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David G. Piepgras, Michael K. Morgan, Thoralf M. Sundt Jr., Takehiko Yanagihara and Lynn M. Mussman

✓ A series of 14 patients with intracerebral hemorrhage after carotid endarterectomy is reviewed. This complication occurred in 0.6% of 2362 consecutive carotid endarterectomies performed at the Mayo Clinic from 1972 through 1986. All hemorrhages occurred within the first 2 weeks after operation and were ipsilateral to the side of the operation. Eight patients died, and only two made a good recovery. Significant risk factors are hypertension and chronic hemispheric hypoperfusion with impaired autoregulation. The “normal pressure-hyperperfusion breakthrough” syndrome was considered to be operative in 12 of the 14 patients. Nine patients had documented hyperperfusion (at least 100% increase of baseline cerebral blood flow) at the time of surgery. In an additional three patients, normal perfusion-pressure breakthrough was inferred by the clinical course and radiological findings, as well as by the absence of alternative explanations. Patients at risk for postendarterectomy intracerebral hemorrhage include those who have a clinical history suggestive of hemodynamic cerebral ischemia, severe carotid stenosis with limited hemispheric collateral flow, and postendarterectomy hyperperfusion, as measured by intraoperative cerebral blood flow. To minimize the risk of hemorrhage in these patients, strict maintenance of blood pressure at normotensive or even relatively hypotensive levels during the intraoperative and early postoperative periods is advised.

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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., Bruce W. Pearson, David G. Piepgras, O. Wayne Houser and Bahram Mokri

✓ Results, complications, and operative techniques of the surgical management of 20 aneurysms of the distal extracranial internal carotid artery (ICA) in 19 patients are reviewed. The proximity of these aneurysms to the styloid process is not considered as a chance occurrence, and the possibility is raised that these lesions are related to trauma from that structure. False aneurysms from spontaneous dissections are believed to occur only in those dissections that begin distally; they are not found in dissections that begin proximally. Treatment was individualized and dependent upon: 1) the size and location of the aneurysm; 2) symptomatology; and 3) hemodynamic considerations based upon intraoperative cerebral blood flow (CBF) measurements determined from the clearance of xenon-133 injected into the ipsilateral ICA. Methods of treatment included: resection of the aneurysm with placement of an interposition saphenous vein graft in seven patients; resection of the aneurysm with end-to-end anastomosis of the ICA in five; ICA ligation in three; clipping of the aneurysm in one; and extracranial-to-intracranial bypass in four. One patient sustained a postoperative cerebral ischemic complication from embolization which resulted in a mild permanent impairment in right hand dexterity. There were no other cerebral ischemic complications in the group, largely attributable, it is thought, to the use of intraoperative CBF measurements and continuous electroencephalograms. Four patients had transient dysphagia from traction damage to the pharyngeal and superior laryngeal nerves, and one patient with preoperative difficulty in swallowing required a gastrostomy. Long-term results have been excellent. Use of the operating microscope facilitated the suturing of the distal anastomosis in cases in which the ICA was reconstructed by an interposition vein graft or end-to-end anastomosis.

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S. V. Ramana Reddy, William E. Karnes, Franklin Earnest IV and Thoralf M. Sundt Jr.

✓ A case of spontaneous vertebral arteriovenous fistula in association with fibromuscular dysplasia is reported. The patient presented with progressive cervical myelopathy and cervical bruit. The pathogenesis of the fistula development and the spinal cord symptoms is discussed. Symptoms subsided after obliteration of the fistula.

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Results and complications of surgical management of 809 intracranial aneurysms in 722 cases

Related and unrelated to grade of patient, type of aneurysm, and timing of surgery

Thoralf M. Sundt Jr., Shigeaki Kobayashi, Nicolee C. Fode and Jack P. Whisnant

✓ Data from 722 consecutive cases with intracranial aneurysms were stored in a computer and later retrieved for analysis. Results and complications (including preoperative death and morbidity) of the surgical management of these patients were correlated with the Botterell grade of the patient in individuals with a recent subarachnoid hemorrhage (SAH), with the type of aneurysm, and with the timing of the surgical procedure. Patients with no SAH within 30 days prior to hospital admission were classified as “no SAH.” Approximately 30% of all patients had sustained more than one hemorrhage. Death and morbidity rates prior to surgery in good-grade patients with a recent SAH exceeded the risk of surgery itself. Rebleeding was the primary cause for death and morbidity in Grade 1 patients: 3% of Grade 1 patients died from a recurrent hemorrhage and 7% deteriorated to a lower grade. Deterioration from ischemia produced by vasospasm related or unrelated to rebleeding exceeded the risks of rebleeding in Grade 2 patients. There was an operative morbidity of 2% and mortality of 2% in patients who were classified as Grade 1 at the time of surgery, but an overall management morbidity of 3% and mortality of 6% in patients who were in Grade 1 at the time of hospital admission. Early surgery in Grade 1 patients was not associated with an increased incidence of delayed ischemia postoperatively. In Grade 2 patients, the operative morbidity and mortality was 7% and 4%, respectively, and the management morbidity and mortality 16% and 11%, respectively. Early surgery in this group was associated with a high frequency of postoperative delayed ischemia (particularly in patients with more than one SAH). Epsilon-aminocaproic acid appeared to protect against a rebleed, but was associated with a higher incidence of postoperative pulmonary emboli. Intraoperative complications were related both to the size of the aneurysm and to its location. Repair of multiple aneurysms did not adversely affect the result. The surgical approach, the importance of using a self-retaining brain retractor, and the technical complications in these cases are discussed.

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Phyo Kim, Robert R. Lorenz, Thoralf M. Sundt Jr. and Paul M. Vanhoutte

✓ The purpose of this study was to determine the cause of the loss of endothelium-dependent relaxation observed in chronic cerebral vasospasm. A bioassay system was developed to measure the release of endothelium-derived relaxing factor (EDRF) from canine basilar arteries. Subarachnoid hemorrhage (SAH) was induced in dogs by two injections of autologous blood into the cisterna magna. Angiograms were performed on the 7th day after SAH to check the presence of chronic vasospasm. The animals were sacrificed on the 8th day, and in vitro experiments were performed on rings harvested from the basilar artery. These confirmed loss of endothelium-dependent relaxation in response to bradykinin and arginine vasopressin in the group with SAH. The basilar arteries were perfused with modified Krebs-Ringer solution. The perfusate was bioassayed with a ring of coronary artery without endothelium (bioassay ring). The release of the EDRF was detected by relaxation of the bioassay ring contracted with prostaglandin F2α. Arginine vasopressin and bradykinin added to the perfusate upstream of the basilar artery caused concentration-dependent release of the EDRF. The direct effect of these peptides on the smooth muscle of the bioassay ring was to cause contraction. The release of the EDRF was identical in basilar arteries from the control and the SAH groups. These results indicate that the release of the EDRF is not impaired during chronic vasospasm, and thus that the loss of the endothelium-dependent relaxation is due to a decreased transfer of the EDRF or a reduced responsiveness of the smooth muscle to the factor.

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John L. D. Atkinson, Thoralf M. Sundt Jr., O. Wayne Houser and Jack P. Whisnant

✓ A retrospective angiographic analysis was designed to extrapolate the frequency of angiographically defined asymptomatic intracranial aneurysms in the anterior circulation from a relatively unbiased clinical series. A total of 9295 angiograms were reviewed from January, 1980, to January, 1987, and, based on these, 278 patients with minimal bias for the presence of an aneurysm were selected. Three patients were found to have incidental aneurysms; thus, the angiographic frequency of patients with asymptomatic aneurysms in this series was 1%. This patient population is skewed toward the older age groups and probably over-represents the incidence of these aneurysms in the population at large. Comparing current subarachnoid hemorrhage statistics and the low frequency of asymptomatic aneurysms suggests that a larger percentage of these aneurysms than was previously thought subsequently rupture. This study contrasts sharply with previous reports quoting a high incidence of aneurysms, and significantly alters the concept and treatment of this disease.

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Thoralf M. Sundt Jr., David G. Piepgras, O. Wayne Houser and J. Keith Campbell

✓ The authors report their initial experience with the use of interposition saphenous vein grafts between the external carotid artery and the proximal posterior cerebral artery. The indications, results, and technical aspects of the operation are reviewed. All patients accepted for surgery were at high risk for a posterior circulation infarct, and all patients with ischemic symptomatology had continued to progress while on anticoagulant drugs or anti-platelet agents. Thus, all patients were at high risk, and 11 of the 14 patients operated on were confined to bed before surgery. Intraoperative graft flows varied from 35 to 170 ml/min, and postoperative graft flows ranged from 75 to 311 ml/min in the patent grafts. There were three early graft occlusions and two late graft occlusions; these all occurred in patients with relatively low flows at the time of surgery (40 ml/min or lower). Subdural hygroma was the next most frequent complication to graft occlusion. It was thought to be caused by the pulsating graft anastomosed to a major vessel through a small opening in the basal arachnoid, which provided a new path for cerebrospinal fluid flow in patients with a degree of preexisting atrophy. One patient with a large aneurysm in the posterior circulation underwent proximal intracranial clipping of the vertebral artery and bypass grafting simultaneously. There were seven excellent results and two good results in nine patients in whom the graft remained patent. In the five patients with graft occlusion, there were two minor strokes, two major strokes, and one death.