Time to REST: epidemiology and burden

Restless legs syndrome (RLS) is a neurological disorder characterized by a compelling urge to move, accompanied by disturbing sensations within the legs. It is now recognized that RLS is a common condition that has a substantial impact on sleep, daily activities and quality of life. Recent data from the REST (RLS Epidemiology, Symptoms, and Treatment) general population study show that symptoms of RLS are present in approximately 7% of the general population, and that 2–3% experience moderate or severe symptoms at least twice a week. Amongst this RLS cohort, approximately 88% reported sensory disturbances and 76% reported sleep-related symptoms. These symptoms had a marked effect on everyday life, with up to 50% of the RLS cohort reporting disruption of everyday activities or personal relationships. Sleep disturbances in turn lead to impaired daytime functioning. RLS is associated with a significant impairment of quality of life, comparable with that seen in chronic medical conditions such as diabetes or depression. Given the significant burden of morbidity associated with RLS, there is a strong case for treatment in patients with troublesome symptoms.     

A nationwide survey of excessive daytime sleepiness in Parkinson's disease in France

To determine the prevalence of excessive daytime sleepiness (EDS) and that of dozing and sudden onset of sleep episodes (SOS) while driving in ambulatory patients with Parkinson's disease (PD) in France, a national sample of private and public neurologists was asked to recruit the first 10 consecutive nondemented PD patients. Each patient completed a questionnaire including the Epworth Sleepiness Scale (ESS) and the likelihood of dozing off and experiencing SOS episodes behind the wheel. Clinical and demographic data were collected. One thousand six hundred and twenty‐five patients with PD were included in the survey. Twenty‐nine percent of the patients suffered from EDS (ESS score ≥10) but only 0.8% declared a high chance of dozing while driving and 0.5% reported totally unpredictable SOS episodes while driving. Risk factors for EDS were male gender, reduced activity of daily living, and a high daily levodopa equivalent dosage. Risk factors for SOS episodes while driving were an ESS score ≥10, male gender, and low Hoehn and Yahr staging. EDS is common in ambulatory patients with PD and is a major risk factor for dozing and for SOS episodes behind the wheel in patients who drive. © 2007 Movement Disorder Society     

Seasonal covariation of the circadian phases of rectal temperature and slow wave sleep onset

There is a scarcity of well-controlled studies of the seasonal variation in circadian rhythmicity. In the present study, the circadian phase of rectal temperature and the onset of slow wave sleep were studied in a series of twelve 24-h experiments, one each month of the year, for six healthy subjects under controlled conditions in a climatic chamber. In winter, as compared with summer, the average circadian rhythm of rectal temperature was phase delayed by 45 min, and the average onset of slow wave sleep was phase delayed by 40 min. The temporal relationship between the circadian phase of rectal temperature and the timing of slow wave sleep was maintained throughout the year. Habitual rising and retiring times covaried as well. Furthermore, the circadian rhythm of rectal temperature followed the timing of the photoperiod across the year, but had a much smaller range of seasonal variation. Apparently, the seasonal variation in the photoperiodic zeitgeber is largely compensated for by the stabilizing influence of secondary zeitgebers. However, in healthy subjects some effect of photoperiodic variation can still be observed.     

Restless legs syndrome in Parkinson's disease: a case-controlled study.

Restless legs syndrome (RLS) is a disorder of motor activity with a circadian pattern, occurring frequently in patients with Parkinson's disease (PD). We sought to estimate the prevalence of RLS in Indian PD patients. One hundred twenty-six consecutive PD patients and 128 healthy age- and sex-matched controls were evaluated using a predesigned questionnaire. RLS was present in 10 of 126 cases of PD (7.9%) and 1 of 128 controls (0.8%, P = 0.01). PD patients with RLS were older than those without RLS (63.70 +/- 7.80 years vs. 57.37 +/- 10.04 years; P = 0.05) and had higher prevalence of depression (40% vs. 10.3%; P = 0.023). No demographic factors or factors related to PD correlated with the presence or severity of RLS. RLS is more common among patients with PD than controls. A greater medical recognition of this disorder is needed in view of available effective treatment.     

Cardiovascular autonomic dysfunction in normotensive awake subjects with obstructive sleep apnoea syndrome

Cardiovascular autonomic function in normotensive awake patients with obstructive sleep apnoea syndrome was studied in 21 normotensive (mean age 48 ± 14 years), drug-free men with obstructive sleep apnoea syndrome. Cardiovascular reflex tests with continuous blood pressure monitoring and biochemical indices were performed the morning after a standard polygraphic sleep recording. A group of 20 agematched (mean age 49 ± 19 years) normal subjects was used as controls. The obstructive sleep apnoea syndrome patients showed higher heart rate and noradrenaline plasma levels (p < 0.05) at rest and a higher blood pressure response to head-up tilt (p < 0.01), suggesting sympathetic overactivity. Respiratory arrhythmia, baroreflex sensitivity index and Valsalva ratio were significantly lower in the obstructive sleep apnoea syndrome group (p < 0.01) whereas the decrease in heart rate induced by the cold face test was significantly higher (p < 0.05) showing a blunting of reflexes dependent on baroreceptor or pulmonary afferents with normal or increased cardiac vagal efferent activity. These abnormalities in autonomic regulation may predispose obstructive sleep apnoea syndrome patients to cardiovascular complications like hypertension and cardiac arrhythmias.     

REM sleep behavior disorder and vocal cord paralysis in Machado-Joseph disease.

We evaluated the occurrence of REM sleep behaviour disorder (RBD) and vocal cord abductor paralysis (VCAP) in a group of 9 Machado-Joseph disease (MJD) patients. RBD was diagnosed by clinical history plus audiovisual polysomnography in 4 men and 1 woman (55%). While dreaming, 4 fell out of the bed and the other injured his arms. Laryngoscopy detected bilateral VCAP in 1 patient with stridor who required emergency tracheotomy, and partial vocal cord abductor restriction in 2. RBD and VCAP are two potentially injurious conditions that should be considered part of the clinical spectrum of MJD.     

阻塞性睡眠呼吸暂停综合征患者肾功能和心钠素的变化分析

目的探讨病人肾功能、心钠素(ANP)的含量变化及经鼻持续气道正压(nCPAP)治疗对阻塞性睡眠呼吸暂停综合征(OSAS)患者的影响。方法选择经多导睡眠图(PSG)确诊为中、重度的OSAS患者11例为试验组,PSG检查正常者14例为对照组，试验组给予nCPAP治疗，分别测定其血尿肌酐、尿量、尿β2-微球蛋白(β2-MG)、血浆心钠素(ANP)，并计算出内生肌酐清除率(Ccr)，比较试验组与对照组及试验组治疗前后各项指标的差异。结果试验组与对照组比较，Ccr,尿β2-MG差异无显著性，经nCPAP治疗后两指标也无明显改变；试验组的夜尿量、血ANP含量显著高于对照组，nCPAP治疗后上述指标均较治疗前明显下降。结论OSAS患者夜尿量增多可能与ANP增加有关，这种增高可以被nCPAP治疗所纠正。     

Lithium increases slow wave sleep: possible mediation by brain 5-HT2 receptors?

The effect of lithium on slow wave sleep (SWS) was studied in ten normal male volunteers using home based cassette sleep recording and automatic sleep stage analysis. Lithium increased SWS, an effect consisten with a reduction in brain 5-HT₂ receptor function.     

阻塞性睡眠呼吸暂停患者临床表现与上气道阻塞部位关系的探讨

目的 观察一组AHI接近的阻塞性睡眠呼吸暂停综合征（OSAS）患者中上气道阻塞部位对多导睡眠监测（PSG）图及临床表现的影响。方法选取36例AHI为30—40的成年男性OSAS患者行再次整夜PSG，加同步上气道及食道压力监测确定上气道最低阻塞部位。比较上气道最低阻塞部位在软腭水平、舌根水平和下咽水平的不同患者中PSG相关参数：平均SaO2、最低SaO2、最长阻塞性呼吸暂停事件时间、呼吸暂停事件中SaO2下降率（dSaO2／dt）、微觉醒指数；以及部分临床表现参数：白日嗜睡程度、入睡前收缩压／清晨收缩压、入睡前舒张压／清晨舒张压以及高血压发生率。结果平均SaO2、最长阻塞性呼吸暂停事件时间和入睡前收缩压／清晨收缩压比值在3种不同上气道最低阻塞部位患者中差异无显著性（P〉0．05），但与软腭水平相比，舌根水平和下咽水平的最低Sa02降低（P〉0．05），dSaO2／dt（％／s）比值增高（P〈0．05），微觉醒指数及白日嗜睡评分增高（P〈0．01），入睡前舒张压／清晨舒张压比值降低（P〈0．05），最低SaO2〈80％的发生率增高（P〈0．01）以及高血压的发生率增高（P〈0．01）。结论AHI接近的OSAS患者上气道阻塞部位在舌根水平以下者与软腭以上水平者相比，阻塞性呼吸暂停事件的致缺氧效率和程度提高，OSAS的临床表现加重。     

Pressure stability of nasal CPAP and bilevel devices

Summary Question of the study   Nasal continuous positive airway pressure (CPAP) prevents collapse of the upper airway during sleep in patients with obstructive sleep apnea provided that a positive transmural pressure can be maintained during inspiration. We examined pressure-flow characteristics in seven CPAP and bilevel devices during spontaneous breathing.
Methods   The CPAP devices were set to a pressure level of 9.8  hPa (10  cm H₂O) and adapted to a pneumotachograph using a standard CPAP hose and an outlet valve. We continuously measured flow, volume and pressure during resting ventilation and increasing voluntary hyperventilation and analysed the dependence of the variables on a breath-to-breath basis.
Results   Mean CPAP pressures differed between the devices (9.9 – 10.6  hPa) despite the same settings. In all machines pressure fell during inspiration to 8.4 – 9.8  hPa and increased during expiration to 11.1 – 11.7  hPa. This effect increased with higher flow rates. Maximum expiratory pressures rose to 12 – 19  hPa at peak flow rates of 2 l/s, mean expiratory pressures to 9.5 – 16  hPa. Inspiratory pressures dropped to 8.5 – 4.5  hPa (minimum) and 10.5 – 6.0 (mean). Bilevel devices showed a higher stability than CPAP devices. Pressure swings during the respiratory cycle increased the additional work of breathing.
Conclusions   Due to differences in mean and effective CPAP levels CPAP devices are not simply exchangeable but should be individually adapted. Patients with higher minute ventilation might benefit from more stable CPAP machines. The impact on patients' compliance remains to be evaluated.