Cases reported "Brain Damage, Chronic"

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11/19. Complete neurological recovery after 13 minutes of hypovolemic hypotension.

    It has been shown experimentally that irreversible brain injury and death may follow after 5-7 min of cerebral ischemia and that even brief periods, 2 min or less, can produce focal damage to the nervous system. All published studies demonstrating a protective effect of barbiturates have been performed in animals. A patient is presented who recovered full neurological function after 13 min of hypovolemic hypotension. This remarkable outcome may have been due to the rapid institution of high-dose barbiturate therapy. The extent to which such therapy affected his outcome is unclear, but does add to the growing body of evidence suggesting a favorable effect from this type of barbiturate therapy.
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12/19. Case report. Computed tomography of the brain in severe hypoglycaemia.

    Computed tomographic (CT) findings in a case of extreme hypoglycaemia induced by an overdose of chlorpropamide are described. brain lesions tend to be preferentially localized along the boundary zones ("watersheds") between the territories of the main cerebral arteries. In our case, generalized brain damage occurred during severe hypoglycaemic coma. Neuropathological changes in this condition have been the subject of previous studies in experimental animals. Computed tomography allows follow-up studies of the human brain damaged by hypoglycaemic coma. Abnormalities revealed by CT probably represent reparative tissue reactions that indirectly reflect the extent of neuronal destruction.
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13/19. Are semantic systems separately represented in the brain? The case of living category impairment.

    Following herpes encephalitis, a patient showed impaired knowledge of animals, fruits and vegetables, flowers and food (so called living things categories), whatever the modality in which stimuli were presented and responses were given. A series of experiments showed that the deficit specifically affected the ability to retrieve the perceptual features of the living stimuli defining their shape, while knowledge of their functional-encyclopedic properties was preserved. The patient had no problems with man-made objects, except when the recall of their colour, or the identification of their sound was requested. It is argued that the retrieval of the perceptual features was potentially disrupted for every type of category, but that the block was compensated for man-made objects, because the close correspondence between shape and function that characterises them provided an alternative route to access their structured form representations. On this account, the selective deficit for living categories seems contingent on the interaction between an overall cognitive impairment--the deficit in retrieving perceptual features--and some intrinsic properties of the stimulus--the factors that have modelled its form--and cannot be taken as evidence that semantic systems are allotted to separate cerebral areas.
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14/19. Hypoxic-ischemic brain damage in the term infant. Lessons from the laboratory.

    Term infants who have sustained brain damage from intrauterine asphyxia can often be classified into one of two distinct clinical and radiologic syndromes. The first consists of damage to the cerebral hemispheres. The second consists of damage predominantly involving the basal ganglia and thalamus. Results of studies of asphyxia in experimental animals are presented.
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15/19. Post-ictal kluver-bucy syndrome after temporal lobectomy.

    In both animals and humans, kluver-bucy syndrome is produced by bilateral temporal lobectomy. It is characterised by hypersexuality, visual agnosia, strong oral tendencies, dietary changes, and hypermetamorphosis. Recurrent, postictal kluver-bucy syndrome occurred transiently after seizures in a female who had undergone unilateral temporal lobectomy. The pathophysiological mechanism may have been postictal dysfunction of the remaining temporal lobe, producing a transient functional bilateral temporal lobectomy.
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16/19. Naming without knowing and appearance without associations: evidence for constructive processes in semantic memory?

    This study describes a patient (SE) with temporal lobe injury resulting from herpes simplex encephalitis, who displayed a previously unreported impairment in which his knowledge of associative and functional attributes of animals was disproportionately impaired by comparison with his knowledge of their sensory attributes (including their visual properties and characteristic sounds). His knowledge of man-made objects was preserved. A striking aspect of the present case was that the patient remained able to name many animals from their pictures, despite making gross errors in generating associative information about these same animals. This suggests that a semantic representation incorporating stored sensory knowledge may be sufficient for naming (at least for biological categories) and associative information may be unnecessary. Semantic knowledge may normally incorporate more information than is necessary for identification. SE's errors were found to be confabulatory and reconstructive in nature and it is argued that this aspect of his performance challenges passive conceptions of semantic memory couched in terms of a catalogue of stored representations. It is proposed that the patient's disorder affects a dynamic, constructive, and inferential component of his knowledge base, and that this component is sensitive to semantic category.
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17/19. Charting the progression in semantic dementia: implications for the organisation of semantic memory.

    A patient, JL, with the syndrome of semantic dementia was assessed longitudinally over a two-year period. The data presented here address the controversy concerning the hierarchical organisation of semantic memory. On a range of category fluency tests, when first tested JL was just within the normal range on the broadest categories of animals and household items, but was virtually unable to produce any instances of specific categories such as breeds of dog or musical instruments. Longitudinal fluency data for the animal category demonstrate that while JL continued to produce the most prototypical responses (cat, dog, horse), other animal labels dropped out early from his vocabulary. On the picture-sorting tests from our semantic memory test battery, JL's discrimination between living things and man-made objects was preserved for a substantial time in conjunction with a marked decline in his sorting ability for more specific categories, particularly features or attributes (e.g. size, foreign-ness, or ferocity of animals). An analysis of naming responses to the 260 Snodgrass and Vanderwart pictures on four occasions suggests a progressive loss of the features of semantic representations that enable discrimination between specific category instances. There was a progressive decline in circumlocutory and category co-ordinate responses with a rise in broad superordinate and cross-category errors. The latter are of particular theoretical interest; on session I, all cross-category errors respected the living/man-made distinction, but by session IV almost half of such errors failed to respect this distinction. The emergence of category prototypes was another notable feature, particularly in the living domain: at one stage, land (or four-legged) animals were all named either cat, dog, or horse. By contrast, within the man-made domain, items were frequently described in terms of their broad use or function, until eventually no defining features were produced. These findings are discussed in the context of competing theories of semantic organisation.
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18/19. Deficits in delayed memory following cerebral malaria: a case study.

    Cerebral malaria is a common disease, but there have not been any reports or investigations of long-term neurological or neuropsychological outcome. We present a case in which severe deficits in delayed memory and naming ability are observed 10 years after the patient contracted cerebral malaria. Neuropsychological testing and medical imaging are both consistent with temporal lobe/hippocampal dysfunction, which corroborates earlier animal research that cerebral malaria is particularly likely to lead to interrupted blood circulation in this area.
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19/19. Neuropharmacologic treatment of hemineglect: a case report comparing bromocriptine and methylphenidate.

    Individuals who have hemineglect fail to attend to stimuli presented on the side of the body contralateral to a brain lesion. Although in animal studies the severity of neglect correlates with the degree of dopamine depletion, in hemineglect patients dopamine-enhancing medications have produced inconsistent results. We present a case of hemineglect following a right cerebrovascular accident in a 68-year-old man treated consecutively with methylphenidate and bromocriptine. Tests sensitive to neglect were administered during treatment with methylphenidate, then after all medications had been discontinued, then when the patient was taking low and moderate doses of bromocriptine, and again after all medications had been discontinued for 4 and 26 days. methylphenidate was superior to no drug treatment. bromocriptine produced more improvement in neglect than methylphenidate. Although the patient showed an exacerbation of his neglect after withdrawal from methylphenidate, performance gains persisted after withdrawal from bromocriptine. Treatment effects appear related to medication choice, timing of drug treatment, and the adaptability of dopaminergic receptor systems.
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