[Show abstract][Hide abstract] ABSTRACT: To compare electroencephalographic spectral analysis obtained by periodogram (calculated by means of Fast Fourier Transform) and autoregressive (AR) modelling for the assessment of hepatic encephalopathy.
The mean dominant frequency (MDF) and the relative power of delta, theta, alpha, and beta bands were computed by both techniques from the electroencephalograms (EEG) of 201 cirrhotics and were evaluated in the clinical and prognostic assessment of the patients.
The values of all the five indexes computed by periodogram and AR modelling matched each other, but the latter provided stable values after the analysis of fewer epochs. Independently of the technique, the relative power of theta and alpha bands fitted the clinical data and had prognostic value. The relative power of beta and delta bands computed by AR modelling fitted more closely with clinical data fitted the clinical data more closely.
The electroencephalographic spectral indexes obtained by periodogram and AR modelling were found to be, on average, undistinguishable, but the latter appeared less sensitive to noise and provided a more reliable assessment of low-power bands.
Full-text · Article · May 2009 · Neurophysiologie Clinique/Clinical Neurophysiology
[Show abstract][Hide abstract] ABSTRACT: Spectral EEG analysis has been claimed to reduce subjective variability in EEG assessment of hepatic encephalopathy and to allow the detection of mild encephalopathy.
To test such assumptions, 43 digital EEG were recorded in 32 cirrhotics without overt encephalopathy or with grade 1 overt encephalopathy; 7 patients were re-tested (2-5 times) in their follow up. All patients underwent psychometric assessment. Nineteen controls were considered. EEG were blindly evaluated by two electroencephalographers and by spectral EEG analysis performed according to 3 different techniques.
The reliability of the classification based on spectral analysis (biparietal technique) was higher than that based on a three-degree qualitative visual reading (concordance/discordance = 58/4 versus 46/16 P < 0.01) and comparable with that of semiquantitative visual assessment based on posterior basic rhythm (concordance/discordance = 55/7 P = 0.5). The accuracy of spectral EEG analysis was higher than that of qualitative visual EEG readings alone (90 versus 75%) and comparable to semi-quantitative visual assessment (87%), however, statistical significance was not reached. In the follow-up, the variations of theta and delta relative power were found to be significantly correlated with psychometric variations.
In conclusion, spectral EEG analysis may improve the assessment of mild hepatic encephalopathy by decreasing inter-operator variability and providing reliable parameters correlated with mental status.
No preview · Article · Sep 1999 · Clinical Neurophysiology
[Show abstract][Hide abstract] ABSTRACT: This article reviews the literature on the role of zinc in liver cirrhosis and dietary zinc supplementation for cirrhotic patients with hepatic encephalopathy. Zinc is a trace metal found in many proteins and enzymes having catalytical, cocatalytical and structural functions. Zinc deficiency has been demonstrated in cirrhotic patients, and dietary supplementation of this metal could benefit the urea cycle, glucose and protein metabolism, and central nervous system neurotransmission in these subjects. After some brief considerations on normal zinc metabolism, the role zinc plays in the central nervous system, and its conduct in patients with hepatic encephalopathy, possible links between zinc deficiency and the pathophysiology of central nervous system dysfunction in cirrhotic patients are discussed. The article concludes with a critical review of favorable and unfavorable evidence for zinc supplementation in patients with hepatic encephalopathy.
No preview · Article · Jan 1998 · Annali italiani di medicina interna: organo ufficiale della Societa italiana di medicina interna
[Show abstract][Hide abstract] ABSTRACT: It is not yet clear if benzodiazepine receptor ligands,implicated in the pathophysiology of hepatic coma, also have a role in subclinical cognitive orneurophysiological alterations in cirrhotic patients. Therefore, we carried out a double-blind,placebo-controlled study to evaluate the effectiveness of flumazenil, a benzodiazepine antagonist,on brainstem auditory evoked responses and on the number connection test in cirrhotic patientswith subclinical neurophysiological or cognitive alterations. Thirteen cirrhotic subjects withsubclinical neurophysiological or cognitive alterations were studied. A total of 3 mg of flumazenilor saline was infused intravenously. Before and after the infusion, the number connection test wasadministered and brainstem auditory evoked responses recorded. After 72 h, patients werecrossed over. Flumazenil did not influence brainstem auditory evoked responses or the numberconnection test. A screening test for benzodiazepines was negative in all subjects. We concludethat benzodiazepine receptor ligands have a negligible role, if any, in the pathophysiology of sub-clinical neurophysiological or cognitive alterations of cirrhotic patients.