Pial Microcirculalion in Subarachnoid Hemorrhage• Microsurgical and microscopic methods were employed in guinea pigs to expose, observe, and measure response characteristics of cerebral cortical pial microvessels and microcirculation to traumatic and nontraumatic experimental subarachnoid hemorrhage. Bleeding produced by vascular micropuncture was associated with a 44.3% arteriolar constriction. Topical application of homologous blood alone produced a 33.2% vasoconstriction. Observed microcirculatory flow characteristics subsequent to such microvascular changes were consistent with those known to be associated with cerebral cortical infarction. These changes could be prevented or reversed by topical application of the alpha adrenergic blocker, phenoxybenzamine. Topical pretreatment with the beta adrenergic blocker, propranolol, prevented blood-induced spasm, but did not reverse such spasm once it had been established. A chemo-mechanical mechanism is suggested as underlying the vasoconstriction associated with rupture of pial microvessels. It is thought that consideration of such microvascular characteristics, in conjunction with those known to be associated with larger intracranial vessels, adds to current knowledge of the pathophysiology of subarachnoid hemorrhage and may be extrapolated to bear future clinical import.Additional Key Words microvessels phenoxybenzamine propranolol image splitting vasospasm adrenergic blocker• It has been known for many years that rupture of intracranial aneurysms is associated with angiographically demonstrable cerebral vasospasm, 13 which can be confirmed visually at the operating table.2 Similar spasm has been noted in patients with traumatic subarachnoid hemorrhage, 46 and is seen less frequently with arteriovenous malformations and other disorders.2 It is clear, however, that blood experimentally introduced into the subarachnoid space by a variety of methods produces spasm of large intracranial arteries. "11 Vasospasm has been a deterrent to the surgical therapy of intracranial aneurysms, being associated with profound neurological deficits and death.1 ' 2t 12~17 Such a grave clinical problem has led to many laboratory investigations on the pathophysiology of blood-induced large vessel spasm.7 ' 9i "• 18~25 The regulation of blood supply to cerebral cortical tissue capillary beds is not exclusively a function of these large arteries, and is at least partially relegated to the precapillary resistance and distributing vessels of the pial microcirculation. systematically examine, by direct in vivo microscopy, pial microcirculatory changes in these states. MethodsForty-five young guinea pigs of both sexes, weighing 400 to 500 gm, were anesthetized with pentobarbital (40 mg per kilogram i.m.). The animals were usually not re-injected with pentobarbital after surgery, so that they were under light anesthesia at the time when their cerebral cortical vessels were studied. Using the Zeiss operating microscope a tracheostomy, right common carotid cannulation, and left pariet...

Three new cases of spinal cord compression due to vertebral hemangioma are reported. The clinical presentation, with spinal pain, radicular radiation, and paraparesis, is similar to that of primary lymphoma, metastatic tumor, and disc disease. If the characteristic plain film changes of vertical trabeculations and striations are present, the preoperative diagnosis is facilitated, but in the majority of cases these are not seen. In some instances, vertebral body or pedicle erosion is present. A myelographic epidural block will be seen on further study. Spinal arteriography can prove helpful. Surgical decompression results in marked neurological improvement if intervention takes place before the onset of complete paralysis. The authors recommend that the diagnosis of vertebral hemangioma be considered in the differential diagnosis of epidural spinal cord compression whenever considered in the differential diagnosis of epidural spinal cord compression whenever a primary malignant neoplasm cannot be identified.

The issue of informed consent at it relates to neurosurgical professional malpractice liability and litigation has been of concern for 20 years or more. The problem persists, and the subject has been addressed by providing patient education with full disclosure regarding neurosurgical procedures. In the process of imparting informed consent, the authors studied the effectiveness of specific neurosurgical health care teaching. One hundred six persons undergoing anterior cervical fusion or lumbar laminectomy were instructed by a neurosurgeon and clinical nurse specialist with a master's degree in neurosurgery. Written testing was performed in each case immediately after a formal teaching session before surgery. Questions were simple and covered only four general topics: 1) diagnosis and surgical techniques; 2) operative risks; 3) postoperative care; and 4) goals and benefits relating to surgery. The mean score on testing immediate retention of information revealed a 43.5% overall performance rate. When patients were tested approximately 6 weeks later, the score dropped to 38.4%. This was statistically significant (chi 2, P less than 0.05). The authors encourage the concept of patient education. The data in the current study, however, suggest that the reasonable and prudent neurosurgeon making a concerted effort at patient education, with the assistance of a professional educator, cannot necessarily expect accurate patient or family recall or comprehension. Fulfillment of the doctrine of informed consent by neurosurgeons may very well be mythical.