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Biomedical subjects

J Gaches

Publications and source records attributed to J Gaches.

At least 19 recordsLinked to original sources
PubMed1991

[Quantified EEG in the diagnosis of Alzheimer's type dementia].

79 subjects (mean age 70.2 ans, 31 males, 48 females) selected as probable dementia of the Alzheimer type, at the early stage of the disease and 17 normal aged people (mean age: 72.2, 5 males, 12 females) were recorded with a 16 channel computerized-EEG (C-EEG) with topographical analysis of the observed changes and with classical visual analysis of the EEG. Quite simple C-EEG parameters as mean dominant frequency (MF) and alpha to theta ratio are able to discriminate patients from normal with a greater accuracy than visual analysis. The values of 8.6 for the MF and 1.3 for the alpha/theta ratio are proposed as cut off values between normal and DAT patients. The topographical analysis appear to be of no additional usefulness in the discrimination of the two groups.

Aged↗
PubMed1989

[The French Society of EEG and Clinical Neurophysiology is 40 years old].

The historical reminder of the foundation of the French EEG Society and the changes which have occurred during its operation show the worry of the Society for a better efficiency all along this last fourty years. A general survey of the scientific activities disclose the contribution of the society in the papers first published in the Revue Neurologique, and, after 1971, in the Revue d'EEG et de Neurophysiologie clinique de Langue française. The French participation in other clinical neurophysiological or scientific meetings in France and abroad is underlined by the important role it has played in the life of the International Federation for EEG Societies. Training of specialized doctors and technicians in the domain of the functional exploration of the nervous system has been a standing preoccupation of the Society, with the teaching of the so-called "Attestation d'EEG" in French universities and the training of technical personnel in specialized schools.

Electroencephalography↗
PubMed1987

[Value of quantitative EEG and EEG mapping in medicine].

Quantitative EEG consists in digitising the EEG from one or several leads and then mathematically processing the signal usually by Fourier spectral analysis. A reduction of the digital information gives characteristic parameters (frequency, amplitude or power, asymmetry, etc.), which can themselves be averaged and submitted to different statistical analysis. Quantitative EEG is particularly suitable for clinical electropharmacology for the assessment of the profiles of psychotropic drugs, for pharmacokinetic correlations of dose-effect relationships and studies of drug bioavailability. The signals obtained from schizophrenic and depressed patients have well defined quantitative EEG characteristics: dissymmetry of the amplitude and hypovariability of the EEG signals. EEg mapping is performed by computer processing of 16 simultaneous EEG lead recordings. This new form of medical imaging is fast, relatively economical and non-invasive, and it is used in psychophysiology to study cognitive tasks and the states of vigilance and sleep. It is also used to study the EEG topography of cerebrovascular accidents, brain tumours, cranial trauma, cerebral degeneration and dementia, and the EEGs of psychiatric patients on psychotropic drugs. EEG mapping represents not only a static and statistical approach by drawing the averaged maps of groups of patients but also a dynamic approach by the recording of sequential individual maps presented as an animated film. The results of this method can be correlated with other medical imaging techniques used to investigate the central nervous system.

Brain Diseases↗
PubMed1986

[EEG mapping in partial epilepsy].

Even if mathematic treatment of EEG signals by Fast Fourier Transformation (FFT) in cases of transient epileptic discharges is still controversial, this method has been applied to 21 cases of epileptic partial seizures. Examples are shown, and compared to CT-Scan data. In 17 cases, EEG mapping identified alterations of basic activities upon a definite area. In addition, a focal peak of maximal alterations displacing itself into the limits of the whole epileptogenic area is demonstrated; it is furthermore suggested that the power spectrum keeps, especially during seizures, a peculiar ("combing") morphology, possibly specific of epileptic diseases.

Adolescent↗
PubMed1986

[Methodology, limitations and value of mapping in electroencephalography].

Data processing is mandatory for EEG mapping. After having used a correct filter and ADC, spectral analysis is completed by interpolating between the spectral values obtained on each recording point to allow a sufficient number of values to be expressed in a grey or color scale on the skull projection plane. The obtention of valid results implies extreme care in data recording and processing. Transitory events (paroxysmal bursts) cannot be detected by spectral analysis. Nevertheless, EEG spectral data mapping is a very good technique to show abnormal EEG focuses in neurology, to study all sorts of neuropsychological reactivities, to follow the evolution of tracings during normal or abnormal aging, metabolic diseases or drug effects.

Aging↗
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↗
PubMed1982

[Herpes simplex encephalitis in neuro-surgery. Electro-encephalographic contribution to early diagnosis (author's transl)].

The electroencephalographic (EEG) signs of acute necrotizing encephalitis are always focalized initially. In over 80% of the cases, the EEG shows local periodical activity with a characteristically short interval between repetitive paroxysms. This was demonstrated by the study of 17 personal observations in which herpes simplex virus was unequivocally identified as the causal agent. This EEG pattern belongs to the general group of "periodical activities". It is an early but transient finding. When observed in an acute clinical picture with fever and encephalic symptoms, it is a major diagnostic feature and should lead to immediate active therapy (neuro-surgery or chemotherapy).

Adolescent↗
PubMed1978

[Herpetic meningo-encephalitis : emergency E.E.G. diagnosis and neurosurgical treatment (author's transl)].

Reporting two cases of true herpetic encephalitis, the authors insist on the great diagnostic value of some nearly constant, but transitory, aspects of localised periodic waves in the E.E.G. An emergency cerebral (usually temporal) resection is then advised. Thus focal infection is reduced and intra-cranial hypertension is prevented. Virologic and electron microscopic studies of the cortical specimen establish with certainty the diagnosis of herpetic encephalitis.

Adult↗
PubMed1977

[Curable ECHO 5 virus encephalitis. Clinical, electroencephalographic, virologic and ultrastructural study].

A 10 1/2 years old boy fell brutally ill with a fit followed by confusion, and then by deep coma, with 40 degrees C fever and morbilliform rash. Consciousnesse came back within ten days, with transient Parkinson-like tremor. Myoclonus persisted for about six months. Complete recovery was followed up for six years. A diagnosis of encephalitis was considered on early EEG evidence (stereotyped repetitive sharp wave bursts) and was confirmed by isolation of ECHO 5 virus from brain specimen, and ultrastructural observation of characteristic cytopathic effect (disappearance of organelles, proliferation of smooth membranes) and of probable viral particules in astrocytes, without any inflammatory process.

Cerebral Cortex↗