Serum Neurofilament Light Protein as a Marker for Diffuse Axonal Injury: Results from a Case Series Study.

Diffuse axonal injury (DAI) is an important cause of morbidity in patients with traumatic brain injury (TBI). There is currently no simple and reliable technique for early identification of patients with DAI, or to prognosticate long-term outcome in this patient group. In the present study, we examined acute serum concentrations of neurofilament light (NFL) in nine patients with severe TBI and DAI using a novel ultrasensitive single molecule array (Simoa) assay. The relationships between the NFL concentrations and MRI in the acute stage as well as clinical outcome and magnetic resonance diffusion tensor imaging (MR-DTI) parameters at 12 months were analyzed. We found that the mean NFL concentrations among the patients displayed a 30-fold increase compared with controls, and that NFL completely discriminated between the patients and controls. We also found a relationship between serum NFL and MR-DTI parameters, with higher NFL concentrations in patients with higher trace (R2 = 0.79) and lower fractional anisotropy (FA) (R 2 = 0.83). These results suggest that serum NFL may be a valuable blood biomarker for TBI, reflecting the severity of DAI.

Cognitive impact of traumatic axonal injury (TAI) and return to work.

OBJECTIVE: Axonal injury (AI) after traumatic brain injury (TBI) is often overlooked as an explanation for cognitive complaints when no damage is detected by computed tomography. The purpose was to assess cognition during the 12 months following a TBI and suspected traumatic axonal injury (TAI). METHODS: The sample included 17 patients younger than 65 years old, however one died. In the acute phase and at 6 and 12 months, cognition, reaction time, psychomotor performance and finger tapping speed were assessed. Working memory and work status were added at 12 months. Acute MRI findings were recorded. RESULTS: After 1 year, all patients still showed cognitive dysfunction. A recovery had been noted at 6 months, but a cognitive decline was indicated for the majority at 12 months. The sick-listed patients had TAI located in the corpus callosum and the brainstem. They were cognitively more impaired and in more areas than the four patients who had returned to work. CONCLUSION: Cognitive screening can identify the long-term impact of TAI identified by conventional MRI, used as a routine clinical technique. For rehabilitation and for insurance-related matters, these injuries must be taken seriously, as a deterioration over time might occur. Further research is needed.