Effect of cerebral injury on cerebrospinal fluid cyclic AMP concentration.

Cerbrospinal fluid (CSF) cyclic adenosine-3', 5'-monophosphate (cAMP) was measured in rabbits after experimental brain injury as well as in patients with cerebral contusion and cerebral concussion. In rabbits a marked elevation lasting for two weeks was observed. From the third week onwards after the injury the CSF cAMP concentration was lower than the basal level before the injury. Dexamethasone partly inhibited the elevation. Ethanol treatment decreased the CSF cAMP values. In man, the CSF cAMP concentration was significantly higher in patients with cerebral contusion than in those with cerebral concussion. Also in the latter group the cAMP values were higher than in control patients. Due to the clear differences between the various groups, measurement of cAMP concentration in CSF might have diagnostic value in evaluation of the severity of cerebral lesion in the acute phase. Also the activities of some enzymes were measured, and the results were parallel with cAMP changes but less striking.