An assessment of progression of brain edema with amino acid levels in cerebrospinal fluid and changes in electroencephalogram in an adult cat model of cold brain injury.

We investigated the relationship between the changes of the electroencephalogram (EEG) and concentration of amino acids (AAs) in cerebrospinal fluid (CSF) using a model of cold brain injury. A cold injury was made over the motor area of anesthetized adult cats (n = 45). The AAs in CSF from cisterna magna and in the blood were assayed by liquid chromatography. Frequency components and spike discharges/100 s in EEG were evaluated. Data were obtained before production of the lesion and every hour for 8 hours after the lesion was made. The AA-levels and EEG after the lesion was made were compared with those obtained in the controls and the sham operation group: S-group (n = 10) which were not significantly different. Glutamate and aspartate were not detected but methionine and serine were detected in the control CSF and S-group. These AAs increased during the first 4 hours (p < 0.05) and decreased thereafter. Significant increases in spike discharge and disappearance of fast wave (p < 0.02), and increase in AAs were concurrently detected. The AAs originated from necrosis in the lesion. During the next 4 hours, increase of phenylalanine, tyrosine, and valine continued (p < 0.05). Slow wave components (p < 0.02) and precursor AAs of neurotransmitters in CSF increased in association with expansion of edema fluid. In conclusion, our findings showed that changes in the concentration of AAs in CSF are useful indices of progression of edema associated with brain contusion.