 (n = 3), 1 week (n = 3), or 3 months (n = 7), and flat-panel three-dimensional rotational radiologic images of the kidneys were obtained. Arterial, medullary, and cortical samples were taken for histologic and scanning electron microscopic investigations. RESULTS Fifteen interlobular renal arteries were successfully embolized by delivering 1.7 mL + or - 0.2 of the embolic agent. All the embolized arteries remained occluded at 3 months, leading to a major atrophy of the embolized portions of the kidneys. Imaging and histologic findings show that the embolic agent provided a distal vessel occlusion and entirely filled the lumen of the arteries up to the glomerular tufts. The homogeneous plug formed by the embolic agent induces very few inflammatory responses. The regenerative tubular processes were arrested at 3 months. CONCLUSIONS The collagen-based embolic agent described here has the properties required to perform embolization. These specific properties lead to very distal vessel embolization. The embolic agent is effective at 3 months in renal embolization.

Radiosurgery: Operative Technique, Pitfalls and Tips

RATIONALE From frame placement to dose administration, each step of the procedure must be optimized in every detail for better preservation of global precision, accuracy, safety and efficacy. METHODS Quality control for resolution, accuracy and acquisition parameter optimization of both computed tomography (CT) scanners and magnetic resonance imaging (MRI) must be performed. Inaccuracies should then be quantified through systematic combination of MRI and CT in the radiosurgery planning system. Topography of petrous structures such as cochlea, vestibulum and facial nerve canal should be visible on the CT scan. T1-weighted volumetric MRI pulse sequences (3DT1) show a contrast-enhanced signal that is useful for both the pons interface delineation in Koos III cases, and the canal ending. High-resolution CISS T2-weighted volumetric pulse sequences (3DT2) allow direct nerve visualization and give superior stereotactic definition attributable to their better resolution minimizing partial volume effects and to their lower magnetic susceptibility minimizing distortions. The 3DT2 pulse sequences with contrast injection, show improved distinction between the pons and the nerves due to signal differences within the schwannomas. Fat saturation pulse sequences are of interest in postmicrosurgery conditions. The previous technical requirements and the dose planning elaboration will be balanced depending on the lesion volume staging (Koos), treatment history (microsurgery), clinical condition (hearing quality), pathological context (NF2) or age of the patient. The recommended marginal dose is 11-12 Gy. Tumor volume delineation allows the calculation of conformity, selectivity and gradient indexes. These global indexes must be weighted according to the relationship to critical structures and functional status of the patient. CONCLUSIONS As an exclusively image-guided surgical method, radiosurgery requires special attention in the choice of imaging modalities and their acquisition parameters need extreme care. Technical nuances during the elaboration of the dose planning itself will directly influence both the toxicity risk and the chance of cure.

One-year efficacy and safety of the Trufill DCS Orbit and Orbit Galaxy detachable coils in the endovascular treatment of intracranial aneurysms: Results from the TRULINE study.

Background and purpose No series reported the mid-term results of Trufill DCS Orbit and Orbit Galaxy detachable coils with independent evaluation. We present the one-year safety and efficacy of these coils in real-life routine clinical practice. Methods A total of 167 patients with 167 aneurysms (39.1% ruptured) were enrolled in the prospective TRULINE study. The primary endpoint was the safety, assessed by the combined morbidity-mortality rate observed since the time of the procedure and up to one-year follow-up. For safety, primary analyses were performed on intent-to-treat population (attempted coils procedure) and all adverse events have been reviewed by an independent Data Safety Monitoring Board. For efficacy, primary analyses were performed on the per-protocol population (patients treated with more than 70% of Trufill coils and not retreated during the follow-up period) and an independent core laboratory evaluated angiographic results. Results At one-year post-procedure, neurologic impairment was observed in 6.5% (95% confidence interval: 3.5–11.8) of the patients, and 2.6% (95% confidence interval: 1.0–6.8) had a permanent neurological deterioration. Three deaths were observed, unrelated to the procedure or coils. At one year, complete occlusion was seen in 52 aneurysms (54.2%), neck remnant in 28 aneurysms (29.2%), and aneurysm remnant in 16 aneurysms (16.7%). During the one-year follow-up, the overall incidence of recurrence was 30.2% with a mean interval of 13.8 ± 4.5 months and the retreatment for major recanalization was needed in nine patients (6.3%). Conclusions The TRULINE study confirms that endovascular coiling with Trufill DCS Orbit and Orbit Galaxy detachable coils is safe and effective.

P-09 Aspect normal du drainage veineux profond dans 2 cas de malformation anévrysmale de la veine de galien

Objectifs Les malformations anevrysmales de la veine de Galien (MAVG) sont supposees etre en rapport avec la persistance de la veine mediale du prosencephale de Markowski, qui n’involue pas en cas de MAVG et devient le collecteur du shunt, caracteristique de la malformation. Les afferences du shunt sont des arteres de la meninge primitive presentes durant la periode embryonnaire pendant laquelle se constitue la malformation. Il a ete egalement suppose que les veines cerebrales internes sont absentes chez les patients presentant une MAVG. Cependant, rien n’indique clairement que les structures veineuses profondes ne puissent pas se developper normalement. Materiels et methodes Nous rapportons 2 cas de patients presentant une MAVG ou le catheterisme veineux retrograde hyperselectif et l’examen IRM ont permis de demontrer la presence de veines cerebrales normales se drainant dans l’ampoule de Galien. Resultats Il est concevable que, comme se fut le cas pour nos patients, seul le catheterisme veineux retrograde permette l’identification angiographique de ce type de drainage. En revanche, l’identification du systeme veineux profond etait aisee sur les coupes fines IRM apres injection de Gadolinium. Conclusion La possibilite de la presence d’un drainage veineux profond dans la veine de Galien doit etre pris en consideration dans la prise en charge therapeutique, surtout si l’on envisage d’occlure la malformation sur le versant veineux.