Challenges in diagnosing hepatic encephalopathy

EASL Clinical Practice Guidelines on the management of hepatic encephalopathy

The EASL Clinical Practice Guidelines (CPGs) on the management of hepatic encephalopathy (HE) present evidence-based answers to a set of relevant questions (where possible, formulated in PICO [patient/population, intervention, comparison and outcomes] format) on the definition, diagnosis, differential diagnosis and treatment of HE. The document does not cover the pathophysiology of HE and does not cover all available treatment options. The methods through which it was developed and any information relevant to its interpretation are also provided.

Epidemiology of Hepatic Encephalopathy

Hepatic encephalopathy (HE) is a complex condition with multiple causes each with varying degrees of severity. HE negatively impacts patients' quality of life, and it is associated with significant burdens to patients and their caregivers. The prevalence of cirrhosis, the most common risk factor for HE, has steadily increased during recent years. In turn, an upsurge in the clinical and health care burdens related to HE is expected in the upcoming years. This article provides a comprehensive review of the epidemiology of HE.

Hepatic Encephalopathy: Definition, Clinical Grading and Diagnostic Principles

In general, hepatic encephalopathy (HE) is defined as a brain dysfunction caused by liver insufficiency and/or portal-systemic blood shunting. This article relates to the so-called type C HE: that is, HE in patients with liver cirrhosis. It manifests as a wide spectrum of neurological or psychiatric abnormalities, ranging from subclinical alterations, detectable only by neuropsychological or neurophysiological assessment, to coma. Several scales have been developed for grading the extent of HE. The most often used is the West Haven criteria (WHC), which differentiate between four grades of clinically overt HE. Patients with liver cirrhosis without clinically overt symptoms of HE but neuropsychological or neurophysiological findings indicating brain dysfunction are considered to have minimal hepatic encephalopathy (MHE). For simplification, some experts suggest differentiating between covert HE (MHE plus grade I HE according to WHC) and overt HE (WHC grades II-IV). Diagnosis of both MHE and overt HE is hampered by the fact that none of the symptoms of HE or the findings in the various diagnostic measures applied are specific. Thus, a diagnosis of HE or MHE can only be made after exclusion of other possible causes of brain dysfunction.

Hepatic encephalopathy: a critical current review

Hepatic encephalopathy (HE) is a serious neuropsychiatric complication of cirrhosis and/or porto-systemic shunting. The clinical symptoms are widely variable, extending from subtle impairment in mental state to coma. The utility of categorizing the severity of HE accurately and efficiently serves not only to provide practical functional information about the current clinical status of the patient but also gives valuable prognostic information. In the past 20–30 years, there has been rapid progress in understanding the pathophysiological basis of HE; however, the lack of direct correlation between pathogenic factors and the severity of HE make it difficult to select appropriate therapy for HE patients. In this review, we will discuss the classification system and its limitations, the neuropsychometric assessments and their challenges, as well as the present knowledge on the pathophysiological mechanisms. Despite the many prevalent hypotheses around the pathogenesis of the disease, most treatments focus on targeting and lowering the accumulation of ammonia as well as inflammation. However, treatment of minimal HE remains a huge unmet need and a big concerted effort is needed to better define this condition to allow the development of new therapies. We review the currently available therapies and future approaches to treat HE as well as the scientific and clinical data that support their effectiveness.

Qualifying and quantifying minimal hepatic encephalopathy

Minimal hepatic encephalopathy is the term applied to the neuropsychiatric status of patients with cirrhosis who are unimpaired on clinical examination but show alterations in neuropsychological tests exploring psychomotor speed/executive function and/or in neurophysiological variables. There is no gold standard for the diagnosis of this syndrome. As these patients have, by definition, no recognizable clinical features of brain dysfunction, the primary prerequisite for the diagnosis is careful exclusion of clinical symptoms and signs. A large number of psychometric tests/test systems have been evaluated in this patient group. Of these the best known and validated is the Portal Systemic Hepatic Encephalopathy Score (PHES) derived from a test battery of five paper and pencil tests; normative reference data are available in several countries. The electroencephalogram (EEG) has been used to diagnose hepatic encephalopathy since the 1950s but, once popular, the technology is not as accessible now as it once was. The performance characteristics of the EEG are critically dependent on the type of analysis undertaken; spectral analysis has better performance characteristics than visual analysis; evolving analytical techniques may provide better diagnostic information while the advent of portable wireless headsets may facilitate more widespread use. A large number of other diagnostic tools have been validated for the diagnosis of minimal hepatic encephalopathy including Critical Flicker Frequency, the Inhibitory Control Test, the Stroop test, the Scan package and the Continuous Reaction Time; each has its pros and cons; strengths and weaknesses; protagonists and detractors. Recent AASLD/EASL Practice Guidelines suggest that the diagnosis of minimal hepatic encephalopathy should be based on the PHES test together with one of the validated alternative techniques or the EEG. Minimal hepatic encephalopathy has a detrimental effect on the well-being of patients and their care-givers. It responds well to treatment with resolution of test abnormalities and the associated detrimental effects on quality of life, liver-related mortality and morbidity. Patients will only benefit in this way if they can be effectively diagnosed. Corporate efforts and consensus agreements are needed to develop effective diagnostic algorithms.

The Clinical Relevance of Minimal Hepatic Encephalopathy--A Critical Look

Minimal hepatic encephalopathy (mHE) is diagnosed in patients with severe liver disease but no clinical symptoms of encephalopathy if either neuropsychological or neurophysiological tests indicate cerebral dysfunction and other possible causes of brain dysfunction have been excluded. mHE is characterized by deficits in attention, visuospatial orientation, visuoconstructive abilities and motor function. Accordingly, mHE can be expected to interfere with a subject's working ability, especially in those occupations that require handiwork, and driving ability. Indeed, about 60% of blue-collar workers with mHE have been shown to be assessed as unfit for work compared to only 20% of white-collar workers, and about 50% of patients with mHE have been judged unfit to drive a car in several studies. mHE interferes with a patient's quality of life and is associated with an increased risk of developing overt HE as well as increased mortality. Whether mHE is of importance for cognitive function after liver transplantation has still to be clarified.