Biomedical subjects

X Leclerc

Publications and source records attributed to X Leclerc.

At least 55 records · Page 3Linked to original sources

PubMed1999

One-and-a-half syndrome in pontine infarcts: MRI correlates.

The one-and-a-half syndrome is characterised by a lateral gaze palsy in one direction and internuclear ophthalmoplegia in the other. It is due to a unilateral lesion of the dorsal pontine tegmentum, involving the ipsilateral paramedian pontine reticular formation, internuclear fibres of the ipsilateral medical longitudinal fasciculus and, usually, the abducens nucleus. The main causes of this rare syndrome are stroke and multiple sclerosis. Few cases have been reported since the introduction of MRI. Our aim was to examine clinicoradiological correlations in six patients with a one-and-a-half syndrome due to a stroke. Ophthalmological symptoms were diplopia, oscillopsia or blurred vision. Four patients had an associated facial nerve palsy, three a hemiparesis and one a unilateral hemihypoaesthesia. MRI revealed an infarct in the pons in all patients. The cause of the infarct was a basilar artery dissection in one patient, bilateral vertebral artery dissection in a second and unknown in the other four. All patients recovered within 2 days to 8 weeks. This study showed a good correlation between the site of the lesion (superior, inferior or extensive pontine ischaemia) and clinical deficits.

Adult↗

PubMed1999

Contrast-enhanced MR angiography of the craniocervical vessels: a review.

The use of MR angiography (MRA) with injection of contrast medium enables imaging of a large volume with a very short acquisition time, providing angiographic images similar to those obtained with catheter angiography. This makes possible investigation of patients in the acute phase of stroke, with examination of the entire length of the cervical arteries from the aortic arch to the circle of Willis. However, the parameters of the sequence must be carefully chosen to optimise image quality, with a compromise between spatial resolution, acquisition time and image contrast. An overview of the technical aspects is presented, including current developments. Different protocol strategies are discussed, including their advantages and limits. Finally, we review the preliminary results of contrast-enhanced MRA for assessment of atherosclerotic lesions of supra-aortic vessels.

Arteriosclerosis↗

PubMed1999

Endovascular treatment of ruptured intracranial aneurysms.

The Guglielmi detachable coil (GDC) is an important tool for the treatment of ruptured intracranial aneuryms by an endovascular approach. This new device may be introduced under fluoroscopy into the aneurysmal sac through a microcatheter. When the coil is judged well positioned, it can be detached with accuracy by electrolytic breakdown. The procedure is completed when a dense coil packing is obtained. When vasospasm is present, papaverin infusion or angioplasty may be used by the endovascular approach as well. Best results are achieved in cases of small aneurysm with small neck. The morbidity and mortality rates in the first 200 patients treated by GDC for a ruptured intracranial aneurysm were 4% and 1.5%, respectively. Complications are generally related to rupture of the malformation by the endovascular device or to thromboembolic events. Despite these promising results, further studies using larger numbers of patients are required to determine the exact role of these procedures in patient care.

Aneurysm, Ruptured↗

PubMed1999

Gadolinium-enhanced fast three-dimensional angiography of the neck: technical aspect.

RATIONAL AND OBJECTIVES: This study sought to assess the feasibility of a contrast-enhanced three-dimensional (3D) magnetic resonance (MR) angiographic sequence for imaging the cervical arteries. METHODS: Ninety-eight consecutive patients underwent contrast MR angiography using a 3D sequence in the coronal plane, including both carotid and vertebral arteries. Gadolinium was injected at the beginning of the sequence. When the contrast was not optimal, a second injection was performed 5 to 10 minutes later. Qualitative assessment was performed for each arterial portion in a consensus manner by three radiologists who judged contrast enhancement, imaging coverage, and artifacts. RESULTS: A second injection was required in 11 patients, and two examinations were not assessable because of motion artifacts. Among the vessels analyzed, 19% were not assessable owing to the limited coverage in 11% and to the low contrast in 9%. Carotid bifurcations were assessable in 95%, whereas vertebral arteries were visualized from their origins to their intradural portions in only 82% of cases. A longitudinal signal-void artifact was found in the center of the arterial lumen of carotid arteries in six patients. CONCLUSIONS: Contrast MR angiography constitutes a promising tool to assess cervical arteries. Some limitations including spatial resolution, timing of injection, and imaging coverage should be overcome in the near future.

Adult↗

PubMed1999

Internal carotid arterial stenosis: CT angiography with volume rendering.

PURPOSE: To determine the reliability of helical computed tomography (CT) with volume rendering for evaluation of internal carotid arterial stenosis. MATERIALS AND METHODS: In 22 patients, 44 carotid arteries were evaluated with helical CT and selective conventional angiography. CT data were displayed on volume-rendered and maximum intensity projection (MIP) images. Stenoses were measured separately on axial, volume-rendered, and MIP images and on conventional angiograms. Each artery was then graded as having no stenosis, mild (< 30%) stenosis, moderate (30%-70%) stenosis, severe (> 70%) stenosis, near occlusion, or occlusion. RESULTS: One case of stenosis was not assessable at axial CT because of an inappropriate scanning plane; four cases were not assessable at MIP CT because of mural calcifications. All carotid arteries were assessable on volume-rendered images despite no depiction of the residual lumen at the site of narrowing in three cases of near occlusion. Correlations between angiography and helical CT were good. Axial, volume-rendered, and MIP images enabled correct classification of stenosis in 88%, 89%, and 90% of arteries, respectively. CT with volume rendering was slightly more sensitive for determining candidates for endarterectomy (i.e., those with > 70% stenosis and near occlusion); sensitivity was 100% and specificity, 92%. CONCLUSION: CT angiography with volume rendering enabled accurate evaluation of carotid disease, even when dense calcifications were present. However, no definite advantage over currently available techniques for CT measurement of stenosis severity was found.

Adult↗

PubMed1999

[Cerebral angiography: a study of complications in 450 consecutive procedures].

PURPOSE: To evaluate all types of complications, both minor and major, associated with modern cerebral angiography. MATERIALS AND METHODS: A prospective study of 450 consecutive cerebral angiographic procedures is reported. RESULTS: One patient (0.2%) died from a cholesterol embolus. In seven patients (1.6%), thromboembolic events occurred within 24 hours after the procedure, leading to transient ischemic symptoms in six and permanent hemiplegia in one. Two patients suffered from acute renal failure (0.4%). Transient cardiac arrhythmias were observed in three patients without consequence on the clinical outcome. Most complications of angiography occurred in patients referred from the neurology department for work-up of stroke syndrome. CONCLUSION: Our results show that morbidity and mortality rates related to the angiographic procedure did not decrease in spite of major improvement of angiographic materiel. Atherosclerosis is the main risk factor for complication. Most of the complications could be avoided by appropriate selection of indications and by using non-invasive techniques such as magnetic resonance angiography or helical CT angiography.

Acute Kidney Injury↗

PubMed1999

Preliminary experience using contrast-enhanced MR angiography to assess vertebral artery structure for the follow-up of suspected dissection.

BACKGROUND AND PURPOSE: Important advances have been made recently in MR angiography with the use of contrast medium injection, which has proved valuable for the imaging of vertebral arteries (VAs) obtained during short scanning times. Our purpose was to assess the feasability of contrast-enhanced fast 3D MR angiography for imaging VAs and to evaluate the long-term follow-up of VA dissections. METHODS: Sixteen consecutive patients with 18 angiographically documented VA dissections (seven occlusive dissections and 11 stenotic dissections, including two each with a pseudoaneurysm) were followed up using both contrast-enhanced 3D MR angiography and cervical T1-weighted MR imaging at a median delay of 22 months. Ten patients underwent MR imaging at the acute phase as well, and nine underwent early follow-up angiography at a median delay of 3 months. MR angiographic findings were determined by consensus, focussing on image quality, presence of residual stenosis, luminal irregularities, and occlusion. RESULTS: Of the 32 VAs, a segment of the artery was not assessable on contrast-enhanced MR angiography in each of four small VAs. A central signal void artifact of cervical arteries was seen in one patient and motion artifacts were seen in two, but images could be interpreted. A venous enhancement was detected in 10 of 16 examinations, but this did not prevent image analysis. Ten of 11 stenotic dissections returned to normal, whereas one stenotic dissection progressed to occlusion. Two pseudoaneurysms detected by initial angiography resolved spontaneously; one was revealed only by delayed MR angiography, and one was detected on an early MR angiogram and proved resolved on a late MR angiogram. Of the seven initially occluded VAs, five reopened, with a hairline residual lumen in each of three. CONCLUSION: This preliminary experience showed that contrast-enhanced MR angiography is a promising tool for imaging VAs; it allows the assessment of VA dissection changes over time. Most lesions tended to heal spontaneously, but persisting occlusion or pseudoaneurysm could be detected during the late course.

Adult↗

PubMed1999

[Clinical aspects and treatment of dural-spinal arteriovenous fistulas with perimedullary venous drainage. 10 cases].

BACKGROUND AND PURPOSE: Spinal dural arteriovenous fistulas (SDAVF) are rare but represent the most frequent spinal arteriovenous malformation. Their clinical manifestations are well known, but their management can still be discussed between surgery and endovascular treatment. The purpose of this study is to emphasize the pre-eminence of surgical management for posterior and postero-lateral fistulas, which are the most common location of the malformation. METHODS: We report a consecutive series of 10 patients with SDAVF treated between July, 1995 and July, 1997. Results are compared with other series of the literature. RESULTS: Clinical manifestations were not specific and the diagnosis was established in most cases only one year after the onset of symptoms, as a progressive myelopathy. Low back pain was present in 4 patients, with pseudo-radicular pain in the lower limbs suggesting spinal degenerative disease in 3 cases. At the time of diagnosis, 8 patients had permanent motor weakness of the lower limbs, usually associated with hypesthesia and sphincterial dysfunction (7 cases). In all cases, the diagnosis was established using MRI. In most cases, the intradural draining spinal veins were also visible on MRI images. The location of the SDAVF was always precised by angiography, and was located between T5 and L1 in our series. Seven patients were successfully operated on, with surgical interruption of the intradural draining vein. Three patients underwent an endovascular treatment, but two of them were operated on later, as control angiography showed recurrence of the SDAVF. The clinical status of patients always improved after treatment, but recovery was incomplete in patients with severe and long lasting neurological deficit. CONCLUSIONS: Surgical interruption of the intradural draining vein is a safe and effective method of treatment of SDAVF, especially for posterior and postero-lateral fistulas. Endovascular treatment is recommended for anterior locations of SDAVF.

Adult↗

PubMed1998

Unusual MRI findings in grey matter heterotopia.

We report unusual MRI patterns in patients with grey matter heterotopia. Standard T1- and T2-weighted spin-echo and inversion-recovery sequences were used in 22 patients presenting with seizures or developmental delay. The images were reviewed for signal change surrounding white matter and for atypical size, morphology or topography. We found 10 cases of subependymal heterotopias 11 of focal subcortical heterotopia and of diffuse subcortical heterotopia. On clinical or MRI grounds, 8 cases were considered unusual: 2 of the subependymal type, 2 of focal subcortical heterotopia with white matter abnormalities, 2 of focal subcortical heterotopia with no clinicoradiological correlation 1 of extensive hemispheric subcortical heterotopia and 1 of diffuse subcortical heterotopia confined to the frontal lobe. The classical classification of heterotopia enables easy radiological diagnosis even in cases with unusual patterns. In some cases, heterogeneity and high signal in surrounding white matter can be found. Cortical dysplasia is the most frequent associated malformation.

Adolescent↗

PubMed1998

Brain-behaviour relationships. Some models and related statistical procedures for the study of brain-damaged patients.

The study of brain-damaged patients provides the opportunity to examine the anatomy of brain functions, and has been renewed by the development of structural neuroimaging. Despite the development of neuroimaging and neuropsychological assessment, major uncertainties persist on the exact delimitation of the brain areas involved in specific processes, and these contribute to the enduring controversies over the effective lesions associated with neuropsychological disorders. These uncertainties are mainly due to the methods used in the study of brain-behaviour relationships, which frequently rely on a group comparison design. The aim of this study was to provide models for the study of brain-behaviour relationships and to assess the reliability of related statistical procedures. In the present work, four theoretical modes of brain-behaviour relationship consistent with neuropsychological data are put forward: unicity, equivalence, association and summation. The first experimental study was based on a simulated population of patients. Lesions associated with the occurrence of a deficit were predetermined according to modes of brain-behaviour relationship and were compared with lesions selected by statistical analysis. The study showed that (i) the group comparison design did not allow determination of the effective lesion, (ii) stepwise regression analysis was sensitive to the relative frequency of lesions, especially when the occurrence of a deficit depended on two lesions, but did not allow determination of the mode of brain-behaviour relationship, and (iii) the classification tree test described the data very satisfactorily and permitted the determination of the mode of brain-behaviour relationships. In order to assess the validity of statistical analyses, a second study was performed in which lesion locations associated with motor weakness in stroke patients were examined. Selected lesions were compared with the anatomy of the human motor system. The study mainly showed that (i) the stepwise regression analysis of selected lesions was not related to the presence of a motor deficit, and (ii) the classification tree test provided perfect agreement with motor weakness predicted by lesion locations and suggested an equivalence mode of brain-behaviour relationship consistent with current neurological knowledge. These studies provide models of brain-behaviour relationships and related statistical procedures that may allow more precise documentation of the anatomy of brain functions and its pathology, and further investigation of the modalities of brain-behaviour relationships.

Behavior↗

PubMed1998

Helical CT for the follow-up of cervical internal carotid artery dissections.

PURPOSE: The aim of this study was to assess the changes over time of internal carotid artery (ICA) dissections by using helical CT. METHODS: Twenty-seven patients with 30 angiographically proved ICA dissections were followed up with helical CT at 7 to 62 months (median, 24 months) after conventional angiography. CT scans, analyzed independently by two radiologists in a blinded fashion, were evaluated for the presence of mural thickening, aneurysmal formation, and arterial occlusion. In cases without persisting occlusion or aneurysm, we measured the external diameter of the ICA at its upper segment. RESULTS: The interobserver agreement was good. Mild mural thickening was observed in four cases of 30 previously dissected ICAs. All stenotic and nearly occlusive dissections without an aneurysm (n = 12) reverted to a normal or nearly normal diameter. Half the aneurysms resolved spontaneously (four of eight). Of the 10 occluded ICAs, nine were recanalized, but their external diameter was significantly smaller than that of normal carotid arteries, and a hypoplastic appearance was seen throughout the cervical segment of the ICA in three cases. CONCLUSION: Most arterial lesions tend to improve or disappear spontaneously, but persisting ICA narrowing may be observed in the late course of occlusive-type dissections.

Adult↗

PubMed1998

[Contribution of fast-sequence three-dimensional MRI angiography with Gadolinium injection in the evaluation of supra-aortic vessels].

Sixty-nine patients with cervical atherosclerotic disease were evaluated by Magnetic Resonance (MR) angiography using a coronal 3D gradient echo gadolinium enhanced sequence. The image quality was evaluated for each artery and ostium on MIP reconstructions. A comparison with conventional angiography was achieved in 27 patients. All MR examinations were assessable; a second injection was performed in ten patients. All carotid bifurcations were visualized. The ostium of the common carotid artery was not assessable in 44% of cases due to the limited coverage. The evaluation of the posterior circulation was good in 90% of cases. The agreement between MR angiography and conventional angiography was good despite a tendency to overestimate moderate stenoses. Stenoses greater than 70%, carotid occlusions and vertebral stenoses greater than 50% were correctly detected.

Adolescent↗

PubMed1998

Contrast-enhanced three-dimensional fast imaging with steady-state precession (FISP) MR angiography of supraaortic vessels: preliminary results.

BACKGROUND AND PURPOSE: The purpose of this study was to assess the effectiveness of contrast-enhanced fast three-dimensional (3D) MR angiography in depicting both the carotid and vertebral arteries in their cervical portions and to compare MR angiography with conventional angiography for the evaluation of arteriosclerotic disease. METHODS: Twenty-seven patients with ischemic cerebral events in the anterior (n = 18) and posterior (n = 9) circulation underwent contrast-enhanced 3D MR angiography in the coronal plane. MR angiograms were examined in a blinded fashion by two observers independently. Stenosis was classified according to the appearance of the residual lumen (no stenosis, mild stenosis, moderate stenosis, severe stenosis, occlusion). Conventional angiography was used as the standard of reference. RESULTS: Proximal great vessels and carotid siphons were not assessable on MR angiograms in 35% of cases owing to limited coverage. All cervical and petrous segments of the internal carotid arteries (ICAs) and 93% of the extracranial vertebral arteries were assessable. Flow-related artifacts were observed in seven cases of severe stenosis, including three with signal void at the site of narrowing and four with signal loss in the distal ICA. Interobserver agreement was good and significant. Overall agreement between 3D MR angiography and conventional angiography was good for the anterior and posterior circulations despite a tendency toward overestimation of stenoses on MR angiograms. Clinically relevant stenoses and occlusions were correctly identified on 3D MR angiograms, providing good sensitivity and specificity. CONCLUSION: Contrast-enhanced 3D MR angiography is a promising tool for assessing arteriosclerotic lesions of supraaortic vessels. Further studies with larger groups are required to determine its value for patient care.

Adult↗

PubMed1997

[Cerebral fat embolism after closed leg injury].

A 21-year-old man sustained a closed fracture of the leg from an industrial accident, without associated head trauma. The orthopaedic treatment consisted of immediate immobilization by setting leg in plaster. Two hours after admission, the Glasgow coma scale score was 10. Four hours after admission he developed a coma (Glasgow coma scale score = 7) with repetitive seizures. No lesion was visible on cerebral CT scan. Chest X-ray was unremarkable. Petechiae on the anterior chest wall and abdomen with bilateral mydriasis occurred. Thrombocytopenia with prothrombine time increase were observed. Magnetic resonance imaging, 27 hours after admission, showed high-intensity areas on T2 weighted views due to fat embolism. Retinal haemorrhages were observed. The bronchoalveolar lavage showing fat staining of tracheal aspirates confirmed the diagnosis of fat embolism. This case report emphasizes the possibility of predominant neurologic manifestations of a fat embolism and the diagnostic help of cerebral magnetic resonance imaging.

Accidents, Occupational↗

PubMed1997

[Study of the carotid artery bifurcation using a helical scanner].

Helical CT is a new technology leading to a rapid acquisition of a large volume during the peak of intravascular enhancement. Indications are large in vascular pathology due to the possibilities of three dimensional (3D) reconstructions providing angiogram-like images. To assess carotid bifurcations, this examination needs the choice of multiple parameters for acquisition (collimation, table speed, can time), injection (volume of contrast material, rate, scan delay) and reconstruction (increment, field of view). Post processing is performed on an independent workstation. Helical CT provides a reliable analysis of carotid artery stenosis. Voluminous calcified plaques constitute the main limiting factor preventing image analysis on the 3D reconstructions. Furthermore, image reconstructions require a long time, study of carotid siphons remains inefficient and examination of the circle of Willis cannot be performed in the same time.

Angiography↗

PubMed1996

[Anesthesia and critical care for endovascular occlusion of ruptured intracranial aneurysms with electrically detachable coils].

The endovascular occlusion of ruptured intracranial aneurysms with electrically detachable coils is a therapeutic approach which seems to be a promising technique. General anaesthesia is considered as being the most adapted for its realisation, as its provides complete immobility and as controlled ventilation and extended monitoring offer optimal conditions for undelayed treatment of haemorrhagic and thromboembolic complications. The available equipment should be the same as that used for conventional surgical treatment of ruptured aneurysms. Anticoagulation is required to prevent thromboembolic complications during and after the procedure. Most teams administer heparin.

Anesthesia, General↗

PubMed1996

Helical CT for the diagnosis of extracranial internal carotid artery dissection.

BACKGROUND AND PURPOSE: We attempted to evaluate the sensitivity of helical CT for the diagnosis of extracranial internal carotid artery (ICA) dissection. METHODS: Sixteen consecutive patients with 18 angiographically confirmed extracranial ICA dissections were studied with a helical CT protocol with large-volume acquisition and thin axial slice reconstructions. A control group including normal and atherosclerotic ICAs was formed for comparison, and a blind interpretation of CT images was made by two observers. We evaluated the presence of stenosis, eccentric lumen, mural thickening, aneurysm, occlusion, and annular contrast enhancement. When the artery seemed to be occluded, we measured the external diameter of the ICA (1) on the occluded side, at its upper portion and most enlarged level, (2) at its lower portion, beyond the bulb, and (3) on the contralateral side, at is upper portion. RESULTS: Interobserver agreement was good except for the presence of annular contrast enhancement. In the stenotic dissection group (n=12), the presence of a narrowed eccentric lumen at the upper portion of the ICA on axial CT images was classified correctly in all cases (sensitivity, 100%; specificity, 100%). An arterial wall thickening was seen in all cases of dissection but also in three cases of the control group. In the occlusive dissection group (n=6), the enlargement of the dissected artery was the best criterion (sensitivity, 100%, specificity, 100%) for occlusive dissection. CONCLUSIONS: Helical CT seems to be a reliable method for evaluating extracranial ICA dissection. The analysis of the residual arterial lumen and the measurement of the external diameter of the carotid artery were the best criteria for the diagnosis. Further studies with larger groups are required to determine whether ICA dissections might be diagnosed using helical CT as a first procedure.

Adult↗

PubMed1996

Cranial nerve palsies due to internal carotid artery dissection: seven cases.

Cranial nerve palsies are rare complications of internal carotid artery (ICA) dissections. The aim of this study is to evaluate the incidence of cranial nerve palsies in consecutive patients with ICA dissection and to describe clinical and radiological characteristics and their evolution over time. This study was conducted in 52 consecutive patients with dissection of the ICA. We have analyzed clinical data of patients with cranial nerve palsy as complication of ICA dissection. We defined ICA dissection as angiographic evidence of a string sign, double lumen, or internal flaps or visualization on magnetic resonance imaging (MRI) or computed tomographic scans of an enlarged arterial wall due to the hematoma. Of 52 consecutive patients with ICA dissection 7 had cranial nerve palsies: 2 had an involvement of the Vth cranial nerve and 5 had lower cranial nerve palsies. Five patients totally recovered while 2 did not after a 2 to 10-month period. The frequency of cranial nerve palsies associated with ICA dissection is higher in our study than in those of the literature. Many patients presenting with cranial nerve palsies due to ICA dissection without any ischemic event are probably not referred to stroke units. Angiography is less sensitive than cervical MRI to detect such patients. Cranial nerve palsies could either be due to compression by the enlarged ICA wall or an ischemia of the nerve.

Adult↗