Pedro J. Barrionuevo

Early scanning electron microscopic evaluation of microvascular maneuvers.

The operating microscope was first used for anastomosis of vessels less than 3 mm. in diameter in 1960.14 Since then, microvascular surgery has played an important role in neurosurgery, as in other surgical specialties, particularly plastic and cardiac surgery.3, 6, ~o, 12, ~3, 17, ls, 22 Cerebral revascularization and small organ transplantation are among the current goals of microvascular surgery. Continued advances in equipment, (ultra-fine forceps and scissors), sutures (10-0 nylon) and technique have improved the percentage of successful anastomoses.4, 16 In spite of these advances, thrombosis of small caliber vessels continues to be a major problem for those performing microvascular anastomoses.

Acute cerebral revascularization following cerebral embolism.

From the of Neurological Surgery, University of Pittsburgh School of Medicine and the Veterans Administration Hospital, Pittsburgh, Pennsylvania, and from the Department of Neurological Surgery, University of California, Davis, Sacramento, California. Supported in part by a grant from the Alcoa Foundation and by a grant-in-aid from the Western Pennsylvania Heart Association. The disability and loss of life resulting from stroke continue to be significant. It has been estimated that thromboembolic cerebral infarcts will cause

The capacity for computed tomography diagnosis of cerebral infarction. An experimental study in the nonhuman primate.

The characteristic serial CT scan appearance of cerebral infarction created by embolization of the middle cerebral artery in the nonhuman primate (10 baboons) is defined. The earliest CT changes are noted by 12 to 24 hours and include generalized ventricular enlargement and a focal region of decreased absorption in the opercula-basal ganglia region. The area of diminished brain absorption is better circumscribed and of lower attenuation coefficient with increasing chronicity. Distinct hydrocephalus, unilateral exophthalmos and ventricular displacement occurred with increased intracranial pressure. Little additional diagnostic information was obtained via intravenous enhancement and care should be taken as mild enhancement may obscure an area of abnormality.

Experimental middle cerebral artery microsurgical embolectomy

SummaryThe canine middle cerebral has been embolized using the method of Molinari. Microsurgical embolectomies were done at two hours and six hours post-embolism. Animals done at two hours remained virtually intact neurologically, and hence fared better than control dogs whose embolus remained in place. Animals done six hours post embolism had increased neurologic morbidity and mortality as compared to the controls. Pathologic study revealed hemorrhagic infarctions in 50% of the animals done six hours post embolism.

Scanning electron microscopic anatomy of the supratentorial basal cisterns.

Arachnoid slips from the canine supratentorial basal cisterns were excised and studied by scanning electron microscopy. The inner face of the arachnoid membrane was examined, and two fundamental surface patterns, fenestrated and embossed, were observed. The remaining fibers and microfibers were anchored to these two surface sheets.

Effects of contrast media on the canine subarachnoid space.

This study reports an investigation of the canine arachnoid membrane using the scanning electronmicroscope (SEM) regarding the effects of contrast material on these structures. In the normal arachnoid membrane, two basic surface patterns were observed; one fenestrated and the other embossed with parallel fibers. Ventriculography was performed on 30 mongrel dogs divided into five groups: control, air, iophendylate, meglumine iothalamate, and Metrizamide. SEM study of the arachnoid membrane from basal cisterns showed no change after air ventriculography. After contrast agents were used, macrophages appeared and fenestrations became closed with a fibrin-like substance.

Staged middle cerebral artery embolectomy

Abstract Microsurgical MCA embolectomy in our experimental situation seems effective if done within 2 hr postembolism. Embolectomy delayed until 6 hr postembolism was significantly less effective, implying that irreversible, ischemic changes develop during these additional 4 hr. Additional canine MCA embolectomies will be staged at specific time intervals between 2 and 6 hr post-embolism, to determine the maximal time interval within which embolectomy may still be beneficial.

Cranial computed tomography in the baboon: normal anatomy.

A simple, reliable, reproducible technique for performing CT scans on baboons is described. The normal morphologic appearance in 12 nonhuman primate (Papio cynocephalusl anubis) brains as defined by CT is correlated with the normal gross pathologic findings on postmortem examination. The orbital contents are also displayed with clarity equivalent to that obtained in man.

Ophthalmologic applications of computed tomography in nonhuman primates.

The orbital contents of 28 baboons are defined by computed tomography (CT), which provides a simple, reliable, reproducible, and accurate technique for the experimental investigation of the orbit of the nonhuman primate. This method is applied to the diagnosis of exophthalmos. The suprasellar and other basal subarachnoid cisterns are precisely delineated using intrathecal enhancement prior to CT imaging (metrizamide CT cisternog-raphy).