Cases reported "Cerebrovascular Disorders"

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1/14. Complete mutism after midbrain periaqueductal gray lesion.

    Several neurophysiological studies have highlighted the role of the midbrain periaqueductal gray matter (PAG) in the initiation of vocalization in various animal species, from frogs to primates. With regard to humans, only two cases of complete mutism following a lesion to the PAG have been reported so far. This article describes a new case of a patient (GM) who, following an ischemic lesion to the periaqueductal gray region of the midbrain, presented with complete and irreversible mutism, though her language comprehension functions and her non-verbal expression capacity were preserved. This clinical case provides evidence that in humans the PAG also acts as a link between different vocalization-eliciting external and internal stimuli (which reach the PAG from sensory and emotional structures) and the vocal-motor coordinating mechanisms in the lower brain stem.
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2/14. Neuroimaging in cerebrovascular disorders: measurement of cerebral physiology after stroke and assessment of stroke recovery.

    nuclear medicine imaging can play an important role in the diagnosis of stroke risk, the differential diagnosis of vascular and parenchymal cerebral abnormalities, and the understanding and management of poststroke recovery. Radionuclide brain-imaging methods can assess hemodynamic, vascular, and metabolic status before and after stroke. Several techniques, including vasodilatory stress imaging with regional cerebral blood flow (rCBF) single-photon emission computed tomography (SPECT), oxygen extraction methods with positron emission tomography (PET), and spectroscopic imaging with magnetic resonance spectroscopic imaging, offer ways to distinguish vascular from parenchymal dysfunction and to determine whether any observed abnormalities in cerebral blood flow are primary or secondary disease manifestations. The value of radionuclide imaging in assessing the efficacy of several interventional surgical procedures is presented. Data from several imaging modalities bearing on the controversial issue of luxury perfusion and reperfusion injury are analyzed, including some of the discrepancies between animal and human clinical data. Imaging evidence for white matter disease and microangiopathy is analyzed, including a quantitative rCBF pattern analysis that distinguishes between typical Alzheimer's disease and microangiopathy by using multivariate analysis of variance curve profile analysis, which shows results of significant differences in the circumferential cortical blood flow profiles at P =.01. Microangiopathy showed rCBF reduction in the frontal and frontotemporal regions as compared with the more typical reduction in posterior temporal-parietal rCBF diminution characteristic of Alzheimer's disease. Several functional neuroimaging approaches to the study of cerebral poststroke reorganization are analyzed in the context of 2 major models of recovery: the resolution of diaschisis and reorganization in spared brain. research on these issues is presented with SPECT, PET, magnetic resonance imaging, and magnetic resonance spectroscopy. Data show how standard structural magnetic resonance imaging, (99m)Tc hexamethylpropylene amine oxime SPECT, PET imaging, and magnetic resonance spectroscopy can be used to identify the extent of permanent damage versus penumbral and remote effects of a stroke. The results of the analysis of the pure-diaschisis model show a high correlation between the rCBF brain SPECT defect volume in the cortex and the magnetic resonance spectroscopic imaging (MRSI) change in the white matter. There is a statistically significant positive correlation between the 2 (P <.01; r(2) = 0.94). The increased creatine/N-acetyl aspartate and reduced rCBF are proposed to be due to an increase in the white matter creatine component due to diaschisis and the repair mechanisms associated with increased astrocytosis, in addition to a reduction of N-acetyl aspartate in diaschitic white matter. xenon-133 dynamic SPECT is shown to be a quantitative and sensitive measure of cerebrovascular status and hemodynamic constraints in both spared and affected brain, providing evidence for reorganization and cerebral plasticity. fluorine-18 PET and (31)P spectroscopic imaging data show reorganizational changes in the contralesional hemisphere after stroke. The phosphocreatine-adenosine triphosphate ratio in the contralesional hemisphere was 38% /- 17% higher than in the ipsilateral hemisphere. The phosphocreatine-adenosine triphosphate ratio was highly correlated (r = 0.88, P <.05) with increasing (18)F-fluorodeoxyglucose uptake. These results showed that there is a parallel change in glucose metabolism and high-energy phosphate metabolism associated with poststroke recovery that is proposed to be due to cerebral reorganization in the contralateral premotor cortex. The value of these results on rehabilitation strategy, including possible criteria for the use of facilitatory versus compensatory approaches, is analyzed.
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3/14. Effect of pyritinol on EEG and SSEP in comatose patients in the acute phase of intensive care therapy.

    The extent and duration of acute disturbances of consciousness depend on the severity and localization of the underlying cerebral dysfunction. The glasgow coma scale (GCS) permits a relevant statement to be made on the course and recovery tendency of functional damage patterns in cerebral, mesencephalic, and brain stem structures. Therapy is directed at exerting a beneficial effect on the disturbed cerebral metabolism by administration of centrally active substances and at utilizing the available reserve plasticity of the brain for any possible recovery of mental performance. The bioavailability and profile of action of pyritinol have been well documented in animal experiments. We have studied the question as to the extent to which the substance influences the depth of coma in patients receiving acute intensive care therapy, and how this can be objectified electrophysiologically in the form of a specific central effect on basal brain structures. In a phase-II pilot study over five days the acute effect of intravenous 60-min. administration of 1,000 mg pyritinol on the depth of coma, the central conduction time (CCT) and the primary complex amplitude (N20/P25) of the SSEP, and on vigilance behavior (spectral edge frequencies and power) was investigated for 90 minutes in each case under intensive-medical steady-state conditions in 10 comatose patients. Because of the differences in the underlying brain damage, the primary depth of coma, age (30-89 years), sex (two female, eight male), as well as previous treatment (surgery, conservative), the significance of the results could not be evaluated by confirmatory statistical analysis.(ABSTRACT TRUNCATED AT 250 WORDS)
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4/14. Lexical organization of nouns and verbs in the brain.

    The analysis of neuropsychological disorders of lexical processing has provided important clues about the general organization of the lexical system and the internal structure of the processing components. Reports of patients with selective dysfunction of specific semantic categories such as abstract versus concrete words, living things versus inanimate objects, animals, fruits and vegetables, proper names and so forth, support the hypothesis that the neural organization of the semantic processing component is organized in these categories. There are reports of selective dysfunction of the grammatical categories noun and verb, suggesting that a dimension of lexical organization is the grammatical class of words. But the results reported in these studies have not provided unambiguous evidence concerning two fundamental questions about the nature and the locus of this organization within the lexical system. Is the noun-verb distinction represented in the semantic or in the phonological and orthographic lexicons? Is grammatical-class knowledge represented independently of lexical forms or is it represented separately and redundantly within each modality-specific lexicon? Here we report the performance of two brain-damaged subjects with modality-specific deficits restricted principally (H.W.) or virtually only (S.J.D) to verbs in oral and written production, respectively. The contrasting performance suggests that grammatical-class distinctions are redundantly represented in the phonological and orthographic output lexical components.
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5/14. Intravascular microcatheter pressure monitoring: experimental results and early clinical evaluation.

    With the use of Tracker and Balt microcatheter systems, intravascular pressure measurements were obtained in an experimental animal model, establishing the reliability of mean blood pressure measurements from these microcatheter systems. In the experimental model, selective occlusion of branches of the external carotid artery with simultaneous pressure measurements showed significant and reproducible changes in intravascular pressures. Also, pharmacologic manipulation of the blood pressure with simultaneous microcatheter and 6-French catheter recordings demonstrated an accurate and linear response of the microcatheter systems to mean blood pressure as it varied from 30 to 130 mm Hg. Preliminary results in humans with vascular malformations yielded similar results. We studied two cases of brain arteriovenous malformations (AVMs), one sigmoid-transverse sinus dural AVM, and one brain arteriovenous fistula (AVF). In these four cases the pressure dropped substantially, approaching the level of the shunt. In the case of the brain AVF, pressures rose in the same vessel after embolization. In the case of the dural AVM, correlation of the venous pouch pressures and the angiographic appearance indicated that shunting was no longer present when the venous and arterial pressures equalized. This system can be of substantial benefit in the evaluation and therapy of these lesions, and may increase our understanding of the physiology of vascular malformations.
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6/14. Controversies concerning neonatal seizures.

    Five issues are discussed with respect to the diagnosis, etiology, treatment, prognosis, and pathogenesis of neonatal seizures. The presentation of a newborn with seizures represents a true emergency and frequently indicates significant neurologic dysfunction or damage to the immature nervous system. Despite the urgency to establish a diagnosis, several unique aspects of neonatal seizures impede prompt recognition. In addition, several etiologic possibilities may be associated with seizures. The efficacy of antiepileptic drugs and the prediction of outcome of patients with neonatal seizures are controversial. Experimental research in developing animals suggests both a selective vulnerability and resistance of the brains of immature animals subjected to neonatal seizures.
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7/14. Hypersexuality in stroke.

    Hyposexuality is a common problem in stroke patients. Some stroke patients, however, may present with hypersexuality. We report three stroke patients who demonstrated hypersexuality and deviant sexual behavior after stroke. Abnormal sexual behavior was noted by members of the stroke rehabilitation team while the patients were in hospital. Details of pre- and poststroke sexual activity were obtained from patients and their spouses. All three patients had temporal lobe lesions on computerized tomography, and all had a history of poststroke seizure activity. The 53-year-old man reported poststroke increase in libido and coital frequency with a tendency towards priapism. The two women (47 and 55 years old) exhibited deviant sexual behavior, mood changes, and hyperphagia. The exact cause of these behavior changes is unknown but they may be related to temporal lobe involvement. Hypersexuality has previously been reported in animals and in patients with temporal lobe seizures.
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8/14. Abnormal deposits of chromium in the pathological human brain.

    Three patients presented with encephalopathies: an undiagnosed degenerative disease of the brain, a degenerative cerebral disease in a patient with a myeloma but without a myelomatous deposit in the CNS and a malignant astrocytoma. Perivascular pallidal deposits (vascular siderosis) containing chromium, phosphorus and calcium plus sometimes traces of other elements were present in the three cases. Such deposits were present in the pallidal parenchyma and around vessels in the cerebellum in one case. calcium and phosphorus are always present in any CNS calcification but the presence of chromium has not been reported. chromium and its compounds (ingested, injected or inhaled) are toxic to humans and animals in trace doses. Approximately 900 cases of chromium intoxication have been reported and usually have had dermatological or pulmonary lesions (including cancer) but there is no report of involvement of the CNS. Sublethal doses of chromium nitrate injected intraperitoneally in rats and rabbits results in the presence of chromium in the brain. A thorough investigation was made to find the source of the chromium in these patients. chromium was found to be present in trace amounts in the radiological contrast agents administered to these patients and in the KCl replacement solution and in mylanta, an antacid, given to one case. The evidence that chromium induced pathological changes in these three brains is circumstantial but shows that chromium can penetrate the human brain. This study indicates that vascular siderosis found in the brains of the majority of middle-aged and elderly humans is not simply an anecdotal pathological curiosity, but that it can serve as a route of entry for toxic products into the brain.
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9/14. Loss of topographic memory with learning deficits.

    A case is reported in which a patient with a vascular accident involving the posterior portion of the minor hemisphere presented a topographic memory loss and also deficits in his ability to learn certain types of new material. The study of this case has led us to re-examine spatial functioning in light of both human and animal research. Based on clinical and experimental evidence we have proposed that a unitary interpretation can account for the various spatial deficits associated with posterior righ hemisphere lesions. We have also suggested that the establishment of a spatial map for orientation probably depends not only on posterior right hemisphere structures but also may require the participation of structures which are more specifically concerned with learning and memory, such as the hippocampus or at least the connections between the hippocampus and these structures.
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10/14. Neurogenic hypertension related to vascular compression of the lateral medulla.

    Neurogenic hypertension may be reproduced consistently in experimental animals, although its clinical significance is unclear. An ectatic loop of the posterior inferior cerebellar (pica) compressed the left vagus nerve root entry-exit zone in two patients with long-standing hypertension. When this loop was mobilized for occipital-pica bypass, the hypertension resolved. These observations suggest that neurovascular compression of the area encompassing the nucleus tractus solitarius may be a sufficient cause of neurogenic hypertension in humans. The structural and functional relationships of these areas of the brain stem and their role in modulating blood pressure are reviewed.
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