Effect Of Hypothermia On The Expressions Of BDNF In Patients With Severe Traumatic Brain Injury

Objective:We treat severe traumatic brain injury(sTBI) patients with mild hypothermia, at the meantime, we also monitor the changes of serum and cerebrospinal fluid (CSF) concentration of brain-derived neurotrophic factor(BDNF) to find whether it has certain advantages compared to routine treatment, reveal the possible mechanism of mild hypothermia for brain protection, and provide theoretical basis for the clinical application of mild hypothermia.Content:(1)To study the effect of mild hypothermia on the expressions of BDNF in patients with sTBI;(2)To study the correlation of the expressions of BDNF between serum and CSF in patients with sTBI;(3)To study the effect of mild hypothermia on the intracranial pressure (ICP), vital signs, blood gases, blood electrolytes and arterial oxygen saturation in patients with sTBI;(4)To study the complications of mild hypothermia and its treatment approachs;(5)To study the effect of mild hypothermia on the prognosis in patients with sTBI.Methods:All 50 patients who were hospitaled in the department of neurosurgery of the Affiliated Hospital of Chinese People's Armed Police Force from April 2008 to March 2009 with sTBI(GCS≤8 points) were randomly assigned into two groups,24 patients with mild hypothermia treatment (mild hypothermia group), and 26 cases with routine treatment(control group). After admission all patients underwent lateral ventriclar puncture drainage, continuous monitoring of ICP, vital signs, blood gases, blood electrolytes and arterial oxygen saturation. Patients with mild hypothermia group were induced mild hypothermia and received routine treatment within 24 hours after brain injury, and maintain the rectal temperature(RT) in 32-35℃, the average RT is(33.5±1.1)℃,the treatment time is 1-7 days,the average is (63.4±21.7) h. The expression level of serum and CSF BDNF was measured by ELISA method. Meantime, the ICP, vital sign, blood gas values, blood electrolytes and arterial oxygen saturation were also measured.24 h later after the ICP returned to normal or near normal, we stop mild hypothermia treatment and using the natural rewarming method with an average of 1℃per 6h, the patients RT return at 36.5-37.5℃after 12-16 h. Mataining the RT of control group patients at 36.5-37.5℃, the drug treatment of the control group is the same as the mild hypothermia group. According to Glasgow Outcome Scale(GOS), the prognosis was evaluated. And using SPSS 11.0 software for statistical analysis.Results:Compared with control group, the expression level of BDNF in serum and CSF with no significant difference in the 1st day after the treatment, then it significantly increased (P<0.05) at the following three days in mild hypothermia group. In addition, there was a significant positive correlation between serum and CSF BDNF levels(P<0.01). At the early stage after injury, ICP of both groups patients were higher than normal and then decreased after treatment. The ICP at 3rd and 7th day of mild hypothermia was significantly lower than the contronl group (P<0.01), and even to the normal range.The vital sign,blood gas values,blood electrolytes and arterial oxygen saturation were not significantly changed. No severe complications were found. The mortality was lower and mean GOS of the patients discharge was improved in mild hypothermia group than that of control group.Conclusion:The ICP of the patients with sTBI will be increased after injury. While conventional drug treatment, we using mild hypothermia can protect brain tissue through increasing the expression level of BDNF in serum and CSF, and decreasing ICP. No severe complications were found. It can effectively improve the prognosis and it is a safe and effective therapy. The parallel changes in BDNF levels in serum and CSF indicate that serum BDNF levels reflect the brain changes in BDNF levels in sTBI.