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Biomedical subjects

A Torvik

Publications and source records attributed to A Torvik.

100 records · Page 6Linked to original sources
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Toxicity of metrizamide and meglumine iocarmate in the spinal subarachnoid space. An experimental study in rats with special reference to long-term effects.

The toxic effects of metrizamide, a new non-ionic contrast medium, and of meglumine iocarmate (Dimer-X), were investigated after injection into the spinal subarachnoid space of rats. Convulsions were seen in 8 of 11 animals with meglumine iocarmate. No such irritative effects seen with metrizamide. Histologic examiniation of the spinal cord was carried out here 4 months. No changes were seen which could be ascribed to toxic effects of the contrast media.

Animals↗
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Two types of brain lesions in Wernicke's encephalopathy.

Analysis of 46 cases of Wernicke's encephalopathy showed that the pathological processes in the thalamus and inferior olives were clearly different from those in the mammillary bodies and the subependymal structures along the third and fourth ventricles and the aqueduct. The latter regions showed a progressive destruction of the neuropil with severe endothelial swelling and a definite sparing of the neurones. In the thalamus and inferior olives, by contrast, the reverse picture was found with neuronal disintegration, sparing of the neuropil, and a mild endothelial swelling. The disintegrating neurones in the thalamus and olives resembled those seen in anoxic necrosis. However, careful comparisons indicated a gradual drop out of the neurones in Wernicke's encephalopathy in contrast to the sudden and simultaneous affection of the neurones in anoxia. Furthermore, the nuclear structure of the affected neurones was better and longer preserved in the Wernicke lesions. The disintegrating neurones in Wernicke's disease were removed by neuronophagia and, in severe cases, the process led to a widespread neuronal loss in the thalamus and olives. The two types of histological processes largely paralleled each other in time and severity and it is suggested that they had the same aetiology.

Adult↗
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Neuropathological diagnoses in elderly patients in Oslo: Alzheimer's disease, Lewy body disease, vascular lesions.

Neuropathological changes in elderly residents of Oslo, Norway were characterised with respect to the cerebral substrates of dementia. Ninety-two brains were examined, representing 41% of all deaths occurring in 10 nursing homes during a 9-month period. The autopsy cohort showed a similar mean age (85 years) and sex ratio (73% female) and proportion of demented patients (75%) compared to all the patients resident in these homes who died during the same period. Clinical data was compiled retrospectively. Diagnosis was made using the CERAD protocol, and criteria for the diagnosis of Lewy body dementia. Lewy body formation was present in 20% and cerebral infarction in 21% of patients. In the demented group (69 patients) 90% fulfilled CERAD criteria for definite or probable Alzheimer's disease. Eight demented cases had absent neocortical neurofibrillary tangles and 6 other cases showed Lewy body dementia (9% of demented patients). A further 8 of these demented cases had brain stem Lewy bodies with only minimal cortical involvement. Thirteen cases (19% of the sample) had cerebral infarcts but these were considered to be clinically significant in only 4 (6%). In the non-demented patients (23) 4 patients had brain stem Lewy bodies and 6 had cerebral infarcts. Despite inclusion criteria biased towards the collection of Alzheimer's disease and normal patients, both Lewy body dementia (7%) and cerebral infarcts contributing to dementia (6%) were frequent.

Aged↗
PubMedDate not supplied

Changes in frequency of cerebrovascular diseases in Oslo, Norway, 1958-1977. An autopsy study.

The frequency of lethal stroke was examined over a 20-year period in a large collection of autopsy material and was compared with the official mortality statistics for the same period. The frequency of lethal stroke in the autopsy material was calculated as a percentage of the total number of autopsied patients in the corresponding age groups. The frequency of strokes found in mortality statistics was calculated as a percentage of all deaths in the corresponding age groups. In the autopsy material the over-all stroke frequency fell by 14 percent. For patients between 40 and 69 years the decline was 25 percent while for patients over 70 years only a minor drop was observed. The most marked decline was 25 percent while for patients over 70 years only a minor drop was observed. The most marked decline was found for intracerebral hemorrhage which decreased by 70 percent in patients between 40 and 69 and by 33 percent for those over 70. For brain infarction the decline was 32 percent in the youngest age group while patients over 70 showed no decrease at all. MOrtality statistics showed a steady decline in the frequency of stroke death and the overall figures in the 2 sources were similar. Figures fo the stroke sub-groups (brain infarction and intracranial hemorrhage) were markedly different from those found in the autopsy records. Frequency of hemorrhage was several times greater than that of infarction in mortality statistics while the reverse was true in the autopsy records. The sources of error are discusses for both materials. It is concluded that the over-all figures for stroke deaths are largely reliable for both autopsy records and mortality statistics. In the mortality statistics the separate figures for hemorrhages and infarction were not correct and long term changes in frequency of these conditions would be interpreted with caution. The figures from the autopsy material are considered to be more reliable and it is concluded that the decline in hemorrhage and infarction described is real.

Adult↗
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How often are brain infarcts caused by hypotensive episodes?

Of 135 patients who were resuscitated after cardiac arrest and who died from one day to several weeks later with morphological signs of systemic cerebral anoxia, there were seven patients (5.2%) with brain infarcts probably caused by hypotensive episodes during or after the resuscitation. There was almost no increase in the frequency of recent brain infarcts with an increasing degree of cerebral atherosclerosis (P greater than 0.90). In contrast, the distribution of ten old brain infarcts in the same material showed a significant correlation to the degree of cerebral atherosclerosis (P less than 0.05). The findings suggest that the combination of cerebral atherosclerotic stenoses and hypotensive is not a major cause of brain infarcts in elderly people. It is suggested that the risk of precipitating brain infarcts by lowering BP in hypertensive patients is not much greater in atherosclerotic than in nonatherosclerotic subjects.

Aged↗
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Auditory evoked brainstem responses (ABR) in coma due to severe head trauma.

Auditory evoked brainstem responses (ABR) were recorded in 11 comatose patients suffering from severe head trauma. The recordings were performed while the patients were being cared for in the neurosurgical intensive care unit. The ABR results, together with the clinical laboratory data, were correlated to the outcome for the patients. In 6 patients who died of their brain injuries, complete autopsies together with transverse cutting of the brainstem were performed in order to chart the extent of the brainstem lesions. Our findings suggest that the ABR test is a reliable diagnostic tool for predicting the outcome of patients comatose as a result of head trauma. The interpretation of the ABR results in cases suspected of brain death is discussed in the light of an illustrative case report.

Brain Death↗
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Trimethyltin poisoning: report of a case with postmortem examination.

A 48-year old woman died six days after intake of an unknown amount of trimethyltin (TMT). Early clinical features were tinnitus, lightheadedness, aggression and episodes of unresponsiveness. She gradually developed coma and died of multiorgan failure. The main pathologic findings were confined to the nervous system which revealed generalized chromatolysis of the neurons in the brain, spinal cord and spinal ganglia. Recent neuronal necrosis, which probably was caused by toxic effect of TMT, was present in the fascia dentata of the hippocampus and in the spinal ganglia. Recent necrosis was also present in the pyramidal cell layer of the hippocampus, cerebral cortex, basal ganglia and Purkinje cell layer of the cerebellum, but some of these changes could have been caused by an anoxic episode shortly before death. Electron microscopy revealed marked accumulation of lysosomal dense bodies and disorganization of the granular endoplasmic reticulum in the neurons. The findings were similar to those described in experimental TMT intoxications. Cytoplasmic zebra bodies, which were described in a previous human case of TMT intoxication, were not observed in the present case.

Autopsy↗
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Topographic distribution and severity of brain lesions in Wernicke's encephalopathy.

The distribution and severity of the brain lesions were studied in 45 cases (age range: 26-84 years) of Wernicke's encephalopathy. The process was acute or subacute (active) in 24 cases and chronic (inactive) in 21. Cases with acute and subacute disease had more extensive and severe lesions than the chronic ones. The majority of the acute cases had lesions involving the mammillary bodies and thalamus and the subependymal structures along the third and fourth ventricles and the aqueduct. Only three acute cases had lesions restricted to the mammillary bodies. Among the chronic cases, the majority of the lesions were restricted to the mammillary bodies and the thalamus. Only two lesions extended as far down as the inferior collicles. Eleven out of 21 chronic cases has isolated lesions of the mammillary bodies. The affection of the mammillary bodies in chronic cases varied from barely visible to subtotal destruction of the tissue. Similarly, the lesions in the thalamus varied from slight gliosis in the dorsomedial nucleus to extensive nerve cell loss in several nuclei. There were similar variations in the severity of the clinical picture. Memory loss was recorded in three cases with isolated lesions of the mammillary bodies.

Acute Disease↗