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1/28. Visualization of intravenously administered contrast material in the CSF on fluid-attenuated inversion-recovery MR images: an in vitro and animal-model investigation.

    BACKGROUND AND PURPOSE: The FLAIR (fluid-attenuated inversion-recovery) pulse sequence has been shown to be sensitive to abnormalities of the subarachnoid space. Our clinical experience led us to investigate whether intravenously injected contrast material can affect the appearance of the subarachnoid space on FLAIR MR images. methods: After noting unexplained high signal in the subarachnoid space on FLAIR images in a patient, we studied two dogs with sequential FLAIR MR imaging after i.v. administration of contrast material. A third dog was studied with a 6-hour delayed FLAIR sequence after triple-dose (0.3 mmol/kg) i.v. contrast administration. CSF was obtained from two animals for measurement of gadolinium concentration. A phantom was developed to determine the lowest concentration at which the effects of gadolinium were evident on FLAIR images in vitro. RESULTS: In all three animals, the appearance of the CSF in the ventricles or subarachnoid space was modified after administration of i.v. contrast. This was most evident on delayed images. The CSF samples showed a gadolinium concentration of 0.007 mmol/L in the dog who received the 0.1 mmol/kg dose and 0.02 mmol/L in the dog who received a triple dose. In our in vitro phantom experiments, gadolinium effects were evident on FLAIR images at a concentration four times lower than those on T1-weighted images. CONCLUSION: I.v. contrast material can cross into the CSF in sufficient concentration to alter the appearance of the subarachnoid space on FLAIR images in normal dogs. Although we encountered two patients with CNS disease in whom enhancement of the CSF was seen on postcontrast FLAIR images, additional investigation is needed in humans to determine whether enhancement may occur at triple dose in healthy subjects.
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2/28. Differential cognitive effects of colloid cysts in the third ventricle that spare or compromise the fornix.

    A series of twelve cases, all of whom had received surgery for the removal of a colloid cyst in the third ventricle, was examined on a series of memory tests. The only consistent predictor of poor memory performance that could be detected from MRIs was the presence of bilateral interruption of the fornix, which occurred in three of the subjects. Although these three cases were poor on tests of learning and recall, there was evidence that recognition was less impaired. The subjects were also tested on a set of recognition and concurrent discriminations that closely matched tests given to non-human primates. Clear parallels were found between the apparent effects of fornix damage in these clinical cases and those observed following more selective surgery in non-human primates. These findings not only indicate that fornix damage is sufficient to induce anterograde amnesia but also support the validity of recent animal tests that are thought to capture aspects of episodic memory.
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keywords = animal
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3/28. Is epilepsy a progressive disease? The neurobiological consequences of epilepsy.

    While primary, or idiopathic, epilepsies may exist, in the vast majority of cases epilepsy is a symptom of an underlying brain disease or injury. In these cases, it is difficult if not impossible to dissociate the consequences of epilepsy from the consequences of the underlying disease, the treatment of either the disease or the epilepsy, or the actual seizures themselves. Several cases of apparent complications of epilepsy are presented to illustrate the range of consequences encountered in clinical practice and the difficulty in assigning blame for progressive symptomatology in individual cases. Because of the difficulty in interpreting clinical material, many investigators have turned to epilepsy models in order to address the potential progressive consequences of recurrent seizures. The authors review experimental data, mainly from animal models, that illustrate short-, medium-, and long-term morphological and biochemical changes in the brain occurring after seizures, and attempt to relate these observations to the human condition.
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keywords = animal
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4/28. The influence of the pineal gland on migraine and cluster headaches and effects of treatment with picoTesla magnetic fields.

    For over half a century the generally accepted views on the pathogenesis of migraine were based on the theories of Harold Wolff implicating changes in cerebral vascular tone in the development of migraine. Recent studies, which are based on Leao's concept of spreading depression, favor primary neuronal injury with secondary involvement of the cerebral circulation. In contrast to migraine, the pathogenesis of cluster headache (CH) remains entirely elusive. Both migraine and CH are cyclical disorders which are characterised by spontaneous exacerbations and remissions, seasonal variability of symptoms, and a relationship to a variety of environmental trigger factors. CH in particular has a strong circadian and seasonal regularity. It is now well established that the pineal gland is an adaptive organ which maintains and regulates cerebral homeostasis by "fine tuning" biological rhythms through the mediation of melatonin. Since migraine and CH reflect abnormal adaptive responses to environmental influences resulting in heightened neurovascular reactivity, I propose that the pineal gland is a critical mediator in their pathogenesis. This novel hypothesis provides a framework for future research and development of new therapeutic modalities for these chronic headache syndromes. The successful treatment of a patient with an acute migraine attack with external magnetic fields, which acutely inhibit melatonin secretion in animals and humans, attests to the importance of the pineal gland in the pathogenesis of migraine headache.
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keywords = animal
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5/28. reflex blink to visual threat.

    The requisite visual modalities for the reflex blink to visual threat have not been thoroughly studied. We identified five patients with different focal cerebral lesions documented on computerized tomography scan who had abnormal blink-to-threat reflexes. One had a homonymous hemianopia secondary to posterior cerebral artery occlusion; another had a unilateral parietal neglect; and a third had a frontal neglect. They did not blink in response to visual stimuli contralateral to their lesion. A cortically blind patient and one with Balint's syndrome did not have a blink response. observation of these and other similar patients and animals previously reported suggests that the blink-to-threat reflex is cortically mediated and requires intact primary visual cortex as well as higher order mechanisms for visual attention mediated in the inferior parietal lobule and frontal eye fields.
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keywords = animal
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6/28. The space of senses: impaired crossmodal interactions in a patient with Balint syndrome after bilateral parietal damage.

    Balint syndrome after bilateral parietal damage involves a severe disturbance of space representation including impaired oculomotor behaviour, optic ataxia, and simultanagnosia. Binding of object features into a unique spatial representation can also be impaired. We report a patient with bilateral parietal lesions and Balint syndrome, showing severe spatial deficits in several visual tasks predominantly affecting the left hemispace. In particular, we tested whether a loss of spatial representation would affect crossmodal interactions between simultaneous visual and tactile events occurring at the same versus different locations. A tactile discrimination task, where spatially congruent or incongruent visual cues were delivered near the patient's hands, was used. Following stimulation of the left hand in the left side of space, we observed visuo-tactile interactions that were not modulated by spatially congruent conditions. In contrast, performance following stimulation of the right hand in the right side of space was affected in a spatially selective manner--facilitated for congruent stimuli and slowed for incongruent stimuli. To dissociate effects on somatotopic and spatiotopic coordinates, we crossed the patient's hands during unimodal tactile discriminations. Tactile performance of the left hand improved when it was positioned in the right hemispace, whereas placing the right hand in left space produced no significant changes, suggesting that left-sided tactile inputs are coded with respect to a combination of limb- and trunk-centred coordinates. These data converge with recent findings in animals and healthy humans to indicate a critical role of the posterior parietal cortex in multimodal spatial integration, and in the fusion of different coordinates into a unified representation of space.
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keywords = animal
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7/28. Fatal cerebral phaeohyphomycosis due to Curvularia lunata in an immunocompetent patient.

    Curvularia infections in humans are relatively uncommon despite the ubiquitous presence of this soil-dwelling dematiaceous fungus in the environment. Originally thought to be solely a pathogen of plants, Curvularia has been described as a pathogen of humans and animals in the last half-century, causing respiratory tract, cutaneous, and corneal infections. Only three previous cases of central nervous system involvement by Curvularia have been documented in the medical literature. We report a fatal case of cerebral Curvularia infection in which there was no known history of immunocompromise or prior respiratory tract or sinus infection in the patient.
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keywords = animal
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8/28. Category-specific naming and comprehension impairment: a double dissociation.

    We describe 2 neurologically impaired patients with lesions involving primarily the left temporal lobe, whose production and comprehension of words in the semantic category of animals were disproportionately spared in 1 case and disproportionately impaired in the other, in comparison to performance with other common categories. This double dissociation provides neurally based evidence for the view that lexical-semantic information is organized categorically.
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keywords = animal
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9/28. neurocysticercosis in panama: preliminary epidemiologic study in the Azuero region.

    neurocysticercosis was not been reported from panama until 1984. The first documented case was a 5-year-old male who lived with his family in a typical subsistence agriculture environment lacking all sanitary amenities. Pigs and other animals ranged freely in and around the home. This report concerns clinical studies of the patient and his family conducted 4 years later. The index case had neurologic sequelae and was strongly seropositive. A cerebral CT scan revealed multiple intracerebral calcifications. Three family members had antibody to cysticercus detected by immunoblot assay. A 7-year-old seropositive sister had an intracerebral calcification detected by CT scan. All 6 family members had completely normal neurologic examinations.
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ranking = 0.16666666666667
keywords = animal
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10/28. Reversible encephalopathy and seizures as a result of conventional vincristine administration.

    An 8-year-old child with acute lymphoblastic leukemia (ALL) developed seizures associated with bilateral lucencies on CT scan during standard induction therapy with vincristine and prednisone. Because of the progressive nature of her symptoms, a brain biopsy was performed and revealed neurotubular dissociation, which, in experimental animal models, is characteristic of vincristine toxicity. All other causes of encephalopathy have been ruled out. The drug was withheld and the clinical symptoms and findings resolved. The occurrence of unusual and severe neurologic side effects during the course of conventional induction therapy for childhood ALL warrants careful evaluation for evidence of vincristine toxicity.
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keywords = animal
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