Leo N. Hopkins

Extracranial-intracranial arterial bypass in the treatment of aneurysms of the carotid and middle cerebral arteries.

Eleven patients with lesions of the internal carotid and middle cerebral arteries that could not be treated by direct approach are presented. Major vessel occlusion was chosen as definitive therapy. Prophylactic extracranial-intracranial bypass was employed in an attempt to reduce the incidence of ischemic complications. Emphasis is placed on complications, from which several important lessons were learned. Our best results occurred in patients with carotid artery lesions treated with bypass and immediate internal carotid ligation. We believe this to be an effective and safe mode of therapy in cases in which direct approach is not feasible. The low risk and high potential benefit of prophylactic bypass justifies its use before major vessel occlusion in selected cases.

Carotid cavernous fistula and false aneurysm of the cavernous carotid artery: complications of transsphenoidal surgery.

Injury to the cavernous internal carotid artery is an unusual and serious complication of transsphenoidal surgery. Two such patients with injury to the carotid artery, referred for endovascular treatment, are reported. The clinical course and successful treatment of these patients, one with an intracavernous false aneurysm and one with a carotid cavernous fistula, are described. A review of these vascular complications of transsphenoidal surgery is presented.

Occipital artery to posterior inferior cerebellar artery bypass for vertebrobasilar ischemia.

Fourteen patients who underwent occipital to posterior inferior cerebellar arterial bypass are reviewed. All of the patients were treated for severe vertebrobasilar ischemia secondary to lesions of the distal vertebral artery. There was no operative death or permanent postoperative morbidity. On follow-up evaluation (averaging 13 months after operation), there has been 100% graft patency and a noticeable improvement in the neurological function in all patients. Operating with the patient in the prone position and avoiding intraoperative hypotension help to minimize the operative morbidity from this procedure.

The microsurgical anatomy of the basilar artery bifurcation.

The vascular microsurgical anatomy in the area of the basilar artery bifurcation is described in 30 autopsy dissections. Particular emphasis is placed on variations of the posterior thalamoperforators and their relation to the proximal posterior cerebral artery and basilar bifurcation.

A Novel Intravascular Drug Delivery Method Using Endothelial Biotinylation and Avidin-Biotin Binding

In this study, a novel intravascular drug delivery system was developed in which a drug injected from a catheter was fixed to the vasculature of the targeted tissue. Cellular proteins of viable endothelial cells were first biotinylated directly by biotinylation reagents, and then bound by an avidinated drug or, using avidin as a linker, a biotinylated drug. In the initial experiments, we studied in vitro the biotinylation of cultured bovine aortic endothelial cells (BAECs) by applying biotinylation reagents (NHS-LC-biotin or sulfo-NHS-LC-biotin) onto the washed intact BAEC monolayers and showed that the amount of biotin bound to the cells depended on the concentration of the biotinylation reagents applied. The cell-bound biotin decreased with time after the biotinylation. When fluorescein-labeled avidin (FITC-avidin) was applied to the biotinylated BAEC monolayers, the FITC-avidin readily bound to the cells. An LDH-release assay showed that sulfo-NHS-LC-biotin was only slightly cytotoxic to the BAECs and a colony formation assay showed only slight adverse effects of the reagent. In vivo studies were carried out on the renal arteries of normal rabbits. A solution of NHS-LC-biotin was injected through a catheter to one kidney to biotinylate its vasculature and the vehicle to the other as control, followed by a perfusion with saline. Finally, a solution of FITC-avidin was injected to both kidneys that were then reperfused with the blood flow following the withdrawal of the catheters. In the histological sections, more than 85% of glomeruli was stained with fluorescein in the biotinylated kidney, whereas no glomeruli were stained in the control. In the kidneys harvested 2 days after the same procedure, most glomeruli were still brightly stained. In the final experiment, biotinylated kidneys were injected with a solution of avidin, followed by a solution of fluorescein-biotin. Control kidneys had no prior biotinylation but received the same injections of avidin and fluorescein-biotin as above. More than 80% of glomeruli were stained in the biotinylated kidneys but none in the controls. This indicated that biotinylated drugs can be anchored to the biotinylated vasculature through avidin without being flushed away by blood flows. No apparent adverse effect was found in the functions of biotinylated kidneys. We propose that this drug delivery system is feasible for the treatment of some pathological conditions of blood vessels such as microvascular proliferation in malignant tumors and for continuous drug delivery in certain target organs.

Ring formation on computerized tomography in the postoperative patient

Ring formation with contrast infusion in computerized tomography has been described with various entities. The current report demonstrates its appearance in three postoperative patients from whom cerebral tumors had been removed. These examples of postoperative ring formation are compared with the ring formation in the scan of an unoperated patient with an intracerebral hematoma.