Biomedical subjects
Publications and source records attributed to A Gaston.
We propose studying signs of cervicothoracic CSF hypotension by MRI. Axial T1-weighted GRE sequence with and without saturation bands positioned above and below the selected image plane, MR venography and MR Angiography with contrast administration are helpful to confirm the venous nature of the epidural thickening and to make the differential diagnosis with infectious or neoplastic epiduritis.
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The authors report the case of a 38-year-old woman with a cavernous DAVF resulting in edematous lesions located in the territory of the ipsilateral basal vein. Transarterial embolization led to subtotal regression of the fistula associated with the regression of cerebral abnormalities. The authors discuss the pathophysiology of the cerebral edematous lesions and the therapeutic consequences according to the venous drainage of the cavernous sinus.
The kinetics of cerebrospinal fluid can be analyzed equally well with velocity imaging and 3D T2-weighted flow sensitive sequences. These techniques constitute a valuable evaluation for intracranial and spinal CSF obstructive pathology.
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We report aqueduct compression by venous ectasia in a 65-year-old man with a dural arteriovenous fistula in the posterior cranial fossa draining into a superior vermian vein. Conventional and phase-contrast MRI showed the aqueduct stenosis and the causative dilated vein.
BACKGROUND AND PURPOSE: Colloid cysts of the third ventricle are rare benign brain tumors. The purpose of this study was to correlate their patterns on MR images with the probability of success of percutaneous treatment. METHODS: Nineteen patients underwent endoscopic treatment for colloid cysts of the third ventricle. The cases were divided into two groups based on difficulty of the aspiration procedure. We reviewed CT scans and MR images and divided cysts into groups based on their signal intensity on the MR images and their density on CT scans. Intensity and density were correlated with difficulty of aspiration during the endoscopic procedure. RESULTS: The aspiration procedure was difficult in 63% of the cases. Eighty-nine percent of hyperdense cysts on unenhanced axial CT scans were categorized as difficult, and 75% of hypodense cysts were categorized as easy. On T2-weighted MR sequences, 100% of low-signal cyst contents were difficult and nearly 63% of high-signal lesions were easy. There was a significant correlation between the T2-weighted sequences and the CT scans regarding the difficulty of the aspiration procedure. CONCLUSION: T2-weighted MR sequences are useful for predicting difficulty of aspiration during stereotactic or endoscopic procedures. A T2-weighted low-signal cyst is correlated with high-viscosity intracystic contents.
We report five cases of intracranial dural arteriovenous fistula (DAVF) with perimedullary venous drainage. All the patients presented with rapidly progressive myelopathy and three had autonomic disorders. The DAVF were on the tentorium cerebelli (two cases), sigmoid (one), superior petrosal (one), and cavernous sinus (one). Slow venous drainage was directed through dilated perimedullary cervical veins. The transverse sinus was occluded in two cases. MRI, performed in four cases, demonstrated high signal on T2-weighted spin-echo sequences in the medulla oblongata and upper cervical spinal cord consistent with oedema, which signal resolved after complete cure of the DAVF in three cases. Embolisation was performed in all cases. It was followed by clinical deterioration in two cases and in the dramatic improvement in the other three, with complete clinical cure in two. Extensive venous thrombosis may explain the deterioration observed in one case.
We report two patients with an idiopathic transdural spinal cord herniation at the thoracic level. Phase-contrast MR imaging was helpful in showing an absence of CSF flow ventral to the herniated cord and a normal CSF flow pattern dorsal to the cord, which excluded a compressive posterior arachnoid cyst.
The purpose of the present study is to report four cases of sinonasal hemangiopericytoma (HP) diagnosed and treated in our department between 1987 and 1998. The pretreatment findings and the treatment are described and discussed in the light of the literature. HP are unusual vascular tumors, featuring pericytes distributed around normal vascular channels. Two of these four cases were located in the nasal cavity and the other two were located in the maxillary sinus. Inside the nasal cavity, HP presented as a protruding reddish-gray mass with marked bleeding on contact. Electron microscopy and immunohistochemical techniques are essential for diagnosis and to distinguish HP from other sarcomatous tumors. Preoperative assessment included routine CT, MRI, arteriography and selective embolization. These tumors must be treated surgically with complete excision. An endonasal approach was performed in two cases of intranasal HP, while a combined external-endonasal approach was required for the other two cases of HP.
3D time-of-flight magnetic resonance angiography (3D TOF MRA) and 2D MRA with presaturation were evaluated in 18 patients with 21 giant intracranial aneurysms. 3D TOF MRA gave optimal images of proximal unruptured and nonthrombosed aneurysms. 2D MRA with presaturation was more informative in cases of distal, haemorrhagic or thrombosed aneurysms and in assessment of their components (thrombus, haemorrhage, patent residual lumen).
BACKGROUND AND PURPOSE: We describe four cases of aneurysmal rupture during embolization with Guglielmi electrodetachable coils (GDCs) in an attempt to identify those aneurysms whose rupture during embolization represents a life-threatening risk; our emphasis is on emergency management, in particular, ventriculostomy. METHODS: Medical records were reviewed retrospectively for 91 aneurysms treated with GDCs 0 to 21 days after subarachnoid hemorrhage. Rupture was ascertained by the presence of extravascular effusion of contrast medium. RESULTS: Of the perforated aneurysms, two involved the anterior communicating artery, one the posterior inferior communicating artery, and one the basilar artery. Only two patients, whose aneurysms were located in the posterior fossa, had major complications (arterial hyperpressure, mydriasis, angiographically documented circulatory arrest or slowing). One of these patients died and the other improved after emergency ventriculostomy. CONCLUSION: Aneurysmal perforation during embolization may be accompanied by severe intracranial hypertension, which causes either a decrease or arrest of cerebral perfusion, the duration of which determines clinical outcome. Emergency ventriculostomy (which should be performed in the angiographic suite) is an effective means to reduce intracranial pressure. Recognition of aneurysms associated with a high risk of mortality by rupture in the course of embolization (recently ruptured small aneurysms, posterior fossa aneurysms, associated ventricular dilatation, massive cisternal hemorrhage) and use of proper logistics should ensure the effective management of this devastating complication.
We describe the evolution of parenchymal cerebral cysticerci on MRI, to assess signs of early cyst degeneration. We studied 15 lesions in four treated and one untreated patient. MRI was performed before therapy and repeated in the 1st month after each course of anticysticercus drugs, every 4 months during the 1st year and then annually; the follow-up period was 8-48 months. Lesions were classified according to changes in four features: cyst content and capsule signal, gadolinium enhancement and oedema signal. We were able to recognise each of the pathological phases; five MRI stages were identified. Stage 1 showed oedema and/or nodular gadolinium enhancement in the tissue invasion phase; stage 2 was cerebrospinal fluid-like signal within a cyst in the vesicular phase; stage 3 showed a thick capsule with an impure liquid content signal and surrounding oedema, in the cystic phase; stage 4 showed the disappearance of the cyst fluid content signal in the degenerative phase; stage 5 showed a calcified lesion in the residual phase. Stage 1 lesions disappeared after therapy; the other progressed from one stage to another. Stage 4 indicated the end of viability of the parasite and determined the point after which treatment was useless. On T2-weighted images changes in the cyst content differed according to the history of the lesion; nodular low intensity followed the natural degeneration of the parasite and a mixed fluid signal with punctate low signal seemed to represent the specific result of therapy. MRI staging can help in the evaluation of indications for treatment and facilitate clinical therapeutic trials.
PURPOSE: To present the clinical and radiologic features of giant perimedullary arteriovenous fistulas (GAVFs) in 12 consecutive cases and to evaluate the results of endovascular treatment. METHODS: We retrospectively reviewed the clinical and radiologic data as well as the results of balloon endovascular treatment obtained from 1980 to 1989. RESULTS: GAVFs, defined as large intradural perimedullary direct arteriovenous high-flow shunts, are revealed mainly in childhood either by subarachnoid hemorrhage or by progressive neurologic disorders. MR imaging and myelography show major vascular dilatations. The angioarchitecture of GAVFs can only be assessed by selective spinal angiography. Ten patients were treated by balloon occlusion resulting in eight anatomic cures and six good clinical results. One balloon migrated to the venous side, leading to clinical deterioration. CONCLUSION: GAVF is a special subgroup of intradural perimedullary arteriovenous fistula. The endovascular approach should be the first line of treatment, with surgery reserved for special circumstances. Nondetachable balloon occlusion is a safe and efficient method for treating GAVFs.
We describe three patients presenting transient ischemic attacks or minor stroke, relapsing despite anticoagulation and antiplatelet therapy, in relation to tight stenosis of the intracranial vertebral arteries, without functional communicating arteries. Percutaneous transluminal angioplasty was successfully performed. We have a 6, 24 and 36 months follow-up. After a review of the literature, we discuss indication and risks of this procedure.
Symptomatic intracranial involvement of vertebral and basilar arteries by atherosclerosis is not accessible to surgical treatment. We report a case of major basilar artery stricture responsible for haemodynamic strokes treated successfully by percutaneous dilatation.
We report a 50-year-old man with an epidermoid cyst of the conus medullaris which showed a nodular gadolinium enhancement on MRI and a blush on angiography. These radiological features are compared with pathological examination.