Serial changes in serum phosphorylated neurofilament and value for prediction of clinical outcome after traumatic brain injury

BACKGROUND: Phosphorylated neurofilament heavy subunit (pNF-H) is a constituent protein of the nerve axon, which leaks into the peripheral blood in various central nervous disorders. This study examined the time course of pNF-H value up to 1 month after injury and investigated the correlation with clinical outcome. METHODS: Serum pNF-H concentration was measured on admission, and at 24 h, 72 h, 1 week, 2 weeks, and 1 month after injury in 20 patients, 15 males and 5 females aged 35–68 years (mean 52 years), with traumatic brain injury (TBI) transported to our hospital between April 2016 and March 2017. The clinical outcome at discharge was evaluated by Glasgow Outcome Scale. RESULTS: The pNF-H value showed no increase in patients without brain parenchymal injury, but pNF-H value increased depending on the severity of brain damage. pNF-H value peaked at 2 weeks after injury. Two patients with peak value exceeding 10,000 unit had very severe injury and died during hospitalization. Peak pNF-H value was 3210 ± 1073 unit in 12 patients with good outcome and 9884 ± 2353 unit in 8 patients with poor outcome (P = 0.0119). CONCLUSION: Serum pNF-H level tended to increase and peak at 2 weeks after injury, and the peak pNF-H value was correlated with clinical outcome after TBI. The temporal profile of blood pNF-H seems to be useful to predict the clinical outcome after TBI.