Dawn Harrison

Increased Cerebral Blood Flow Velocity in Children With Mild Sleep-Disordered Breathing: A Possible Association With Abnormal Neuropsychological Function

OBJECTIVE. Sleep-disordered breathing describes a spectrum of upper airway obstruction in sleep from simple primary snoring, estimated to affect 10% of preschool children, to the syndrome of obstructive sleep apnea. Emerging evidence has challenged previous assumptions that primary snoring is benign. A recent report identified reduced attention and higher levels of social problems and anxiety/depressive symptoms in snoring children compared with controls. Uncertainty persists regarding clinical thresholds for medical or surgical intervention in sleep-disordered breathing, underlining the need to better understand the pathophysiology of this condition. Adults with sleep-disordered breathing have an increased risk of cerebrovascular disease independent of atherosclerotic risk factors. There has been little focus on cerebrovascular function in children with sleep-disordered breathing, although this would seem an important line of investigation, because studies have identified abnormalities of the systemic vasculature. Raised cerebral blood flow velocities on transcranial Doppler, compatible with raised blood flow and/or vascular narrowing, are associated with neuropsychological deficits in children with sickle cell disease, a condition in which sleep-disordered breathing is common. We hypothesized that there would be cerebral blood flow velocity differences in sleep-disordered breathing children without sickle cell disease that might contribute to the association with neuropsychological deficits. DESIGN. Thirty-one snoring children aged 3 to 7 years were recruited from adenotonsillectomy waiting lists, and 17 control children were identified through a local Sunday school or as siblings of cases. Children with craniofacial abnormalities, neuromuscular disorders, moderate or severe learning disabilities, chronic respiratory/cardiac conditions, or allergic rhinitis were excluded. Severity of sleep-disordered breathing in snoring children was categorized by attended polysomnography. Weight, height, and head circumference were measured in all of the children. BMI and occipitofrontal circumference z scores were computed. Resting systolic and diastolic blood pressure were obtained. Both sleep-disordered breathing children and the age- and BMI-similar controls were assessed using the Behavior Rating Inventory of Executive Function (BRIEF), Neuropsychological Test Battery for Children (NEPSY) visual attention and visuomotor integration, and IQ assessment (Wechsler Preschool and Primary Scale of Intelligence Version III). Transcranial Doppler was performed using a TL2-64b 2-MHz pulsed Doppler device between 2 pm and 7 pm in all of the patients and the majority of controls while awake. Time-averaged mean of the maximal cerebral blood flow velocities was measured in the left and right middle cerebral artery and the higher used for analysis. RESULTS. Twenty-one snoring children had an apnea/hypopnea index <5, consistent with mild sleep-disordered breathing below the conventional threshold for surgical intervention. Compared with 17 nonsnoring controls, these children had significantly raised middle cerebral artery blood flow velocities. There was no correlation between cerebral blood flow velocities and BMI or systolic or diastolic blood pressure indices. Exploratory analyses did not reveal any significant associations with apnea/hypopnea index, apnea index, hypopnea index, mean pulse oxygen saturation, lowest pulse oxygen saturation, accumulated time at pulse oxygen saturation <90%, or respiratory arousals when examined in separate bivariate correlations or in aggregate when entered simultaneously. Similarly, there was no significant association between cerebral blood flow velocities and parental estimation of childs exposure to sleep-disordered breathing. However, it is important to note that whereas the sleep-disordered breathing group did not exhibit significant hypoxia at the time of study, it was unclear to what extent this may have been a feature of their sleep-disordered breathing in the past. IQ measures were in the average range and comparable between groups. Measures of processing speed and visual attention were significantly lower in sleep-disordered breathing children compared with controls, although within the average range. There were similar group differences in parental-reported executive function behavior. Although there were no direct correlations, adjusting for cerebral blood flow velocities eliminated significant group differences between processing speed and visual attention and decreased the significance of differences in Behavior Rating Inventory of Executive Function scores, suggesting that cerebral hemodynamic factors contribute to the relationship between mild sleep-disordered breathing and these outcome measures. CONCLUSIONS. Cerebral blood flow velocities measured by noninvasive transcranial Doppler provide evidence for increased cerebral blood flow and/or vascular narrowing in childhood sleep-disordered breathing; the relationship with neuropsychological deficits requires further exploration. A number of physiologic changes might alter cerebral blood flow and/or vessel diameter and, therefore, affect cerebral blood flow velocities. We were able to explore potential confounding influences of obesity and hypertension, neither of which explained our findings. Second, although cerebral blood flow velocities increase with increasing partial pressure of carbon dioxide and hypoxia, it is unlikely that the observed differences could be accounted for by arterial blood gas tensions, because all of the children in the study were healthy, with no cardiorespiratory disease, other than sleep-disordered breathing in the snoring group. Although arterial partial pressure of oxygen and partial pressure of carbon dioxide were not monitored during cerebral blood flow velocity measurement, assessment was undertaken during the afternoon/early evening when the child was awake, and all of the sleep-disordered breathing children had normal resting oxyhemoglobin saturation at the outset of their subsequent sleep studies that day. Finally, there is an inverse linear relationship between cerebral blood flow and hematocrit in adults, and it is known that iron-deficient erythropoiesis is associated with chronic infection, such as recurrent tonsillitis, a clinical feature of many of the snoring children in the study. Preoperative full blood counts were not performed routinely in these children, and, therefore, it was not possible to exclude anemia as a cause of increased cerebral blood flow velocity in the sleep-disordered breathing group. However, hemoglobin levels were obtained in 4 children, 2 of whom had borderline low levels (10.9 and 10.2 g/dL). Although there was no apparent relationship with cerebral blood flow velocity in these children (cerebral blood flow velocity values of 131 and 130 cm/second compared with 130 and 137 cm/second in the 2 children with normal hemoglobin levels), this requires verification. It is of particular interest that our data suggest a relationship among snoring, increased cerebral blood flow velocities and indices of cognition (processing speed and visual attention) and perhaps behavioral (Behavior Rating Inventory of Executive Function) function. This finding is preliminary: a causal relationship is not established, and the physiologic mechanisms underlying such a relationship are not clear. Prospective studies that quantify cumulative exposure to the physiologic consequences of sleep-disordered breathing, such as hypoxia, would be informative.

Cerebral Blood Flow Velocity and Cognition in Children Before and After Adenotonsillectomy

OBJECTIVE. The goal was to determine whether amelioration of sleep-disordered breathing through adenotonsillectomy would reduce middle cerebral artery velocity in parallel with improvements in cognition and behavior. METHODS. For 19 children (mean age: 6 years) with mild sleep-disordered breathing, and 14 healthy, ethnically similar and age-similar, control subjects, parents repeated the Pediatric Sleep Questionnaire an average of 12 months after adenotonsillectomy. Children with sleep-disordered breathing underwent repeated overnight measurement of mean oxyhemoglobin saturation. Neurobehavioral tests that yielded significant group differences preoperatively were readministered. Middle cerebral artery velocity measurements were repeated with blinding to sleep study and neuropsychological results, and mixed-design analyses of variance were performed. RESULTS. The median Pediatric Sleep Questionnaire score significantly improved postoperatively, and there was a significant increase in mean overnight oxyhemoglobin saturation. The middle cerebral artery velocity decreased in the sleep-disordered breathing group postoperatively, whereas control subjects showed a slight increase. A preoperative group difference was reduced by the postoperative assessment, which suggests normalization of middle cerebral artery velocity in those with sleep-disordered breathing. The increase in mean overnight oxyhemoglobin saturation postoperatively was associated with a reduction in middle cerebral artery velocity in a subgroup of children. A preoperative group difference in processing speed was reduced postoperatively. Similarly, a trend for a preoperative group difference in visual attention was reduced postoperatively. Executive function remained significantly worse for the children with sleep-disordered breathing, compared with control subjects, although mean postoperative scores were lower than preoperative scores. CONCLUSIONS. Otherwise-healthy young children with apparently mild sleep-disordered breathing have potentially reversible cerebral hemodynamic and neurobehavioral changes.

Sleep habits and neurobehavioural correlates in young children who snore

Objective: Does snoring during pregnancy influence development of pre-eclampsia?Method: Five hundred and three pregnant women were presented a questionnaire concerning snoring, daytime sleepiness a ...withdrawn O141 Sleep-wake cycle in ballet dancers M. GLOS, T. PENZEL, J. STRAUCH, C. THEOBALD and I. FIETZE Interdisciplinary Center of Sleep Medicine, Charité-Universitaetsmedizin Berlin, Berlin, Germany and Staatsballett Berlin, Berlin, Germany Introduction: Ballet dancers are top athletes and artists with extreme demands on their body and intellectual functions. In this group a normal work schedule on a weekly basis is absent and moreover, half of the week working days last until late evenings. Methods: We investigated the sleep-wake cycle over a period of three months prior to a premiere of a new performance by using actigraphy in 28 (17w, 11 m) ballet dancers (mean age 27 5 years, BMI 19 2) of the ‘‘Staatsballett Berlin’’, a big independent ballet institution of the three institutionalized opera houses in Berlin, Germany. Before starting the actigraphy recording (Actiwatch, Cambridge Neurotechnology Ltd, Cambridge, UK) which was accompanied by filling in activity diaries and sleep logs on a daily basis, a physical examination as well as a sleep medical examination and ambulatory polygraphy (Embletta PDS, Embla Systems, Broomfield, CO, USA) was performed. Results: Out of the 28 ballet dancers who were included, 24 of them completed the study after three months. Altogether we found a regular sleep-wake cycle but no circaseptan rhythm in this population. In addition a delayed sleep phase was predominant. In the course of three month the sleep efficacy (SE) was reduced significantly (82 to 77 percent, Po0.01) without changes in the amount of movements and total sleep time (TST) during the night. These findings were independent of the gender of the ballet dancers. The parameters SE and TST are generally lower than in the general age matched German population. These results were accompanied by diminished mental health scores (SF12 questionnaire) and diminished concentration capabilities (d2 test). Conclusion: The preparation time of a new performance in the course of three month caused additional stress in the investigated ballet dancers which was apparent in a diminished sleep quality. In order to guarantee a good status of health and the high degree of physical and mental capability a good management of rest and a activity is needed. As a consequence a dedicated room for rest has been installed at the opera for the ballet dancers. r 2008 European Sleep Research Society, JSR 17 (Suppl. 1), 1–271 Spotlight on Circadian Clock Works On and Off Stage 81

Language function in young children with sleep-disordered breathing

Objective: Does snoring during pregnancy influence development of pre-eclampsia?Method: Five hundred and three pregnant women were presented a questionnaire concerning snoring, daytime sleepiness a ...withdrawn O141 Sleep-wake cycle in ballet dancers M. GLOS, T. PENZEL, J. STRAUCH, C. THEOBALD and I. FIETZE Interdisciplinary Center of Sleep Medicine, Charité-Universitaetsmedizin Berlin, Berlin, Germany and Staatsballett Berlin, Berlin, Germany Introduction: Ballet dancers are top athletes and artists with extreme demands on their body and intellectual functions. In this group a normal work schedule on a weekly basis is absent and moreover, half of the week working days last until late evenings. Methods: We investigated the sleep-wake cycle over a period of three months prior to a premiere of a new performance by using actigraphy in 28 (17w, 11 m) ballet dancers (mean age 27 5 years, BMI 19 2) of the ‘‘Staatsballett Berlin’’, a big independent ballet institution of the three institutionalized opera houses in Berlin, Germany. Before starting the actigraphy recording (Actiwatch, Cambridge Neurotechnology Ltd, Cambridge, UK) which was accompanied by filling in activity diaries and sleep logs on a daily basis, a physical examination as well as a sleep medical examination and ambulatory polygraphy (Embletta PDS, Embla Systems, Broomfield, CO, USA) was performed. Results: Out of the 28 ballet dancers who were included, 24 of them completed the study after three months. Altogether we found a regular sleep-wake cycle but no circaseptan rhythm in this population. In addition a delayed sleep phase was predominant. In the course of three month the sleep efficacy (SE) was reduced significantly (82 to 77 percent, Po0.01) without changes in the amount of movements and total sleep time (TST) during the night. These findings were independent of the gender of the ballet dancers. The parameters SE and TST are generally lower than in the general age matched German population. These results were accompanied by diminished mental health scores (SF12 questionnaire) and diminished concentration capabilities (d2 test). Conclusion: The preparation time of a new performance in the course of three month caused additional stress in the investigated ballet dancers which was apparent in a diminished sleep quality. In order to guarantee a good status of health and the high degree of physical and mental capability a good management of rest and a activity is needed. As a consequence a dedicated room for rest has been installed at the opera for the ballet dancers. r 2008 European Sleep Research Society, JSR 17 (Suppl. 1), 1–271 Spotlight on Circadian Clock Works On and Off Stage 81