Analysis of EEG tracings in frequency and time domain in hepatic encephalopathy

Spectral EEG analysis in hepatic encephalopathy (HE) is usually performed disregarding the effect of epoch length, statistical errors and equipment noise. A study on these items was carried out. In addition, spectral analysis and a new analysis, performed in time domain, were compared in the assessment of HE. The EEG tracings of 73 cirrhotic patients with HE were analyzed. Artifact-free periods of about 1 min were selected. Equipment noise was measured by short-circuiting all the electrodes. The equipment noise was notable below 1.5 Hz; the best epoch length was 4s and the statistical errors were minimal for the band with the highest relative power. Nineteen per cent of the tracings were unstable. The spectral values were found to be related to liver function and to the degree of HE, whereas the relationship with psychometric variables was poor. The indexes computed by time-domain analysis were found to be better related to psychometric findings. We have provided information on the optimisation of spectral EEG analysis and presented a time-domain analysis giving results related to psychometric tests and liver function.

[1]  L. Seeff,et al.  Comparison of lactulose and neomycin in the treatment of chronic portal-systemic encephalopathy. A double blind controlled trial. , 1977, Gastroenterology.

[2]  P. Amodio,et al.  Diagnostic tools for the detection of subclinical hepatic encephalopathy: comparison of standard and computerized psychometric tests with spectral-EEG , 1996, Metabolic Brain Disease.

[3]  A. Dawson,et al.  Method for Measuring Cerebral Dysfunction in Patients with Liver Disease , 1970, British medical journal.

[4]  G. Knoll,et al.  Single-photon emission computed tomography , 1983, Proceedings of the IEEE.

[5]  S. Taylor-Robinson.  Applications of magnetic resonance spectroscopy to chronic liver disease. , 2001, Clinical medicine.

[6]  Tabershaw Ir,et al.  Benzene and leukaemia. , 1977 .

[7]  R. Pugh,et al.  Transection of the oesophagus for bleeding oesophageal varices , 1973, The British journal of surgery.

[8]  R. Butterworth.  Pathophysiology of Hepatic Encephalopathy: A New Look at Ammonia , 2002, Metabolic Brain Disease.

[9]  Alan H. Lockwood,et al.  Positron Emission Tomography in the Study of Hepatic Encephalopathy , 1998, Metabolic Brain Disease.

[10]  S. Sherlock,et al.  The electroencephalograph in liver disease. , 1957, Lancet.

[11]  P. Angeli,et al.  Clinical features and survivial of cirrhotic patients with subclinical cognitive alterations detected by the number connection test and computerized psychometric tests , 1999, Hepatology.

[12]  W. Hop,et al.  Subclinical hepatic encephalopathy impairs daily functioning , 1998, Hepatology.

[13]  H. Conn.  Trailmaking and number-connection tests in the assessment of mental state in portal systemic encephalopathy , 1977, The American Journal of Digestive Diseases.

[14]  J. Meulstee,et al.  The diagnosis of subclinical hepatic encephalopathy in patients with cirrhosis using neuropsychological tests and automated electroencephalogram analysis , 1996, Hepatology.

[15]  Jones Ea,et al.  Methods for Assessing Hepatic Encephalopathy , 1983, Seminars in liver disease.

[16]  L. Caregaro,et al.  Study on the Sternberg Paradigm in Cirrhotic Patients Without Overt Hepatic Encephalopathy , 1998, Metabolic Brain Disease.

[17]  W. Hop,et al.  The prognostic significance of subclinical hepatic encephalopathy , 2000, American Journal of Gastroenterology.

[18]  S. Bluml,et al.  Proton magnetic resonance spectroscopy: the new gold standard for diagnosis of clinical and subclinical hepatic encephalopathy? , 1996, Digestive diseases.

[19]  N. Gitlin,et al.  The diagnosis and prevalence of subclinical hepatic encephalopathy in apparently healthy, ambulant, non-shunted patients with cirrhosis. , 1986, Journal of hepatology.

[20]  J Theiler,et al.  Low Doses of Ethanol Reduce Evidence for Nonlinear Structure in Brain Activity , 1998, The Journal of Neuroscience.

[21]  Y. Beers.  Introduction to the theory of error , 1953 .

[22]  J. Guérit,et al.  Spectral versus visual EEG analysis in mild hepatic encephalopathy , 1999, Clinical Neurophysiology.

[23]  M. Morgan,et al.  Methods for Diagnosing Hepatic Encephalopathy in Patients with Cirrhosis: A Multidimensional Approach , 2004, Metabolic Brain Disease.

[24]  P. Angeli,et al.  Prevalence and prognostic value of quantified electroencephalogram (EEG) alterations in cirrhotic patients. , 2001, Journal of hepatology.

[25]  L. Caregaro,et al.  Visual attention in cirrhotic patients: A study on covert visual attention orienting , 1998, Hepatology.

[26]  M. Morgan,et al.  Characteristics of Minimal Hepatic Encephalopathy , 2004, Metabolic Brain Disease.

[27]  W. Hop,et al.  The prognostic significance of subclinical hepatic encephalopathy. , 2000 .

[28]  A. Lockwood,et al.  Positron‐emission tomographic localization of abnormalities of brain metabolism in patients with minimal hepatic encephalopathy , 1993, Hepatology.

[29]  S. Luise,et al.  Neuropsychological–Neurophysiological Alterations and Brain Atrophy in Cirrhotic Patients , 2003, Metabolic Brain Disease.

[30]  Klaus P. Ebmeier,et al.  Regional cerebral blood flow and cognitive function in patients with chronic liver disease , 1991, The Lancet.

[31]  S W Schalm,et al.  Quantitative EEG analysis and evoked potentials to measure (latent) hepatic encephalopathy. , 1992, Journal of hepatology.

[32]  M. Vlieger,et al.  Objective measurement of hepatic encephalopathy by means of automated EEG analysis. , 1984, Electroencephalography and clinical neurophysiology.