[Comparative results of 99mTc scintigraphy and computerized tomography after contrast injection in cerebral pathology (author's transl)]. / Résultats comparés de la scintigraphie isotopique au 99mTc et de la tomodensitométrie après injection du produit de contraste en pathologie cérébrale.

140 patients have been investigated by means of computerized tomography (CT) after contrast injection and radionuclide scan (RN scan). For patients with stroke (56 cases), RN uptake was more frequent (80%) at the 15th day of evolution, enhancement of hypodense images at CT reaches 100% at the 21st day. For the others pathologies (hematoma, tumors), the main difference between both examinations, was the volume of the lesions detected. RN uptake and CT enhancement both show the same blood brain barrier disturbance.

Cerebral blood flow and metabolism during etomidate anaesthesia in man.

The effects of etomidate on regional cerebral blood flow (rc.b.f.) and cerebral metabolic rate for oxygen (CMRo2) were studied in seven patients undergoing diagnostic carotid angiography. Following determination of baseline rc.b.f. while awake, the patients were anaesthetized with a single dose of etomidate 15 mg. Thereafter, an infusion of etomidate (2 or 3 mg min-1) was administered. Etomidate decreased both rc.b.f.10 (mean decrease 34%) and CMRo2 (mean decrease 45%). It was concluded that etomidate is a potent cerebral metabolic depressant. Furthermore, the cerebrovascular reactivity to carbon dioxide was maintained under etomidate anaesthesia.

Effects of a diazepam-fentanyl mixture on cerebral blood flow and oxygen consumption in man.

The effects of a mixture of diazepam and fentanyl on cerebral blood flow (c.b.f.) and cerebral metabolism of oxygen (CMRo2) were studied in eight normal subjects and 13 patients with organic brain disease. The coupling of flow and metabolism and the carbon dioxide responsiveness of the c.b.f. were studied also. In the normal subjects the injection of the mixture resulted in a significant decrease in c.b.f. (34%), and a similar decrease in CMRo2 (34.5%). The vasoreactivity of the brain to carbon dioxide was maintained. C.b.f. decreased in all patients with intracranial pathology.

[Pneumoencephalotomography under diaz-analgesia and narco-analgesia]. / Encéphalotomographie gazeuse sous diazanalgésie et narco-analgésie.

The authors reported 92 observations of anesthesia for gaseous encephalotomography interest the adult. The contrast produce is air. 49 under diazanalgesia and myoresolution. Diazepam, +Fentanyl, pancuronium bromide N2O to 60 p. 100. 25 under diazanalgesia and myoresolution. Diazepam, +Fentanyl, succinylcholine, N2O to 60 p. 100. 18 under narco-analgesia and myoresolution. +Fentyl, pancuronium bromide N2O to 60 p. 100. The conditions of the study are described in the first part. The results and their analysis permit the appreciation of: - the patient confort, the quality of the examination; -the respect of the hemodynamics for this examination, reputed to be "difficult"; -the immediatly noticeable diminution of side effects; -the absence of side effects; -the justification and interesting of the control ventilation; -the quality of waking up. In the conclusion the authors underline the interest of their different techniques and the possibility of using them in operations in sitting position in neurosurgery, and all important chirurgical intervention.

Vascular thrombosis induced by direct electric current. A new technique for therapeutic embolisation; animal experimentation; first clinical applications.

A first series of experiments showed that the passage of a direct current along a positive electrode immersed in heparinised blood caused the formation of an adhering clot whose diameter increased with time and current intensity. A second series of experiments was done on 10 rabbits as follows: under general anaesthesia, a catheter used as a guide to the positive electrode was surgically inserted in the abdominal aorta. The negative electrode was placed on the thigh. A direct current (10 mA, 10V) was applied for 10-20 min. The first two clinical applications in man of this new method of treatment by electric current thrombosis were carried out using catheterisation of branches of the external carotid and cervical arteries.

Cerebral blood volume and water extraction from cerebral parenchyma by hyperosmolar contrast media.

The attenuation coefficients of cerebral parenchyma and systemic blood were simultaneously measured at varying times after injection of two contrast agents with differing osmolarities. Cerebral parenchyma was in fact denser than the theory would predict. The osmolarity of the iodinated contrast agents seems to play only a very minor part. However, liposolubility could perhaps explain the leakage of iodine across the BBB and thus the increase in the attenuation coefficient of cerebral parenchyma.

Comparative results of 99mTc-pertechnetate scintigraphy and computerized tomography after contrast injection in cerebral pathology.

Fifty-six patients presenting acute cerebral ischemia were investigated by means of 160 CT and 90 RN scans. CT was positive before contrast injection in 90% of cases. A total of 120 CTs were done before and after contrast injection. Only 31% of the ischemic areas were enhanced. Out of 90 RN scans, 50 showed localized uptake. The peak of scintigraphic detection was found on the 15th day of evolution, while enhancement at CT was more frequent between the 15th and 21st days. For the hematomas (13 cases) detection by RN scan depends on the size of the lesion. Among the 47 patients presenting cerebral tumor, the RN uptake depends above all on the intensity of the BBB lesion. RN uptake and CT enhancement both show the same blood-brain barrier disturbance.

Prognostic value of rCBF measurements and CT in focal cerebral ischemia.

CT is the most effective examination technique for studying the evolution of ischemic attacks, but if performed within the first 3 weeks it does not allow prognosis of possible evolution towards necrosis. CBF measurement and vasoreactivity tests under Althesin do allow this prognosis. Thirty patients whose evolution was checked clinically and by repeated CT examinations (89 in all) underwent CBF measurements (intra-arterial xenon 133) and vasoreactivity tests. In all cases (17 patients) where vasoreactivity had completely disappeared (inverse steal), the infarct evolved towards necrosis.

[Vasoreactivity of cerebral infarct to barbiturates and other intravenous anesthetics]. / Vasoréactivité des infarctus cérébraux aux barbituriques et autres anesthésiques intraveineux.

The effect of a barbiturate, Sodium thiopental (Nesdonal), on the cerebral circulation in 13 patients with a cerebral ischemic attack is studied. Its action is compared to the action of other intravenous anesthetics (Alfatésine - Etomidate - diazanalgésie) used in neuro-anesthésia. The study is on a total of thirty patients. The regional cerebral blood flow (RCBF) is measured by the intra-carotid injection of Xe133. The anesthetics studied acted like vasoconstrictive agents on the healthy brain. They diminish the RCBF. At the leel of ischemic lesions the response is abolished, even inversed : the flow remains unchanged, even increases. It is the inverse steal syndrome. This action, comparable to the action of hypocapnia, has both a diagnostic and a prognostic value.

[Electrophysiologic aspects of the effects of etomidate in man]. / Aspects électrophysiologiques de l'action de l'étomidate chez l'homme.

Recordings were electroencephalographical (EEG with spectral analysis), polygraphical (EMG, EKG, breathing). Visual and Auditory Cerebral Evoked Responses were also recorded. The depth of narcosis was quantified upon EEG data. The reactivity during the narcosis and the mechanisms of action of Etomidate on the "non specific structures" are discussed. Cautions should be taken with the use of tomidate in anesthesiology with epileptic and arteriopathic patients.

[Effect of etomidate on cerebral blood flow and oxygen metabolism in man]. / Effets de l'étomidate sur le débit sanguin cérébral et le métabolisme de l'oxygène chez l'homme.

The effects of Etomidate on cerebral blood flow (C.B.F.) and cerebral oxygen consumption (C.02 C.) were studied in 13 patients in a neuroradiology department. Induction of anaesthesia was ensured using a standard dose of 15 mg of Etomidate, followed by a constant rate infusion (2.8 mg/kg/hour). Seven subjects were considered to be normal whilst six were suffering from tumour pathology. Under the influence of Etomidate, C.B.F. in the normal subjects decreased by 34 p. 100 and C.02 C. by 46.7 p. 100. The relationship between C.B.F. and arterial PC01 was studied under the influence of Etomidate: cerebral vasoactivity to C02 was maintained. A special study was made of focal changes in flow in patients with tumour pathology. Under the influence of Etomidate, there were zones of adaptation of flow, indicative of vasoparalysis situated opposite the tumour.

Variations in the measurement of regional cerebral blood volume by CAT.

The cerebral blood volume (CBV) has been measured by transverse axial tomography. The attenuation coefficient of 100 "pixels" located in a well determined region was measured before and after injection of a contrast material (Telebrix 38). The attenuation coefficient of blood samples was measured by CT in a phantom. Blood samples were drawn before and after injection at the same time as the tomographic section (time: half rotation of the scanner). The volume was calculated by the (formula: see text). The values obtained with very early measurements (1--5 min after injection), were very close to those measured by other methods (3--5 ml/100 ml). For 5 patients, the CBV was measured by the same method at different times: 20 measures between 2 and 50 min after the injection. The CBV seemed to vary in function with time according to the equation: CBV in ML%: ate-bt + Vo (t = time in minutes: a = integration constant, a = 1.94; b = time constant, b = 0.089; Vo = real CBV). The apparent variation of CBV was the result of two factors related to the blood-brain barrier, (1) water movement from the extravascular space towards the intravascular space, related to the hyperosmolarity of the contrast medium. The variations of osmolarity and haematocrit values measured after contrast injection did confirm this hypothesis; and (2) iodine movement from the intravascular space towards the extravascular space, due to the toxicity of the material (hyperosmolarity, Na ions, etc). The measurement of CBV by CT is only possible if the contrast materials do not modify the blood-brain barrier. The use of actual materials allows the study of the blood-brain barrier behaviour and enables to make an estimate of the cerebral extra-cellular space. But CT is not a right method of CBV measurement with the contrast medium in use nowadays.

[Cerebral blood flow and metabolism under "diazanalgesia" (author's transl)]. / Débit et métabolisme cérébral sous diazanalgésie.

"Diazanalgesia" employs the combination diazepam + fentanyl. Its effects were studied on regional cerebral blood flow and oxygen metabolism in 8 normal subjects, who were examined angiographically. During diazanalgesia, cortical blood flow falls by 56 p. 100. The mean hemispheric flow calculated over 10 min falls by 34 p. 100. Cerebral O2 consumption (VcO2) falls by 34 p. 100. However, large individual variations are found which suggests that the fall in blood flow is not due solely to the decrease in O2 metabolism. The decreases in flow are not proportional to the amount fentanyl, and there is no direct relation between falls in VcO2 and amount of fentanyl. Cerebral vaso-reactivity to CO2 persists but is reduced under diazanalgesia compared with the waking state.

[Changes in regional blood flow of the brain during althesin anaesthesia (author's transl)]. / Modification du débit sanguin régional du cerveau au cours de l'anesthésie par l'alfatésine.

The effect of Althesin on local blood flow in the brain was studied using intra-carotid Xenon 133 in 18 subjects: 6 apparently normal, 6 with diffuse cerebro-vascular pathology, and 6 cases of ischaemic cerebral accidents identified by scintigraphy, tomodensitometry and angiography. Blood flow decreased under Althesin in the first 2 groups, although to a lesser extent in the second group, with a concomitant decrease in oxygen metabolism. In the third group a "paradoxical" increase in blood flow was observed in infarcts, and a decrease proportional to the rest of the brain in limited ischaemia which had subsequently regressed. The "Althesin test" proposed by Rasmussen (1975) thus reveals the existence of a disconnection between blood flow and metabolism within cerebral infarcts, and provides a possible means of differentiating the latter from reversible ischaemias.