Abstract 4: Sex Steroid Level Alterations in the Blood and Cerebrospinal Fluid Following Severe Traumatic Brain Injury
Introduction: Elevated endogenous and exogenously administered estrogens are neurologically protective in animal models of brain injury in both males and females, noting up to 65% less ultimate injury in those receiving estrogen. Scientific reports reveal that many patients experience declines in blood levels of sex steroids following severe traumatic brain injury (TBI). Normally, uninjured individuals have a CSF sex steroid level that is 1/10 that of their serum level. Reports of CSF levels of sex steroids following TBI are lacking.
Hypothesis: Endogenous sex steroid levels in the CSF and blood change rapidly following TBI, and may correlate with short-term outcomes.
Methods: Serial CSF and blood samples were collected from patients with severe TBI (GCS 3– 8) who required placement of a therapeutic ventriculostomy. Following ventriculostomy placement, CSF and blood samples were obtained every 4 hours for the 1st 24 hours post-injury, then every 8 hours for post-injury days 2–5.
Results: Preliminary analyses of 10 patients, including male and female, both young and older (post-menopausal) show rapid changes in all sex steroids, with increasing post-traumatic CSF estradiol levels observed. CSF estradiol levels between 26 –314 pg/ml (nl 2– 6 pg/ml) were noted. In all patients, a CSF estradiol/serum estradiol ratio of >1 in at least one paired sample was associated with good recovery. Ratios of up to 13.56 [244 pg/ml (CSF)/18 pg/ml (serum)] were noted in male patients with good outcomes. CSF estradiol levels that were consistently lower than serum levels were associated with mortality.
Conclusions: CSF levels of estradiol in TBI patients are much higher than in normal individuals. This increased estradiol appears to be produced in the brain, and is associated with improved outcomes. Further studies are necessary to validate these finding.