Cerebral blood flow (CBF) and cerebrovascular reserve capacity (CRC) were measured by stable xenon computerized tomography (Xe-CT) and acetazolamide test in 15 patients with cerebrovascular disease before and after extracranial-intracranial (EC-IC) bypass surgery for minor stroke, reversible ischemic neurological deficit or transient ischemic attack. All had angiographically shown occlusive lesions of the major arterial trunk. In the present series, global analysis showed that the bypass did not increase the resting rCBF, but did increase the rCRC. We divided the patients into four groups according to the preoperative resting rCBF and rCRC. All 3 patients with normal resting rCBF and reduced rCRC showed postoperative improvement of rCRC. Of 6 patients with reduced CBF and reduced CRC, three had postoperative increase in resting CBF and four had increased CRC. One of two patients with reduced CBF and normal CRC showed only an increase in CRC. We propose that reduced CRC or reduced CBF with reduced CRC are criteria for selection of candidates for bypass surgery. We conclude that Xe-CT with the Diamox test is a useful and simple method for evaluating cerebral hemodynamics. Preoperative grouping with a combination of preoperative resting rCBF and preoperative rCRC is useful for predicting the effect of EC-IC bypass surgery.

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This report describes a study of brain stem blood flow (BBF) change under various grades of brain stem ischemia in a new experimental rat model. The main damage was caused by occlusion of the median and paramedian perforating arteries of the basilar artery. In this model, hyperperfusion was generally observed in cases of mild or moderate ischemia within 1 hr after recirculation and lasted for approximately 1 hr. During hyperperfusion, BBF increased to over 60 ml/100 g brain/min and was significantly greater than basal values (p <0.01). The fact that hyperperfusion was unobserved in some cases might be due to the degree of damage to the medulla oblongata. Hypoperfusion or lack of reflow phenomena was also followed by severe ischemia with remarkable hypotension. It is fairly clear from our results that the pattern of postischemic hyperperfusion is responsible for decreased oxygen availability in the brain stem and dysfunction of autoregulation. Acetazolamide reactivity was disturbed and had an inverse response during hyperperfusion. Such phenomena can be explained by paralytically dilated vessels due to ischemia. If BBF falls below a critical level, as we have seen, postischemic hyperperfusion may be induced with dysfunction of autoregulation and inverse acetazolamide reactivity due to vasoparalysis in the brain stem. brain stem ; ischemia ; recirculation ; blood flow ; rat Permanent and transient experimental ischemic models have recently been developed using various laboratory animals. Rats in particular have many advantages : a) They are relatively inexpensive even when a large number of experiments are necessary ; and b) The use of small brain ischemia models has become important as a result of the development of quantitative autoradiographic techniques for investigating cerebrovascular system function. Though there have been many supratentorial ischemic models using variety of techniques, there have been few involving the posterior fossae. This report describes a study of brain stem blood flow (BBF) change under various grades of brain stem ischemia in a

In 1960, Holtermüller and Wiedemann described chondrodystrophic hydrocephalus as Kleeblattschädel syndrome. In the present paper, we review 23 cases of this syndrome associated with hydrocephalus, including 2 cases of our own. Of these 23 cases, 8 involved communicating hydrocephalus and 15 non-communicating hydrocephalus. It has been speculated that the associated hydrocephalus results from basilar impression, compression of infratentorial structures, aqueductal stenosis in non-communicating hydrocephalus, and impairment of venous drainage and cerebral spinal fluid flow at the level of the constrictive cranial ring in communicating hydrocephalus. Our present cases also showed this cranial ring, as demonstrated by skull X-rays and computed tomography scans. Since cloverleaf skull syndrome often has other general anomalies, we consider the hydrocephalus in this syndrome to have causes associated with the osteocartilaginous system.

Deepening anesthesia from 0.5 to 1.0 MAC was maintained with no difference between the two agents during 4h of neurosurgery.