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Biomedical subjects

B Gueguen

Publications and source records attributed to B Gueguen.

26 records · Page 2Linked to original sources
PubMed1985

Electroencephalographic Cartography. I. By means of mini- or microcomputers. Reliability and interest of this electrical non-invasive brain imagery.

We have recorded control subjects, neurological and psychiatric patients (n = 217 sequences recorded over both hemispheres). Minicomputers (HP Fourier analyzer, HP 1000) for spectral analysis provided 10 spectral parameters over 5 spectral frequency bands (delta, theta, alpha, beta 1, beta 2, raw EEG). For each recorded sequence, 90 EEG maps could be computed over both hemispheres. Topo-EEGs were stored in an EEG image data bank. An EEG mapping microcomputer system linked with a digital polygraph (Alvar Electronic, REEGA 2000) has been used simultaneously. White noises have been fed into both computers for testing spatial resolution. Ten topo-EEGs have been recorded in control subjects and patients. The microcomputer system has provided very reliable topographical results when compared to similar maps generated by the minicomputer. A common average reference has been used. First clinical applications have been studied (brain strokes, brain tumors). The method appears very reliable in comparison with CT scans.

Adult↗
PubMed1984

[Hypokalemic paralysis after prolonged absorption of a non-alcoholic pastis in a diabetic].

A typical case of glycyrrhizin-induced hypokalemic paralysis in a diabetic patient is presented. Hypokalemia was responsible for a generalized muscle weakness with a rise in serum muscular enzymes and cardiovascular disorders, which improved under potassium supplementation and spironolactone therapy. The pseudoaldosteronism syndrome with low plasma renin activity and aldosteron suggested aldosteron -like liquorice intoxication. Patient's interrogation revealed regular consumption of a common aperitive drink: a non-alcoholic pastis containing small amounts of glycyrrhizin. The discrepancy between the severity of clinical manifestations and the ingested amounts of glycyrrhizin is explained by the diabetic state.

Beverages↗
PubMed1983

Iontophoretic investigation of identified SFO angiotensin responsive neurons firing in relation to blood pressure changes.

Activity of 29 histologically identified units in the SFO was recorded in parallel to blood pressure monitoring. The responsiveness of these units to angiotensin II (AII) applied either iontophoretically or via the carotid artery (IC) was investigated together with the capacity of the vasodilator substance NO2- to block the AII response. Fifty-five% of the SFO units responded to iontophoretic application of AII (vs. 27% in the surrounding areas). SFO units were also activated by blood pressure depressions, either as a mirror image (type B) or only restricted to the initial descendent phase of the hypotensive wave (type A). But 8 of the 29 units responded in a mixed A and B fashion, i.e., dramatic firing in the very beginning of the hypotension followed by a sustained moderate response until recovery. Hypertensive spontaneous fluctuations rarely and inconsistently elicited an inhibitory response. An unexpected phenomenon of a hypotensive response following IC injections of low doses of AII was observed and used in this investigation. These observations together with the finding that vasoplegics inhibited unit firing suggest that the SFO is equipped with units able to sense a reduction in local vessels' calibre and fire in relation to it. When activated chemically, electrically or mechanically these units may then trigger hypertensive, antidiuretic and drinking responses.

Angiotensin II↗
PubMedDate not supplied

[Role of electroencephalography in the diagnosis of acute cerebral diseases].

It appears from a study of 100 cases of acute cerebral disease that electroencephalography is valuable as part of the diagnosis strategy and not only to establish the correct final diagnosis. This examination therefore plays a non-negligible role in neurological practice. In a number of diseases it provides information that no other examination can provide, being a dynamic, functional method of brain tissue analysis.

Acute Disease↗
PubMedDate not supplied

Giant extramedullary arteriovenous fistula supplied by the anterior spinal artery: treatment by detachable balloons.

A case of a large extramedullary arteriovenous fistula in a young man, which was deemed inoperable, is described. The fistula was mainly supplied by the anterior spinal artery and was responsible for a progressive myeloradicular syndrome. Successful treatment with detachable balloons was carried out. Along with this case report, a review is made of the different types of extramedullary arteriovenous fistulas and their treatment based upon 11 cases seen at Lariboisière Hospital: type 1 is a plain small fistula where embolization is contraindicated; type 2 shows an enlarged anterior spinal artery with dysplastic vein and may be embolized with solid particles; type 3 is a very large multipediculated fistula where the best treatment seems to be detachable balloons. The indications for using detachable balloons for temporary occlusion and for definitive treatment are reviewed. Special emphasis is placed on the possibility of detaching balloons without the need for a coaxial catheter.

Adult↗
PubMedDate not supplied

[Memory disorders in the elderly: complementary examinations--for whom?].

Recognizing the existence of memory disorders in elderly subjects necessarily involves developing a diagnostic strategy to identify the causes. Three types of complementary investigation are available: neurophysiological and neurobiological tests, and anatomical and functional brain imaging studies. Major efforts have been made to identify diagnostic markers on the electroencephalogram. Quantified EEG may have a certain value. However, it provides a plethora of data and there is no consensus on which items are most relevant on the EEG, whether the patient is awake or asleep. Evoked 'cognitive' potentials may also provide useful data, particularly to distinguish between the different types of degenerative dementia. Exaggerated pupil dilation in response to a mydriatric drug has also been put forward as a diagnostic test. The results, however, are controversial. For the time being there is no diagnostic laboratory parameter that can be used routinely, even if studies of the proteins tau and P97 are promising. Molecular genetics-based studies have identified a number of chromosomal abnormalities in certain families. Apart from studies of chromosome 19 and apolipoprotein 3, these markers have no practical utility. Allele sigma 4 is associated with a higher risk of Alzheimer's disease. Apolipoprotein E phenotyping can of course be of diagnostic value, but no more so than neuropsychological or neuroimaging methods. On the other hand, it is difficult to derive a predictive test. It also seems difficult to develop a diagnostic strategy without including brain imaging studies. The value of morphological imaging (CT, MRI) in the diagnosis of dementias is clear. Volumetric measurements of certain brain structures might be a useful diagnostic approach for early detection. Functional brain imaging methods (PET and SPECT) appear particularly suited to the diagnosis of degenerative dementias. The presence of functional abnormalities at onset, and, even before the first clinical signs appear, is clearly valuable.

Aged↗