Autonomic and peripheral neuropathy in endstage liver disease and following liver transplantation

Contemporary management of pain in cirrhosis: Toward precision therapy for pain

Chronic pain is highly prevalent in patients with cirrhosis and is associated with poor health-related quality of life and poor functional status. However, there is limited guidance on appropriate pain management in this population, and pharmacologic treatment can be harmful, leading to adverse outcomes, such as gastrointestinal bleeding, renal injury, falls, and hepatic encephalopathy. Chronic pain can be categorized mechanistically into three pain types: nociceptive, neuropathic, and nociplastic, each responsive to different therapies. By discussing the identification, etiology, and treatment of these three mechanistic pain descriptors with a focus on specific challenges in patients with cirrhosis, we provide a framework for better tailoring treatments, including nonpharmacologic therapies, to patients' needs.

Neuromuscular Complications of SARS-CoV-2 and Other Viral Infections

In this article we review complications to the peripheral nervous system that occur as a consequence of viral infections, with a special focus on complications of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). We discuss neuromuscular complications in three broad categories; the direct consequences of viral infection, autoimmune neuromuscular disorders provoked by viral infections, and chronic neurodegenerative conditions which have been associated with viral infections. We also include discussion of neuromuscular disorders that are treated by immunomodulatory therapies, and how this affects patient susceptibility in the current context of the coronavirus disease 2019 (COVID-19) pandemic. COVID-19 is associated with direct consequences to the peripheral nervous system via presumed direct viral injury (dysgeusia/anosmia, myalgias/rhabdomyolysis, and potentially mononeuritis multiplex) and autoimmunity (Guillain Barré syndrome and variants). It has important implications for people receiving immunomodulatory therapies who may be at greater risk of severe outcomes from COVID-19. Thus far, chronic post-COVID syndromes (a.k.a: long COVID) also include possible involvement of the neuromuscular system. Whether we may observe neuromuscular degenerative conditions in the longer term will be an important question to monitor in future studies.

Relation between the severity of liver cirrhosis and neurological symptoms, nerve conduction study results, and motor unit number estimation

Liver cirrhosis is a global health problem that can be associated with several neurological manifestations. We aimed to assessment of the relation between the severity of the liver cirrhosis and the neurological symptoms, nerve conduction studies (NCS), as well as detecting subclinical neuropathic affection using motor unit number estimation (MUNE) technique. This cross-sectional study was conducted on 56 cirrhotic patients and 61 age- and sex-matched healthy controls. Neurological manifestations, Child-Pugh classification, Model for End-Stage Liver Disease score, NCS and MUNE using a modified spike-triggered averaging technique were studied. Forty-five (80.3%) of the cirrhotic patients had neurological manifestations. Muscle cramps were the most frequently reported manifestation, followed by fatigue and then numbness. NCS abnormality was significantly related to the presence of neurological symptoms (p < 0.001) and not only to peripheral numbness. Only fatigue was significantly related to the lower MUNE values (p < 0.017). Child-Pugh classification progression was significantly related to the presence of fatigue and abnormal NCS results (p < 0.001); no similar relation was detected between the Child-Pugh classification and the MUNE value (p = 0.103). Higher MELD scores were significantly related to NCS abnormalities (p = 0.014) and negatively correlated, although not significantly, with the MUNE values (r = -0.246 and p = 0.067). The progression of liver cirrhosis was related to the presence of neurological manifestations and nerve conduction abnormalities. Nerve conduction abnormalities may be present even in the absence of clinical numbness. A decline in motor unit number could explain the pathophysiology of fatigue in cirrhotic patients.

Gastrointestinal Disorders and the Nervous System

PURPOSE OF REVIEW

This article describes the neurologic sequelae of various nutritional micronutrient deficiencies, celiac disease, inflammatory bowel disease, and liver disease. Where relevant, appropriate treatments for these conditions are also discussed. The developing field of the microbiome and nervous system interaction is also outlined.

RECENT FINDINGS

Pathology in the gastrointestinal system can affect the nervous system when it causes micronutrient deficiency, when immune responses created by the gastrointestinal system affect the nervous system, when toxins caused by gastrointestinal organ failure harm the nervous system, and when treatments aimed at a gastrointestinal medical condition cause damage to the nervous system as a side effect.

SUMMARY

This article addresses familiar concepts and new developments in the treatment and understanding of diseases that affect the gut and nervous system simultaneously.

The role of autonomic dysfunction in cirrhotic patients before and after liver transplantation. Review of the literature

In patients affected by hepatic cirrhosis, autonomic dysfunction is a common finding; usually it is asymptomatic but it may correlate with increased mortality and morbidity before, during and after liver transplant, due to hemodynamic instability in the course of stressful events like sepsis, gastrointestinal bleeding and reperfusion after transplantation surgery. Hyperdynamic circulation and hepatic dysfunction seem to play a role in the pathogenesis of autonomic dysfunction, even if pathophysiological mechanisms are not completely known. We present a revision of previous literature about prevalence, pathophysiological mechanisms, clinical features, and mortality and morbidity of autonomic dysfunction secondary to hepatic cirrhosis.

An association of large-fibre peripheral nerve dysfunction with non-invasive measures of liver fibrosis secondary to non-alcoholic fatty liver disease in diabetes

AIM

To examine for an association of elevated lower-limb vibration perception threshold (VPT) with NAFLD fibrosis.

METHODS

Two cohorts from a tertiary diabetes centre were studied - Cohort 1, n=456 with type 1 or 2 diabetes, and Cohort 2, n=106 with type 2 diabetes mellitus. All underwent a detailed assessment, including VPT measurement. Cohort 2 also had liver ultrasound and transient elastography (TE). NAFLD Fibrosis Score (NFS) was calculated for all with available data. Follow-up VPT measurements on participants in Cohort 1 to 2014 were also collected if available.

RESULTS

Adjusted risk of higher VPT category (≥25V but <50V, or ≥50V, c.f. < 25V) was greater for high-risk NFS in both cohorts (Cohort 1, OR 2.22 [95% CI 1.24-3.98, p=0.007] and Cohort 2, OR 4.51 [95% CI 1.08-18.87], p=0.039) and higher liver stiffness measurement (LSM) by TE in Cohort 2 (OR for each unit natural log increase in LSM of 2.42 (95% CI 1.13-5.19), p=0.023). In Cohort 1, in those with VPT<50V and complete data, those with higher NFS had greater odds of increasing VPT category after 2.2 (IQR 1.5-2.9) years.

CONCLUSIONS

Higher VPT associates with markers of liver fibrosis due to NAFLD in diabetes mellitus.

Association between non-alcoholic fatty liver disease and autonomic dysfunction in a Chinese population

BACKGROUND

Autonomic dysfunction (AD) accompanying with chronic liver disorders led to an increased risk of mortality. However, researches that investigated the association between non-alcoholic fatty liver disease (NAFLD) and AD were insufficient.

AIMS

To study the association of NAFLD with AD in middle-aged and elderly Chinese adults.

DESIGN

Four thousand nine hundred seventy-four adults aged 40 years or older were enrolled in this cross-sectional study. NAFLD was diagnosed by hepatic B-mode ultrasonography. Autonomic function was assessed using a simple EZSCAN test by measuring sudomotor function, with an AD index > 50% defined as a manifestation of AD.

METHODS

Pearson correlation, multiple stepwise linear regression, univariate and multivariate logistic regression was employed to examine the relationship between NAFLD and AD, controlling for potential confounders.

RESULTS

The prevalence of AD was significantly higher in participants with NAFLD than those without (40.75 vs. 26.86%, P < 0.0001). Age, body mass index, status of diabetes, sex, diastolic blood pressure and prevalent NAFLD, were positively correlated with AD index in multiple stepwise linear regression analysis (all P < 0.05), whereas total cholesterol was negatively related to it (P = 0.0043). Compared with the participants without NAFLD, those with NAFLD had an increased odds of the prevalent AD (odds ratio 1.38; 95% confidence interval 1.15-1.64; P = 0.0004) after controlling for multiple confounders.

CONCLUSIONS

The presence of NAFLD was significantly associated with AD, as indicated by abnormal sudomotor function. The association was independent from various conventional risk factors.

Autonomic dysfunction in chronic liver disease

It is becoming increasingly clear that quality of life (QOL) is impaired in those with chronic liver disease (CLD). One of the most important contributors to impaired QOL is the symptomatic burden which can range from slight to debilitating. Autonomic dysfunction accounts for a significant proportion of these symptoms, which can be common, non-specific and challenging to treat. Investigating the autonomic nervous system can be straight forward and can assist the clinician to diagnose and treat specific symptoms. Evidence-based treatment options for autonomic symptoms, specifically in CLD, can be lacking and must be extrapolated from other studies and expert opinion. For those with severely impaired quality of life, liver transplantation may offer an improvement; however, more research is needed to confirm this.

Long-term effect of liver transplantation on cirrhotic autonomic cardiac dysfunction

There is little information on the long-term effect of liver transplantation (LT) on cardiac autonomic dysfunction in cirrhotic patients. We compared cardiac autonomic function before and in the long-term after LT. In a transversal study, we investigated 30 cirrhotics awaiting LT, 15 clinically stable patients 2-6 years after LT and 27 healthy controls. Seven cirrhotic patients were studied before LT, and 6, 12 and 33 months after LT, in a prospective fashion. Cardiac autonomic function was measured by heart rate variability (HRV) analysis during 24-h electrocardiogram recording. In the transversal study, patients with cirrhosis as compared to healthy controls had significantly reduced standard deviation of normal-to-normal RR intervals (SDNN) (p<0.001) and of the square root of the mean of squared differences between adjacent NN intervals (RMS-SD) (p<0.01), while the ratio between low frequency (LF) and high frequency (HF) at night was significantly (p<0.05) increased. Liver transplanted patients had significantly (p<0.001) higher SDNN values than cirrhotics, while RMS-SD and LF/HF at night did not differ. In the prospective study, SDNN progressively increased after LT and was significantly (p<0.05) higher at 12 and 33 months, compared to the pre-operative value. RMS-SD and LF/HF at night did not change after LT. In conclusion, the overall HRV decrease present in cirrhosis, measured by SDNN values, is partially corrected in the long-term after LT. However, parasympathetic impairment, measured by RMS-SD and LF/HF at night, is not affected even in the long-term after operation.

Autonomic dysfunction in chronic liver disease

Autonomic dysfunction (AD) is common in chronic liver disease (CLD) of all aetiologies and even more so in those awaiting transplantation. As yet, the pathophysiology is not completely understood but the clinical effects are dramatic for the patient, who has a heavy symptomatic burden. There are several considerations, specific to liver disease, which complicate AD. Outlined here is a practical guide for clinicians detailing the common presentations and consequences of AD, investigation techniques and treatment options. As morbidity and mortality is increased in CLD patients with AD its recognition, investigation and management is important to all who encounter such patients.

Population prevalence and symptom associations of autonomic dysfunction in primary biliary cirrhosis

Patients with primary biliary cirrhosis (PBC) frequently experience significant fatigue thought to result from as-yet-unidentified central nervous system (CNS)-mediated processes. Pilot studies have suggested that autonomic dysfunction is a frequent occurrence in PBC and may contribute to the pathogenesis of this fatigue. The degree to which autonomic dysfunction affects the PBC population as a whole, and its interrelationship with other symptoms experienced by PBC patients remains unstudied. In this study, we used a geographically defined, fully representative PBC patient cohort to study the prevalence of symptoms of autonomic dysfunction and its relationship with other symptoms of PBC. Symptoms of cardiovascular autonomic dysfunction (as assessed using the Orthostatic Grading Scale [OGS]) were significantly more frequently reported and significantly more severe in PBC patients than in both matched normal controls (40% versus 6% with moderate or worse orthostasis (P < .0001), mean OGS score 3.2 +/- 3.4 versus 1.3 +/- 1.9, P < .005) and in patients with primary sclerosing cholangitis and in severity were independently associated with severity of fatigue and cognitive symptoms (both r2 = 0.3, P < .0001). Thirteen of 20 patients with an OGS value > 4 (moderate severity and worse) had significant abnormality in autonomic regulation of blood pressure, which was identified on dynamic testing.

CONCLUSION

Symptoms suggestive of autonomic dysfunction frequently occur in PBC patients and reflect dysregulation of actual blood pressure. Autonomic dysfunction is independently associated with both fatigue and, importantly, symptoms of cognitive dysfunction, suggesting the potential for significant organic sequelae.

Conduction and excitability properties of peripheral nerves in end-stage liver disease

The pathophysiology of hepatic neuropathy is poorly understood, but membrane depolarization due to a toxic inhibition of oxidative metabolism has been proposed. We investigated the relationship between nerve excitability properties, nerve dysfunction, and liver function in 11 pretransplant patients, the majority of whom were oligo- or asymptomatic for peripheral neuropathy. Abnormalities were detected on clinical examination (6), large-fiber nerve conduction (4), and thermal quantitative sensory testing (10). Small-fiber involvement was characterized by elevation of warm more than cold detection thresholds. Autonomic dysfunction was less frequent (4). Nerve excitability parameters in both upper and lower limbs provided evidence of membrane depolarization compared with controls, even in those patients without a history of alcohol abuse. No clear correlation was found between neurophysiological indices and scores of hepatic reserve or various blood parameters including ammonia level. Although chronic membrane depolarization may be involved, the degree of depolarization in large fibers was small, and its role in the pathophysiology of neuropathy uncertain.

Bilateral Drop-Foot After Orthotopic Liver Transplant

Patients may demonstrate various neuromuscular abnormalities after liver transplantation. We report a patient who developed bilateral drop foot after orthotopic liver transplantation. He was diagnosed with critical illness polyneuropathy. During follow-up, his complaints gradually recovered and his electrodiagnostic findings improved.

Preoperative optimization of patients with liver disease

PURPOSE OF REVIEW

Recent papers relevant to the preoperative evaluation and optimization of patients with severe liver disease will be discussed. The emphasis will be placed on cardiovascular, pulmonary, and renal complications. Other aspects such as preoperative management of hepatitis B and C, other infectious issues, and liver cancer will not be discussed because this rarely involves the anesthesiologist.

RECENT FINDINGS

Dobutamine stress echocardiography has been the cornerstone of cardiac evaluation of liver transplant candidates. Combining liver transplantation with cardiac procedures has been shown to be feasible. While mild hepatopulmonary syndrome is well-tolerated, severe hepatopulmonary syndrome carries a fairly high mortality rate. New treatment modalities of severe portopulmonary hypertension have been introduced, and may have advantages over epoprostenol administration. Hepatic hydrothorax requires similar therapy to ascites [repeated thoracentesis or paracentesis, and transjugular intrahepatic portosystemic shunt (TIPS)], but refractory hydrothorax may require other interventions. Hepatorenal syndrome may improve by increasing renal blood flow through the use of vasoconstrictors (vasopressin, norepinephrine) in combination with albumin administration. Interventional radiologists can now change the flow through an established TIPS. Hepatic encephalopathy may result in some irreversible changes in the brain. It remains difficult to predict whether a patient with acute fulminant failure will recover spontaneously. Support devices that include hepatocytes show early promising results. The coagulation changes in living donors are incompletely understood. Finally, autonomic neuropathy as a complication of severe liver disease results in more hemodynamic instability.

SUMMARY

Recent advances in preoperative evaluation and optimization are presented and discussed.