Biomedical subjects

O Benoit

Publications and source records attributed to O Benoit.

At least 19 recordsLinked to original sources

PubMed2005

[Percutaneous compression plate for pertrochanteric fixation of hip fractures: surgical technique and first results].

We have used a minimally invasive technique for fixation of trochanteric fractures since 2003. We use the percuntaneous compression plate described by Gotfried. We describe here the osteosynthsis technique and our special approach which limits operative time. This technique avoids wide opening of the aponeurosis of the tensor fascia lata, major detachment, and section of the vastus lateralis. The plate is inserted via a 2-cm incision over the greater trochanter. Head and shaft screws are inserted via a second incision measuring 3 to 4 cm. Perfect reduction before plate insertion is the key to success. The results of our first twenty cases have demonstrated an uneventful postoperative period and a short operative time of 25 minutes on average. Peri-operative bleeding has been very limited. Radiographic healing was obtained in three months. Weight bearing was possible immediately after fixation in five cases and was delayed in fifteen. There were two early displacements which were analyzed.

Aged↗

PubMed2003

[Extensor tendon rupture after dorsal surgery of the rheumatoid wrist: analysis of nine reviewed cases].

We led a retrospective study to determine the causes of the tendon ruptures post-operating in the surgery of the wrist rheumatoid dorsal and to estimate the clinical result. At follow-up, we measured the extension lag and the rolling-up of fingers by the distance palm-pulps. Nine patients were so revised in the average of 40 months, average age was of 50.7 years. The tendon ruptures arose in 3 months in 67% of the cases. Seven times, a procedure on the distal radio-ulnar joint had been necessary (5 Sauvé-Kapandji and 2 Darrach). Thirty tendons had been concerned in this study, that is 3.3 tendons on average (1-5). Two main causes were found: attrition on the stub ulnaire and great intra-tendinous synovitis (per operating observation). At the revision, the lag extension means was 23 degrees (0-40). Rolling-up of the long fingers was complete 4 times on 7. The best results were observed after tendinous grafting or index proprius transfer with a lateral suture. Tendinous adhesions had arisen 6 times and persisted still at 3 patients. Our study underlines the interest to stabilize the stub ulnaire to prevent the post-operating ruptures and proposes a transfer or a graft in front of tendons very weakened by the synovitis.

Adult↗

PubMed2003

[A 36 month prospective study of 12 plate osteosyntheses of distal radius fractures].

INTRODUCTION: We performed a prospective study of 12 intra-articular distal radial fractures. The fractures were treated with an anterior plate together with posterior pinning. The aim of the study was to examine whether it was technically feasible to fix such fractures using this technique and to assess the stability of the fixation at follow up. METHOD: Twelve articular fractures were included with a mean age of 47.1 years. All patients were followed up from first admission to the 36th postop month with clinical and radiological checks. RESULTS: At follow up, we found 8 good and excellent clinical results, 3 fair and 1 poor. The combination of an anterior plate with posterior pinning allowed a good initial reduction but could not protect from secondary displacement particularly in the presence of a comminuted metaphysal fracture. DISCUSSION: This procedure gave clinically satisfactory results but did not control ulnar variance. This procedure should be combined with bone grafting in complex metaphysal fractures and epiphysal screws should be used whenever possible.

Bone Nails↗

PubMed2001

[Fracture-dislocation of the second carpometacarpal joint. Case report and review of the literature].

A 26-year-old man was involved in a car crash then he presented an isolated trauma of the hand. We found out a dorsal dislocation of the second carpometacarpal joint with trapezoid fracture and a Rolando fracture. In emergency, closed reduction with percutaneous wires to stabilize, was performed. In the same time, the Rolando fracture was treated by internal fixation (plate). In a second time, after computerized tomography of the carpus, the trapezoid was reduced through a dorsal incision and held with two Kirschner-wires. At last follow-up one year after injury, the result was good. All movements of the wrist and fingers were full and pain free. Thumb index pinch and grasp were approximately 80% those of the uninjured hand. The mechanisms of injury, anatomic factors and management of seventy-one cases of similar trauma (included at least a dislocation of the second carpometacarpal joint) were reviewed in the literature.

Accidents, Traffic↗

PubMed2000

Effects of zopiclone on the rest/activity rhythm after a westward flight across five time zones.

The effects of zopiclone on the rest/activity rhythm were investigated after a westward flight with a 5-h phase delay (Grenoble-Martinique). The rest/activity rhythm was recorded continuously with an actigraph monitor during a 6-day baseline episode in Grenoble and a 6-day sojourn in Martinique. Rectal temperature was recorded before the flight on day 2 and after the flight on days 2 and 5. Subjective jet-lag score was assessed before the flight on days 1 and 2 and in Martinique on days 1, 2, 5 and 6. Zopiclone (7.5 mg) or placebo were administered double blind 30 min prior to bedtime during the first 4 post-flight days (D1-D4). Under zopiclone treatment, sleep was less fragmented on the first post-flight night and the curtailment of sleep duration observed on D2 and D3 under placebo was prevented. During day-time, subjects tended to be more active than with placebo. By contrast, subjective jet-lag scores did not differ between both groups. Zopiclone seemed to accelerate the readjustment of the rest/activity rhythm and the normalisation of the phase relationship between sleep and the temperature rhythm. Zopiclone probably exerts its "resetting" effects on jet-lag desynchronosis by facilitating sleep induction rather than via a chronobiotic action.

Analysis of Variance↗

PubMed2000

Slow (0.7-2 Hz) and fast (2-4 Hz) delta components are differently correlated to theta, alpha and beta frequency bands during NREM sleep.

OBJECTIVES: Spectral power of 40 all-night sleep EEGs (Cz-Pz bipolar lead) recorded in 20 healthy young subjects was calculated after normalization on 30-s consecutive epochs by means of an autocorrelation method based on a 15-order autoregressive model. METHODS: The spectral parameters were calculated for the 7 main EEG bands: slow delta (0.7-2 Hz); fast delta (2-4 Hz); theta (4-8 Hz); alpha (8-12 Hz); sigma (12-16 Hz); beta1 (16-35 Hz); and beta 2 (>35 Hz). RESULTS: Strong negative correlations were found between power in the fast delta and either the alpha or the beta bands and between slow delta and theta bands, whereas the two delta bands showed little correlation with each other. CONCLUSION: The possibility that theses different relationships of slow and fast delta components with other frequency bands might reflect the neocortical or the thalamocortical origin of the delta waves is discussed.

Adult↗

PubMed1999

Automatic sleep EEG analysis using filter banks.

Filter banks analysis is an easy and quick computing way to implement time-scale methods, these being well suited for short events as well as for large waveforms detection tasks. We propose a non-uniform oversampled filter banks to analyze sleep EEG single channel signal, the different subbands matching the classical EEG rhythms. In order to preserve the temporal shapes information, filter banks are oversampled. Coupling the informations conveyed by the different outputs allow to perform an automatic hypnogram.

Adult↗

PubMed1997

Disruption of sleep recovery after 36 hours of exposure to moderately bright light.

Eight young adults were exposed to either 36 hours of moderate bright light (BL; 1,000-2,000 lux) or a light/dark cycle (L/D < 50 lux) during constant routine. Sleep was recorded on the two subsequent recovery sleeps (R1 and R2) and compared to baseline. After the BL exposure, the rebound of stage 4 sleep and slow wave activity (SWA) were split over R1 and R2, whereas after the L/D cycle, the stage 4 sleep debt was almost completely compensated for during R1. During R1, stage 2 sleep and wakefulness accumulated faster in the BL condition than in the L/D condition. An elevation of the temperature level was also found during R1 of the BL condition. No differences between light conditions were found in urinary levels of melatonin or cortisol secreted during R1 or R2. Homeostasic process does not appear to be affected by the BL condition. A modification in the sleep-wake balance and a change in the temporal relationship between the circadian system and the sleep-wake cycle are discussed.

Adult↗

PubMed1997

EEG analysis using non-uniform oversampled filter banks.

Time-frequency or time-scale methods are well suited for short events as well as for large waveforms detection tasks. Filter banks analysis is an easy and quick computing way to implement these methods. We propose a non-uniform oversampled filter banks to analyze EEG single channel signal, the different subbands matching the classical EEG rhythms. We use oversampled filter banks to preserve the temporal shapes information. In order to illustrate this method, we show different spindle temporal structures as also their meaning in terms of sleep stage detection.

Adult↗

PubMed1996

[Sleep-wakefulness rhythm disorders].

The circadian system is synchronized on 24-hour by the light-dark synchronizer and by the social time cue. The circadian rhythm sleep disorders share a common underlying chronobiological basis. These disorders may be due to either jet-lag, shift-work or to lesions of the peripheral visual pathway. The delayed sleep phase syndrome, the advanced sleep phase syndrome, the non 24-hour syndrome as well as the irregular sleep-wake patterns are described. Therapeutic approaches, in particular with melatonin and (or) bright light, are presented.

Circadian Rhythm↗

PubMed1996

Detrimental influence of bright light exposure on alertness, performance, and mood in the early morning.

The aim of this study was to assess the effects of exposure for one night to moderate bright light (BL) on subjective and objective measures of alertness, performance, and mood. Eight subjects were exposed to either BL or dim light (DL) during one night. During the previous day, they were exposed to bright light in both experimental conditions. Nocturnal BL suppressed melatonin secretion and increased body temperature. The ability to stay awake during the night, as measured by the power density in the alpha band, was significantly improved by BL exposure. BL also improved subjective alertness and performance during the first part of the night. However, improvements in the last two variables were followed by marked disruption in early morning patterns, with deterioration of mood and motivation.

Adult↗

PubMed1996

Homeostatic and circadian aspects of sleep regulation in young poor sleepers.

Poor sleepers are a valid model for studying sleep/wake regulation in insomnia. The respective influence of the homeostatic and circadian components of this regulation was studied using various protocols (habitual sleep, recovery after sleep deprivation, bedrest, sleep latency in MSLT and RTSW procedures, and circadian rhythms of body temperature and alertness during a 24-hour constant routine). Poor sleepers were compared to age matched good sleepers studied using similar procedures. The main results are reviewed. Our findings do not support a deficiency in the homeostatic component of sleep/wake regulation. An abnormality in the relationship between the sleep/wake cycle and temperature rhythm cannot be excluded, although most of our results are consistent with the hyperarousal hypothesis.

Adult↗

PubMed1996

The effect on body temperature and melatonin of a 39-h constant routine with two different light levels at nighttime.

Eight healthy subjects were studied during 39-h spans (from 07:00 on one day until 22:00 the second) in which they remained awake. During one experiment, subjects were exposed to 100 lux of light between 18:00 and 8:00, and during a second experiment, they were exposed to 1000 lux during the same time span. Throughout the daytime period, they were exposed to normal daylight (1500 lux or more). The nighttime 1000-lux light treatment suppressed the melatonin metabolite aMT6s, while the 100 lux treatment did not. On the treatment day, the 1000 lux, in comparison to the 100 lux, light treatment resulted in both an elevated temperature minimum and a delay in its clock-time occurrence overnight. No real circadian phase shift in the temperature, urinary melatonin, or cortisol rhythms was detected after light treatment. This study confirmed that nocturnal exposure to lower light intensities is capable of modifying circadian variables more than previously estimated. The immediate effects of all-night light treatment are essentially not different from those of evening light. This may be important if bright light is used to improve alertness of night workers. Whether subsequent daytime alertness and sleep recovery are affected by the protocol used in our study remains to be determined.

Adult↗

PubMed1994

Effect of a single dose (10 mg) of zolpidem on visual and spectral analysis of sleep in young poor sleepers.

Four non-consecutive nights of sleep were recorded in eight young volunteers complaining of chronic poor sleep. The subjects received a placebo or a 10 mg zolpidem dose prior to bedtime according to a Latin square double-blind design. All-night spectral analyses of the Cz-Pz lead were associated to the standard polysomnography. According to the visual scoring performed with the Rechtschaffen and Kales criteria, zolpidem significantly increased the stage 4 amount and reduced waking. Compared to placebo no difference in sleep stages was observed when the scoring was based on the power in the 0.7 to 4-Hz band. In zolpidem nights power was significantly reduced in the 4 to 8-Hz band during NREM (stages 2, 3 and 4) and was increased in the 2 to 4-Hz band during REM sleep. A significant reduction of fast activities over 12 Hz was observed during the first 3 h of sleep. Concerning slow wave activity, the only change noted was a significant slowing of its build-up rate at the beginning of cycle 1.

Adult↗

PubMed1994

Circadian pattern of motor activity in major depressed patients undergoing antidepressant therapy: relationship between actigraphic measures and clinical course.

The 24-hour motor activity pattern was evaluated in 26 inpatients with major depression at treatment onset and after 4 weeks of antidepressant therapy. Clinical state, depression, and psychomotor retardation, as well as motor activity level and circadian rhythm, were simultaneously assessed. Treatment responders and nonresponders were also considered. Diurnal hypoactivity and reduced 24-hour rhythm amplitude were found at treatment onset. Activity level increased significantly on discharge. The rest-activity cycle for each depressed patient fit a cosine function of 24-hour periodicity. Data tended to show no phase shift but a large intragroup phase variability. Preliminary findings of a negative correlation between basic activity level and clinical improvement, and a trend toward responders having a lower activity level than nonresponders, suggest that activity could be used to predict therapeutic response.

Adult↗

PubMed1993

Temperature drop and sleep: testing the contribution of SWS in keeping cool.

Sleep and body temperature characteristics were studied in man in baseline (B), 24 h-constant routine (CR) and recovery (R) after the CR. The sleep advanced and deepened the trough of the minimum temperature when compared with CR. No relevant difference in minimum body temperature, or in the slope of temperature decrease was found, however, between B and R sleeping nights. No correlation was found between the amount of slow wave sleep and body cooling. The results do not support a homeostatic role of slow wave sleep in brain and/or body cooling.

Adult↗

PubMed1993

Effect of morning bright light on body temperature, plasma cortisol and wrist motility measured during 24 hour of constant conditions.

Using 24 h constant conditions, time course of body temperature, plasma cortisol and wrist motility was measured in response to a 3 day morning 2 h bright light pulse. This protocol demonstrated that a 2000 lux illumination was sufficient to elicit a shift of about 2 h of temperature minimum and cortisol peak. In reference session, actimetric recordings showed a circadian time course, closely in relation with core temperature. Bright light pulse resulted in a decrease of amplitude and a disappearance of circadian pattern of actimetry.

Adult↗

PubMed1993

Bright light affects alertness and performance rhythms during a 24-h constant routine.

The aim of the present study was to assess the stimulating effects of bright light (BL) on subjective and objective alertness. Eight subjects were exposed to either bright light or dim light (DL) during a 24-h constant routine (0900-0900). Bright light failed to modify either the 24-h course or the level of body temperature. Compared to DL, BL delayed the circadian trough of motor activity by 2 h. During the night, relative to the dim-light condition, BL significantly increased subjective and objective (EEG test) alertness and improved performances. Thus, BL exposure partly counteracted the effects of sleep deprivation and/or the circadian trough on alertness and performances. During the day, BL only improved the mood and motivation levels. However, the time course of mood and motivation was not affected by the BL exposure, a nocturnal circadian trough occurring at 0630 in both light conditions.

Arousal↗