Alterations of norepinephrine levels in plasma and CSF of patients after traumatic brain injury in relation to disruption of the blood-brain barrier

Background. In injured brain tissue with a disrupted blood-brain barrier (B BB) catecholamines such as norepinephrine (NE) are known to enhance glucose consumption and cerebral blood flow but may lead to an energy-depletion in creasing the risk of ischemia. Therefore it is of great interest whether th e exogenous administration of NE used mainly to maintain an adequate cerebr al perfusion pressure influences CSF NE levels or not, and whether elevated plasma or CSF levels of NE can influence the actual clinical condition. We addressed this issue by measuring the levels of NE in CSF and plasma and c orrelating them with the actual clinical condition of the patients. Methods. In 29 patients with severe TBI (<8 points on the Glasgow Coma Scal e: GCS) NE levels were analysed by high performance liquid chromatography ( HPLC) in paired blood and CSF specimens which were collected from days 1 to 14 after severe TBI (total number of pairs = 121). The integrity of the BB B was evaluated by determining the CSF/serum albumin ratio. The clinical co ndition of the patients was assessed by GCS. Results. Elevated plasma and CSF NE: levels were observed in 50% of all sam ples, most consistently in patients treated with NE. NE elevation in CSF wa s independent of whether or not the BBB remained intact. There was no corre lation between GCS and the levels of NE in CSF or plasma either in samples from the treated or the untreated group. Interpretation. Exogenous administration of NE seems to increase NE levels in plasma and CSF. However, in this group of patients with severe TBI there was no clinical evidence that exogenous administration of NE was detriment al to the traumatized patients.