C-type natriuretic peptide concentrations in the plasma and cerebrospinal fluid of patients with subarachnoid hemorrhage

Background: Cerebral vasospasm is a poor resulting outcome of a ruptured ce rebral aneurysm; to clarify the mechanism of vasospasm it is important to i mprove this outcome. C-type natriuretic peptide (CNP) is present in the bra in as a cerebral vasodilator; it is also an endothelium-derived relaxing fa ctor produced via cGMP. We speculated that CNP might be an inhibitor of cer ebral vasospasm after subarachnoid hemorrhage (SAH). Methods: To clarify the role of CNP in cerebral vasospasm after SAH, we con ducted 1 week monitoring of CNP concentrations in the plasma and cerebrospi nal fluid (CSF) of 26 patients who had undergone clipping within 24 hours o f the occurrence of SAH, and divided them into group A (positive for angiog raphic spasm) and group B (negative for angiographic spasm). We also examin ed CNP concentrations in the CSF of patients who were receiving spinal anes thesia for small orthopedic operations, as reference patients. Results: The CNP concentration in the CSF on day 1 was higher than in the r eference patients and decreased in both test groups, but we did not observe any significant difference between the groups. CNP concentrations in the p lasma did not change in either group. Conclusions: CNP concentrations in the CSF were high in the acute phase aft er SAH, whereas plasma CNP concentrations remained constant. However, our f indings did not support our hypothesis because we did not find any relation ship between vasospasm and changes in CNP concentrations in the CSF.