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Biomedical subjects

D Samson-Dollfus

Publications and source records attributed to D Samson-Dollfus.

At least 19 recordsLinked to original sources
PubMed1992

[Automatic analysis of sleep-wake states during the first year of life].

Automatic analysis on infant sleep tracing was first considered as an aid to the rapid construction of hypnograms. It has long been thought more complicated than in adults, because of the significant changes in electrogenesis during the first year of life, resulting in difficulty to adapt to the criteria of Rechtschaffen and Kales (1968), even if modified, or to those of Anders et al (1971). In fact, these studies have shown that automatic analysis of sleep EEG tracings permit an easier analysis of the changes in electrogenesis according to subject age, sleep stage and time of night. Moreover, automatic analysis of parameters which change with the sleep-wake stages shows the continuity of these changes, and therefore the somewhat arbitrary nature of conventional hypnogram classification. The mathematical treatment of this information facilitates their visualisation, and permits a better analysis of circadian and ultradian variations that could scarcely be formalized by classical hypnogram analysis. In the study of maturation occurring during the first months of life, automatic signal processing will require adaptation that will lead to new forms of reasoning.

Circadian Rhythm↗
PubMed1991

[Electroencephalography and normal aging].

It is a widely accepted that normal ageing hardly modifies basal rythms: alpha frequency remains occipital, symmetrical, and reactive when eyes are opened. There is probably a frequency decrease, but this is hard to determine individually in the absence of longitudinal studies. In any event, alpha frequency never drops below 9 cycles per second until after 80 years of age. Localized and mostly left-sided temporal abnormalities in normal subjects have been noted several times in the literature. However, these pose the problem of early detection of brain damage in patients with hypertension, heart of pulmonary disease. Therefore, further EEG studies on normal and pathological cerebral ageing should investigate clinically well-defined populations.

Aging↗
PubMed1991

[EEG in elderly cardiac patients without cerebral lesions].

Ageing is known to be accelerated by risk-factors. The continuity between normal and pathological ageing is still quite disputed. Concerning cerebral ageing, the use of statistical methods on electroencephalographic (EEG) parameters appeared to be interesting. In this study, three different groups of elderly subjects were examined by EEG: normal subjects without neurological nor cardiac disease, subjects with Alzheimer-dementia (AD) and cardiac patients without cerebral clinical signs. Stepwise discriminant analysis showed that EEG-parameters discriminating normal subjects from cardiac patients were different from those discriminating AD-patients from normal. Furthermore, AD-patients could be well-discriminated from elderly cardiac patients.

Aged↗
PubMed1989

[An aid to the electrophysiological diagnosis of diabetic peripheral neuropathy].

The electrophysiological diagnosis of peripheral neuropathy in diabetics becomes increasingly difficult with the increase in number of parameters measured. We have examined 102 subjects: 60 diabetics, 32 control subjects and 10 with impaired glucose tolerance. From the 37 recorded parameters during 8 examinations, a linear discriminant analysis allowed us to separate the 19 diabetics with clinical neuropathy and the control subjects with only 5 parameters, with a good concordance (96%): the motor conduction velocities (MCV) of the peroneal and median nerves, the amplitude of the action potential (AP) of the sural nerve, the Hmax/Mmax ratio and the M latency of the Hoffman reflex. These parameters, weighted with a coefficient, constitute a score of discrimination. This score has been tested by the Jackknife method on the same sample (94% of well-classified patients), then validated on the other patients. Thus we propose a method to aid the diagnosis of diabetic peripheral neuropathy, without the arbitrary character of the classical single parameter method, and allowing easy repetition.

Adult↗
PubMed1989

[Positive rolandic sharp waves, periventricular ischemia and neurologic outcome. Prospective study in 66 premature infants].

A prospective study concerning 66 prematures born after 32 weeks of gestation showed a 33% incidence of positive rolandic sharp waves (PRSW) on EEGs. The results showed a good sensitivity (Se = 95%) and specificity (Sp = 93%) of PRSW for the diagnosis of periventricular ischemia with motor sequelae. A PRSW frequency higher than one per minute and its persistence on 2 successive EEGs constitutes an indication of severity of the lesions. This study emphasizes the necessity of several EEG recordings in prematures.

Brain Ischemia↗
PubMed1988

[Gastroesophageal reflux during++ sleep in obese patients].

Evidence of relationship between gastrooesophageal reflux (GER) and obstructive apneas in some near-miss children, led us to investigate its possibility in adults. Our purpose was to look for 1) sleep stages of GER occurrence, and 2) the possible chronological link between sleep apneas and GER. Eight obese patients were investigated. Esophageal pHmetry was carried out on two consecutive nights. On the second night, sleep polygraphy was performed including EEG, EOG, EMG, nasal and buccal flows, thoracic and abdominal motions. Esophageal pHmetry was analyzed between the onset of sleep and the definite waking. Fifteen GER episodes occurred in 4 of the 8 patients. Fourteen of them occurred during wakefulness or transient arousals. Only 1 occurred during REM sleep. Four hundred forty five apneas were recorded in 7 patients. None of the obstructive apneas, or mixed apneas followed or preceded a GER. In 1 patient, 2 central apneas succeeded to GER during REM sleep. We conclude that 1) GER, as in healthy subjects, occurs essentially during wakefulness or transient arousals; 2) in these patients, we did not establish a causal relationship between GER and obstructive apneas nor between apneas and GER.

Aged↗
PubMed1988

Sleep organization in children at risk for sudden infant death syndrome.

The organization of sleep was studied in four groups of 6-month-old babies: monitored near-miss babies (NM), monitored siblings (HR), nonmonitored siblings (LR), and siblings considered at low risk but monitored because of marked parental anxiety (PA). It was studied using the method of cumulated occurrences and orthogonal polynomial fitting introduced for the analysis of sleep by Gaillard and Martinoli in 1976. No monitoring effect was found. We also found no difference between the groups when the usual sleep scores were used. However, differences were found with the polynomial adjustment method: there was more quiet sleep stage 3 in NM than in any other group. There was less waking state and more paradoxical sleep at the end of the night in PA and NM than in HR or LR babies. This suggests that the differences may not be related so much to real risk as to parental comportment.

Cerebral Cortex↗
PubMed1987

[Study of basal rhythms in normal and pathologic subjects by EEG mapping].

The topography of basic EEG rhythms brings a new dimension to our understanding of normal and pathologic electrogenesis in the brain. But our experience has shown that it is valuable to make use of the numeric spectral data in order to best decide which rhythms should be mapped. This study demonstrates that quantification of basic EEG rhythms is valuable, not only for beta activity in pharmacology or as an aid for the diagnosis and localization of epilepsy (as has been reported in the literature), but for the other rhythms as well. Our experience to date suggests that EEG rhythms be divided into two major groups: 1) occipital rhythms of extremely variable power which have a peak frequency equal to or greater than 8 Hz and which react to eye opening and 2) parietal-central rhythms which have a frequency equal to or less than 7.5 Hz and which are unreactive to eye opening. Alteration of these characteristics may occur as a result of widely different types of pathology but are usually not visible in the traditional EEG.

Adult↗
PubMed1987

[Retrospective study of 25 sudden death in 25 infants hospitalized during the neonatal period].

During a 6 years period, 25 newborns admitted to a neonatal intensive care unit died suddenly in the first year of life. The risk of sudden death in this specific population is 5% and reaches 7.4% in the low birth weight population (less than or equal to 2,500 g). In 12 infants, the sudden death was partially explained; in 7 infants, the sudden death remained unexplained on the basis of clinical and necropsic findings; in 6 infants, the clinical data did not justify the sudden death but necropsies were not performed. A comparison with matched living control infants showed that there was a significant increase of minor malformations of the branchial arch system and that in the sudden infant death group, threatening premature labour was more frequent during the mothers' pregnancies.

Abnormalities, Multiple↗
PubMed1986

[Slow-wave paradoxical sleep during the 1st year of life].

A typical aspect of the EEG during Paradoxical Sleep (PS) was noted in 76% of 68 infants, 3 to 11 months old. This consisted in delta waves of high amplitude recorded during PS. These waves were seen from the beginning to the end of the first year of life; they could occupy all or part of each stage of PS and were seen at any time during the night. Few works have been published by other authors on the same subject. However, Tanguay et al. (1974) have observed that high delta waves in PS were present until four and a half year of age and that the relative delta power in PS decreased slowly between the first and fifth year of life. The problem consisted in finding out whether this type of tracing was related to the immaturity of some brain structures.

Child Development↗
PubMed1986

[Gastro-esophageal reflux and nocturnal sleep in the adult: method and results obtained in healthy subjects].

Esophageal pH has been studied at night in six healthy subjects. A pH electrode was placed 5 cm above the low esophageal sphincter and sleep state was monitored. The subjects were connected to the recording devices during two nights, but the recording was performed only during the second night. A pH drop superior to 2 units and lasting longer than 30 sec was estimated as a gastro-esophageal reflux (GER). GER episodes were determined from beginning of sleep to definite waking. Ten GER appeared in four of the six subjects. They occurred both during transient arousals or complete wakefulness, but never in NREM or REM sleep. These results are consistent with those previously reported in normal subjects. On the contrary, GER were reported during REM sleep or NREM sleep in 'near miss' sudden infant death infants and in asthmatic children. Thus, the dysfunction of the esophagus might be considered either as the origin of the diseases, or as one of their consequences.

Adult↗
PubMed1986

[Electroretinogram and chronic poisoning by synthetic antimalarials].

Electroretinograms (ERG) obtained before and during chloroquine therapy have been compared. The results showed an increase in the amplitude of A, X and B waves. These results are in contradiction with those of other authors having reported that A and/or B waves decreased in cases of lesions of the retina due to the chloroquine. Such discrepancies may be due to the fact that ERG were recorded at different stages of impregnation of the retina by the chloroquine, and perhaps, because of a specific and early impregnation of the ganglion cells. It seems absolutely necessary to record the ERGs regularly in order to detect when the waves begin to decrease, since this may be the threshold of a real intoxication.

Chloroquine↗
PubMed1986

[Topographic aspects of visual evoked potentials recorded after flash-pattern stimulation in normal subjects].

Visual evoked responses have been recorded on 14 leads placed on the scalp. They were localised on the central, parietal, temporal and occipital regions. The common reference was linked-ears. The stimulus consisted of a flash pattern. The size of the pattern and of each square was respectively of 20 degrees and 30 min. The stimulation of the total visual field had evoked two families of curves. One of these types of curves was posterior (occipital, temporal and parietal) and consisted in a positive, negative, positive wave (100, 136, 200 msec on average) and the second type was localised on the central leads and much more rhythmic than the posterior response. The initial complex (negative, positive, negative, positive: 70, 92, 120, 178 msec) was followed by a slow after-discharge. The half-field stimulation evoked a P100 component on the contralateral posterior leads, but this P100 was less prominent on the ipsilateral posterior leads. The modifications were particularly evident at the level of the temporal posterior electrodes. This P100 component was the only wave to be modified by half-field visual stimulation. The posterior N136 and P200 wave and all the rhythmic central response were exactly the same with half or total visual field stimulation. The results have obviously shown that the different waves of the visual evoked responses are not coming from the same sources. The interpretation of multichannel evoked recordings was therefore very difficult.

Adult↗
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↗
PubMed1986

[Development of a criterion for the automatic detection of sleep spindles in the infant].

The authors present a model for automatic detection of spindles during the different sleep stages. Baseline spindle-free EEG was modelized on a 10 sec recording using an autoregressive model. Spindles were thereafter detected using the quadratic error from this baseline model on successive 1 sec periods. This automatic detection is in a 95.7% agreement with visual analysis.

Computers↗
PubMed1986

Positive rolandic sharp waves and periventricular leukomalacia in the newborn.

Four cases of periventricular ischemia without hemorrhage in premature infants are described in which positive rolandic sharp waves (PRSW) were predominant in the electroencephalogram (EEG). These findings suggest the relationship of PRSW to periventricular ischemia rather than to intraventricular hemorrhage, per se, as has been considered by most investigations in the past. These PRSW can provide an early indication of periventricular leukomalacia.

Electroencephalography↗