Concentrations of sulfur-containing free amino acids in lumbar cerebrospinal fluid from patients with consciousness disturbances.

The concentrations of sulfur-containing amino acids (taurine, methionine, cystine, cystathionine, homocystine) in lumbar CSF from patients with consciousness disturbances and controls were measured, and it was investigated whether there was any correlation between the sequential changes of these amino acid concentrations and of the level of consciousness. In all patients, thyrotropin-releasing hormone (TRH) was administered and the changes of levels of consciousness and amino acid concentrations were followed before and after administration. The concentrations of taurine and cystathionine from the patients were significantly lower, and methionine and cystine significantly higher than those from the controls; they returned to the control values in parallel with improvement of consciousness level. Homocystine was not detected in either patients or controls. These results suggest that the alteration in the level of consciousness is associated with distortion of sulfur-containing amino acid metabolism within the central nervous system, at least in the CSF.