Cases reported "Cerebral Infarction"

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1/25. Adverse effect of dopamine agonist therapy in a patient with motor-intentional neglect.

    Studies in animals and humans report dopamine agonists can improve neglect. Because dopamine deficit reduces intention to act, it has been suspected the dopamine agonist bromocriptine would improve deficient hemispatial intention. Thus, the effect of bromocriptine on line bisection was examined in a patient with neglect and failure of the action-intention system. The 58-year-old patient had left-sided neglect from a right cerebral infarction involving both cortical and subcortical (striatal) structures. It was determined that neglect on a line bisection task was attributable to a motor-intentional bias by testing under congruous and incongruous video monitoring. Testing sessions were held before starting bromocriptine, on 20 mg/d, and after stopping bromocriptine. The patient's ipsilesional bias increased on bromocriptine, and improved when bromocriptine was stopped. bromocriptine may worsen neglect if putamenal receptors are damaged. dopamine agonists may activate the normal hemisphere, increasing an intentional bias. Clinicians using dopaminergic pharmacotherapy should assess patients for this possible adverse effect.
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2/25. A specific thrombin inhibitor (argatroban) ameliorated cerebral blood flow in the patients with acute cerebral infarction.

    Argatroban, one of the arginine derivatives, has been reported to have a safe and potent antithrombin action. This compound is active in several animal models of thrombosis and also has been shown to improve general neurological symptomatology, general subjective symptomatology and general daily behavior in the patients with acute thrombosis. This was considered to reflect remarkable improvement of microcirculation. No published clinical data, however, exist on the effect of argatroban on cerebral blood flow (CBF) change during acute stroke. Three patients with acute cerebral infarction were subjected to this study. Intravenous argatroban injection (2.5 mg/hr) was continued in 48 hours. Regional CBF (rCBF) was measured before and after injection of argatroban using Xe-CT method. Argatroban increased CBF not only in the injured side hemisphere or penumbra, but also contralateral side of lesion in the patients with acute cerebral infarction.
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3/25. Neuronal representation of object orientation.

    The dissociation between object identity and object orientation observed in six patients with brain damage, has been taken as evidence for a view-invariant model of object recognition. However, there was also some indication that these patients were not generally agnosic for object orientation but were able to gain access to at least some information about objects' canonical upright. We studied a new case (KB) with spared knowledge of object identity and impaired perception of object orientation using a forced choice paradigm to contrast directly the patient's ability to perceive objects' canonical upright vs non-upright orientations. We presented 2D-pictures of objects with unambiguous canonical upright orientations in four different orientations (0 degrees, -90 degrees, 90 degrees, 180 degrees ). KB showed no impairment in identifying letters, objects, animals, or faces irrespective of their given orientation. Also, her knowledge of upright orientation of stimuli was perfectly preserved. In sharp contrast, KB was not able to judge the orientation when the stimuli were presented in a non-upright orientation. The findings give further support for a distributed view-based representation of objects in which neurons become tuned to the features present in certain views of an object. Since we see more upright than inverted animals and familiar objects, the statistics of these images leads to a larger number of neurons tuned for objects in an upright orientation. We suppose that probably for this reason KB's knowledge of upright orientation was found to be more robust against neuronal damage than knowledge of other orientations.
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4/25. Preserved visual lexicosemantics in global aphasia: a right-hemisphere contribution?

    Extensive testing of a patient, GP, who encountered large-scale destruction of left-hemisphere (LH) language regions was undertaken in order to address several issues concerning the ability of nonperisylvian areas to extract meaning from printed words. Testing revealed recognition of superordinate boundaries of animals, tools, vegetables, fruit, clothes, and furniture. GP was able to distinguish proper names from other nouns and from nonwords. GP was also able to differentiate words representing living things from those denoting nonliving things. The extent of LH infarct resulting in a global impairment to phonological and syntactic processing suggests LH specificity for these functions but considerable right-hemisphere (RH) participation in visual lexicosemantic processing. The relative preservation of visual lexicosemantic abilities despite severe impairment to all aspects of phonological coding demonstrates the importance of the direct route to the meaning of single printed words.
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5/25. diffusion MRI in ischemic stroke compared to pathologically verified infarction.

    BACKGROUND: diffusion MRI abnormality correlates with pathology in animal ischemic stroke models. A combined retrospective and prospective analysis of consecutive patients over a 3-year period who had a clinical diagnosis of probable new ischemic stroke, underwent diffusion MRI, and were later studied at autopsy was performed. methods: Inclusion criteria for the retrospective analysis were 1) symptom onset within 14 days of presentation, 2) diffusion MRI within 28 days of symptom onset, and 3) autopsy within 16 weeks of symptom onset. patients with suspected further infarcts between MRI and autopsy were excluded. The locations of all areas of MRI abnormality were identified by a blinded neuroradiologist, and recent infarcts were identified by review of pathologic records and microscopic slides. RESULTS: Eleven patients were identified who fulfilled inclusion criteria, with 25 discrete pathologic infarcts. diffusion MRI abnormality corresponded to pathologically verified infarction in 23 cases, was present in two locations where no pathologic infarct was identified, and was absent in two locations where an infarct was present at autopsy. In two cases, despite clinical suspicion of acute ischemic stroke, no MRI abnormality or pathologic infarct was found. The sensitivity and specificity of diffusion MRI were 88.5% (95% CI, 69.9% to 97.6%) and 96.6% (95% CI, 91.5% to 99.1%). Accuracy was 95.1% (95% CI, 90.2% to 98%). Three further patients who died during the course of the retrospective analysis were studied prospectively, and are described separately. CONCLUSIONS: These findings suggest high accuracy of diffusion MRI for detection of ischemic infarction compared with pathologic examination.
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6/25. See-saw nystagmus and brainstem infarction: MRI findings.

    A patient with see-saw nystagmus had a lesion localized by magnetic resonance imaging (MRI) to the paramedian ventral midbrain with involvement of the right interstitial nucleus of Cajal. This the first MRI study of see-saw nystagmus associated with a presumed brainstem vascular event. Our findings support animal and human studies suggesting that dysfunction of the interstitial nucleus of Cajal or its connections is central in this disorder.
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7/25. Are some memory deficits unique to lesions of the mammillary bodies?

    The role of the mammillary bodies in human memory is still in debate. A recent model of human amnesia proposes similar functions for the mammillary bodies and the hippocampus. But the main evidence for this model comes from animal studies using the delayed non-matching to sample paradigm. We describe a patient who developed a severe memory impairment after surgical removal of a germinoma. Postsurgical high resolution MRI revealed bilaterally shrunken mammillary bodies and an infarct of the left mammillary body. There were no other relevant lesions. Neuropsychological testing showed mildly impaired frontal lobe functions (executive functions, working memory and word fluency), almost intact learning and recognition, but severely impaired free and delayed recall. Experimental investigations revealed a reduced but preserved release of proactive interference and a pronounced impairment of recency and source judgments. We conclude that the mammillary bodies do play a prominent role in human memory, although the role differs slightly from that of the hippocampus.
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8/25. Clonal human (hNT) neuron grafts for stroke therapy: neuropathology in a patient 27 months after implantation.

    Although grafted cells may be promising therapy for stroke, survival of implanted neural cells in the brains of stroke patients has never been documented. Human NT2N (hNT) neurons derived from the NTera2 (NT2) teratocarcinoma cell line were shown to remain postmitotic, retain a neuronal phenotype, survive >1 year in host rodent brains and ameliorate motor and cognitive impairments in animal models of ischemic stroke. Here we report the first postmortem brain findings of a phase I clinical stroke trial patient implanted with human hNT neurons adjacent to a lacunar infarct 27 months after surgery. Neurofilament immunoreactive neurons were identified in the graft site, fluorescent in situ hybridization revealed polyploidy in groups of cells at this site just like polyploid hNT neurons in vitro, and there was no evidence of a neoplasm. These findings indicate that implanted hNT neurons survive for >2 years in the human brain without deleterious effects.
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9/25. Is autotopoagnosia real? EC says yes. A case study.

    We report a case of pure autotopagnosia (AT) following a left subcortical vascular accident. The absence of any language disorder, general mental deterioration or other cognitive impairments in this patient allowed an in-depth study of AT. Several tests of body representation and object and animal representation, as well as tests assessing semantic skills were administered to verify current interpretations of AT. Results showed a clear-cut dissociation between defective performances in body representation tests and normal performances on tests involving other kinds of stimuli.The patient's performances were particularly defective on tests relying on visuo-spatial body representation, but her semantic and linguistic knowledge seemed to be spared. This dissociation between different aspects of body representation supports Sirigu et al.'s hypothesis that multiple, partially independent systems are involved in body knowledge. In agreement with this hypothesis, in the present patient AT seems be due to a deficit in a system that processes the structural properties and relative position of single body parts.The present results, reporting the first observation of a subject not affected by any cognitive impairment other than AT, strongly support the existence of a system specifically devoted to body representation.
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10/25. sleep and dream suppression following a lateral medullary infarct: a first-person account.

    consciousness can be studied only if subjective experience is documented and quantified, yet first-person accounts of the effects of brain injury on conscious experience are as rare as they are potentially useful. This report documents the alterations in waking, sleeping, and dreaming caused by a lateral medullary infarct. Total insomnia and the initial suppression of dreaming was followed by the gradual recovery of both functions. A visual hallucinosis during waking that was associated with the initial period of sleep and dream suppression is described in detail. Since the changes in sleep and their recovery are comparable to results of animal experiments, it can be concluded that damage to the medullary brain stem causes extreme but short-lived alterations in conscious state and that substantial recovery occurs even though the damage to the brain stem endures.
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