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hypoxie chronique et activité électrique du cerveau

Veuillez trouver ci-dessous, les résumés et références de certains articles relatifs au sommeil, en instance de parution, annoncés sur Pubmed.

-Une étude à paraître dans Acta Paediatrica traite de l’impact sur la qualité du sommeil et les fonctions respiratoires, des équipements de maintien de nuit prescrits aux enfants souffrant de paralysie cérébrale infantile sévère.

-Une étude publiée par la revue Addictive Behaviors analyse la composition du sommeil d’un échantillon d'adolescents grands consommateurs de marijuana et d’alcool, pendant une période donnée d’abstinence.

-La revue Brain Topography publie une étude de l’incidence de l’hypoxie chronique des patients atteints de syndrome d’apnées obstructives du sommeil sur l’activité électrique du cerveau.

-Une étude de la revue Pharmacology, biochemistry and behavior explore les effets de l’administration de l’antidépresseur tricyclique Amitriptyline sur la sensibilité thermique de rats en privation de sommeil.

-Une étude à paraître dans la revue Vascular Medicine s’interroge sur les corrélations entre le diamètre de l’artère humérale, le flux sanguin et la dilatation artérielle médiée par le flux sanguin dans un contexte de troubles respiratoires du sommeil et d’exploration d’une dysfonction endothéliale.  

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“Sleep quality and respiratory function in children with severe cerebral palsy using night-time postural equipment: a pilot study”, in Acta Paediatrica, novembre 2009

Hill CM, Parker RC, Allen P, Paul A, Padoa KA.

Division of Clinical Neurosciences, School of Medicine, University of Southampton, Southampton, UK. cmh2@southampton.ac.uk

“BACKGROUND: Night-time postural equipment (NTPE) prevents contractures and hip subluxation in children with severe physical disabilities. However, impact on sleep quality and respiratory function has not been objectively studied. METHODS: Ten children with severe cerebral palsy (CP), mean age of 10.9 (range: 5.3-16.7) years, were recruited from a community population. Polysomnography was undertaken on two nights, once with the child sleeping in their NTPE and once sleeping unsupported. Randomization to first night condition controlled for first night effects. RESULTS: Night-time postural equipment use was associated with higher mean overnight oxygen saturation for three children but lower values for six children compared with sleeping unsupported. There were no differences in sleep quality between the conditions. The study group had lower overnight oxyhaemoglobin saturation values, less rapid eye movement (REM) sleep and higher arousal indices compared with typically developing children. CONCLUSION: This pilot study indicated that children with severe CP risk respiratory compromise in sleep irrespective of positioning. Further study will determine if the observed trend for mean overnight oxygen saturation to be lower within positioning equipment reflects random night-to-night variation or is related to equipment use. We suggest that respiratory function is assessed when determining optimal positioning for children using night-time positioning equipment.”

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“Sleep architecture in adolescent marijuana and alcohol users during acute and extended abstinence”, in Addictive Behaviors, novembre 2009

Cohen-Zion M, Drummond SP, Padula CB, Winward J, Kanady J, Medina KL, Tapert SF.

Department of Psychiatry, University of California, San Diego, CA 92161, United States. mcohenzion@gmail.com

“This study examined sleep changes following cessation of marijuana and alcohol use during late adolescence. Twenty-nine heavy marijuana and alcohol users and 20 matched controls were studied during a 28-day monitored abstinence period. Sleep was examined as a function of prior substance use during Nights 1-2 and Nights 27-28. On Night 2, percent rapid eye movement sleep was predicted by past month alcohol use, whereas percent slow wave sleep was predicted by marijuana intake. By Night 28, neither alcohol nor marijuana use predicted any sleep architecture measure. However, on Night 28, indices of period limb movements (PLMs) in sleep were predicted by marijuana and alcohol intake. Results indicate that in adolescents: (1) cessation of heavy marijuana and alcohol use may influence sleep; (2) most sleep abnormalities abate within several weeks of abstinence; and (3) PLMs may increase following abstinence.”

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“Characteristic changes in brain electrical activity due to chronic hypoxia in patients with obstructive sleep apnea syndrome (OSAS): a combined EEG study using LORETA and omega complexity”, in Brain Topography, novembre 2009

Toth M, Faludi B, Wackermann J, Czopf J, Kondakor I.

Department of Neurology, Medical Center, University of Pécs, Pécs, Rét utca 2, Hungary. toth_martin@yahoo.com

“EEG background activity of patients with obstructive sleep apnea syndrome (OSAS, N = 25) was compared to that of normal controls (N = 14) to reflect alterations of brain electrical activity caused by chronic intermittent hypoxia in OSAS. Global and regional (left vs. right, anterior vs. posterior) measures of spatial complexity (Omega) were used to characterize the degree of spatial synchrony of EEG. Low resolution electromagnetic tomography (LORETA) was used to localize generators of EEG activity in separate frequency bands. Comparing patients to controls, lower Omega complexity was found globally and in the right hemisphere. Using LORETA, an increased medium frequency activity was seen bilaterally in the precuneus, paracentral and posterior cingulate cortex. These findings indicate that alterations caused by chronic hypoxia in brain electrical activity in regions associated with influencing emotional regulation, long-term memory and the default mode network. Global synchronization (lower Omega complexity) may indicate a significantly reduced number of relatively independent, parallel neural processes due to chronic global hypoxic state in apneic patients as well as over the right hemisphere.”

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“Systemic amitriptyline administration does not prevent the increased thermal response induced by paradoxical sleep deprivation.” in Pharmacology, biochemistry and behavior, novembre 2009

Damasceno F, Skinner GO, Gomes A, Araújo PC, de Almeida OM.

Department of Pharmacology and Psychobiology, Institute of Biology, State University of Rio de Janeiro, Av. 28 de Setembro, 87-Fundos, 20551-030 Rio de Janeiro, Brazil.

“Sleep deprivation has been associated with hyperalgesia in humans and in animal models. The tricyclic antidepressant amitriptyline is used as an analgesic drug in patients and in animal models of chronic pain, including that associated with spinal nerve injury. Pain hypersensitivity following paradoxical sleep deprivation (PSD) and that following peripheral nerve injury seem to share common spinal mechanisms. Accordingly, we evaluated the effects of amitriptyline (acutely and chronically administered) on the increased thermal response observed in PSD rats (72 or 96 h). Rats were evaluated for thermal sensitivity using a hot plate (52 degrees C or 46 degrees C) at 1 or 24 h after the last administration of the drug. Following the hot plate test, motor behavior was analyzed in an open field arena for a period of 5 min. Paw withdrawal latency response to temperatures of 46 degrees C and 52 degrees C was significantly lower in PSD and in 24-hour post-PSD rats than in controls and it was not modified by amitriptyline (3, 10 and 30 mg/kg). Analgesic effects and reduced motor behavior were only observed in control groups. Overall, these findings indicate that a period of PSD can influence pain modulatory mechanisms, and that amitriptyline action is insufficient to reduce PSD-enhanced thermal sensitivity.”

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“Brachial artery diameter, blood flow and flow-mediated dilation in sleep-disordered breathing” in Vascular Medicine, novembre 2009

Chami HA, Keyes MJ, Vita JA, Mitchell GF, Larson MG, Fan S, Vasan RS, O'Connor GT, Benjamin EJ, Gottlieb DJ.

Department of Medicine, Boston University School of Medicine; VA Boston Healthcare Systemhchami@bu.edu.

“Abstract Clinic-based, case-control studies linked sleep-disordered breathing (SDB) to markers of endothelial dysfunction. We attempted to validate this association in a large community-based sample, and evaluate the relation of SDB to arterial diameter and peripheral blood flow. This community-based, cross-sectional observational study included 327 men and 355 women, aged 42-83 years, from the Framingham Heart Study site of the Sleep Heart Health Study. The polysomnographically derived apnea-hypopnea index and the hypoxemia index (percent sleep time with oxyhemoglobin saturation below 90%) were used to quantify the severity of SDB. Brachial artery ultrasound measurements included baseline diameter, percent flow-mediated dilation, and baseline and hyperemic flow velocity and volume. The baseline brachial artery diameter was significantly associated with both the apnea-hypopnea index and the hypoxemia index. The association was diminished by adjustment for body mass index, but remained significant for the apnea-hypopnea index. Age-, sex-, race- and body mass index-adjusted mean diameters were 4.32, 4.33, 4.33, 4.56, 4.53 mm for those with apnea-hypopnea index < 1.5, 1.5-4.9, 5-14.9, 15-29.9, >/= 30, respectively; p = 0.03. Baseline flow measures were associated with the apnea-hypopnea index but this association was non-significant after adjusting for body mass index. No significant association was observed between measures of SDB and percent flow-mediated dilation or hyperemic flow in any model. In conclusion, this study supports a moderate association of SDB and larger baseline brachial artery diameter, which may reflect SDB-induced vascular remodeling. This study does not support a link between SDB and endothelial dysfunction as measured by brachial artery flow-mediated dilation.”

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