In contmdistinction to the widespread use of imaging ultrasound in exmnining many other l'egions of the body, ultrasonography of the centralnervow; system has been seriously limited because high· frequency ultrasound dues not readily penetrate the bon y covering of this organ system. The difl'iculty in using ultrasound to visualize lm1in and spinal cord structm·es is a paradox in the history of medical ultr:•sonogmphy hecause much of the interest in the early days of this field of diagnostic imaging was in the central nervous system. ~lore than 30 years ago, French et a!. used A-mode s<:anning to localize il subcortical brain tumor in an e:\+ cised postmortem specimen. U! Advances in central nervous system ultrasonography have been made, however, in applic.ltions in which the skull or vertebral bodies have not impeded the pasage of ultrasound waves. There have been three pl'incipal areas of such applkations: postoperative scanning through craniectomy portals, : l .~ imaging through the fontanels of infants,5·6 and intraoperative ultrasonography.Operative use of imaging ultrasound for brain disease was first employed in the 1960s. ' :' "-II However, the A-mode scanning available then presented problems of interpretation which prevented widespread applkation of this dia~nostic tool. ~lore recent adnmces in ultrasound technology, particularly the development of high-resolution real-time B-mode scanners, have eliminated manv of the em~ lier difHculties in operative imaf,ting. This IHL'i re· suited in u renewed trial of ultrasonic scanning in various types of operations on the hrain 1 :2 -:H and spinal cord. ~. 2l iAs part of a pro~ra m to assess the utility of op· erative ultrasonography in a number of surgical dis· ciplines. we employed ultrasound imaging during brain and spinal cord surgery. \Ve have reviewed our experience of spedfic applications in terms of the impact of ultrasonography on management during opemtion. From this analysis we have de· termined the situations in which ultrasonograph~· during neurosurgery can be most helpful. This analvsis has enabled us to establish criteria for the most productive use of ultrasound during brain and spinal cord surgery and is the basis of this report. METHODSOperative ultrasonography during neurosurgical procedures was performed with real-time B-mode instruments employing mechanically driven sectorscanning transducers. High Stoy. Philips, and Dia-155

SUMMARY: Does the world need another ICA classification scheme? We believe so. The purpose of proposed angiography-driven classification is to optimize description of the carotid artery from the endovascular perspective. A review of existing, predominantly surgically-driven classifications is performed, and a new scheme, based on the study of NYU aneurysm angiographic and cross-sectional databases is proposed. Seven segments -cervical, petrous, cavernous, paraophthlamic, posterior communicating, choroidal, and terminus -are named. This nomenclature recognizes intrinsic uncertainty in precise angiographic and cross-sectional localization of aneurysms adjacent to the dural rings, regarding all lesions distal to the cavernous segment as potentially intradural. Rather than subdividing various transitional, ophthalmic, and hypophyseal aneurysm subtypes, as necessitated by their varied surgical approaches and risks, the proposed classification emphasizes their common endovascular treatment features, while recognizing that many complex, trans-segmental, and fusiform aneurysms not readily classifiable into presently available, saccular aneurysm-driven schemes, are being increasingly addressed by endovascular means. We believe this classification may find utility in standardizing nomenclature for outcome tracking, treatment trials and physician communication.

No abstract

Platelet deposition in the microcirculation may play a role in focal cerebral ischemia. We investigated platelet deposition in selected parts of the cat brain after temporary middle cerebral artery occlusion. Ten anesthesized cats were given autologous indium-lll-labeled platelets and chromium-51-labeled erythrocytes. The right middle cerebral artery was occluded with miniature aneurysm clips for 3 hours via a transorbital approach; blood pressure was reduced concomitantly to decrease the collateral circulation. Removal of the clips initiated a 45-minute period of normotensive reperfusion. After sacrifice, the brain was removed and sectioned for comparison of right-versus left-hemisphere platelet deposition. Platelets were selectively deposited in the territory of the occluded right middle cerebral artery. Significant deposition was found in the caudate nucleus, internal capsule, parietal cortex, and the centrum semiovale. Our findings support the evidence that platelets are deposited in the microvasculature during temporary severe focal cerebral ischemia. (Stroke 1989;20:664-667) P latelet deposition in the cerebral microcirculation may play a role in focal cerebral ischemia. Morphologic techniques failed to implicate erythrocytes in microcirculatory obstruction during focal cerebral ischemia.1 Few studies have focused on the role of platelets in microcirculatory changes during cerebral infarction.2 -5 No study has used an experimental model analogous to clinical focal cerebral ischemia.We undertook this study to evaluate platelet deposition induced by temporary occlusion of the right middle cerebral artery (MCA) followed by reperfusion in cats. Materials and MethodsBlood (30 ml) from adult cats was collected through a catheter inserted into the femoral vein with citrate-phosphate-dextrose (CP-NIH formulation) as the anticoagulant. Lactated Ringer's solution (20 ml) was administered intravenously to augment vascular volume. The blood was treated with 50 nmol prostaglandin E] to prevent platelet activation and was centrifuged at 280g for 20 minutes at 25° C to separate platelet-rich plasma from the erythrocytes. The platelets were pelleted by centrifugation at l,500g for 15 minutes, and the From the Departments of Neurosurgery (J.J.J., R.M., R.M.C.)