Assessment of intracranial hemodynamics in sleep apnea syndrome.

BACKGROUND AND PURPOSE: Sleep apnea syndrome may lead to changes in cerebral hemodynamics due to altered alveolar ventilation. We investigated the dynamics of CO2- and blood pressure-regulated alterations of cerebral blood flow velocities during apneic episodes and evaluated CO2 reactivity during different sleep stages. METHODS: A computer-assisted pulsed Doppler system (2 MHz) was used for continuous overnight recordings of middle cerebral artery flow patterns together with simultaneous polysomnography, continuous blood pressure recordings, and measurements of end-expiratory CO2 in six patients with sleep apnea syndrome. RESULTS: Increases in mean flow velocity of 19-219% and in blood pressure of 12.5-83.1% could be observed during the apneic episodes, with maximum increases during rapid eye movement (REM) sleep. CO2 reactivity was in the normal range (4.4 +/- 1.2%) in the waking state and was markedly increased during sleep stages 1 and 2 (p less than 0.005 compared with awake). The greatest increase was found during REM sleep, with a rise of up to three times the waking value (p less than 0.0001 compared with sleep stage 2). CONCLUSIONS: The changes of mean flow velocity could be interpreted as reactive adaptation processes because of CO2 and blood pressure increases corresponding to apnea. The increased CO2 reactivity during sleep may indicate a "hypersensitivity" of intracranial vascular CO2 or pH receptors and a disturbance of central catecholaminergic and cholinergic systems. The pronounced velocity changes during apneic episodes and the concomitant alterations of vessel wall tension might lead to microangiopathies and macroangiopathies due to chronic strain on the brain vessels.     

Prostaglandin D synthase (beta-trace) in healthy human sleep

STUDY OBJECTIVES: The prostaglandin D system plays an important role in animal sleep. In humans, alterations in the prostaglandin D system have been found in diseases exhibiting sleep disturbances as a prominent symptom, such as trypanosoma infection, systemic mastocytosis, bacterial meningitis, major depression, or obstructive sleep apnea. Assessment of this system's activity in relation to human physiologic sleep was the target of the present study. DESIGN: Serum concentrations of lipocalin-type prostaglandin D synthase (L-PGDS, former beta-trace), and plasma levels of the pineal hormone melatonin were measured in 20 healthy humans (10 women, 10 men; aged: 23.3 +/- 2.39 years) at 4-hour intervals over a period of 5 days and nights, which included physiologic sleep, rapid eye movement sleep deprivation, and total sleep deprivation. In addition, the serum L-PGDS and plasma melatonin levels of 6 subjects were determined under conditions of bright white (10,000 lux) or dark red light (< 50 lux) in a crossover design during total sleep deprivation. Nocturnal blood sampling was performed by a through-the-wall tube system. L-PGDS was measured by an automated immunonephelometric assay, and melatonin was analyzed by direct radioimmunoassay. RESULTS: Serum L-PGDS concentrations showed marked time-dependent changes with evening increases and the highest values at night (P < .0005). This nocturnal increase was suppressed during total sleep deprivation (P < .05), independent of external light conditions and melatonin secretion. Rapid eye movement sleep deprivation had no impact on circulating L-PGDS levels. CONCLUSIONS: The circadian L-PGDS pattern and its suppression by total sleep deprivation indicate an interaction of the prostaglandin D system and human sleep regulation. L-PGDS measurements may well provide new insights into physiologic and pathologic sleep regulation in humans.     

Effects of chronic treatment with methadone and naltrexone on sleep in addicts

Previous studies have described sleep disturbance secondary to chronic opiate use and abuse. Drug-dependency insomnia is of interest because chronic sleep disturbances can promote depressive symptoms which could lead to a drug relapse. For the first time we compared the polysomnographic parameters of 10 methadone-substituted outpatients and 10 naltrexone-treated outpatients. Methadone (-opioid agonist) produced a marked fragmentation of the sleep architecture with frequent awakenings and a decrease in EEG arousals. In comparison with methadone and controls, the naltrexone (-opioid antagonist) group showed the shortest sleep latency and the longest total sleep time. These data indicate that -agonists and -antagonists have different effects on sleep. The implications, especially the involvement of opioid-dopamine interactions on sleep and movements during sleep, are discussed.     

Neural correlates of tinnitus duration and Distress: A positron emission tomography study

Cerebral ¹⁸F‐deoxyglucose positron emission tomography (FDG‐PET) has shown altered auditory pathway activity in tinnitus. However, the corresponding studies involved only small samples and analyses were restricted to the auditory cortex in most studies. Evidence is growing that also limbic, frontal, and parietal areas are involved in the pathophysiology of chronic tinnitus. These regions are considered to mediate perceptual, attentional, and emotional processes. Thus, the aim of the present study was the systematic evaluation of metabolic brain activity in a large sample of tinnitus patients. Ninety one patients with chronic tinnitus underwent FDG‐PET. The effects of tinnitus severity (assessed by a tinnitus questionnaire score), duration and laterality were evaluated with statistical parametric mapping (SPM) in whole brain analyses. In addition, region of interest analyses were performed for primary auditory areas. Tinnitus duration correlated positively with brain metabolism in right inferior frontal, right ventro‐medial prefrontal, and right posterior cingulate cortex. Tinnitus distress correlated positively with activation of left and right posterior inferior temporal gyrus as well as left and right posterior parahippocampal–hippocampal interface. Region of interest analysis demonstrated an overactivation of left in contrast to right Heschl's gyrus independently from tinnitus laterality and anatomical hemispheric differences. Tinnitus duration and distress were associated with areas involved in attentional and emotional processing. This is in line with recent findings indicating the relevance of higher order areas in the pathophysiology of tinnitus. Earlier results of asymmetric activation of the auditory cortices in tinnitus were confirmed, i.e., left‐sided overactivation was found independently from tinnitus laterality. Hum Brain Mapp, 2013. © 2011 Wiley Periodicals, Inc.     

Disturbed sleep in children with Tourette syndrome: a polysomnographic study

OBJECTIVE: To evaluate objective data on sleep quantity/quality and motor activity during night sleep in children with Tourette syndrome (TS). METHOD: Polysomnography of 17 unmedicated TS children (ages: 7;11-15;5, mean: 11;10 years) without comorbid attention-deficit hyperactivity disorder (ADHD) was compared with 16 age-, sex- and IQ-matched healthy controls. Sleep analyses according to the procedure of Rechtschaffen and Kales were supplemented by counting epochs with short arousal-related movements (相似文献   

High-frequency repetitive transcranial magnetic stimulation decreases cigarette smoking

BACKGROUND: The mesolimbic dopaminergic reward system seems to play a crucial role in reinforcing effects of nicotine. Recently, acute high-frequency repetitive transcranial magnetic stimulation (rTMS) of frontal brain regions has been shown to efficiently modulate the mesostriatal and mesolimbic dopaminergic system in both animals and humans. For this reason, we investigated whether high-frequency rTMS would be able to influence nicotine-related behavior by studying rTMS effects on craving and cigarette smoking. METHOD: Fourteen treatment-seeking smokers were included in a double-blind crossover trial, conducted in 2002, comparing single days of active versus sham stimulation. Outcome measures were rTMS effects on number of cigarettes smoked during an ad libitum smoking period and effects on craving after a period of acute abstinence. RESULTS: High-frequency (20-Hz) rTMS of left dorsolateral prefrontal cortex reduced cigarette smoking significantly (p <.01) in an active stimulation compared with sham stimulation. Levels of craving did not change significantly. CONCLUSION: High-frequency rTMS may be useful for treatment in smoking cessation.     

Altered motor cortex excitability in tinnitus patients: a hint at crossmodal plasticity

Idiopathic tinnitus is a frequent and often debilitating auditory phantom perception of largely unknown pathological conditions. In electrophysiological and functional neuroimaging studies, affected subjects have shown excessive spontaneous activity in the central auditory system. To further investigate the underlying central nervous component, we assessed motor cortex excitability in 19 patients with chronic tinnitus by means of transcranial magnetic stimulation (TMS). When results were compared with data from 19 healthy controls matched for age and sex, we found significantly enhanced intracortical facilitation in tinnitus patients. These findings parallel excitability changes after limb amputation and experimental deafferentation. Our results give further support to crossmodal interactions involving neuroplastic changes in some forms of tinnitus and may help to better understand mechanisms of maladaptive cortical reorganisation involved in phantom perceptions.     

Is there a specific polysomnographic sleep pattern in children with attention deficit/hyperactivity disorder?

The aim of the study was to characterize the sleep pattern in children with attention deficit/hyperactivity disorder (ADHD). By means of polysomnography (PSG), sleep patterns were studied in 17 unmedicated preadolescent boys rigorously diagnosed with ADHD and 17 control boys precisely matched for age and intelligence. Although ADHD children did not display a general sleep alteration, major PSG data showed a significant increase in the duration of the absolute rapid eye movement (REM) sleep and the number of sleep cycles in ADHD group when compared with controls. In addition, REM sleep latency tended to be shorter in ADHD children. These results suggest that in ADHD children, a forced REM sleep initiation may produce a higher incidence of sleep cycles and may also contribute to an increased duration of the absolute REM sleep. The overall pattern of the findings implies that a forced ultradian cycling appears characteristic for the sleep in ADHD children, which may be related to alterations of brain monoamines and cortical inhibitory control accompanying the ADHD psychopathology.