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David G. Piepgras, Thoralf M. Sundt Jr., Ashvin T. Ragoonwansi and Lorna Stevens

✓ A series of 280 cases of cerebral arteriovenous malformations (AVM's) treated surgically between June, 1970, and June, 1989, is reviewed with particular focus on the preoperative seizure history and follow-up seizure status. Follow-up evaluation (mean duration 7.5 years) was achieved in 98% of cases and was accomplished through re-examinations, telephone interviews, and written questionnaires. Overall, 89% of the surviving patients with a follow-up period of greater than 2 years were free of seizures at last examination.

Of the 280 patients in this series. 163 had experienced no seizures preoperatively. A recent follow-up study (with a minimum duration of 2 years or to death) was available in 157 of these 163 cases; 21 patients had died. Of the 136 surviving patients, only eight (6%) were having new ongoing seizures. In the 128 (94%) who had remained seizure-free, 73% were receiving no anticonvulsant agents while 27% were taking anticonvulsant prophylaxis. The 2-year minimum follow-up study in 110 of the 117 patients with preoperative seizures revealed that eight (7%) had died. Of the 102 surviving patients, 85 (83%) were seizure-free (with 48% no longer receiving anticonvulsant therapy), while 17 (17%) still suffered intermittent seizures. However, of these 17 patients, 13 reported their seizures to be improved compared to preoperatively; the seizures were the same in two patients and were worse in two patients.

An actuarial analysis was conducted comparing the life expectancy of patients following surgery for AVM's with the expected survival of a general white population of the same age and sex in the West Northcentral region of the United States. No statistically significant difference was found. There were seven perioperative deaths (three from cerebral hemorrhage, two from pulmonary emboli, and two from obstruction of venous drainage) and 22 deaths during the follow-up period. Of these 22 deaths, the cause was unknown in four patients, apparently unrelated to the AVM in 13, and directly or indirectly related to the patient's neurological condition prior to surgery or due to surgery performed for resection of the AVM in five.

There was a statistically significant relationship between the size and location of the AVM and the clinical presentation. Patients with small AVM's (< 3 cm) were more likely to present with hemorrhage whereas those with large AVM's were more likely to present with seizures.

Conclusions from this study are: 1) there is a low incidence of a new seizure disorder following surgery: 2) chances for resolution or control of a pre-existing seizure disorder are good: 3) although resolution of seizures or seizure control was achieved postoperatively in AVM's of all sizes, this benefit was highest in smaller as opposed to larger AVM's; and 4) ultimately, there is a good capacity for recovery from pre-existing neurological deficits or those resulting from surgery.

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Francis H. Tomlinson, Daniel A. Rüfenacht, Thoralf M. Sundt Jr., Douglas A. Nichols and Nicolee C. Fode

✓ Arteriovenous (AV) fistulas of cerebral and spinal arteries are characterized angiographically by an immediate AV transition without a capillary bed or “nidus” as occurs in AV malformations (AVM's). The clinical presentation, morphology, radiology, and treatment of 12 patients with cerebral AV fistulas and of 12 patients with spinal AV fistulas are reviewed. In the patients with cerebral lesions, headache and seizure disorders were the most common presentations followed by subarachnoid hemorrhage, cardiac failure, progressive neurological dysfunction, and incidental detection on prenatal ultrasound study. In patients with spinal AV fistulas, weakness and sensory disturbance in the lower extremities were the most frequent clinical presentations followed by back pain, disturbances of micturition, and grand mal seizure. The etiology of the symptom complex produced by AV fistulas in each of these locations differed, with venous hypertension being important in spinal cord lesions.

Of the patients with cerebral lesions, nine had a single AV fistula, one had two fistulas, and two had multiple fistulas. An AVM was observed in five patients with fistulas (two large, three small). Nine patients exhibited extramedullary AV fistulas of the spine, of whom eight had a single fistula and one had three fistulas; three patients had intramedullary spinal AV fistulas. An arterial aneurysm was found in association with two fistulas, one cerebral and one spinal. Venous ectasias or varices, frequently exhibiting mural calcification, were observed to be prominent in all AV fistulas involving cerebral arteries and in two involving spinal arteries. The location and size of the venous complexes reflected the diameter of the fistula. In addition to conventional imaging techniques (cerebral angiography, computerized tomography, and magnetic resonance (MR) imaging), MR angiography was a helpful adjunct in the evaluation of fistulas. Treatment strategies employed for AV fistulas in both locations included open surgical and endovascular procedures, frequently used in combination. A satisfactory outcome was observed in all patients.

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Fredric B. Meyer, David G. Piepgras, Thoralf M. Sundt Jr. and Takehiko Yanagihara

✓ Twenty cases treated with emergency embolectomy for acute occlusion of the middle cerebral artery were reviewed. There were 10 males and 10 females, with an average age of 55 years. The left middle cerebral artery was involved in 17 patients and the right in three. Flow was restored in 16 patients (75%). The embolus originated in the heart in seven, the carotid artery in seven, the aorta in three, an aneurysm in one, and an indeterminate source in two. It was technically most difficult to achieve patency with atheromatous emboli from the aorta. Two patients (10%) had an excellent result with no neurological deficit, five (25%) were left with a minimal deficit but were employable, seven (35%) had a fair result but were still independent and employable, four (20%) did poorly, and two (10%) died. Patients with an associated ipsilateral carotid artery occlusion did poorly. Collateral flow, as judged from preoperative angiograms, was the best predictor of outcome.

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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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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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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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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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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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Fredric B. Meyer, Robert E. Anderson, Tony L. Yaksh and Thoralf M. Sundt Jr.

✓ Intracellular brain pH, cortical blood flow, and electroencephalograms (EEG's) were recorded in severely and moderately ischemic regions in 10 control and 10 nimodipine-treated rabbits prior to and following major branch occlusion of the middle cerebral artery (MCA). Preocclusion cortical blood flow was 51 ml/100 gm/min and intracellular brain pH was 7.01 in both the control and the treated animals. After MCA occlusion, the severely ischemic regions in the control group showed initial and 4-hour postocclusion flows of 12.7 and 5.2 ml/100 gm/min with a brain pH of 6.64 and 6.08, respectively. In animals given nimodipine after MCA occlusion, blood flow increased from 10.5 to 18.8 ml/100 gm/min, with an associated elevation in intracellular brain pH from 6.57 to 6.91. Comparable findings were observed in areas of moderate ischemia. Improvements in cortical blood flow, intracellular brain pH, and EEG attenuations produced by nimodipine were all statistically significant. Inspection of the cortex revealed reversal of cortical pallor and small-vessel spasm following treatment with nimodipine. It is hypothesized that nimodipine exerts its effects through reversal of ischemia-induced secondary vasoconstriction, and that this drug may be an important adjunctive treatment for patients with focal cerebral ischemia.