CMRO2 and CBF by the oxygen-15 inhalation technique. Results in normal volunteers and cerebrovascular patients.

The oxygen-15 inhalation technique has been applied to the quantitation of regional CBF, CMRO2 and OER with positron emission tomography. The introduction of corrections for gamma-ray attenuation, and for recirculation, has allowed us to obtain values for CBF, CMRO2 and OER in close agreement with values obtained using other techniques. In 27 normal volunteers mean CMRO2 shows values ranging from 4.

Quantitative measurement of regional cerebral blood flow and oxygen metabolism in man using 15O and positron emission tomography: theory, procedure, and normal values.

A method is described for quantifying regional cerebral blood flow (rCBF), oxygen extraction (rOER), and oxygen utilization (rCMRO2) in man non-invasively, using inhaled 15O-labeled CO2 and O2 and positron emission tomography. The theoretical considerations and practical aspects are described. The results of rCBF, rCMRO2, and rOER for gray and white matter in normal volunteers are presented.

Regional cerebral oxygen utilization and blood flow in normal man using oxygen-15 and positron emission tomography.

Quantitative determination of regional cerebral blood flow (rCBF), regional cerebral oxygen utilization (rCMRO2) and regional oxygen extraction ratio (rOER) was performed in 11 normal volunteers by an oxygen 15 inhalation method and positron emission tomography. Regional values comparable with figures from the literature have been obtained. This non-invasive approach offers the possibility of a simultaneous quantitative evaluation of these physiological parameters in health and disease.

Regional impairment of cerebral oxidative metabolism in Parkinson's disease.

Twenty-two patients affected by idiopathic Parkinsonism were studied using the oxygen-15 inhalation technique. The production of labelled metabolic water was found to be decreased in the parietal cerebral cortex, indicating an impairment in oxidative metabolism. This metabolic defect was localised mainly to the parietal cortex of the affected hemispheres; in non-affected hemispheres of patients presenting with unilateral Parkinsonism, the uptake was normal.

Radioactive oxygen 15O studies in cerebral neoplasms.

Methods of diagnosis and anatomical localization of cerebral neoplasms have reached a high level of efficiency. A new method of studying cerebral circulation and metabolism by a simple noninvasive technique of steady-state imaging during the inhalation of radioactive oxygen and radioactive oxygen-labelled CO2 is described. The results of preliminary studies of a group of cerebral neoplasms of various histological types are presented and the implications discussed.

Circulatory and metabolic aspects of cerebral ischemia in experimental animals and in men.

In normal conditions, there is a precise link between regional metabolism and blood flow in the brain. In pathological states there may be an uncoupling between CBF and metabolism, due to many mechanisms. In particular, anaerobic glycolisis, membrane depolarization, and altered neurotransmitter release are relevant for the final damage of the tissue.

Non-invasive regional study of chronic cerebrovascular disorders using the oxygen-15 inhalation technique.

The regional cerebral metabolism-to-perfusion imbalance has been studied in the three main categories of cerebrovascular disorders in a chronic phase of the disease, using the non-invasive oxygen-15 inhalation technique. In patients presenting with a history of transient ischaemic attacks, regional defects in cerebral perfusion were greater than for the corresponding oxygen uptakes. Areas of relative ischaemia within which there was an enforced increase in the oxygen extraction ratio were highlighted.

Study of regional cerebral metabolism and blood flow relationships in man using the method of continuously inhaling oxygen-15 and oxygen-15 labelled carbon dioxide.

A new technique for assessing regional oxygen use and blood flow has been applied to a wide range of neurological patients. The method couples the brain's high metabolic demand for oxygen with a shortlived radioactive form of this metabolite, namely oxygen-15 (half life: 2.1 min).

Selective Activation of peripheral nerve fibre groups of different diameter by triangular shaped stimulus pulses.

1. The differential block of cutaneous nerve fibres has been achieved with a simple method of electrical stimulation, employing a single pair of active electrodes. 2.

Superior orbital fissure syndrome. Review of 130 cases.

Superior orbital fissure syndrome is a symptomatologic complex, consisting of retroorbital pain, paralysis of extraocular muscles, impairment of first trigeminal branches and frequent involvement of the optic nerve. From a review of 130 published cases including two personal observations, it appears that the clinical subdivisions and the several eponymic differentiations of this syndrome are unjustified on the basis of etiologic, therapeutic and prognostic elements. Only the presence--or absence--of optic signs may allow to hold the clinically useful distinction between the often 'benign' superior orbital fissure syndrome without optic nerve involvement, and the orbital apex syndrome where orbital exploration may be recommended.