Norman L. Chater

A SCANNING ELECTRON MICROSCOPY STUDY OF MICRO-ARTERIAL DAMAGE AND REPAIR

The effects of microvascular clamps on the femoral vessels of rats were studied, using the SEM. The early changes observed were (1) local fusiform dilatation of the area secondary to necrosis of the muscular wall, (2) flattening of the longitudinal ridges in the endothelial (3) loss of laminar flow, (4) endothelial sloughing, (5) platelet aggregation, and (6) leukocyte adherence and diapedesis. The repair of the endothelium occurred by an early replication of the adjacent undamaged endothelial cells -- with their subsequent migration across a platelet bed. The coverage was complete in one week, although reorientation of the neo-endothelial cells took longer. On the basis of this study and our clinical experience, we think the ideal microvascular clamp would possess the following characteristics: small size, light weight, mechanical simplicity, flat jaws (one to two mm in diameter) coated with a non-slip surface, and calibrated to produce a pressure less than 30 gm per mm2. In addition the clamp should be unaffected by blood, autoclaving, or repeated use. No such clamp is commercially available now, but we hope that one will be available in the near future.

Thumb replacement: Great toe transplantation by microvascular anastomosis

Abstract A successful microsurgical great toe to thumb transplant has been presented. The technique, problems and complications have been discussed.

Neurosurgical Extracranial-Intracranial Bypass for Stroke: With 400 Cases

An update of the current status of neurosurgical microvascular bypass for problems of cerebrovascular occlusive disease is presented. In 400 patients who have undergone operations by one surgeon, the results are encouraging in cases of transient ischemic attacks with hemodynamic lesions previously considered inoperable or inaccessible in the cerebral vasculature. The permanent neurological morbidity rate is 2% and the present operative mortality rate is 2.5%. The incidence of stroke to date on the side of a functioning bypass is 0.9% per year. Average follow-up is 55 months.

Successful replantation of two avulsed scalps by microvascular anastomoses.

Two cases of immediate replantation of avulsed scalps by microvascular anastomosis are presented. This method of treatment seems to offer significant economic, social, and psychological advantages over split-skin grafting of the calvarium, or other presently used treatments. The need for secondary reconstructive procedures after a successful replantation is minimal, or nil. The mechanism of scalping is reviewed, and it is related anatomically to the structure of the galea aponeurotica. Specific recommendations are made regarding the immediate care of the avulsed scalp and the denuded calvarium, the value of a team approach in replantation, and various technical aspects of the procedure and postoperative management. The more frequent use of interpositional vein grafts is urged.

IMPROVED PATENCY RATES IN MICROVASCULAR SURGERY WHEN USING MAGNESIUM SULFATE AND A SILICONE RUBBER VASCULAR CUFF

A new technique for microvascular anastomoses, using magnesium sulfate and a silicone rubber cuff, has been studied. Patency rates of 100 percent were achieved for anastomoses of small arteries and veins in rats. If small vessel anastomoses are to be used widely for the elective transplantation of composite tissue, high patency rates must be assured—and the described procedure may facilitate this achievement.

The Spectrum of Cerebrovascular Occlusive Disease Suitable for Microvascular Bypass Surgery

This work was supported in part by NINDS training Grant #5593 (Dr. Spetzler). From the Departments of Neurological Surgery and Radiology, Ralph K. Davies Medical Center, San Francisco, and the Department of Neurological Surgery, University of California School of Medicine, San Francisco. Address for reprints is: N. Chater, M.D., Microsurgical Unit, Ralph K. Davies Medical Center, San Francisco, California 94114. INTRODUCTION

Revascularization of the scalp by microsurgical techniques after complete avulsion.

A total scalp replantation was performed after a complete traumatic avulsion of the scalp with skull fracture. Multiple arterial and venous anastomoses were required. Satisfactory healing occurred, and the patient has had a subsequent uneventful cranioplasty to fill a bony defect, with normal scalp healing.

Microneurosurgical Arterial Bypass for Cerebral Ischemia: The San Francisco Experience

At the last Symposium on Extracranial-Intracranial Anastomoses for Cerebral Ischemia in 1976,16 our group presented our experience in a series of 140 patients6 harboring vascular lesions that were otherwise inoperable or inaccessible. We would like—as Dr. Chater has put it—to “pause again and reflect on what has been factually accomplished, what is encouraging at the present time, and what are the problem areas awaiting solutions”.

Augmentation of collateral hemispheric blood pressure following superficial temporal to middle cerebral artery anastomosis: documentation by ocular plethysmography

Ocular plethysmography (OPG) is a noninvasive technique that indirectly records systolic and diastolic pressures of the ophthalmic arteries. (1) In patients with total occlusion of the internal carotid artery (ICA) proximal to the origin of the ophthalmic artery, recording of ocular arterial pressure waves may provide an accurate estimate of collateral hemispheric blood pressure (CHBP) distal to the carotid occlusion. OPG was thus considered potentially valuable for documenting augmentation of CHBP following extra- to intracranical bypass.

Long-term patency of occipital artery-middle cerebral artery bypass demonstrated by angiography

An angiogram, performed on a patient who had had an occipital artery-middle cerebral artery bypass 7 1/2 years previously, showed that the bypass had remained patent and functional. Technical aspects of this operation are discussed. Support for the reliability of cerebral revascularization procedures is given.