Correlation between neurotrophic factor expression and outcome of children with severe traumatic brain injury

Objectives We evaluated the neurotrophic factors [nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), glia-derived neurotrophic factor (GDNF)] expression and their association with the severity and outcome of children with traumatic brain injury. Design Prospective observational clinical study. Setting Pediatric intensive care unit. Patients Fourteen children with severe head injury; 12 controls with obstructive hydrocephalus. Measurement Cerebrospinal fluid (CSF) and plasma samples were collected 2 h (T1) and 24 h (T2) after head injury. Neurotrophic factor levels were measured using an immuno-enzymatic assay. Main results In patients, neurotrophic factor mean levels were significantly different in both CSF and plasma, showing high levels of BDNF compared to NGF and GDNF. Considering T1 and T2 expression, in the CSF the level of NGF increased from 3.5±0.4 pg/ml to 48.2±11.7 pg/ml (p<0.001); BDNF decreased from 4854.0±1303.7 pg/ml to 593.0±114.8 pg/ml (p<0.001), while GDNF did not undergo significant variations. In plasma, no significant changes were observed. Regarding severity and outcome, BDNF levels showed a sharp peak after head injury, but the only significant association was between NGF expression in the CSF and a good outcome versus a poor outcome (p=0.007). Conclusions The variations in neurotrophic factor levels reflect an endogenous attempt at neuroprotection against biochemical and molecular changes after traumatic head injury. BDNF represents an early marker of brain injury, while NGF expression in the CSF was indicative of a good outcome and the role of this neurotrophin in the treatment of children with severe head injury may be hypothesized.