Hypoglossal nerve stimulation therapy on peripheral arterial tonometry in obstructive sleep apnea: a pilot study.

PURPOSE: Hypoglossal nerve stimulation (HGNS) is being increasingly utilized in the setting of moderate-severe obstructive sleep apnea (OSA). While moderate-severe OSA confers excess cardiovascular risk, the impact of HGNS on cardiovascular requires further investigation. With the advent of peripheral arterial tonometry (PAT), one can non-invasively study real-time changes to the autonomic nervous system. This study evaluates the effect of HGNS therapy on autonomic output, using PAT-integrated polysomnography. METHODS: Subjects included adult patients undergoing 2-month post-operative HGNS titration studies with PAT-integrated polysomnography. Apneic and hypopneic events with arousal during stage 2 sleep were identified at increasing levels of stimulation. With each event, PAT signal attenuations were recorded, processed, and analyzed. RESULTS: Nine subjects were enrolled, and eight met inclusion criteria (mean age 67.8 ± 12.4 years; 50% female). The PAT signal did not significantly change before and during stimulation (mean pre-stimulation 43.4 ± 1.7, mean intra-stimulation 41.1 ± 22.5, p = 0.53) in any patient. The ratio of the PAT signal maximum and minimum amplitudes during sleep breathing events largely demonstrated very weak correlation (R2 = <0.12). Across all subjects, poor linear correlation was present between HGNS and PAT signal attenuation (R2 = 0.028) in both adjusted and unadjusted analyses. CONCLUSIONS: Using PAT-integrated polysomnography, PAT output does not appear to be affected by HGNS stimulation at clinical thresholds. These findings support the absence of autonomic system alterations by twelfth nerve stimulation and support the clinical use of PAT-based devices for post-HGNS monitoring. Larger studies examining hard cardiovascular endpoints with HGNS are needed.

Automated selective disruption of slow wave sleep.

BACKGROUND: Slow wave sleep (SWS) plays an important role in neurophysiologic restoration. Experimentally testing the effect of SWS disruption previously required highly time-intensive and subjective methods. Our goal was to develop an automated and objective protocol to reduce SWS without affecting sleep architecture. NEW METHOD: We developed a custom Matlab™ protocol to calculate electroencephalogram spectral power every 10s live during a polysomnogram, exclude artifact, and, if measurements met criteria for SWS, deliver increasingly louder tones through earphones. Middle-aged healthy volunteers (n=10) each underwent 2 polysomnograms, one with the SWS disruption protocol and one with sham condition. RESULTS: The SWS disruption protocol reduced SWS compared to sham condition, as measured by spectral power in the delta (0.5-4Hz) band, particularly in the 0.5-2Hz range (mean 20% decrease). A compensatory increase in the proportion of total spectral power in the theta (4-8Hz) and alpha (8-12Hz) bands was seen, but otherwise normal sleep features were preserved. N3 sleep decreased from 20±34 to 3±6min, otherwise there were no significant changes in total sleep time, sleep efficiency, or other macrostructural sleep characteristics. COMPARISON WITH EXISTING METHOD: This novel SWS disruption protocol produces specific reductions in delta band power similar to existing methods, but has the advantage of being automated, such that SWS disruption can be performed easily in a highly standardized and operator-independent manner. CONCLUSION: This automated SWS disruption protocol effectively reduces SWS without impacting overall sleep architecture.

Altered cortical and subcortical local coherence in obstructive sleep apnea: a functional magnetic resonance imaging study.

Obstructive sleep apnea (OSA) syndrome is the most common sleep-related breathing disorder, characterized by excessive snoring and repetitive apneas and arousals, which leads to fragmented sleep and, most importantly, to intermittent nocturnal hypoxaemia during apneas. Considering previous studies about morphovolumetric alterations in sleep apnea, in this study we aimed to investigate for the first time the functional connectivity profile of OSA patients and age-gender-matched healthy controls, using resting-state functional magnetic resonance imaging (fMRI). Twenty severe OSA patients (mean age 43.2 ± 8 years; mean apnea-hypopnea index, 36.3 h(-1) ) and 20 non-apneic age-gender-body mass index (BMI)-matched controls underwent fMRI and polysomnographic (PSG) registration, as well as mood and sleepiness evaluation. Cerebro-cerebellar regional homogeneity (ReHo) values were calculated from fMRI acquisition, in order to identify pathology-related alterations in the local coherence of low-frequency signal (<0.1 Hz). Multivariate pattern classification was also performed using ReHo values as features. We found a significant pattern of cortical and subcortical abnormal local connectivity in OSA patients, suggesting an overall rearrangement of hemispheric connectivity balance, with a decrease of local coherence observed in right temporal, parietal and frontal lobe regions. Moreover, an increase in bilateral thalamic and somatosensory/motor cortices coherence have been found, a finding due possibly to an aberrant adaptation to incomplete sleep-wake transitions during nocturnal apneic episodes, induced by repetitive choke sensation and physical efforts attempting to restore breathing. Different hemispheric roles into sleep processes and a possible thalamus key role in OSA neurophysiopathology are intriguing issues that future studies should attempt to clarify.

Sleep architecture in patients with fibromyalgia / Arquitectura del sueño en pacientes con fibromialgia

The main objective of this work was to evaluate the characteristics of sleep in patients diagnosed with fibromyalgia syndrome. Sleep architecture in 32 patients with fibromyalgia and 20 healthy controls was evaluated. Following the recommendations of the International Federation of Clinical Neurophysiology, polysomnographies were conducted with fibromyalgia patients and the control subjects. The fibromyalgia patients showed alterations in cyclic organization of sleep and an increased number of periodic leg movements associated with cortical arousals. No significant differences were found in respiratory and oximetry variables or in alpha-delta sleep. The results support that fibromyalgia patients present an increase of superficial sleep at the expense of deep sleep and also an increase of periodic leg movements, which could have a pathogenic effect, facilitating the onset of the illness. Lastly, we discuss the results and propose some future lines of research (AU)

El objetivo central del trabajo fue evaluar las características del sueño en pacientes con fibromialgia. Se evaluó la arquitectura del sueño en 32 pacientes con fibromialgia, utilizando como controles 20 personas sanas. Tanto a las pacientes fibromiálgicas como a los controles se les realizó una polisomnografía de acuerdo con las recomendaciones de la Federación Internacional de Neurofisiología Clínica. Las pacientes con fibromialgia mostraron alteraciones en la organización cíclica del sueño, así como mayor número de movimientos periódicos de las piernas asociados a despertares corticales. No se han obtenido diferencias significativas en las variables respiratorias ni oximétricas, tampoco en el sueño alfa-delta. Los resultados obtenidos indican que las pacientes con fibromialgia presentan incremento del sueño superficial en detrimento del sueño profundo, así como un incremento de los movimientos periódicos de las piernas, que podrían actuar de forma patogénica, favoreciendo la aparición de la enfermedad. Finalmente, se discuten los resultados y se proponen futuras líneas de investigación (AU)

Portable monitoring and autotitration versus polysomnography for the diagnosis and treatment of sleep apnea.

STUDY OBJECTIVES: To compare a clinical pathway using portable monitoring (PM) for diagnosis and unattended autotitrating positive airway pressure (APAP) for selecting an effective continuous positive airway pressure (CPAP) with another pathway using polysomnography (PSG) for diagnosis and treatment of obstructive sleep apnea (OSA). DESIGN: Randomized parallel group SETTING: Veterans Administration Medical Center PATIENTS: 106 patients with daytime sleepiness and a high likelihood of having OSA MEASUREMENTS AND RESULTS: The AHI in the PM-APAP group was 29.2 +/- 2.3/h and in the PSG group was 36.8 +/- 4.8/h (P= NS). Patients with an AHI > or = 5 were offered CPAP treatment. Those accepting treatment (PM-APAP 45, PSG 43) were begun on CPAP using identical devices at similar mean pressures (11.2 +/- 0.4 versus 10.9 +/- 0.5 cm H2O). At a clinic visit 6 weeks after starting CPAP, 40 patients in the PM-APAP group (78.4% of those with OSA and 88.8% started on CPAP) and 39 in the PSG arm (81.2% of those with OSA and 90.6% of those started on CPAP) were using CPAP treatment (P = NS). The mean nightly adherence (PM-APAP: 5.20 +/- 0.28 versus PSG: 5.25 +/- 0.38 h/night), decrease in Epworth Sleepiness Scale score (-6.50 +/- 0.71 versus -6.97 +/- 0.73), improvement in the global Functional Outcome of Sleep Questionnaire score (3.10 +/- 0.05 versus 3.31 +/- 0.52), and CPAP satisfaction did not differ between the groups. CONCLUSIONS: A clinical pathway utilizing PM and APAP titration resulted in CPAP adherence and clinical outcomes similar to one using PSG.

Trastornos de sueño en la distrofia miotónica tipo 1 / Sleep disorders in myotonic dystrophy type I

Evaluamos los trastornos de sueño en ocho pacientes con distrofia miotónica tipo 1 confirmada genéticamente, con edades comprendidas entre 38 y 58 años. Los pacientes fueron estudiados mediante polisomnografía y test de latencias múltiples de sueño. Encontramos excesiva somnolencia diurna en el 75% de los pacientes, no justificable por los eventos respiratorios durante el sueño. El modafinil mejoró este síntoma en todos ellos (AU)

We investigated the sleep disorders in eight patients with genetically confirmed myotonic dystrophy type 1, aged from 38 to 58 years. Patients were studied with nocturnal polysomnogram and multiple sleep latency tests. We found excessive daytime sleepiness in 75% of them, not accountable for respiratory events during sleep. Modafinil improved this symptom in all of them (AU)

Phosphorous31 magnetic resonance spectroscopy after total sleep deprivation in healthy adult men.

STUDY OBJECTIVES: To investigate chemical changes in the brains of healthy adults after sleep deprivation and recovery sleep, using phosphorous magnetic resonance spectroscopy. DESIGN: Three consecutive nights (baseline, sleep deprivation, recovery) were spent in the laboratory. Objective sleep measures were assessed on the baseline and recovery nights using polysomnography. Phosphorous magnetic resonance spectroscopy scans took place beginning at 7 am to 8 am on the morning after each of the 3 nights. SETTING: Sleep laboratory in a private psychiatric teaching hospital. PARTICIPANTS: Eleven healthy young men. INTERVENTIONS: Following a baseline night of sleep, subjects underwent a night of total sleep deprivation, which involved supervision to ensure the absence of sleep but was not polysomnographically monitored. MEASUREMENTS AND RESULTS: No significant changes in any measure of brain chemistry were observed the morning after a night of total sleep deprivation. However, after the recovery night, significant increases in total and beta-nucleoside triphosphate and decreases in phospholipid catabolism, measured by an increase in the concentration of glycerylphosphorylcholine, were observed. Chemical changes paralleled some changes in objective sleep measures. CONCLUSIONS: Significant chemical changes in the brain were observed following recovery sleep after 1 night of total sleep deprivation. The specific process underlying these changes is unclear due to the large brain region sampled in this exploratory study, but changes may reflect sleep inertia or some aspect of the homeostatic sleep mechanism that underlies the depletion and restoration of sleep. Phosphorous magnetic resonance spectroscopy is a technique that may be of value in further exploration of such sleep-wake functions.

Sleep disorders.

Humans spend approximately one third of their lives asleep. Although the same medical disorders that occur during wakefulness persist into sleep, there are many disorders that occur exclusively during sleep or are manifestations of a disturbance of normal sleep-wake physiology. The most common reason for referral to a sleep laboratory is OSA, whereas the most common sleep disorder is insomnia. Effective treatments now exist for many sleep disorders, such as OSA and RLS, and a major breakthrough in the treatment of narcolepsy seems imminent. Because all disease processes are adversely affected by insufficient sleep, it is essential that the practicing physician understand the causes and treatments of the common sleep disorders.