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Biomedical subjects

F Laffont

Publications and source records attributed to F Laffont.

At least 19 recordsLinked to original sources
PubMed1991

Auditory evoked responses (AER) and augmenting-reducing phenomenon in patients with progressive supranuclear palsy (PSP).

Variations in amplitude and latency of P1, N1 and P2 waves of AER induced by increasing the stimulus intensity (augmenting-reducing) were measured in PSP patients and compared to those observed in normal subjects. The studied population included 17 patients (10 male, 7 female, mean age 66 +/- 8 yr) with a typical PSP symptomatology and 17 normal subjects (10 male, 7 female, mean age 66 +/- 9 yr). All subjects from both the groups showed a normal auditory threshold (less than 30 db SPL or a moderately increased threshold never exceeding 10 db SPL). Nine patients had normal BAER; 4 patients showed an abnormal III wave; 3 patients showed an abnormal V wave. One patient had a poorly individualized BAER. Latencies and amplitudes of P1, N1 and P2 waves derived from Cz and Fz (linked ear reference) were studied with 50, 60, 70 and 80 db intensities and for each patient slopes of amplitude-stimulus intensity and latency-stimulus intensity curves were studied. Although patients showed decreased AER amplitudes, the augmenting-reducing phenomenon was not different from controls regarding either latency or amplitude changes with increasing stimulus intensity. Previous studies had established a negative correlation between the augmenting-reducing responses and HVA levels in the cerebrospinal fluid (CSF). Similarity of augmenting-reducing mechanisms in PSP and normal subjects favors the hypothesis of unimpaired mesocortical and mesolimbic dopaminergic pathways in PSP. This hypothesis is also supported by postmortem studies using biochemical markers.

Aged↗
PubMed1990

[Detection and peripheral or central localization of sensory pathway involvement of the lower limbs by somatosensory evoked potentials].

In the presence of more or less atypical sensory or sensorimotor symptoms the questions that arise most frequently concern the authenticity of the disorders and the precise level of the lesion. In this study, somatosensory evoked potentials (SEPs) to stimulation of the tibial nerve at the ankle were recorded at different levels in 35 healthy subjects and 32 patients with sensory disorders. Recording electrodes were placed at the popliteal fossa (peripheral sensory nerve conduction velocity), at the T12-L1 level (medullary potential: N21) and at the vertex (P40 wave). The spine to cortex time interval was measured. A systematic study of evoked responses to median nerve stimulation was performed. The 32 patients were divided into 4 groups: Group I (3 cases) had slowed sensory conduction velocity (SCV), similar delay in N21 latency and normal N21-P40: peripheral neuropathy. Group II (4 cases) had normal SCV, delayed N21 latency and normal N21-P40: radicular or conus medullaris injury. Group III (19 cases) had normal SCV, normal N21 latency and lengthened N21-P40 interval. A study of responses to median nerve stimulation made it possible to discriminate between spinal and cortical or subcortical impairment. Group IV (6 cases) had abnormalities from any two of the three groups defined above. In 24 out of 32 patients (75 p. 100), further investigations (myelography, MRI, EMG) confirmed the localization determined by evoked responses. In the other 8 patients (25 p. 100) whose clinical picture suggested a medullary or radicular impairment, SEPs alone clearly revealed an injury. SEPs can distinctly show a spinal impairment and determine the choice of further investigations.

Adult↗
PubMed1989

[Efficacy of uvulopalatopharyngoplasty (UPPP) and modifications in sleep structure in the sleep apnea syndrome (SAS)].

Thirty-four patients (32 male, 2 female; mean age 53 +/- 7 years) with confirmed sleep apnea syndrome (SAS) were studied before and after uvulopalatopharyngoplasty (UPPP). Clinical symptoms were tiredness, excessive daytime sleepiness and snoring. All patients were overweight. Patients underwent a thorough physical and oropharyngeal examination and polysomnography before and 3 months after surgery. On the basis of post-operative results, patients are divided into 3 groups: --group 1: 16 cured patients: apnea index (A.I./h) 38 +/- 17 before and 4.4 +/- 4 apneas/h sleep after surgery. Improved nocturnal hypoxemia: mean minimum oxyhemoglobin saturation (SAO2) before and after UPPP in NREM sleep 83 +/- 4% v. 90 +/- 4% in REM sleep 76 +/- 11% v. 85 +/- 7%. Uninterrupted sleep is restored; --group 2: 8 improved patients: A.I./h of 64 +/- 11 before and 20 +/- 6 after UPPP: improved nocturnal hypoxemia: mean minimum SAO2 in NREM sleep 74 +/- 10% before and 86 +/- 6% after UPPP: in REM sleep 59 +/- 9% before and 79 +/- 6% after UPPP, lower amount and percentage of fragmented sleep; --group 3: 10 non-improved patients: A.I./h unchanged 55 +/- 22% before and 50 +/- 20% after UPPP. Persistent nocturnal hypoxemia: mean minimum SAO2 in NREM sleep 76 +/- 13 before and 81 +/- 12% after UPPP: in REM sleep 63 +/- 16% before and 65 +/- 24% after UPPP. Sleep remains fragmented. In this last group patients are more overweight and all suffer from severe SAS with greater nocturnal oxyhemoglobin desaturation. Surgical treatment by UPPP is shown to be effective for 70% of our patients. Better results are obtained when SAS is less severe and overweight less important.

Adult↗
PubMed1989

Effect of age on auditory evoked responses (AER) and augmenting-reducing.

Auditory evoked responses (AER) were obtained from Cz and Fz in 30 adults (14 male, 16 female) from 20-80 years old. Sound bursts (1000 Hz-200 msec) of four different intensities were used. Peak to trough amplitudes of P1N1 and N1P2 and latencies of P1, N1 and P2 peaks were measured with increasing stimulus intensity and slopes of amplitude - intensity and latency - intensity curves were analysed for assessment of an age effect. The main result is that the increase in P1N1 amplitude with increasing stimulus intensity is more pronounced in older persons. Previous studies have established a negative correlation between the augmenting-reducing responses and HVA levels in the CSF (with lower amounts of HVA in the CSF of "augmenters"). Decreased dopamine metabolism in old subjects could account for our results, so further studies should focus on patients with pathological dopamine deficiencies.

Acoustic Stimulation↗
PubMed1989

[Effects after 3 months of uvulopalatopharyngoplasty in the treatment of obstructive sleep apnea syndromes in adults].

The results at three months of uvulopalatopharyngoplasty (UPPP) have been evaluated in thirty adult patients with an obstructive sleep apnoea syndrome (SAOS). For the group overall the mean apnoea index (IA) decreased from 57 apnoeas per hour and the mean maximal desaturation decreased to 60% post operatively. However in the overall results different individual facts overlap. 20 of the 30 patients, or 67%, have an IA post operatively of less than 50% of the pre-operative value (responders). 14 of these or 47% have a post operative IA of less than 10 apnoeas per hour, a value considered as non pathological. Finally 33% of the patients have no improvement in their post operative IA (non responders). A stricking diminution of nocturnal desaturation and of the disorganisation of sleep was seen in responders to UPPP. No predictive factor for the results of UPPP could be determined. This study shows that UPPP is an effective treatment in a large number of patients having SAOS at the price of minor and transitory complications.

Adult↗
PubMed1988

A syndrome of REM and non-REM sleep reduction and lateral gaze paresis after medial tegmental pontine stroke. Computed tomographic scans and anatomical correlations in four patients.

A common pattern of reduction in both rapid eye movement and non-rapid eye movement sleep associated with various lateral gaze paralyses was present in four cases of brain-stem stroke. From computed tomographic scan data, clinical inferences, and, in two cases, neuropathologic sections, the common lesions were localized in the medial pontine tegmentum, ie, the inner part of the gigantocellular and pontis centralis caudalis nuclei. These data in humans were compared with lesions obtained experimentally in cats.

Adult↗
PubMed1988

[Sleep abnormalities and evoked potentials (VEP-BAER-SEP) in progressive supranuclear palsy].

Few physiological studies have been performed in PSP. We studied: sleep abnormalities in 36 h polygraphic recordings; changes of PEV after pattern-reversal stimulation, of BAER and of short latency SEP after stimulation of the median nerve. The population was for the 1st group: 18 patients with full typical symptomatology, for the 2nd group: 7 patients with likely diagnose of PSP and for the 3rd group: 10 normal subjects as control sample. All patients of the 1st group had sleep abnormalities: decrease of total sleep time; decrease of the percentage of REM sleep; morphological abnormalities (specially horizontal ocular square wave jerks). Detail is given of the repartition of such abnormalities in the two groups of patients. There is no correlation between sleep abnormalities and the natural history of the disease. The PEV and BAER, abnormalities were present in 50% of the cases. The PES were always normal. The help that can be provided by electrophysiological studies in the diagnose of PSP is discussed (particularly in group 2).

Aged↗
PubMed1988

[Sleep and dreams in Korsakoff's amnesia due to alcoholism].

Sleep and dreams in 15 chronic alcoholic patients with amnesia were compared with sleep and dreams of 15 age- and sex-adjusted normal subjects. The patients were subjected to psychological tests in order to determine their I.Q. and their memory disturbances. All subjects had two nights of polygraphic recordings; the first tested the natural sleep organization. During the second night, they were awakened 7 min after the onset of each REM sleep episode, and, at least once, 20 min after the onset of a stage II episode, in order to record on a tape their dream reports according to a standardized protocol. The sleep patterns of the amnesic patients did not show any significant alteration. However, after wakening during the night, patients exhibited a higher tendency to return to REMS than controls. There was still some dream activity in those patients, although noticeably less frequently, and their dream activity had a very poor verbal expression. However, there was no change with respect to the spatio-temporal organization, sensorial perceptions, motor activity and verbalizations during their dreams.

Adult↗
PubMed1987

Two distinct classifications of adult epilepsies: by time of seizures and by sensitivity of the interictal paroxysmal activities to sleep and waking.

Two hundred and thirty-six adult epileptic outpatients were classified twice: firstly according to the time of seizures reported by the patient or his family in diurnal, nocturnal, awaking and diffuse epilepsies (Es) and secondly according to the sensitivity to sleep or waking of the interictal paroxysmal activities (PA) observed during a polysomnographic night session with a sleep PA increase, with a waking PA increase, with PA indifferent to sleep and waking or with few or no PA. The stability of the sensitivity of the PA to sleep and waking was 84%. Patients with diurnal epilepsy have more frequently myoclonic attacks and a lower seizure frequency. Patients with a sleep PA increase have less frequently generalized motor seizures, more frequently partial complex seizures, a higher seizure frequency, higher total night PA density and more frequently the appearance of new PA during sleep. Patients with a waking PA increase had more frequently massive myoclonus, rarely the appearance of new PA during sleep and a high total night PA density. There is no significant relationship between the two classifications. Neither classification succeeds in discriminating the electro-clinical type of the epilepsies.

Adolescent↗
PubMed1987

[EEG spectral analysis in sylvian ischemia with normal value tracings].

The EEG power spectral analysis of 8 patients with a definite sylvian ischemia, the standard EEG of which was normal, was determined in comparison with the date of a control group (N = 14). We calculated the right-left power spectral differences in 4 symmetrical bipolar leads for 5 rhythms (delta: 1.2-3.1 Hz, theta: 3.5-7 Hz, alpha: 7.4-12.3 Hz, beta 1: 12.9-14.1 Hz and beta 2: 15.2-17.2 Hz). For each patient, the spectral difference is measured in comparison with the normal range of the control group with an alpha risk of 5%. There are 54 asymmetries favouring the lesioned side (mostly in 5 patients) and 6 the opposite, without predominance of a particular rhythm with the exception of the beta 2 rhythm which presents no asymmetries.

Aged↗
PubMed1985

Electroencephalographic spectral power and lateralized motor activities.

The powers of the theta (3.5-7 Hz), alpha (7.4-12.3 Hz) and beta 1 (12.9-14.8 Hz) rhythms were analysed in symmetrical derivations. Sixteen right-handed young male adults were observed: at rest, with eyes closed (EC) (4 sequences) and eyes open (EO) (4 sequences); during right then left tonic alternate or sequential movements of the hand and while gazing to the right then to the left. At rest there exists a clear and significant spectral dominance to the right which does not appear in all the rhythms or in all the derivations. As far as the alpha rhythm EC is concerned, individual analysis of the sequences shows that of those which are significantly lateralized, three-quarters are lateralized towards the right. Right motor activity exaggerates, left motor activity diminishes, this right electrical dominance. Lateral gaze is the most powerful activity in this respect. At each derivation, comparison of intensities during right and left activities shows that the contralateral movements diminish the spectral power in the 3 bands studied. This effect seems to be obtained most frequently at the centro-parietal level. The spectral power at rest compared with that during motor activity is higher constantly for theta rhythm, in almost half the cases for the alpha and occasionally for the beta 1.

Adult↗
PubMed1985

[Study of early somatosensory evoked potentials by stimulation of the median nerve at the wrist in 6 patients with unilateral thalamic lesions].

Somatosensory evoked potentials were recorded at Erb's point, over the cervical spine (C7) and over the cortex: parietal and frontal electrodes were contralateral and ipsilateral to the stimulus which was applied on the median nerve at the wrist. The stimulation was performed on 2 control groups, the first consisting of 10 subjects (average age: 33.6 years), the second of 16 subjects (average age: 66.2 years) and on 6 patients presenting unilateral thalamic lesions. These lesions were circumscribed, ischaemic or haemorrhagic and were visualized by a scanner. In 5 of our patients, a diffusion of the P14 wave with normal latency and a delay in the N20 cortical wave was obtained at the parietal electrode contralateral to the stimulus and homolateral to the lesion. Normal latencies were observed for the diffusion of the N18 wave recorded at the frontal electrode contralateral to the stimulus. In the 6th patient, the evoked potentials were normal. The results of the somatosensory evoked potentials observed in our patients are discussed in the context of the anatomical lesions.

Adult↗
PubMed1985

[Spinal and cortical SEP's in healthy subjects and paraplegics].

SEPs are evoked by electrical stimulation of tibial nerve in the fossa poplitea. Surface electrodes, located in S1, L4, L2, T12 with a reference in T6, can record lumbar evoked potentials and calculate a peripheral sensitive velocity. Bipolar leads between electrodes located in T12, T9, T6, T3 and C7 record medullary potential and calculate a medullary transit velocity. The cortical potential is monitored between C'z and a non-cephalic reference. 25 controls and 10 paraplegic patients are studied. In controls, sensitive peripheral velocity is 59 m/sec. The lumbar potential is composed of two negative waves, respectively due to the activation of sensitive roots and to the medullary potential. The medullary transit velocity, measured by the increase of the latency of the culmination of this negative wave along the spine, is 60 m/sec. The cortical potential is composed of two stable waves P30 N38 which are observed in every control; these waves are followed by a succession of positive and negative waves. In the 10 paraplegic patients, complete anesthesia observed in 5 cases is associated with an absence of cortical potential, and the hypoesthesia observed in 5 cases is associated with a cortical potential with a reduced amplitude (2 cases) or an increased latency (3 cases). In these last 3 cases, the medullary potential allows to specify the location of slowing of the transit velocity.

Adult↗
PubMed1984

Sleep disturbances in a case of brain-stem lesions; pharmacological study.

A pharmacological study was carried out of a case of severe insomnia following brain-stem lesions; several polygraphic controls were used. Initially total duration of sleep was brief (less than 4 h) with a high REM/NREM ratio and a short paradoxical sleep (PS) latency. In addition, periodic breathing and tremor were observed. Slow injection of delta-sleep-inducing peptide (DSIP) improved sleep both quantitatively and qualitatively, although PS latency remained short. These effects were reversible. The effects of 5-HTP + benzerazide, of L-DOPA + benzerazide (Modopar) and of clonazepam (Rivotril) were compared.

Brain Stem↗
PubMed1983

Influence of waking and sleep stages on the inter-ictal paroxysmal activity in partial epilepsy with complex seizures.

Twenty-six patients suffering from partial epilepsy with complex seizures underwent polysomnographic recording. Paroxysmal activity (PA) densities in waking and sleep stages were assessed. Total PA densities of one night were found to be an increasing function of the seizure frequency in the previous period. Nineteen patients had more PA during sleep, 5 others in the waking state and the two remaining patients exhibited no differences in PA densities between sleep and waking. Nocturnal seizures were reported by patients showing the sleep PA increase pattern; they also used more anti-convulsants than patients showing the waking PA increase pattern. Differences in PA densities between these two groups were more pronounced in the more desynchronized (waking) and the more synchronized (stages 3 + 4) cortical states. The modulation by slow wave sleep stages was independent of, and superimposed on, the sleep/waking one.

Adolescent↗