Disruption of sleep architecture in minimal hepatic encephalopathy and ghrelin secretion

Sleep disturbances in chronic liver disease

Sleep disturbances are common in chronic liver disease and significantly impact patient outcomes and quality of life. The severity and nature of sleep disturbances vary by liver disease etiology and severity. While there is ongoing research into the association between liver disease and sleep-wake dysfunction, the underlying pathophysiology varies and, in many cases, is poorly understood. Liver disease is associated with alterations in thermoregulation, inflammation, and physical activity, and is associated with disease-specific complications, such as HE, that may directly affect sleep. In this article, we review the relevant pathophysiologic processes, disease-specific sleep-wake disturbances, and clinical management of CLD-associated sleep-wake disturbances.

The Glymphatic System May Play a Vital Role in the Pathogenesis of Hepatic Encephalopathy: A Narrative Review

Hepatic encephalopathy (HE) is a neurological complication of liver disease resulting in cognitive, psychiatric, and motor symptoms. Although hyperammonemia is a key factor in the pathogenesis of HE, several other factors have recently been discovered. Among these, the impairment of a highly organized perivascular network known as the glymphatic pathway seems to be involved in the progression of some neurological complications due to the accumulation of misfolded proteins and waste substances in the brain interstitial fluids (ISF). The glymphatic system plays an important role in the clearance of brain metabolic derivatives and prevents aggregation of neurotoxic agents in the brain ISF. Impairment of it will result in aggravated accumulation of neurotoxic agents in the brain ISF. This could also be the case in patients with liver failure complicated by HE. Indeed, accumulation of some metabolic by-products and agents such as ammonia, glutamine, glutamate, and aromatic amino acids has been reported in the human brain ISF using microdialysis technique is attributed to worsening of HE and correlates with brain edema. Furthermore, it has been reported that the glymphatic system is impaired in the olfactory bulb, prefrontal cortex, and hippocampus in an experimental model of HE. In this review, we discuss different factors that may affect the function of the glymphatic pathways and how these changes may be involved in HE.

Minimal Hepatic Encephalopathy Affects Daily Life of Cirrhotic Patients: A Viewpoint on Clinical Consequences and Therapeutic Opportunities

Minimal hepatic encephalopathy (MHE) is a frequent complication of hepatic encephalopathy (HE) and can affect up to 80% of patients with liver cirrhosis. It is characterized by the lack of obvious clinical signs and the presence of alterations detectable using psychometric or electrophysiological testing focused on attention, working memory, psychomotor speed and visuospatial ability. Ideally, each patient should be tested for this condition because, despite the absence of symptoms, it has severe repercussions on daily life activities. It may be responsible for an inability to drive, sleep disturbances, risk of falls and inability to work. Some studies have highlighted its prognostically unfavorable role on mortality and risk of "overt" HE (OHE). Finally, MHE severely affects the lives of patients and caregivers, altering their quality of life and their socioeconomic status. Several treatments have been proposed for MHE treatment, including non-absorbable disaccharides, poorly absorbable antibiotics, such as rifaximin, probiotics and branched-chain amino acids, with promising results. For this reason, early diagnosis and intervention with appropriate measures is essential, with the aim of improving both performance on psychometric tests, as well as clinical aspects related to this condition.

Sleep and liver disease: a bidirectional relationship

Sleep is a complex, highly regulated process essential for human health and wellbeing. Increasingly, sleep-wake disturbance has been implicated in the pathogenesis of chronic liver disease, particularly the development and progression of non-alcoholic fatty liver disease and alcohol-related liver disease. Patients with cirrhosis also have a high burden of sleep abnormalities with substantial implications for their quality of life and physical health. This Review summarises the epidemiology and pathophysiology of sleep-wake disturbance in liver disease and discusses the multiple converging pathways leading to abnormal sleeping patterns in patients with cirrhosis. This includes contributions from altered melatonin metabolism, neuromuscular complications, and aberrant thermoregulation. In turn, a vicious cycle is established whereby disrupted sleep can further contribute to liver disease progression. We also begin to unravel the complex, interlinking relationship between sleep-wake disturbance and hepatic encephalopathy, discussing both overlapping and distinct mechanisms and clinical features. Finally, we summarise the current and future therapeutic approaches aiming to improve sleep quality in patients with cirrhosis.

Comprehensive Overview of Sleep Disorders in Patients with Chronic Liver Disease

The impact of sleep disorders (SDs) on patients with chronic liver diseases (CLD) is tremendous. SDs are frequently encountered among these patients and interfere with their quality of life. This review aims to present the data available so far about the prevalence, phenotypes, and proposed pathophysiological mechanisms of SDs in CLD. Moreover, we proposed to search the literature regarding the most reliable methods to assess SDs and the possible therapeutic options in patients with CLD. The main results of this review show that when it comes to prevalence, the percentages reported vary widely between studies performed among populations from the USA or Europe and those coming from Asian countries. Furthermore, it has been proven that SDs may also be present in the absence of neurocognitive disorders attributable to hepatic encephalopathy (HE), which contradicts traditional suppositions where SDs were considered part of the clinical scenario of HE. Currently, there are no specific recommendations or protocols to assess SDs in CLD patients and data about the therapeutic management are limited. Taking into consideration their impact, a protocol for diagnosing and managing SDs should be developed and included in the daily practice of hepatologists.

Sleep disturbances in patients with liver cirrhosis: prevalence, impact, and management challenges

Sleep-wake disturbances are common in liver cirrhosis and associated with impaired quality of life. The most common abnormalities are insomnia (difficulties falling asleep and maintaining sleep, or unrefreshing sleep), excessive daytime sleepiness, and sleep-wake inversion (disturbances of circadian rhythmicity). The underlying pathophysiological mechanisms for sleep disturbances in cirrhosis are complex and may include disturbed metabolism of melatonin and glucose, alterations in thermoregulation, and altered ghrelin secretion profiles. Sleep-wake abnormalities are related to the presence of hepatic encephalopathy (HE) and improvement in sleep parameters can be observed when HE is properly managed. A few non-specific treatments for sleep-wake abnormalities have been tried with encouraging results for hydroxyzine and modafinil. However, due to the potential for medication toxicity in these disabled patients, further studies are needed to address the potential role of non-drug therapies in this population (eg, cognitive behavioral therapy, mindfulness, yoga) that have demonstrated usefulness in insomnia disorders.

Wake-up Call to Clinicians: The Impact of Sleep Dysfunction on Gastrointestinal Health and Disease

Sleep dysfunction is an epidemic affecting a large portion of the adult population. Recent studies have linked sleep dysfunction with an upregulation of proinflammatory cytokines (eg, tumor necrosis factor-α, interleukin-1 and interleukin-6), the implications of which can have a profound impact on a variety of gastrointestinal disease. In particular, sleep dysfunction seems to accelerate disease states characterized by inflammation (eg, gastroesophageal reflux disease, irritable bowel syndrome and functional dyspepsia, chronic liver disease, inflammatory bowel disease, and colorectal cancer). This article evaluates the complex interplay between sleep dysfunction and gastrointestinal health and disease.

Improvement of sleep architecture parameters in cirrhotic patients with recurrent hepatic encephalopathy with the use of rifaximin

BACKGROUND AND AIM

Sleep disorders are frequently reported in patients with cirrhosis and hepatic encephalopathy (HE). This study assessed the effect of rifaximin on sleep architecture parameters in patients with recurrent HE.

PATIENTS AND METHODS

This sequential, prospective, and exploratory study involved all patients with cirrhosis and recurrent HE admitted between June 2014 and September 2015. HE was assessed according to the West-Haven Classification. Patients underwent 24-h polysomnography (PSG) and 7-day actigraphy. Rapid eye movement (REM) sleep was considered to be an indicator of good sleep quality. Patients completed questionnaires assessing the quality of sleep and sleepiness. After a 28-day course of rifaximin, the same assessment was repeated.

RESULTS

Fifteen patients were included (nine men, mean age: 57±11 years). Child-Pugh scores ranged from B7 to C15. Before rifaximin, the mean HE score was 2.7±0.7. Data from PSG analysis indicated long total sleep time (TST): 571±288 min, and limited REM sleep: 2.5% TST (0-19). Seven-day actigraphy showed an impaired number of steps: 1690/24 h (176-6945). Questionnaires indicated that patients experienced impaired sleep quality and excessive daytime sleepiness. After rifaximin, HE scores decreased to 1.7±0.6 (P<0.001). REM sleep increased to 8.5% TST (0-25) (P=0.003). No changes were observed for TST, number of steps, and on questionnaires.

CONCLUSION

Patients with recurrent HE suffer from poor sleep quality and excessive daytime sleepiness. On 24-h PSG, rifaximin improves objective sleep architecture parameters with no changes in the subjective quality of sleep and sleepiness.

Increased serum interleukin-6, not minimal hepatic encephalopathy, predicts poor sleep quality in nonalcoholic cirrhotic patients

BACKGROUND

Sleep-wake disturbances are common in patients with cirrhosis and have a considerable effect on health-related quality of life; however, the underlying mechanism behind the phenomenon is unclear. Cytokines are involved in the mediation of signalling pathways regulating fibrogenesis, leading to cirrhosis. In addition, increased cytokines could contribute to sleep disturbances.

AIM

To determine the relationship between pro-inflammatory cytokines and sleep disturbance in cirrhotic patients.

METHODS

Ninety-eight nonalcoholic cirrhotic patients without overt hepatic encephalopathy were enrolled in this cross-sectional study. The Pittsburgh Sleep Quality Index (PSQI) was used to assess sleep quality. The Psychometric Hepatic Encephalopathy Score (PHES) was used to examine cognitive performance and define minimal hepatic encephalopathy (MHE). The Hospital Anxiety and Depression Scale (HADS) was used to evaluate the mood status of the patients. Pro-inflammatory cytokines that include interleukin 6 (IL-6) and tumour necrosis factor-α, as well as HBV-DNA or HCV-RNA levels were determined in patients.

RESULTS

A total of 56 (57%) cirrhotic patients were identified as 'poor' sleepers (PSQI > 5). After multivariate analysis, IL-6 (P = 0.001) and HADS scores (P = 0.002) were found to be independent predictive factors of poor sleep quality. No significant relationships were observed between the sleep indices and the presence of MHE. HCV-RNA, but not HBV-DNA, viraemia was associated with sleep disturbance in cirrhotic patients.

CONCLUSIONS

Sleep disturbance is found commonly in cirrhotic patients and a high serum IL-6 level is predictive of poor sleep quality. Minimal hepatic encephalopathy by itself may not contribute to sleep dysfunction in cirrhotic patients.

Brain oscillatory activity during sleep shows unknown dysfunctions in early encephalopathy

Electroencephalographic recordings in cirrhotic patients without overt hepatic encephalopathy (HE) have mainly been performed during wakefulness. Our aim was to quantify their alterations in nocturnal sleep electroencephalogram (EEG). In 20 patients and 20 healthy volunteers, we recorded a nocturnal digital polysomnography. Different sleep parameters were measured. Besides, we performed quantitative analysis of EEG (qEEG) as follows: spectral power in the different sleep stages was calculated in the frequency bands low δ, δ, θ, α, and σ. Also, the mean dominant frequency and Sleep Indexes were obtained. In comparison with controls, the group of patients showed (1) different alterations in both the microstructure and the macrostructure of sleep; (2) an increase in, both, θ band power and the average mean dominant frequency during rapid eye movement (REM); (3) in all sleep stages, a decrease of sleep electroencephalogram spectral power in low δ band and an increase in δ band: and (4) in stages N3 and REM, significant increases in the minimum of mean dominant frequency and in the respective sleep indexes. Therefore, in cirrhotic patients without overt HE, and likely having minimal hepatic encephalopathy, we found different alterations in both the microstructure and the macrostructure of nocturnal sleep. Also, sleep qEEG showed a brain dysfunction in slow oscillatory mechanisms intrinsic of sleep stages, with an increase in the frequency of its maximal electroencephalogram synchronization, from low δ to δ band. These alterations may reflect the onset of encephalopathy; sleep qEEG may, thus, be an adequate tool for its brain functional evaluation and follow-up.

Clinical significance of therapy using branched-chain amino acid granules in patients with liver cirrhosis and hepatocellular carcinoma

The liver is the major organ for the metabolism of protein, fat and carbohydrate. A nutritional approach is required in the treatment of cirrhosis, which is frequently complicated with protein-energy malnutrition. Several advanced treatment approaches for hepatocellular carcinoma (HCC) have been established in the past decade. HCC is often complicated by cirrhosis, so treatment of the underlying liver diseases is also necessary to improve the prognosis. Branched-chain amino acid (BCAA) granules were developed originally for the treatment of hypoalbuminemia associated with decompensated cirrhosis. However, subsequent studies found various other pharmacological actions of this agent. We review the clinical significance of therapy using BCAA granules in patients receiving different treatment approaches for cirrhosis and HCC based on the published work as well as our own data.

Correlation between degree and quality of sleep disturbance and the level of neuropsychiatric impairment in patients with liver cirrhosis

Sleep disturbances are common in patients of cirrhosis and has a significant effect on their health related quality of life (HRQOL). Thus far, no study has demonstrated a systematically studied significant correlation between the sleep disturbance observed and the neuropsychiatric impairment status of patients of cirrhosis. On the basis of PHES, we divided 100 cirrhotics into those having minimal hepatic encephalopathy (MHE) (PHES≤-5) and those not (NMHE). Now, in these MHE (n=46) and NMHE (n=54) patients, sleep disturbance was measured with Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS) and HRQOL with SF-36(v2) questionnaire. Sixty (60 %) patients were found to be 'poor sleepers' (PSQI>5) while 38 (38 %) patients had excessive daytime sleepiness (ESS≥11). Univariate and multivariate analyses showed MHE has significant effect among 'poor sleepers' (P<0.0001) as well as on those with EDS (P<0.0001). Significant correlation existed between PHES and both the sleep parameters of PSQI (r = -0.518, P <0.0001) as well as ESS (r = -0.383, P <0.0001), implying independently strong correlation between poor cognition and the presence of night time sleep disturbance and excessive daytime sleepiness among cirrhotics. Significant correlation existed between PSQI and ESS and the various scales and component scores of SF-36(v2) signifying the negative impact of sleep disturbance on the HRQOL. In conclusion, both night time sleep disturbance and excessive daytime sleepiness have significant relation with the neuropsychiatric impairment in patients of cirrhosis and are significantly associated with the observed impairment in HRQOL.

Effect of obstructive sleep apnea on the sleep architecture in cirrhosis

STUDY OBJECTIVES

Sleep disturbances in cirrhosis are assumed to be due to hepatic encephalopathy (HE). The interaction between cirrhosis, prior HE, and obstructive sleep apnea (OSA) has not been evaluated. We aimed to evaluate the additional effect of cirrhosis with and without prior HE on the sleep architecture and perceived sleep disturbances of OSA patients.

METHODS

A case-control review of OSA patients who underwent polysomnography (PSG) in a liver-transplant center was performed. OSA patients with cirrhosis (with/without prior HE) were age-matched 1:1 with OSA patients without cirrhosis. Sleep quality, daytime sleepiness, sleep quality, and sleep architecture was compared between groups.

RESULTS

Forty-nine OSA cirrhotic patients (age 57.4 ± 8.3 years, model for end-stage liver disease (MELD) 8.3 ± 5.4, 51% HCV, 20% prior HE) were age-matched 1:1 to OSA patients without cirrhosis. Apnea-hypopnea index, arousal index, sleep efficiency, daytime sleepiness, and effect of sleepiness on daily activities were similar between OSA patients with/ without cirrhosis. Sleep architecture, including %slow wave sleep (SWS), was also not different between the groups. MELD was positively correlated with time in early (N1) stage (r = 0.4, p = 0.03). All prior HE patients (n = 10) had a shift of the architecture towards early, non-restorative sleep (higher % [N2] stage [66 vs 52%, p = 0.005], lower % SWS [0 vs 29%, p = 0.02], lower REM latency [95 vs 151 minutes, p = 0.04]) compared to the rest. Alcoholic etiology was associated with higher latency to N1/N2 sleep, but no other effect on sleep architecture was seen.

CONCLUSIONS

OSA can contribute to sleep disturbance in cirrhosis and should be considered in the differential of sleep disturbances in cirrhosis. Prior HE may synergize with OSA in worsening the sleep architecture.

Induced hyperammonemia may compromise the ability to generate restful sleep in patients with cirrhosis

In patients with cirrhosis, hyperammonemia and hepatic encephalopathy are common after gastrointestinal bleeding and can be simulated by an amino acid challenge (AAC), or the administration of a mixture of amino acids mimicking the composition of hemoglobin. The aim of this study was to investigate the clinical, psychometric, and wake-/sleep-electroencephalogram (EEG) correlates of induced hyperammonemia. Ten patients with cirrhosis and 10 matched healthy volunteers underwent: (1) 8-day sleep quality/timing monitoring; (2) neuropsychiatric assessment at baseline/after AAC; (3) hourly ammonia/subjective sleepiness assessment for 8 hours after AAC; (4) sleep EEG recordings (nap opportunity: 17:00-19:00) at baseline/after AAC. Neuropsychiatric performance was scored according to age-/education-adjusted Italian norms. Sleep stages were scored visually for 20-second epochs; power density spectra were calculated for consecutive 20-second epochs and average spectra determined for consolidated episodes of non-rapid eye movement (non-REM) sleep of minimal common length. The AAC resulted in: (i) an increase in ammonia concentrations/subjective sleepiness in both patients and healthy volunteers; (ii) a worsening of neuropsychiatric performance (wake EEG slowing) in two (20%) patients and none of the healthy volunteers; (iii) an increase in the length of non-REM sleep in healthy volunteers [49.3 (26.6) versus 30.4 (15.6) min; P = 0.08]; (iv) a decrease in the sleep EEG beta power (fast activity) in the healthy volunteers; (v) a decrease in the sleep EEG delta power in patients.

CONCLUSION

AAC led to a significant increase in daytime subjective sleepiness and changes in the EEG architecture of a subsequent sleep episode in patients with cirrhosis, pointing to a reduced ability to produce restorative sleep.

Progressive reduction of sleep time and quality in rats with hepatic encephalopathy caused by portacaval shunts

Patients with liver cirrhosis show sleep disturbances. Insight into their relationship with hepatic encephalopathy (HE) can be obtained using animal models of HE. The aims of this work were to assess (1) whether rats with portacaval shunts (PCS), a model of HE, show alterations in sleep and if they are similar to those in patients with HE; (2) Whether hyperammonemia plays a role in these sleep alterations; and (3) the time course of sleep alterations in these animal models. Rats were subjected to PCS to induce HE. Another group of rats was fed an ammonium-containing diet to induce hyperammonemia. Polysomnographic recordings were acquired for 24 h and sleep architecture was analyzed in control, PCS, and hyperammonemic rats at 4, 7, and 11 weeks after surgery or diet, respectively. PCS rats show a significant reduction in rapid eye movement (REM) and non-rapid eye movement (NREM) sleep time and increased sleep fragmentation, whereas reduced sleep occurs at 4 weeks and worsens at 7 and 11 weeks, sleep fragmentation appears at 7 weeks and worsens at 11 weeks. Hyperammonemic rats show decreased REM sleep, starting at 7 weeks and worsening at 11 weeks, with no changes in NREM sleep or sleep fragmentation. Therefore, PCS rats are a good model to study sleep alterations in HE, their mechanisms, and potential treatment. Mild hyperammonemia mainly impacts mechanisms involved in REM generation and/or maintenance but does not seem to be involved in sleep fragmentation.