Evoked potentials for the evaluation of latent hepatic encephalopathy in pediatric liver transplant candidates

Methods for diagnosing hepatic encephalopathy in patients with cirrhosis: a multidimensional approach

There is no "gold standard" for diagnosing hepatic encephalopathy in patients with cirrhosis. In consequence, the presence of this condition, unless floridly overt, is often missed. As a result, the majority of patients are denied the benefits of treatment. There are a number of individual techniques, which access different aspects of cerebral function that can be used, singly or in combination, to provide diagnostic information in this condition, including mental state assessment, psychometric testing, electroencephalography, sensory and cognitive evoked potentials, and neuroimaging. These have been variously applied to the study of hepatic encephalopathy but fundamental differences in the essential aims of the studies, as well as differences in the patient populations and the acquisition and analysis of the data, have made comparisons difficult. Thus, there is no clear consensus as to the sensitivity, specificity, or validity of these tests when used alone or in combination. There are, however, a number of additional methods that could be used to analyze the electrophysiological data, and a number of alternative evoked potentials that could be measured to provide better diagnostic information. In addition, there are a number of techniques, such as critical flicker frequency and smooth pursuit eye movements, which have not yet been applied systematically in this condition and which may provide useful diagnostic information. Clearly the methods for assessing hepatic encephalopathy need to be reviewed, newer methods for analyzing the electrophysiological data and newer techniques for assessing alternative aspects of cerebral function need to be explored for their diagnostic utility. This process should aim at developing a multidimensional diagnostic tool.

Stage IV hepatic encephalopathy associated with acute blindness after liver transplantation

A 5-yr-old boy who diagnosed acute liver failure and Stage IV hepatic encephalopathy underwent living related liver transplantation and awakened with persistent hand motions visual loss. Serum Tacrolimus, electrolytes, magnesium levels were normal as well as blood pressure. His neurologic and opthamologic examinations were otherwise normal. Visual evoked potential (VEP) was prolonged and brain magnetic resonance immaging (MRI) revealed bilateral parietooccipital white matter signal abnormalities with gliosis. During follow up his visual loss resolved spontoneously as well as the VEP and MRI abnormalities. In this case we aimed to point out hepatic encephalopathy might be a cause of postoperative visual loss and serial VEP analysis is an important diagnostic tool for monitoring visual function of liver graft recipients in the post-operative period.