Current and future diagnosis of hepatic encephalopathy.

This short communication is based on the lecture given by the author entitled “Current and Future Diagnosis of Hepatic Encephalopathy” at the 5th Hannover International Conference on Hepatic Encephalopathy held in Mainz, Germany in May 2009. The presentation was based on published literature and abstracts and involved a concise review of currently available strategies to diagnose hepatic encephalopathy (HE). The talk started with an overview of the clinical scales that are currently used to diagnose HE (Ferenci et al. 2002). Clinical methods that were discussed were the West-Haven Scale, the Hepatic Encephalopathy Scoring Algorithm (HESA), the Clinical Hepatic Encephalopathy Staging Scale (CHESS) and the Porto-Systemic Encephalopathy (PSE) index (Conn et al. 1977, Teasdale and Jennett 1974, Blei and Cordoba 2001, Hassanein et al. 2008, 2009). The standard currently used is the West-Haven scale that divides patients with HE from stages 0 through 4 (Teasdale and Jennett 1974). Stage 4 is coma while stage 0 is technically “normal”. Stage 1 is characterized by “trivial lack of awareness, euphoria or anxiety, shortened attention span and impairment of addition or subtraction” while stage 2 onwards, disorientation starts. The West Haven scale has been criticized for its subjectivity, especially in the initial stages of 0 through 2. Specifically, there is little agreement between observers at different centers regarding their interpretation of HE grade using the West-Haven criteria alone (Hassanein et al. 2009). This subjective nature is also difficult to overcome while designing and interpreting HE trials that are conducted on a multi-center basis. This led to an overview of the CHESS, which is a simple 9-question scale used to characterize orientation and current awareness that is still undergoing validation (Ortiz et al. 2007). The PSE index and HESA were discussed briefly as scales that blend clinical and psychometric/neurophysiologic measures. The PSE index, consisting of clinical assessment, EEG, arterial ammonia, trail-making test time and asterixis, has not been used widely since its components are inter-related and not specific (Ferenci et al. 2002). The HESA, is a blended scale consisting of clinical evaluation of the mental status and neuropsychological parameters. It seeks to improve upon the West-Haven criteria by dividing HE into four grades with the neuropsychological assessment in addition to the pure clinical assessment as in the West-Haven Scale (Hassanein et al. 2008, 2009). The psychometric tests used are simple, such as computations, construction ability and memory (Hassanein et al. 2009). The role of HESA is evolving and it needs further validation. A brief mention was made of asterixis as a physical finding in HE and the lack of specificity and sensitivity of this clinical finding alone (Ferenci et al. 2002). The presence of asterixis in renal failure and carbon dioxide narcosis and its absence in early and very advanced HE was highlighted. The specialized tests currently available for HE were then presented under the broad headings of psychometric and neuro-physiologic tests (Ferenci et al. 2002).