Qualifying and quantifying minimal hepatic encephalopathy

Abstract

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.

Hepatic Encephalopathy: Definition, Clinical Grading and Diagnostic Principles

“…Specialized centers frequently use computerized electroencephalogram (EEG) analysis and/or critical flicker frequency (CFF) in addition to psychometric measures for diagnosing MHE [11, 12]. However, widespread use of the EEG as diagnostic tool is impeded by limited access to this method.…”

“…A combination of different neuropsychological and neurophysiological diagnostic approaches appears rational, since there is no complete overlap in the results when comparing the various measures available [11–15]. Recently, a combination of the currently most frequently used methods—the PHES, EEG and CFF—has been recommended for screening [12].…”

Hepatic encephalopathy: Diagnosis and management

“…Thus, ANT can be recommended for everyday use in hepatological practice. For centres that are highly motivated in the care of HE, more accurate tools are the psychometric HE score (PHES), the critical flicker frequency (CFF) and the quantified electroencephalogram (qEEG) . Computerised tests to assess attention, working memory or inhibition can be conducted in patients with high skill.…”

“…For centres that are highly motivated in the care of HE, more accurate tools are the psychometric HE score (PHES), the critical flicker frequency (CFF) and the quantified electroencephalogram (qEEG). 23 Computerised tests to assess attention, 24,25 working memory 26 or inhibition 27,28 can be conducted in patients with high skill. Thus, these tools are probably more useful for detecting minimal HE in asymptomatic patients than attempting to grade the entire spectrum of covert HE, which also includes mildly symptomatic patients, whose cooperation and ability to perform such tests is doubtful.…”

Electroencephalogram Abnormalities in Very Young Children with Acute Hepatitis A Infection: A Cross-Sectional Study

“…This method provides a sensitive and reliable procedure for screening neurophysiological disorders (14). Abnormal EEG has been noted as an early diagnostic sign for brain dysfunction in the absence of overt or minimal HE (15,16). There is a shortage on studies concerned with EEG abnormalities in neurologically asymptomatic children with HAV infection.…”