Increased adrenomedulun in cerebrospinal fluid after traumatic brain injury in children: A preliminary report

Introduction: Adrenomedullin is a recently discovered vasoactive peptide. Infusion of adrenomedullin increases regional cerebral blood flow and reduces infarct volume after vascular occlusion in rats¹. In humans, increased cerebral adrenomedullin has been identified in patients following cardiopulmonary bypass and subarachnoid hemorrhage^2,3. Following traumatic brain injury (TBI) in children, cerebral hypoperfusion is frequently observed and is associated with poor outcome⁴. We hypothesized that adrenomedullin levels would be increased in cerebrospinal fluid (CSF) of children following severe TBI. Methods: Total adrenomedullin concentrations were measured using a radioimmunometric assay, by investigators blinded to patient identification. Ventricular CSF samples (n=36) were collected from 10 children during the first 10 d after severe TBI (GCS <8). Control CSF was obtained from 5 children undergoing lumbar puncture, who had normal CSF parameters and no evidence of CNS infection. Patients underwent standard neurointensive care, including CSF drainage. Data were analyzed using a univariate regression model. Results: Adrenomedullin concentration was markedly increased in CSF of children following TBI vs control (mean level 10.65 vs 1.51 fmol/ml, p=0.006). All 36 case samples had an adrenomedullin concentration above the median value for the controls (1.52 fmol/ml). Conclusion: We conclude that the vasoactive peptide, adrenomedullin, is increased in the CSF of children following TBI. We speculate that adrenomedullin participates in the endogenous response to cerebral hypoperfusion after TBI.