Brain Natriuretic Peptide and Cerebral Vasospasm in Subarachnoid Hemorrhage

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Abstract
Background and Purpose —Hyponatremia has been shown in association with cerebral vasospasm (CVS) following aneurysmal subarachnoid hemorrhage (SAH). In the past few years there has been increasing evidence that brain natriuretic peptide (BNP) is responsible for natriuresis after SAH. The purpose of the present study was to investigate the relationship between BNP plasma concentrations and CVS after aneurysmal SAH. Methods —BNP plasma concentrations were assessed at 4 different time periods (1 to 3 days, 4 to 6 days, 7 to 9 days, and 10 to 12 days) in 19 patients with spontaneous SAH. BNP plasma levels were investigated with respect to neurological condition, SAH severity on CT, and flow velocities measured by means of transcranial Doppler . Results —Thirteen patients had Doppler evidence of CVS; 7 of these had nonsymptomatic CVS. In 6 patients, CVS was severe and symptomatic, with delayed ischemic lesion on CT in 5 of these. CVS was severe and symptomatic in 6 patients, and delayed ischemic lesions were revealed on CT in 5 of these. BNP levels were found to be significantly elevated in SAH patients compared with control subjects ( P =0.024). However, in patients without CVS or with nonsymptomatic CVS, BNP concentrations decreased throughout the 4 time periods, whereas a 6-fold increase was observed in patients with severe symptomatic CVS between the first and the third periods ( P =0.0096). A similar trend in BNP plasma levels was found in patients with severe SAH compared with those with nonvisible or moderate SAH ( P =0.015). Conclusions —In conclusion, our results show that BNP plasma levels are elevated shortly after SAH, although they increase markedly during the first week in patients with symptomatic CVS. The present findings suggest that secretion of BNP secretion after spontaneous SAH may exacerbate blood flow reduction due to arterial vasospasm.