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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Focal brain ischemia was induced by middle cerebral artery occlusion in the rat. The volume of cerebral damage was determined 2 days later by MRI in vivo and in the same animals histologically. The edema volume as measured by MRI and the histologically determined infarction was highly correlated. As a consequence, the neuroprotective effect of the N-methyl-D-aspartate (NMDA) receptor antagonists CGP 40116 and MK 801 were similar with both methods. Excitotoxic neurodegeneration in the rat striatum was induced by direct injection of quinolinic acid. The degree of damage was evaluated in vivo 1 day later by quantitative MRI, and 7 days later by measuring the activities of neuronal marker enzymes choline acetyltransferase and glutamic acid decarboxylase. Striatal damage assessed using the three approaches was highly correlated. Cerebroprotective efficacy of the NMDA receptor antagonist CGP 40116 was indistinguishable based on all methods. MRI was more reproducible than the enzymatic methods and was faster and simpler than histologic examination for routine analysis of excitotoxic damage and cerebroprotection in vivo in a pharmaceutical research environment.
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PMID:Application of magnetic resonance imaging to the measurement of neurodegeneration in rat brain: MRI data correlate strongly with histology and enzymatic analysis. 136 Oct 20

Two patients who postoperatively developed extensive multiseptated hydrosyringomyelia following surgical repair of a lumbal meningomyelocele are reported. Since MRI has been available, an increasing number of reports showed that MRI is useful in the diagnosis of hydrosyringomyelia. Hydrosyringomyelia can be considered as a dysraphic lesion. Etiology and pathogenesis of hydrosyringomyelia are still not fully understood. Probably arachnoidal adhesions and cord tethering in both patients may be potential factors in producing cystic degeneration of the underlying structure secondary to ischemia.
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PMID:Magnetic resonance imaging of progressive hydrosyringomyelia in two patients with meningomyelocele. 145 50

We present two patients with clinical features of infarction in the distribution of the anterior inferior cerebellar artery (AICA) who had vertigo as an isolated symptom for several months prior to infarction. Both had risk factors for cerebrovascular disease and other episodes of transient neurologic symptoms not associated with vertigo. At the time of infarction they developed vertigo, unilateral hearing loss, tinnitus, facial numbness, and hemiataxia. MRI identified hyperintense lesions in the lateral pons and middle cerebellar peduncle on T2-weighted images. Audiometry and electronystagmography documented absent auditory and vestibular function on the affected side. Since the blood supply to the inner ear and the vestibulocochlear nerve arises from AICA, a combination of peripheral and central symptoms and signs is characteristic of the AICA infarction syndrome. The vertigo that preceded infarction may have resulted from transient ischemia to the inner ear or the vestibular nerve.
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PMID:Vertigo and the anterior inferior cerebellar artery syndrome. 146 78

In 20 patients with an angiographically documented coronary artery stenosis of > or = 70% and normal LV function at rest MRI was performed before and after dipyridamole infusion (0.75 mg/kg BW). In all patients MIBI-SPECT was obtained at rest and after dynamic symptom-limited exercise. In 18 patients MIBI-SPECT showed ischemia and in 18 patients dipyridamole MRI showed a wall motion impairment. In the segments representing the 29 stenosed vessels ischemia in MIBI-SPECT was diagnosed correctly in 24 instances (sensitivity 83%, specificity 90%) and a wall motion abnormality was present in MRI in 23 instances (sensitivity 79%, specificity 90%). Dipyridamole GE-MRI is not superior to MIBI-SPECT in the diagnosis of ischemia.
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PMID:[Effort-induced myocardial wall motion abnormalities in the magnetic resonance tomogram: a comparison with effort MIBI SPECT]. 146 52

Forty-six migraineurs and 69 age- and sex-matched controls referred for MRI scans of the brain were evaluated for the incidence of intracranial pathology. Axial long TR/short TE and long TR/long TE and sagittal short TR/short TE scans were performed in all patients. Enhancement with Gd-DTPA was performed in all controls and in nine migraineurs. Six of 46 (13%) of the migraineurs had white matter lesions versus three of 69 (4.3%) of the controls. The white matter lesions in migraineurs were seen in a younger age group than in the controls. These findings agree with recent MRI studies. Ischemia or an immune-based white matter demyelination are possible mechanisms for the white matter lesions.
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PMID:MRI in migraineurs. 146 10

The present study was undertaken to characterize the formation of ischemic brain edema using diffusion-weighted and T2-weighted magnetic resonance imaging in a rat model of focal ischemia. The extent of edema formation was measured from multislice diffusion-weighted and T2-weighted spin-echo images acquired at various times after ischemia. The spin-spin relaxation time (T2) and the apparent diffusion coefficient in normal and ischemic tissue were also determined. The results show that on the diffusion-weighted images the lesion was clearly visible at 30 minutes after ischemia, while on the T2-weighted images it became increasingly evident after 2-3 hours. On both types of images the hyperintense area increased in size over the first 48 hours. After 1 week the hyperintensity on the diffusion-weighted images rapidly disappeared and evolved as a hypointense lesion in the chronic phase. These results confirm the high sensitivity of diffusion-weighted MRI for the detection of early ischemia. The temporal course of the edema observed on T2W-images is in agreement with the reported increase of total water content occurring in this model. The increase of the lesion observed on the diffusion-weighted images during the first 2 days points to an aggravation of cytotoxic edema that parallels the changes in free water shown by the T2-weighted images. It is shown that the highly elevated T2's of the infarcted area several days after ischemia can substantially contaminate the diffusion-weighted images.
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PMID:Temporal evolution of focal cerebral ischemia in the rat assessed by T2-weighted and diffusion-weighted magnetic resonance imaging. 148 46

The eigenimage filter was used to evaluate the results of a MRI study of cerebral ischemia in a rat model. This linear filter segments a desired feature in an image sequence from other features which may interfere with its observation. The animals were imaged temporally, after occlusion of the middle cerebral artery, to investigate the evolution of the ischemic process. The temporal evolution of ischemia was evaluated by analysis of the "eigenimages," calculated T2 and T1 map images, and images for the angles between signature vectors defined in the eigenimage technique. The eigenimages and angle map images demonstrated an improved visibility of the lesion at all time points, as compared to the original images and T2 and T1 map images. The eigenimages also demonstrated signal intensity changes within the area of ischemia. These changes are speculated to be related to variations in local cerebral blood flow resulting in varying degrees of tissue damage. The eigenimage intensities and the angles between signature vectors demonstrated time-related changes similar to the T2 and T1 values. Since the eigenimage filter and angle calculations are not dependent upon physical models (like T2 and T1), and the errors associated with these models, they may be preferable as methods for tissue characterization.
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PMID:Analysis of the evolution of focal cerebral ischemia in the rat using the eigenimage filter. 151 50

The authors report 2 cases of unilateral cerebellar atrophia presenting in the neonatal period with facial peripheral palsy and iso-immune thrombocytopenia respectively. The recognition of cerebellar atrophia has been made by MRI. Unilateral cerebellar atrophia be due to ischemia. MRI seems to be a useful tool in the recognition of cerebellar malformations in the neonatal period.
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PMID:[Unilateral cerebellar atrophy in 2 newborn infants. Value of MRI]. 155 Apr 51

Neuroimaging with CT and MRI is a basis for decision making in individual head-injured patients and also provides a classification of patients according to severity of damage, patterns of injury, pathophysiologic mechanisms and prognosis. Such classifications can be based on the intracranial lesions identified: subdural, extradural, and intracerebral hematomas, contusions, and shearing lesions, or indirect indications of raised intracranial pressure and brain swelling: shift, obliteration of the third ventricle and basal cisterns, and signs of ischemia. The appropriate classification for early diagnosis and acute decision making may differ from the assessment of severity of damage, prognosis and late sequelae. Parallel systems of classification, suitable for these purposes, are proposed.
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PMID:Computed tomographic and magnetic resonance imaging classification of head injury. 158 13

Three cases of bilateral deafness with cytologically-demonstrated meningeal carcinomatosis are reported. The first patient, a 64-year old man, presented with bilateral deafness, gait disturbances, and bilateral facial paresis. The second patient, a 78-year-old man, had bilateral deafness, unsteady gait and fluctuations in consciousness. The last patient, a 69-year-old man, complained of bilateral deafness and severe headache, and presented with right facial paresis and left laterodeviation while walking. All three patients had abnormal cochleo-vestibular findings and brainstem auditory evoked responses (BAER) that suggested peripheral lesions with absent or very delayed I waves. The brain CT scans with an without contrast enhancement were entirely normal, and the diagnosis was established by lumbar puncture. From our own cases and a review of the literature, deafness in meningeal carcinomatosis may start unilaterally but becomes bilateral in less than a week. Vestibular disturbances may not be apparent, but they can be demonstrated in almost all cases. Facial paresis or plegia is also a very frequent finding. The destruction of the eighth and seventh cranial nerves is probably due to direct infiltration by neoplastic cells as well as to ischemia through compression of the nerve supplying vessels. The 3 cases presented here emphasize once again the important fact that meningeal carcinomatosis remains a cytological diagnosis, several lumbar punctures being sometimes necessary, and that cerebrospinal fluid studies cannot yet be supplanted by other diagnostic techniques like contrast-enhanced CT or MRI with gadolinium.
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PMID:[Bilateral deafness, an initial manifestation of meningeal carcinomatosis]. 160 23


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