Cerebrospinal fluid levels of cyclic nucleotides in meningitis and idiopathic polyneuritis

Cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP) were measured in cerebrospinal fluid (CSF) and plasma from 7 patients with bacterial meningitis, 9 patients with serous meningitis, 5 patients with idiopathic polyneuritis and 15 reference patients. A significantly (P less than 0.01) higher mean concentration of CSF cAMP was found in serous meningitis (33.8 +/- 12.5 nmol/l) compared to the reference group (20.2 +/- 4.0 nmol/l). No significant difference could be observed between the patients with purulent meningitis compared to the reference group. The CSF cAMP concentration (11.0 +/- 2.8 nmol/l) for idiopathic polyneuritis was significantly (P less than 0.01) lower than in the reference group. No difference in CSF levels of cGMP or in the cAMP/cGMP ratios were detected between the groups. Our data suggest that the ratio between cAMP concentrations in CSF and plasma may aid in the differential diagnosis between serous and purulent meningitis.