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At least 1,621 records · Page 90Linked to original sources
PubMed2006

Peri-infarct reorganization of motor function in patients with pontine infarct.

OBJECTIVES: Combined functional MRI (fMRI) and diffusion tensor tractography (DTT) imaging provides a powerful vehicle for the investigation of motor recovery mechanisms. Using this combined method, we investigated the motor recovery mechanism in patients with pontine infarct. DESIGN: We evaluated six healthy control subjects and two patients with pontine infarct at 6 months from onset. fMRI was performed at 1.5 T with timed hand grasp-release movements. For DTT, we used each of the 32 noncollinear diffusion-sensitizing gradients. Three-dimensional reconstructions of the fiber tracts were obtained with FA <0.3, angle >45 degrees as termination criteria. RESULTS: fMRI data revealed activation only in the contralateral primary sensorimotor cortex during movement of either hand. DTI findings from controls and the unaffected hemisphere of the patients showed that the corticospinal tract descended through the known corticospinal tract pathway. However, the tracts of the affected hemisphere in the patients were observed to pass along peri-infarct areas (patient 1: lateral, patient 2: posterior) in the pons. CONCLUSIONS: It seems that the peri-infarct areas compensate for corticospinal tract damage at the pons; this may be one mechanism of motor recovery for patients with pontine infarct.

Adult↗
PubMed2006

Paediatric cerebral venous thrombosis.

Cerebral venous thrombosis (CVT) in children is a multifactorial serious disease. It is being increasingly diagnosed, mainly because of more sensitive diagnostic procedures and increasing clinical awareness. The clinical manifestations can be life-threatening and cause long-term neurological deficits. Thromboembolism in children is a multifactorial disorder in which both genetic and acquired risk factors play a role. CVT occurs in various clinical settings, including infection, dehydration, renal failure, trauma, cancer and haematological disorder with multiple risk factors. Clinical manifestations of CSVT are nonspecific and may be subtle. Most of the clinical scenarios occur at all ages and the clinician should consider this diagnosis in a wide range of acute neurological presentations in childhood. CVT can have an extremely variable clinical presentation, mode of onset, imaging appearance and outcome. Its prognosis remains largely unpredictable. Diffusion and perfusion MRI may play a role in detecting venous congestion and CT or MR venography are now the methods of choice for investigation of cerebral venous thrombosis. The options for treatment of infants and children include standard or low molecular weight heparin for 7-10 days followed by oral anticoagulants for 3-6 months. Specific treatment with anticoagulation is controversial in children, but has been established as appropriate therapy in adults. Anticoagulant treatment with heparin is probably safe and beneficial for children with sinus thrombosis, even those with intracranial haemorrhages.

Age Factors↗
PubMed1991

[An autopsy case of multiple sclerosis with bilateral continuous cystic lesions along lateral ventricles and caudate-callosal angles (Wetterwinkel)].

A 47-year old female had a fever about 39 degrees C of unknown origin for 2 days. Soon she developed pain in the bilateral lower extremities followed by gait disturbance and vesicorectal disorder. Prednisolone was administered with an improvement. However, she developed paresthesia in the upper extremities 1 month later, and then gradually paraplegia another 5 month later. Nystagmus, painful tonic spasm, facial spasm, and visual disorder also appeared. These symptoms repeatedly exacerbated and remitted with administration of prednisolone. We examined this patient at age 53, CBC, blood chemistry, urinalysis, ECG and chest X-ray were normal. Serum IgG and IgA level were decreased. CSF protein content and IgG level were remarkably increased. EEG showed diffuse theta activities. MRI studies revealed high intensity signals in the putamen, deep frontal and periventricular white matter region. Pulse therapy of methylprednisolone was performed effectively for several times. She died of respiratory and heart failure 6 years after the onset. Autopsy revealed bilateral continuous cystic lesions along the lateral ventricles extending from the frontal tips of anterior horns to the occipital tips of posterior, and further, to the temporal tips of lateral horns; the caudate-callosal angeles (Wetterwinkel) were more severely and widely affected bilaterally. There were also old and fresh demyelinated lesions scattered in the cerebral white matter, brainstem, cerebellum, and spinal cord. Although this case is considered to have typical MS from clinical and pathological findings, there have been only a few reports of MS with such continuous cystic lesions in the cerebral hemispheres as seen in this case.

Brain Diseases↗
PubMed1989

Neuromyelitis optica in the elderly.

Acute transverse myelitis and monolateral optic neuritis developed within a few weeks of each other in a 68-year-old woman. CSF findings consisted of elevated protein, pleocytosis, increased IgG and presence of one oligoclonal band in the electrophoresis. MRI investigation revealed diffusely increased signal on the T2-weighted images in the cervical and thoracic tracts of the spinal cord. Notwithstanding an intense steroid therapy, the patient died after 6 weeks. Despite the absence of post-mortem examination, clinical, laboratory and neuroimaging findings are consistent with the diagnosis of neuromyelitis optica (NO) related to multiple sclerosis. This case serves to document that NO can occur initially at an advanced age.

Aged↗
PubMed1988

Pigmented villonodular synovitis. Diagnosis and differential diagnosis.

PVNS is a proliferative disorder that can affect joints, tendons and bursae. Its etiology is unknown. The most widely accepted theories attribute this disorder to a chronic inflammatory response or a benign neoplasm of fibrohistiocytic origin. On gross specimens, the synovial changes are characterized by villous and/or nodular hyperplasia. This disorder occurs most frequently in the third or fourth decades of life and has no sex predilection. As a joint problem, it favors the knee and hip. As a tendon abnormality, it favors the digits. Plain film findings include 1) soft tissue swelling, 2) increased density of the synovium secondary to hemosiderin deposition, 3) multiple subchondral cysts, and 4) extrinsic cortical pressure erosions. Cartilage space narrowing, if present, is gradual and occurs later than the other plain film findings. Arthrography can demonstrate the nodular synovial changes and determine if the process is diffuse or focal. MRI can, in some cases, reveal areas of decreased signal within the hyperplastic synovium reflecting the deposition of hemosiderin. The major roentgen differential diagnoses of articular PVNS include uncalcified synovial chondromatosis, tuberculous arthritis, and hemophilic arthropathy.

Bone Cysts↗
PubMed1994

[Klippel-Trenaunay syndrome and ischemic neurologic complications].

In 1900 Klippel and Trenaunay defined a new entity characterized by cutaneous angioma associated with varices and hypertrophy of bone and soft tissues. The syndrome is present in the earliest years and becomes accentuated as the child grows. It typically affects one half of the body. We report two cases of Klippel-Trenaunay syndrome. The first patient presented with flaccid paraplegia. On T1-weighted MRI sequences a diffuse heterogeneous high-intensity signal was visible opposite the T8 and T9 vertebral bodies. Spinal cord angiography showed occlusion of the anterior spinal artery issued from Adamkiewicz's artery, suggesting thrombosis. Serum fibrinopeptide A level was very high and compatible with hypercoagulability. The second patient presented with left hemiplegia caused by a right superficial sylvian artery infarct, and carotid angiography showed an image of right internal carotid artery dissection. These two cases suggest that Klippel-Trenaunay syndrome includes a state of hypercoagulability facilitating the occurrence of arterial thrombotic accidents, and an abnormality of the arterial wall capable of determining spontaneous dissection. A study of arterial wall-dependent coagulation factors should establish a link between these two aetiological factors. All this argues in favor of a diffuse vascular pathology, which makes this syndrome close to phakomatoses.

Adult↗
PubMed1993

[A case of chronic thinner intoxication developing hyperkinésie volitionnelle three years after stopping thinner abuse].

We reported a 25-year-old male with chronic thinner intoxication. He had been sniffing thinner from the age of 15 to 20. Since the age of 20, he developed gait disturbance, weakness of lower extremities, and scanning speech. At the age of 23, three years after he stopped sniffing thinner, he had hyperkinésie volitionnelle (HV) of bilateral upper extremities. MRI study revealed diffuse high intensity areas in the cerebral white matter, thinning of the corpus callosum, and cerebellar and brainstem atrophy on T1 weighted images. On T2 weighted images, low intensity areas in the thalamus, the striatum, the anterior limb of the internal capsule, the tegmentum of midbrain, high intensity areas in middle cerebellar peduncle, the posterior limb of the internal capsule, the lateral part of the cerebral peduncle, and the cerebral white matter were noted. HV almost disappeared with 2.5 mg of clonazepam daily administered. The disappearance of HV by ischemic compression of his arm suggested that input from the periphery might be relevant to the etiology of HV. The time interval between exposure to thinner and the recognition of HV in our case was in agreement with that between the occurrence of cerebrovascular disease and the recognition of HV in the previous reports. We postulated that HV in this case was the manifestation of the denervation hypersensitivity in the dentatorubroolivary system.

Adult↗
PubMed1995

[Results of magnetic resonance imaging in the acute phase of cerebral infarction].

Brain ischemia is now possible to trace through the multiple facets of MRI, morphological as well as functional. Experimental studies have been conducted for many years and clinical feasibility is reached. Although the initial decrease in blood flow does not influence morphological imaging, this early phase is shown with functional MRI, either with diffusion imaging or with cerebral blood volume imaging. The later is achieved either with the calculation of the integral of the first passage of a bolus of a diffusible paramagnetic agent or with the circulation of positive or negative blood pool contrast agents. This may serve to confirm an early diagnosis before inclusion in therapeutic trials. Immediate metabolic changes are reflected on phosphorus and proton spectroscopy achievable during the same session as imaging. This type of information may at this stage serve as a reference. It allows observation of the turnover of lactate over time in the lesion and the neuronal loss shown by decreased N-acetyl-aspartate. Edema, as a reaction to ischemia, builds up over time and has already been described for long as it modifies T1- and T2- weighted sequences. Similarly the breakdown of the blood-brain barrier is well known on conventional sequences because it produces contrast enhancement.

Acute Disease↗
PubMed1995

[Primary amyloidosis of bones. MRI aspects].

Primary systemic amyloidosis is a rare cause of vertebralcollapse. We describe a patient who presented multiplecollapsed vertebrae. Magnetic resonance imaging (MRI) demonstrated a diffuse bone marrow abnormality. A diffuse low signal throughout the vertebral bodies on T1 and T2 weighted spin-echo images were observed. A bone biopsy confirmed the suspected diagnosis of vertebral involvementby amyloid. MR imaging can be of interest to evaluate the bone spreading of a known amyloidosis and to help in the diagnosis of amyloidosis in the case of non traumatical vertebral fractures.

Amyloidosis↗
PubMed1997

[Folic acid deficiency with leukoencephalopathy and chronic axonal neuropathy of sensory predominance].

A 44-year-old, alcoholic, woman developed a prolonged folate deficiency with a chronic predominantly axonal sensory polyneuropathy. The cerebral CT and MRI revealed a diffuse, clinically asymptomatic, leukoencephalopathy. A partial improvement of the neurological symptoms was observed after two months of oral administration of folate. Neurological complications of folate deficiency are rare and similar to those observed in cobalamin deficiency. Both cobalamin and folate deficiencies may interfere with the synthesis of the central myelin. This case report illustrates the possibility to observe a leukoencephalopathy due to folate deficiency, in association with the classical polyneuropathies and/or subacute combined degenerations of the spinal cord.

Adult↗
PubMed2005

Probabilistic anatomical connectivity derived from the microscopic persistent angular structure of cerebral tissue.

Recently developed methods to extract the persistent angular structure (PAS) of axonal fibre bundles from diffusion-weighted magnetic resonance imaging (MRI) data are applied to drive probabilistic fibre tracking, designed to provide estimates of anatomical cerebral connectivity. The behaviour of the PAS function in the presence of realistic data noise is modelled for a range of single and multiple fibre configurations. This allows probability density functions (PDFs) to be generated that are parametrized according to the anisotropy of individual fibre populations. The PDFs are incorporated in a probabilistic fibre-tracking method to allow the estimation of whole-brain maps of anatomical connection probability. These methods are applied in two exemplar experiments in the corticospinal tract to show that it is possible to connect the entire primary motor cortex (M1) when tracing from the cerebral peduncles, and that the reverse experiment of tracking from M1 successfully identifies high probability connection via the pyramidal tracts. Using the extracted PAS in probabilistic fibre tracking allows higher specificity and sensitivity than previously reported fibre tracking using diffusion-weighted MRI in the corticospinal tract.

Anisotropy↗
PubMed2005

Evaluation of a new Spin-echo diffusion-weighted sequence on a 0.35 T open magnetic resonance imaging (MRI)-system: first experiences within 3 h after acute stroke.

In acute stroke, diffusion-weighted magnetic resonance imaging helps to select patients who are eligible for thrombolysis, but is almost exclusively implemented on closed-bore scanners, which make monitoring of patients difficult. We developed and tested a cardiac gated Spin-echo diffusion-weighted sequence with prescan finetrim and motion correction on an open system with 0.35 T. Nineteen stroke patients appropriate for thrombolytic therapy by clinical criteria were enrolled in a prospective study on an intention-to-treat basis. In all but one patient, computed tomography and magnetic resonance imaging including the new diffusion-weighted sequence were performed within 3 h after symptom onset. Images were evaluated for acute cerebral ischemia and hemorrhage by two radiologists blinded to clinical information. Magnetic resonance imaging required a mean total acquisition time of 26 min. Sensitivity for early infarction was 94% in diffusion-weighted imaging and 73% in computed tomography. Six patients were excluded from thrombolysis due to an infarct size of more than 1/3 of the territory of the middle cerebral artery exclusively diagnosed with diffusion-weighted imaging. Hemorrhage was recognised by both, magnetic resonance imaging and computed tomography. We conclude that in acute stroke, diffusion-weighted imaging with an open system at 0.35 T is practicable. The implemented sequence reliably demonstrated the size of the infarction and improved the selection of patients who are eligible for thrombolysis.

Adult↗
PubMed2005

Motor recovery mechanism of diffuse axonal injury: a combined study of transcranial magnetic stimulation and functional MRI.

PURPOSE: The purpose of this study was to investigate the motor recovery mechanism following diffuse axonal injury (DAI) using transcranial magnetic stimulation (TMS) and functional MRI (fMRI). METHODS: Twenty-six hands of 13 control subjects and 14 affected hands of 8 patients (two hemiparetics and six quadriparetics) were evaluated. All the patients were initially diagnosed with DAI and were evaluated after they had reached their maximal motor recovery. fMRI was performed at 1.5 T using a hand grasp-release movement paradigm and TMS was applied with a round coil over the vertex. RESULTS: fMRI revealed that both normal subjects and patients with DAI showed increased contralateral primary sensori-motor cortex activation during affected hand movement. The motor evoked potentials (MEPs) of the patient group was slightly delayed in latency and significantly increased in duration and turns. The relative MEP amplitude, phase, and excitatory threshold were not significantly different between the groups. CONCLUSIONS: These findings may indicate the heterogeneity of the axons in the recovery process of the corticospinal tract. It seems that the motor recovery in patients who had suffered DAI was attributable to the recovery of the corticospinal tract.

Adult↗
PubMed2002

[Diffusion tensor analysis: principles and applications].

Diffusion tensor analysis represents a versatile yet powerful application of magnetic resonance imaging (MRI). Early applications of diffusion weighted imaging(DWI), especially those related to ischemic brain disease were quickly overshadowed by more advanced applications of DTA, namely, those dealing with anisotropy analysis. Considering the array of possibilities, from neuronal tract tracing to neuronal density imaging, DTA is rapidly becoming an indispensable tool not only in neuroscience but also in clinical investigations of the brain.

Brain↗
PubMed1999

An evaluation of the time dependence of the anisotropy of the water diffusion tensor in acute human ischemia.

We have performed MRI examinations to determine the water diffusion tensor in the brain of six patients who were admitted to the hospital within 12 h after the onset of cerebral ischemic symptoms. The examinations have been carried out immediately after admission, and thereafter at varying intervals up to 90 days post admission. Maps of the trace of the diffusion tensor, the fractional anisotropy and the lattice index, as well as maps of cerebral blood perfusion parameters, were generated to quantitatively assess the character of the water diffusion tensor in the infarcted area. In patients with significant perfusion deficits and substantial lesion volume changes, four of six cases, our measurements show a monotonic and significant decrease in the diffusion anisotropy within the ischemic lesion as a function of time. We propose that retrospective analysis of this quantity, in combination with brain tissue segmentation and cerebral perfusion maps, may be used in future studies to assess the severity of the ischemic event.

Anisotropy↗
PubMed2001

Diffusion-weighted mr in cerebral venous thrombosis.

The diagnosis of cerebral venous thrombosis is often difficult both clinically and radiologically and until now there is no method available to predict if brain lesions, detected clinically and using conventional brain imaging methods, may lead to full recovery, as expected in vasogenic edema or ischemic infarcts and even a hematoma. New fast neuroimaging techniques such as diffusion-weighted imaging (DWI) are sensitive to different reasons of changes in local tissular water concentration thus giving further insight into the pathophysiological mechanism as well as prognosis of cerebral venous thrombosis. We report the cases of 18 consecutive patients with a diagnosis of cerebral venous thrombosis based on clinical and imaging criteria. All patients underwent magnetic resonance imaging (MRI) of the brain, which comprised isotropic diffusion-weighted MR. Diffusion-weighted MRI showed positive findings in 17/18 cases. In 7 cases the clot could be directly visualized as an area of hyperintensity in the affected vein on DWI. In 7 cases DWI showed areas of signal loss corresponding to hematomas. In 6 cases DWI showed changes in signal intensity that were more subtle. In 4 cases of superficial venous thrombosis, there were areas of decreased ADC values (0.65-0.79 x 10(-3) mm(2)/s) whereas in 2 cases of deep venous thrombosis, increased DWI intensities could be found that corresponded to both an increase and a decrease in ADC, corresponding to a coexistence of cytotoxic and vasogenic edemas. Diffusion-weighted MRI can demonstrate directly the presence of an intravenous clot in a select number of patients. It can also demonstrate early ischemic changes, and can differentiate conventional T2-weighted MR areas of cytotoxic from vasogenic edema.

Adult↗
PubMed1997

The temporal evolution of MRI tissue signatures after transient middle cerebral artery occlusion in rat.

We have developed a multiparameter magnetic resonance imaging (MRI) cluster analysis model of acute ischemic stroke using T2 relaxation times and the diffusion coefficient of water (ADCw). To test the ability of this model to predict cerebral infarction, male Wistar rats (n = 7) were subjected to 2 h of transient middle cerebral artery (MCA) occlusion, and diffusion and T2 weighted MRI were performed on these rats before, during and up to 7 days after MCA occlusion. MRI tissue signatures, specified by values of ADCw and T2 were assigned to tissue histopathology. Significant correlations were obtained between MRI signatures at different time points and histopathologic measurements of lesion area obtained at 1 week. In addition, we compared the temporal evolution of MRI tissue signatures to a separate population of animals at which histological data were obtained at select times of reperfusion. A significant shift (p < or = 0.05) within signatures reflecting tissue histopathology was demonstrated as the ischemic lesion evolved over time. Our data suggest, that the MRI signatures are associated with the degree of ischemic cell damage. Thus, the tissue signature model may provide a noninvasive means to monitor the evolution of ischemic cell damage and to predict final outcome of ischemic cell damage.

Animals↗
PubMed2002

Iatrogenic Creutzfeldt-Jakob disease following human growth hormone therapy: case report.

We report the case of a 41-year-old man with iatrogenic Creutzfeldt-Jakob disease (CJD) acquired after the use of growth hormone (GH) obtained from a number of pituitary glands sourced from autopsy material. The incubation period of the disease (from the midpoint of treatment to the onset of clinical symptoms) was rather long (28 years). Besides the remarkable cerebellar and mental signs, the patient exhibited sleep disturbance (excessive somnolence) from the onset of the symptoms, with striking alteration of the sleep architecture documented by polysomnography. 14-3-3 protein was detected in the CSF, and MRI revealed increased signal intensity bilaterally in the striatum, being most evident in diffusion-weighted (DW-MRI) sequences. This is the second case of iatrogenic CJD associated with the use of GH reported in Brazil.

14-3-3 Proteins↗