Articles: subarachnoid-hemorrhage.
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Early changes in intracranial pressure (ICP), ICP volume index, and resistance to absorption of cerebrospinal fluid induced by experimental subarachnoid hemorrhage were studied in cats. After SAH, the ICP was slightly elevated, and there was a decrease in the buffering capacity of the intracranial space and a sharp rise in outflow resistance. ⋯ It is suggested that the marked increase in ICP during blood infusion into the subarachnoid space is caused by intracranial volume loading and the simultaneous increase in cerebrospinal fluid outflow resistance. It is concluded that the reported relationship between increased cerebrospinal fluid outflow resistance and increased ICP supports the hypothesis of a strong increase in ICP during subarachnoid hemorrhage in human subjects.
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According to several studies, the amount of subarachnoid blood on the initial computed tomogram of patients with aneurysmal subarachnoid hemorrhage has predictive value with respect to infarction and outcome. Of several methods for assessing the amount of subarachnoid blood, none has been subjected to a study of interobserver agreement. ⋯ The Spearman rank correlation coefficients for the sum of the scores for subarachnoid and intraventricular blood were very high. Summed scores for extravasated blood are suitable as a baseline variable in follow-up studies of patients with subarachnoid hemorrhage.
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Comparative Study
Magnetic resonance imaging with aneurysmal subarachnoid hemorrhage: comparison with computed tomography scan.
Magnetic resonance studies of 27 consecutive preoperative and 33 postoperative patients with cerebral aneurysm and subarachnoid hemorrhage were reviewed. Magnetic resonance imaging using a 0.5- or 0.22-Tesla unit was at least as accurate as computed tomography scan for detection of acute subarachnoid hemorrhage. ⋯ Ischemic lesions, particularly fresh lesions caused by delayed cerebral vasospasm, were much better shown on magnetic resonance imaging than on computed tomography scan. Nonferromagnetic Sugita clips caused significant artifacts, but the area of artifacts was consistently smaller, and a reasonable evaluation of structures relatively closer to the clip was possible with magnetic resonance imaging rather than computed tomography scan.
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Case Reports
Traumatic rupture of intracranial vertebral artery due to hyperextension of the head: reports on three cases.
In three cases of fatal basal subarachnoid hemorrhage due to rupture of the normal intracranial vertebral artery, the ruptures appeared to have been caused by overstretching of the vertebral artery from traumatic hyperextension of the head. In the first case, that of a 31-year-old male pedestrian who, while intoxicated, had been hit from behind by a car, symmetrically located bilateral complete and incomplete tearing of the vertebral arteries was found. In both of the other two cases, involving women aged 37 and 51 found dead after receiving fist blows to the face while intoxicated, complete rupture of the vertebral artery was found. The blood alcohol concentrations of the three cases ranged from 1.6 to 1.7 mg/g at autopsy.
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The cerebrovascular response to CO2 was evaluated by measuring relative changes in blood flow velocity within the middle cerebral artery by transcranial Doppler ultrasonography during normo-, hypo-, and hypercapnia. In seven patients without subarachnoid hemorrhage (five with unruptured arteriovenous malformations and two with aneurysms), the CO2 vasoreactivity was tested on the side of the middle cerebral artery with normal flow velocities opposite the lesion. A baseline CO2 reactivity test was obtained in each patient and then repeated under constant intravenous infusion of nimodipine, 2 mg/hr. ⋯ Two months later, after full recovery from the subarachnoid hemorrhage and normalization of the velocities, a third measurement of CO2 reactivity was obtained as a baseline control. No significant effect of nimodipine on CO2 vasoreactivity could be demonstrated in any of the test periods. In the second week after a subarachnoid hemorrhage, a significant reduction of the cerebrovascular response to CO2 was found (P less than 0.005).