Quantification of the electroencephalographic theta/alpha ratio for the assessment of portal-systemic encephalopathy following implantation of transjugular intrahepatic portosystemic stent shunt (TIPSS).

The aim of the study was the quantification of metabolically caused electroencephalographic changes of portal-systemic encephalopathy, a prototype of hepatic encephalopathy. We examined 12 patients with liver cirrhosis before and after implantation of a transjugular intrahepatic portosystemic stent shunt (TIPSS) by means of quantitative digital electroencephalography (EEG). One month after TIPSS implantation, all patients showed an increase in the power of the theta frequency band as well as a decrease in the power of the alpha frequency band. To reduce the error variance, we formed the quotient of the relative power of the theta and alpha frequency band. Theta/alpha quotient values over 0.7 indicate a general change of the EEG with a sensitivity of 93% and a specificity of 87%. The results we have to hand indicate a correlation between the albumin concentration and the theta/alpha quotient 1 and 3 months after TIPSS. No significant correlation was revealed with regard to the Child-Pugh score or the liver function parameters cholinesterase, bilirubin, and prothrombin time. Neither the arterial ammonia concentration nor the performance in the psychometric test showed significance in relation to the theta/alpha quotient. Substances with a high albumin bond and potential neurotoxicity may--in the case of lower albumin levels--be absorbed with increased frequency in the CNS and may be responsible for the observed EEG change.