High Plasma Levels of Neuropeptide Y Correlate With Good Clinical Outcome But are not Correlated to Cerebral Blood Flow or Vasospasm After Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE: Delayed cerebral ischemia (DCI) is a serious and frequent complication following subarachnoid hemorrhage. Treatments with convincing effect are lacking and the pathophysiology behind DCI remains poorly understood. Neuropeptide Y (NPY) is a potent endogenous vasoconstrictor and a role of NPY in the development of DCI has been proposed. This study investigated the relationship between plasma-NPY and cerebral blood flow (CBF), cerebral vasospasm, DCI, and clinical outcome. METHODS: In 90 patients with subarachnoid hemorrhage, NPY was measured in peripheral blood days 2 to 11. Any occurrence of DCI was recorded and CBF was quantified day 3 and day 8 using computed tomography (CT) perfusion. CT angiography was performed day 8. Clinical outcome was assessed after 3 months. RESULTS: No correlation was found between plasma-NPY and CBF or angiographic vasospasm. The correlation between reduced plasma-NPY and DCI reached borderline statistical significance (P=0.05). Increased levels of NPY measured on days 2 to 4 were correlated to good outcome (P=0.006). CONCLUSIONS: Our findings in peripheral blood were not supportive of a causal relationship between NPY secretion and DCI. Although high levels of plasma-NPY were correlated with good clinical outcome, NPY did not show promise as a clinically useful biomarker.