Reduction of highly elevated plasma levels of gamma-aminobutyric acid does not reverse hepatic coma.

The pathogenesis of coma in patients with fulminant hepatic failure is still unknown, but there is some evidence that decreased hepatic metabolism of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) may be involved. If this hypothesis is true, reduction of increased GABA levels in patients with hepatic encephalopathy should reduce the depth of hepatic coma. In the case described here, highly elevated plasma GABA levels were reduced by cross-circulation with baboon liver. No amelioration of the coma was observed, thus suggesting that decreased hepatic metabolism of GABA is not critically involved in hepatic encephalopathy.