E. Méary

Magnetic resonance imaging and dynamic CT scan in cervical artery dissections.

Background and Purpose The typical magnetic resonance imaging picture of arterial dissection, namely, a narrowed eccentric signal void surrounded by a semilunar signal hyper- intensity (corresponding to the mural hematoma) on Tl- and T2-weighted images, has been repeatedly reported, but the sensitivity of magnetic resonance imaging for the diagnosis of cervical dissection is poorly known. Another technique, dynamic computed tomography, may provide evidence of mural hematoma, but there has been no systematic evaluation of this technique. The aims of this study were to assess both the sensitivity of routine 0.5-T magnetic resonance imaging for the detection of a typical picture of cervical artery dissection and the value of dynamic computed tomographic scans to provide evidence of dissecting hematoma. Methods Fifteen consecutive patients with angiographicaUy confirmed extracranial internal carotid (n=9) or vertebral (n=10) dissections were studied using a standardized 0.5-T spin-echo magnetic resonance imaging protocol with axial slices. Twelve of these patients had dynamic computed tomo- graphic scans at the site of the dissection suggested by angiography. Results A typical magnetic resonance imaging picture of cervical artery dissection was observed in 12 of 15 (80%) patients and in 13 of 19 (68%) dissected vessels. The sensitivity of magnetic resonance imaging was higher in internal carotid (78%) than in vertebral (60%) dissections and in stenotic-type dissections (85%) than in occlusive or aneurysmal-type dissections. The dynamic computed tomographic scan showed the mural hematoma in 11 of the 12 (92%) patients and in 12 of 15 (80%) dissected vessels. Conclusions Routine 0.5-T magnetic resonance imaging with axial slices is a sensitive technique for the diagnosis of dissection, but in about 20% of patients with cervical artery dissection magnetic resonance imaging will demonstrate no typical abnormality. Dynamic computed tomographic scans are a sensitive neuroimaging procedure to confirm the presence of the mural hematoma, but it needs to be directed by prior angiography.

Aneurysmal forms of cervical artery dissection : associated factors and outcome.

Background and Purpose — The natural history of aneurysmal forms of cervical artery dissection (CAD) is ill defined. The aims of this study were to assess (1) clinical and anatomic outcome of aneurysmal forms of extracranial internal carotid artery (ICA) and vertebral artery (VA) dissections and (2) factors associated with aneurysmal forms of CAD. Methods — Seventy-one consecutive patients with CAD were reviewed. Aneurysmal forms of CAD were identified from all available angiograms by 2 neuroradiologists. The frequency of arterial risk factors, of multiple vessel dissections, and of artery redundancies was compared in patients with and without aneurysm. Patients with aneurysm were invited by mail to undergo a final clinical and radiological evaluation. Results — Of the 71 patients, 35 (49.3%) had a total of 42 aneurysms. Thirty aneurysms were located on a symptomatic artery (ICA, 23; VA, 7) and 12 on an asymptomatic artery (ICA, 10; VA, 2). Patients with aneurysm had multiple dissections of cervical vessels (18/35 versus 7/36;P =0.005) and arterial redundancies (20/35 versus 11/36;P =0.02) more frequently than patients without aneurysm. They were also more often migrainous (odds ratio=2.7 [95% CI, 0.8 to 8.5]) and tobacco users (odds ratio=2.2 [95% CI, 0.7 to 6.3]). Clinical and anatomic follow-up information was available for 35 (100%) and 33 patients (94%), respectively. During a mean follow-up of >3 years, no patient had signs of cerebral ischemia, local compression, or rupture. At follow-up, 46% of the aneurysms involving symptomatic ICA were unchanged, 36% had disappeared, and 18% had decreased in size. Resolution was more common for VA than for ICA aneurysms (83% versus 36%). None of the aneurysms located on an asymptomatic ICA had disappeared. Conclusions — Although aneurysms due to CAD frequently persist, patients carry a very low risk of clinical complications. This favorable clinical outcome should be kept in mind before potential harmful treatment is contemplated.

Evaluation of Hyperintense Vessels on FLAIR MRI for the Diagnosis of Multiple Intracerebral Arterial Stenoses

Background and Purpose— Hyperintense vessel sign (HVS) on fluid-attenuated inversion recovery (FLAIR) has been described in hyperacute stroke patients with arterial occlusion. We sought to determine whether HVS was more frequent in patients with intracerebral arterial stenoses than in those without stenosis regardless of the presence of a brain infarct. Methods— In this case-control study (19 symptomatic patients with multiple intracerebral arterial stenoses compared with 19 age-matched asymptomatic patients without stenosis), we looked for HVS (ie, focal or tubular hyperintensities in the subarachnoid space) on FLAIR images. We compared the proportion of HVS-positive patients in the 2 groups and evaluated the concordance between the arterial distribution of stenoses on angiogram and that of HVS on FLAIR. Results— HVS was found in 13 of 19 patients (68%) in the study group and 1 of 19 control patients (5.2%) (P <0.0001). The concordance between the territorial distribution of stenoses on angiogram and HVS on FLAIR was higher for the right and left middle cerebral artery (&kgr;=0.6 and 0.63, respectively) compared with the right and left anterior cerebral artery (&kgr;=0.35 and 0.2, respectively). HVSs were observed in 1 of 7 patients with posterior cerebral artery stenoses on angiogram. HVSs were seen equally in patients with acute focal (7 of 10) or diffuse (6 of 9) cerebral involvement. In the 6 HVS-positive patients with acute stroke confirmed by MRI, additional HVSs were observed in a different arterial territory than that of the stroke lesion. Conclusions— Although their significance remains unclear, multiple HVSs are more frequently observed in symptomatic patients with multiple intracerebral stenoses than in asymptomatic patients without stenosis.

Magnetic resonance imaging in lateral sinus hypoplasia and thrombosis.

Lateral sinus thrombosis may be difficult to differentiate angiographically from lateral sinus hypoplasia, which mainly affects its proximal transverse portion. Using magnetic resonance imaging, we evaluated six patients who demonstrated poor filling or lack of filling of one or both lateral sinuses at angiography. In each patient, magnetic resonance imaging unambiguously demonstrated either lateral sinus thrombosis or lateral sinus hypoplasia. The latter was characterized by a frank asymmetry in size (surface of section) of the transverse portion of the lateral sinuses on parasagittal images without any abnormal signal in the course of the sinus. Lateral sinus thrombosis was indicated by increased intraluminal signal on all planes and with all pulse sequences. By virtue of its freedom from bone-related artifact, its multiplanar imaging capability, and its sensitivity to both blood flow and thrombus formation, magnetic resonance imaging is an excellent tool for the evaluation of lateral sinus thrombosis or hypoplasia.

Imagerie des métastases intracrâniennes chez l'adulte.

Intracranial metastases account for up to 35% of intracranial tumors in adult. They can involve any part of the central nervous system: brain, meninges and cranial nerves. Any systemic tumor can metastasize to the brain; the most common primaries include lung, breast and melanoma. Imaging plays a major role in the evaluation and management of patients with metastatic brain tumors. This article discusses optimal CT and MR imaging protocols and describes imaging features and distinguishing characteristics of cerebral and meningeal metastases.

Primary Angiitis of the Central Nervous System: Magnetic Resonance Imaging Spectrum of Parenchymal, Meningeal, and Vascular Lesions at Baseline

Background and Purpose— Primary angiitis of the central nervous system remains challenging. To report an overview and pictorial review of brain magnetic resonance imaging findings in adult primary angiitis of the central nervous system and to determine the distribution of parenchymal, meningeal, and vascular lesions in a large multicentric cohort. Methods— Adult patients from the French COVAC cohort (Cohort of Patients With Primary Vasculitis of the Central Nervous System), with biopsy or angiographically proven primary angiitis of the central nervous system and brain magnetic resonance imaging available at the time of diagnosis were included. A systematic imaging review was performed blinded to clinical data. Results— Sixty patients met inclusion criteria. Mean age was 45 years (±12.9). Patients initially presented focal deficit(s) (83%), headaches (53%), cognitive disorder (40%), and seizures (38.3%). The most common magnetic resonance imaging finding observed in 42% of patients was multiterritorial, bilateral, distal acute stroke lesions after small to medium artery distribution, with a predominant carotid circulation distribution. Hemorrhagic infarctions and parenchymal hemorrhages were also frequently found in the cohort (55%). Acute convexity subarachnoid hemorrhage was found in 26% of patients and 42% demonstrated pre-eminent leptomeningeal enhancement, which is found to be significantly more prevalent in biopsy-proven patients (60% versus 28%; P=0.04). Seven patients had tumor-like presentations. Seventy-seven percent of magnetic resonance angiographic studies were abnormal, revealing proximal/distal stenoses in 57% and 61% of patients, respectively. Conclusions— Adult primary angiitis of the central nervous system is a heterogenous disease, with multiterritorial, distal, and bilateral acute stroke being the most common pattern of parenchymal lesions found on magnetic resonance imaging. Our findings suggest a higher than previously thought prevalence of hemorrhagic transformation and other hemorrhagic manifestations.

Magnetic resonance imaging findings three weeks after discectomy: misleading appearance of recurrent herniation, with nerve root enhancement

Abstract A patient with right-sided L5 sciatica and low back pain experienced a symptom recurrence 3 weeks after surgical removal of a right-sided L4-L5 disk herniation. Magnetic resonance imaging (MRI) was suggestive of recurrent disk herniation and showed enhancement of the right L5 root. This case emphasizes the difficulties met in interpreting imaging studies done too early after surgery.

Embolie gazeuse cérébrale et médullaire

L’embolie gazeuse correspond a la presence de gaz dans les structures vasculaires et resulte generalement de la iatrogenie de certaines procedures medicales et chirurgicales ainsi que des accidents de plongee. L’embolie gazeuse cerebrale est une cause rare d’ischemie cerebrale arterielle ou veineuse (mecanisme retrograde), mais la distinction entre ces 2 localisations semble difficile dans certains cas. Au niveau medullaire, l’embolie gazeuse est retrouvee quasi exclusivement dans le cadre d’accidents de decompression. La prise en charge therapeutique est specifique a cette etiologie.

Seizures as the initial symptom of a diffuse dura mater and choroids plexus haematopoiesis revealing myelofibrosis

A 63-year-old woman was admitted with a one-month history of visual loss, headaches and seizures. On initial examination, she was confused with bilateral papilloedema, enlarged liver and spleen, associated with cutaneous purpura. Laboratory examinations revealed pancytopaenia: haemoglobin level was 9.5 g/dL, white blood cell count 4500 per millimetre cube and platelet count 65,000 per millimetre cube. A peripheral blood smear revealed anisocytosis, poikilocytosis, teardrop cells, and leukoerythroblastic changes. Brain MRI revealed an irregular, lobulated thickening of the dura mater, surrounding the brain and extending along the falx cerebri (Fig. 1A—D). The meningeal thickening

NR-WP-59 Cas cliniques en neuro-oncologie

Objectifs pedagogiques Proposer un outil d’evaluation de pratiques professionnelles (EPP) en Neuro-oncologie a partir de dossiers radio-cliniques. Messages a retenir L’IRM est un outil incontournable en neuro-oncologie. Le protocole doit etre adapte a chaque patient selon le contexte clinique et le type de lesion tumorale recherche. Les nouvelles techniques (IRM perfusion, ASL, spectroscopie, transfert de magnetisation et scanner de perfusion / permeabilite) permettent d’augmenter la sensibilite et la specificite de la demarche diagnostique, et d’evaluer plus precisement le profil evolutif.