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Biomedical subjects

J de Rougemont

Publications and source records attributed to J de Rougemont.

11 recordsLinked to original sources
PubMed1991

Long-term suppression of tremor by chronic stimulation of the ventral intermediate thalamic nucleus.

The usefulness of high-frequency stimulation of the ventral intermediate nucleus (Vim) as the first neurosurgical procedure in disabling tremor was assessed in 26 patients with Parkinson's disease and 6 with essential tremor. 7 of these patients had already undergone thalamotomy contralateral to the stimulated side, and 11 others had bilateral Vim stimulation at the same time. Chronic stimulating electrodes connected to a pulse generator were implanted in the Vim. Tremor amplitude at rest, during posture holding, and during action and intention manoeuvres was assessed by means of accelerometry. Of the 43 thalami stimulated, 27 showed complete relief from tremor and 11 major improvement (88%). The improvement was maintained for up to 29 months (mean follow-up 13 [SD 9] months). Adverse effects were mild and could be eradicated by reduction or cessation of stimulation. This reversibility and adaptability, allowing control of side-effects, make thalamic stimulation preferable to thalamotomy, especially when treatment of both sides of the brain is needed.

Aged↗
PubMed1990

[Memory disorders following rupture of anterior communicating artery aneurysm. 22 cases].

Twenty-two patients who underwent surgery for ruptured aneurysm of the anterior communicating artery were investigated by a battery of neuropsychological tests, including memory evaluation tests. According to the results obtained at these tests the patients were divided into three groups: 1) 7 patients had no memory disorders; 2) 10 patients presented with memory disorders affecting memory; their complaints concerned behavior, and the memory deficit was discovered at neuropsychological examination; 3) 5 patients presented with an obvious amnesic syndrome, and the tests confirmed a severe learning deficit and a severe forgetting while recognition remained normal in 4 patients. Age, residual lesions at CT and electrophysiological signs of focalization correlated well with the residual neuropsychological disorders. Leaving aside quantitative aspects, the memory deficits observed in the second and third groups seemed to be qualitatively different and might correspond to different anatomical and functional sequelae.

Adult↗
PubMed1979

Correlative study between computerized transverse scanning and stereoimpedoencephalography in space-occupying lesions of the brain.

Stereoimpedoencephalography (SIEG) is routinely used by the authors during stereotactic investigations of glial brain tumours prior to stereotactic implantation of isotopes or prior to conventional surgery: the brain tissue impedance is measured along a probe track according to the four electrodes impedance technique. The correlation between the tissue structures and the corresponding impedance values has been studied by comparison with the CATScan data reported on the stereotactic schedules; impedance values are influenced by changes in arterial pCO2 and also by other unknown factors; in order to avoid these uninterpretable changes of the impedance, the recorded values have been normalized with respect to the average impedance along a control track in the normal hemisphere. As a rule, the impedance profile exhibits a "hole" at the site of the pathological processes like tumours as well as surrounding oedema, and the delimitation of the pathological area is very similar to that obtained by the CATScan. There is a good linear correlation between the values of normalized impedance and the x-ray absorption as given by the computer listing of the CATScan. Lastly, statistical values of normalized impedances are determined for the main structures of the brain, showing that the tumour tissue has an impedance equal to half the impedance of the normal tissue.

Brain Neoplasms↗
PubMed1978

[Delineation of brain tumors by stereo-impedo-encephalography (SIEG) (author's transl)].

Authors describe the SEEG technique which is routinely used during stereotactic investigations of brain tumors. By the way of the Talairach's stereoencephalographic electrodes, the brain tissue impedance is measured along the probe trajectory with a four electrode impedancemeter (0.25 mA; 5 KHz). The impedance profile provides a good pattern of the brain structures which are crossed; in pathological areas, the impedance significantly decreases as well in gliomas as in edema; cysts and CSF spaces also decrease the recorded impedance. As a contrary, metastases and meningiomas increase the impedance. SEEG appears to be a sharp method for stereotactic delineation of the brain tumors; a larger series as well as the real-imaginary decomposition of the impedance are needed for a best selectivity of the method.

Adult↗
PubMed1978

[Intracranial pressure. IV - Relationships with post capillary vascular pressures (author's transl)].

The authors have demonstrated experimentally in dogs that, in all cases, the cortical venous pressure (Pvco) is higher than the intracranial pressure (PIC), which always remains higher than the sagittal sinus venous pressure (PSLS). The difference between Pvco and PIC remains statistically equal to 8 mm Hg and can be explained by the "Vascular Waterfall" phenomenon; during Queckenstedt's test, the intracranial venous volume does not change, and is not the cause for the increase of PIC; this increase is due to the constancy of the difference between PIC and PSLS, which is induced by the resorption of CSF through the arachnoïd villi. Increases in Pvco and PIC are shown to be equal to 70% and &2% respectively of the change in PSLS. Any other factor that increases PIC (injections in the cisterna magna, pharmacological effects) does not change PSLS, which remains equal to zero. As long as the cerebral blood flow is constant, the increase in cerebro-vascular resistance of the veins at the site of their junction to the sagittal sinus must be compensated upstream by a vasodilatation, which leads to a new distribution of the pressures along the cerebro-vascular bed.

Animals↗
PubMed1978

Electrical impedance brain scanner: principles and preliminary results of simulation.

In previous studies, the authors have shown the importance of impedance recording by stereotactic procedures for brain tumor detection. In this study they report the principles and the first results of an attempt to obtain the impedance value of any given point inside the brain by an external way. The experimental device is mainly made of a set of 128 electrodes, surrounded by an electrode guarding monitored by an operational amplifier the purpose of which is to made the electric field uniform and to enable a focused measure of the impedance by each of the 128 electrodes. The effect of this electrode guarding is demonstrated, and the present sensitivity of the prototype is shown on various obstacles. conductive or non-conductive; the influence of an impedance barrier on this sensitivity is the project of an impedometric scanner is described, and the problems due to the non-linear propagation of electric currents and to the anisotropic properties of the brain tissue are evaluated.

Brain↗
PubMed1976

[Hyperproduction of CSF in choroid plexus papillomas in children].

Two cases of papilloma of the choroid plexus in children, one in the fourth ventricle and the other in the central part of the left lateral ventricle, are reported. Hyperproduction of CSF could be suspected in the first case by the productive character of pre-operative external ventricular drainage and demonstrated in the second by measurement of pre and post-operative flow rates through a ventriculo-peritoneal bypass which had been installed previously. The origin of this over-production of CSF is discussed, in the pathogenesis of hydrocephalus, in comparison with other factors such as subarachnoid haemorrhage, hyperproteinorachia impairing the resorption of CSF.

Cerebellar Ataxia↗
PubMed1975

[Intracranial pressure. II. Experimental verification of a mathematical model].

The authors report the results of experiments (performed on the dog in vitro and in vivo) which were designed to verify hypotheses made concerning vascular elasticity and characteristics of CSF resorption, as well as to test the validity of a mathematical model that was described in a previous paper. The authors concluded that the equations of the model account for most of the phenomena satisfactorily, but fail to predict a rebound phenomena which occurs after sudden injections in the cisterna magna. The elasticity coefficient S appears to be constant over a range of 200 mm Hg. On the other hand, the filtration coefficient K depends upon pressure, probably due to morphological changes in the size and shape of the CSF valves. These discrepancies are taken into account in a more general model that is presented in the following paper.

Animals↗
PubMed1975

[Intracranial pressure. III. Trial generalized theory].

The authors reported previously an elementary mathematical model of intracranial pressure (ICP) as well as result from an experimental verification of the model. The experimental tests revealed that certain factors had been neglected in the theoretical formation, and the present article offers an expanded version of model which takes into account those factors: changes in the formation of the CSF as a function of ICP; cerebral vasomotricity; cortical and sinusal venous pressures, and variations of the filtration coefficient of the subarachnoidal spaces. A generalized mathematical model of ICP, in the form of four equations, is proposed. The major aspects of both normal and pathological ICP are studied in the light of this model, and are integrated into a generalized theory.

Brain Death↗
PubMedDate not supplied

[Semiologic aspects of traumatic coma (author's transl)].

After studying 85 patients with severe traumatic coma and reviewing the published literature, the authors propose a simple clinical procedure for the diagnostic of such cases. This classification is based on signs without any ambiguity, easily recognized by different physicians, and of pathognomonic significance. These include reaction to pain, testing four reflexes integrated at different levels in the brain stem, pupil morphology, and spontaneous ocular movements. The clinical features corresponding to different levels of dysfunction in the brain are described and their characteristics outlined. The importance of motor reactivity to pain associated to the brain stem reflexes (fronto-orbicular, photomotor, horizontal and vertical oculo-encephalic) is stressed.

Brain Stem↗