Association between pupillometric sleepiness measures and sleep latency derived by MSLT in clinically sleepy patients

OBJECTIVES

The multiple sleep latency test (MSLT) has been employed extensively in clinical and research settings as a gold standard for objectively measuring sleepiness. In a general population or in a variety of work settings, however, a more convenient, rapidly administered measuring method is preferable. We examined the potential utility of pupillometry by comparing its objective measures, pupillary unrest index (PUI) and relative pupillary unrest index (RPUI), with MSLT-derived sleep latency (SL).

METHODS

The study cohort comprised 45 patients (39 males, 6 females, mean age 38.9 ± 11.3 years) referred to the Sleep Disorders Center for the two-nap SL test. SL was measured twice before noon, and pupillometric measurement was performed immediately before each SL test. Subjective sleepiness was measured by using the Epworth Sleepiness Scale (ESS).

RESULTS

The association between PUI and SL was significant and far closer than that between RPUI and SL. A significant difference was observed between the two groups, based on each subject's experience of drowsy driving accidents over the past 3 years in the PUI and RPUI, as well as in SL. The subjective sleepiness measure, ESS, did not relate to any other physiological sleepiness measures.

CONCLUSIONS

In our study cohort, the pupillometric sleepiness measure, PUI, was significantly correlated with, and behaved in a manner equivalent to, MSLT-derived SL in clinically sleepy patients. However, several points remain to be carefully examined before applying pupillometry for screening sleepiness in a general population, or in occupational settings.

[A sleep disordered breathing as the lifestyle-related diseases]

Lifestyle related disease is a generic term for diseases such as cardiovascular diseases, diabetes mellitus and cancer caused by life style or life habit, and one of its fundamental causes is obesity. The reason why most people put on weight after their middle age is mainly because of the increase of visceral fat by the decrease in basal metabolism and the amount of momentum despite of unchanging appetite. Due to this sequence of weight gain, after middle age upper respiratory tract becomes narrower, and it worsens obstructive sleep apnea syndrome (OSAS). Since mastication is to provoke and maintain arousal, OSAS patients, who especially feel strong sleepiness, tend to encourage them to be obesity by frequent mastication that leads them to the tendency to overeat. Two main symptoms of OSAS are snoring and sleepiness; however, the essence of sleepiness is the worse quality of sleep due to apnea. In addition, a vicious circle is eventually generated because sleep deprivation and sleep disorders affects hypertension and glucose intolerance, and those worsen lifestyle disease. In order to break this off, it is necessary to review life style and habit, and improve not only on diet and exercise therapy but also on sleep.

Three-dimensional patterns of early acetabular cartilage damage in hip dysplasia; a high-resolutional CT arthrography study

OBJECTIVE

The purpose of this study was to examine the three-dimensional (3D) progression patterns of early acetabular cartilage damage in hip dysplasia using high-resolutional computed tomography (CT) arthrography.

DESIGN

Thirty-two dysplastic hips of 26 Japanese symptomatic females including 21 hips in pre-stage of osteoarthritis (Kellgren-Lawrence (K-L) grade 0; mean patient age, 32.0 years) and 11 hips in early stage of osteoarthritis (K-L grade 1 or 2; mean patient age, 32.8 years) were examined. Isotropic high-resolutional CT arthrography with an image resolution of 0.5 mm in any orthogonal direction was performed. A 3D acetabular cartilage model was generated and we evaluated distribution of cartilage thickness in 12 zones after dividing the weight-bearing area of the hip joint in radial and lateral/medial directions.

RESULTS

In pre-stage of osteoarthritis, significant differences in cartilage thickness were observed between the lateral and medial zones in all radial regions, most prominently in the antero-superior region. In early stage of osteoarthritis, no significant differences in cartilage thickness were observed, except in the most posterior region. The lateral-medial (LM) ratio was defined as cartilage thickness in the lateral zone divided by that in the medial zone, and hips with the LM ratio in the antero-superior region of <1.4 had significantly more extensive involvement of labral tears than hips with the LM ratio of ≥1.4.

CONCLUSIONS

In hip dysplasia, acetabular cartilage damage was probably occurred in the antero-superior lateral area. The LM ratio may be a sensitive index to quantify early cartilage damage associated with extent of labral disorders.

Non-linear analysis of stabilograms with alcoholic intake

Equilibrium function in the cerebellum (vestibulo-cerebellar system) can deteriorate under the influence of alcohol. In the Romberg posture, the center of gravity, which was measured every 50 ms by stabilometry, appeared to shift with alcohol ingestion. In the previous study, a locus in the center of gravity (stabilogram) was converted to values of statistical indices such as area of sway, total locus length, and locus length per unit area, although these indices could not always distinguish between the statokinesigrams sampled from seven healthy young males in sober and intoxicated states. This measurement was made with an AMTI force plate. In this study, "translation error" was estimated in a d-dimensional embedding space in order to compare statokinesigrams recorded before and after the ingestion of doubly diluted brandy in 30 s (1 ≤ d ≤ 10). We succeeded in validating a stochastic differential equation as a mathematical model of the body sway. The randomness in the model was preserved after alcohol intake and significantly increased in the medial/lateral direction. Visual information referred by the postural control system when standing might be interfered by the effects of intoxication, which was regarded as disturbance. This method is considered to be useful to diagnose the disorders of the vestibulocerebellar system.

[Associated factors for drowsy driving among licensed drivers]

OBJECTIVE

The aim of this study is to reveal factors associated with both dozing off at the wheel and motor vehicle accidents (MVAs) with sleep apnea syndrome (SAS) as well as other descriptive variables for driving set as independent factors.

METHODS

We conducted an anonymous questionnaire survey on drivers who visited the Tokyo Metropolitan Driver and Vehicle Licensing Center in order to renew their driver's license from September 25 to 29, 2006. The survey requested information regarding self reported experience of dozing off at the wheel, MVAs, usual mileage, length of license holding period, and the participants' awareness of SAS. We obtained data from 3,236 drivers (response rate: 61.8%).

RESULTS

The rates for previous experience of feeling sleepiness at the wheel, that of dozing off at the wheel, and that of near-miss or actual MVA due to dozing off at the wheel among the participants were 40.4%, 20.3%, and 10.4% respectively. Multivariate logistic regression analysis revealed that dozing off at the wheel was significantly associated with male gender, long-term holding of a driver's license (> or = 3, < 10 years: OR = 1.58, 95% CI: 1.04-2.42, > or = 10, < 20 years: OR = 2.23, 95% CI: 1.47-3.38, > or = 20,< 30 years: OR = 1.89, 95% CI: 1.23-2.90 > or = 30 years: OR = 1.85, 95%CI: 1.18-2.89), higher usual mileage (> or = 30 km per a week: OR = 1.35, 95% CI: 1.06-1.73), appearance of sleepiness shortly after starting driving (< 2 hrs: OR = 1.99, 95% CI: 1.60-2.47), either having awareness or a diagnosis of SAS. As to experience of near-miss or actual MVA due to dozing off at the wheel, factors including male gender, long-term holding period of driver's license (> or = 3, < 10 years: OR = 2.02, 95% CI: 1.15-3.55, > or = 10, < 20 years: OR = 2.10, 95% CI: 1.19-3.70), appearance of sleepiness shortly after starting driving (< 2 hrs: OR = 1.70, 95% CI: 1.30-2.24), either having awareness or diagnosis of SAS were significantly associated.

CONCLUSION

Not only habituation effects and fatigue due to long driving but also SAS have a significant impact on the occurrence of sleepiness related MVAs. Moreover, early diagnosis and treatment of SAS is necessary so that we can avoid dozing off at the wheel, resulting in near-miss or actual MVA.

Loading and knee alignment have significant influence on cartilage MRI T2 in porcine knee joints

OBJECTIVE

Physiological magnetic resonance imaging (MRI) under loading or knee malalignment conditions has not been thoroughly investigated. We assessed the influence of static loading and knee alignment on T2 (transverse relaxation time) mapping of the knee femoral cartilage of porcine knee joints using a non-metallic pressure device.

METHODS

Ten porcine knee joints were harvested en bloc with intact capsules and surrounding muscles and imaged using a custom-made pressure device and 3.0-T MRI system. Sagittal T2 maps were obtained (1) at knee neutral alignment without external loading (no loading), (2) under mechanical compression of 140 N (neutral loading), and (3) under the same loading conditions as in (2) with the knee at 10 degrees varus alignment (varus loading). T2 values of deep, intermediate, and superficial zones of the medial and lateral femoral cartilages at the weight-bearing area were compared among these conditions using custom-made software. Cartilage contact pressure between the femoral and tibial cartilages, measured by a pressure-sensitive film, was correlated with cartilage T2 measurements.

RESULTS

In the medial cartilage, mean T2 values of the deep, intermediate, and superficial zones decreased by 1.4%, 13.0%, and 6.0% under neutral loading. They further decreased by 4.3%, 19.3%, and 17.2% under varus loading compared to no loading. In the lateral cartilage, these mean T2 values decreased by 3.9%, 7.7%, and 4.2% under neutral loading, but increased by 1.6%, 9.6%, and 7.2% under varus loading. There was a significant decrease in T2 values in the intermediate zone of the medial cartilage under both neutral and varus loading, and in the superficial zone of the medial cartilage under varus loading (P<0.05). Total contact pressure values under neutral loading and varus loading conditions significantly correlated with T2 values in the superficial and intermediate zones of the medial cartilages.

CONCLUSIONS

The response of T2 to change in static loading or alignment varied between the medial and lateral cartilages, and among the deep, intermediate, and superficial zones. These T2 changes were significantly related to the contact pressure measurements. Our results indicate that T2 mapping under loading allows non-invasive, biomechanical assessment of site-specific stress distribution in the cartilage.

[Heart failure]

It seems that the causes of the insomnia are dyspnea and an orthopnea in the heart failure patient. But, only such a fit is not the cause of the insomnia because it complains about the insomnia even if heart failure is slight. An obstructive sleep apnea (OSA) is the risk of the heart failure. A heart failure patient often complicates a central sleep apnea (CSA) and a Cheyne-Stokes respiration (CSR), and has much sleep fragmentation and difficulty maintaining sleep. And sleep disorders are sometimes started by the medications such as the cardiovascular system agent thing; beta blocker and the statins. Sleep disorders represent a major challenge in terms of differential diagnosis in heart failure patients. This is particularly relevant to insomnia and sleep disordered breathing (SDB) such as OSA, CSA and CSR. Thus, expending the knowledge on both insomnia and SDB may contribute to improve medical quality among physician.

[Hypertension]

People are sleeping less in modern societies. It is said that short duration of sleep could play a role in the etiology of not only diabetes mellitus (DM) but also hypertension. Sleep disorders inducing sleep fragmentation and sleep deprivation, such as insomnia, obstructive sleep apnea syndrome (OSAS), and periodic limb movement disorder (PLMD), have been suggested to be independent risk factors for hypertension. OSAS is associated with a range of cardiovascular complications, in particular hypertension. All of hypertensive patients should be routinely screened for possible sleep disorders.

Glucose intolerance in Japanese patients with obstructive sleep apnea

OBJECTIVE

Obstructive sleep apnea syndrome (OSAS) often accompanies obesity and diabetes mellitus. This study was performed to investigate the prevalence of glucose intolerance and to determine independent predictors for insulin resistance in patients with OSAS.

METHODS

A cross-sectional study of 679 OSAS patients with an apnea-hypopnea index (AHI)>or=5/h and 73 controls subjects (AHI<5/h) was done in a tertiary university-based medical center. They were assessed by nocturnal polysomnography and underwent an oral glucose tolerance test.

RESULTS

The prevalence of diabetes mellitus in OSAS patients was higher than that of the control group (25.9% vs. 8.2%, p<0.001) and 424 patients (62.4%) received a new diagnosis of impaired glucose tolerance or diabetes mellitus. The very severe OSAS group (AHI >or=45/h) had significantly higher homeostasis model assessment of insulin resistance (HOMA-IR) and HOMA beta-cell function than the other OSAS groups (AHI<45/h) and the control group. In a logistic regression model adjusting for potential confounders: age, AHI, minimum SpO(2) and body mass index (BMI), only BMI was associated with insulin resistance (HOMA-IR>3) (odds ratio: 1.272, 95% confidence interval 1.206-1.343, p<0.0001).

CONCLUSION

Glucose intolerance was more common in patients with OSAS. Insulin resistance was associated not with AHI but rather with BMI.

[A case of multiple systemic atrophy (MSA) analyzed by acoustic sound for nocturnal inspiratory stridor]

A 70-year old woman was admitted because of sleep maintenance insomnia with severe respiratory sounds during sleep. Polysomnography (PSG) revealed frequent respiratory events, particularly hypopneas, throughout the night associated with severe oxygen desaturation, and inspiratory stridor, which was shown to have a high-pitched frequency by acoustic sound analysis. She also presented fine finger tremor due to parkisonism, increased bilateral tendon responses, cerebellar ataxic gait, and dysautonomia. Therefore, we concluded that she suffered from multiple systemic atrophy (MSA). Nasal continuous positive airway pressure (nCPAP) treatment was successful. Characteristic PSG findings and analysing the snoring sound are important in the early diagnosis of sleep-related disordered breathing in MSA.

Metabolic Syndrome in Japanese Patients with Obstructive Sleep Apnea Syndrome

We investigated the prevalence of metabolic syndrome in patients with obstructive sleep apnea syndrome (OSAS) referred to a tertiary university-based medical center. A cross-sectional study of patients with a definite diagnosis of OSAS was performed using new diagnostic criteria for metabolic syndrome that were designed for the Japanese population. Clinical features and comorbidities related to metabolic syndrome were compared between 819 patients with OSAS (719 men and 100 women) and 89 control subjects without OSAS. Metabolic syndrome was significantly more common in the patients with OSAS than in the controls (49.5% vs. 22.0% for men, p < 0.01; 32.0% vs. 6.7% for women, p < 0.01). Men with OSAS (apnea-hypopnea index [AHI] > or =5/h) had a higher risk of metabolic syndrome compared with controls (odds ratio [OR]: 3.47; 95% confidence interval [CI]: 1.84-6.53). There was a significantly increased risk of metabolic syndrome in men with moderate OSAS (AHI: 15-29.9/h) (OR: 2.83; 95% CI: 1.42-5.66) and men with severe OSAS (AHI > or =30/h) (OR: 5.09; 95% CI: 2.67-9.71). Women with OSAS (AHI> or =5/h) also had an increased risk of metabolic syndrome (OR: 6.59; 95% CI: 1.47-29.38), and the risk was significantly higher in women with severe OSAS (AHI > or =30/h) (OR 14.00; 95% CI: 2.93-66.82). Risk factors for metabolic syndrome differed by gender: in men, age, body mass index (BMI), and OSAS (AHI > or =15/h) were significantly associated with metabolic syndrome, whereas, in women, BMI was the only risk factor for metabolic syndrome. The increase of metabolic syndrome in Japanese OSAS patients suggests that this patient population is burdened with multiple risk factors for cardiovascular disease.

[Sleep apnea syndrome]

Obstructive sleep apnea syndrome (OSAS) is strongly associated with cardiovascular disease which means these patients could suffer sudden death from these cardiovascular diseases, but it is a rare case that common OSAS itself causes sudden death directly. On the other hand, we never wrongly diagnose serious sleep-related breathing disorders (SBDs) such as sleep hypoventilation syndrome, OSAS patients with cardiovascular disease (i.e. ischemic heart disease, cardiac arrhythmia and cardiac failure) and bilateral vocal cord paralysis caused by multiple system atrophy as common OSAS. This section describes how to distinguish these SBDs from common OSAS.