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Atheromatous disease of the carotid artery

Correlation of angiographic, clinical, and surgical findings

O. Wayne Houser, Thoralf M. Sundt Jr., Colin B. Holman, Burton A. Sandok and Robert C. Burton

✓Angiograms of patients who underwent carotid artery surgery were correlated with the surgical findings, cerebral blood flow measurements, and the following manifestations of cerebral ischemia: amaurosis fugax, transient cerebral ischemia,small completed infarct, generalized cerebral ischemia, and progressing stroke. The degree of carotid stenosis and presence of ulcerating plaques and soft thrombi could be predicted accurately; tiny ulcerations were not angiographically identifiable in the presence of severe stenosis. Generalized cerebral ischemia corresponded closely with severe degrees of bilateral carotid stenosis or unilateral occlusion in conjunction with contralateral stenosis. Internal carotid to middle cerebral artery slow flow was found in many patients with a progressing stroke or an unstable neurological state. Retrograde ophthalmic flow was found frequently in symptomatic patients with high-grade stenotic lesions at the origin of the internal carotid artery. Localized alterations included small vessel occlusion, retrograde collateral flow, avascular areas, focal slow flow, and reactive hyperemia and were correlated with symptoms of focal cerebral ischemia.

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Thoralf M. Sundt Jr., Frank W. Sharbrough, Robert E. Anderson and John D. Michenfelder

✓ Ninety-three endarterectomies for carotid stenosis were monitored with cerebral blood flow (CBF) measurements, and 113 with both CBF measurements and a continuous electroencephalogram (EEG). Significant CBF increase occurred only when carotid endarterectomy was for a stenosis greater than 90%. A high correlation between CBF and EEG indicated when a shunt was required. To sustain a normal EEG, the CBF ascertained by the initial slope technique must be 18 ml/100 gm/min at an arterial carbon dioxide tension (PaCO2) of 40 torr. The degree of EEG change below this level during occlusion reflected the severity of reduced blood flow and was reversible with replacement of a shunt. The value and limitations of these monitoring techniques and a concept of ischemic tolerance and critical CBF are discussed.

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Mitchell R. Smigiel Jr. and Thoralf M. Sundt Jr.

✓The comparative effectiveness of isoproterenol (Isuprel), phentolamine (Regitine), and phenoxybenzamine (Dibenzyline) in modifying basilar arterial spasm induced by the topical application of arterial blood was studied in cats. None of these agents was effective in inhibiting initial peak constriction. Each reduced the duration of the vasospasm. The results indicate that both alpha-blockade and beta-stimulation can alter the course of blood-induced cerebral vasospasm.

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John R. Little, Thoralf M. Sundt Jr. and Frederick W. L. Kerr

✓ The sequential neuronal alterations that occur during the early phase of developing cortical infarction in the squirrel monkey were studied by light and electron microscopy. A technique used to select ischemic tissue based on spectrophotometry is described. Neuronal shrinkage, characterized by angularity, cytoplasmic eosinophilia, and nuclear pyknosis on light microscopy and by an increase in electron density of the cytoplasmic and nucleoplasmic matrix on electron microscopy, was the predominant reaction. The increased electron density of the cytoplasm and nucleoplasm suggested a diffuse alteration at the molecular level and the appearance of this abnormality between 3 and 6 hours corresponded with the development of an irreversible neurological deficit. In contrast, approximately 10% of the neurons became very swollen and pale. The pattern of perineuronal astrocytic alterations suggested that some form of interaction involving fluid transfer may exist between astrocyte and neuron and that shrinkage or swelling of neurons may depend in part upon the presence or absence of direct fluid exchange with astrocytes. Most terminal boutons became progressively shrunken and dense resembling the changes which occur in anterograde axonal degeneration. Swelling and fragmentation of large lysosomes occurred at 12 hours. Disruption of neural membranes was widespread by 24 hours and was more severe in swollen neurons.

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Thoralf M. Sundt Jr., Burton M. Onofrio and John Merideth

✓ Initial experience with intravenously administered isoproterenol and lidocaine hydrochloride in 14 patients with severe spasm from subarachnoid hemorrhage is summarized. All patients were actively deteriorating from progressive spasm without other major complications; 12 of 14 improved, and two died. The method of treatment, results, and rationale for this method of therapy are discussed.

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Clip-grafts for aneurysm and small vessel surgery.

Part 4: Relative application to various aneurysms and repair of anterior communicationg aneurysms using right-angle clip holder.

Thoralf M. Sundt Jr.

✓ Analysis of the use of the clip-graft for intracranial aneurysms indicates that the clip-graft is chiefly applicable to internal carotid and anterior communicating artery aneurysms. The development of the right-angle clip holder has extended its use to anterior communicating artery aneurysms that project posteriorly or superiorly. The dangers of dissection in the septal region are discussed. With few exceptions, the clip-graft is not applicable to the vertebrobasilar system or middle cerebral artery trifurcation aneurysms, although it has been used for aneurysms arising from the trunk of the latter vessel.

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Thoralf M. Sundt Jr., William C. Grant and Julio H. Garcia

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Clip-Grafts for Aneurysm and Small Vessel Surgery

Part 3: Clinical Experience in Intracranial Internal Carotid Artery Aneurysms

Thoralf M. Sundt Jr. and Francis Murphey

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Clip-Grafts for Aneurysm and Small Vessel Surgery

Part 1: Repair of Segmental Defects with Clip-Grafts; Laboratory Studies and Clinical Correlations

Thoralf M. Sundt Jr. and John D. Nofzinger