Research Reports - Mental fatigue after mild traumatic brain injury
Brain Imaging Behav. 2016 Jan 18. [Epub ahead of print]
Liu K(1), Li B(1), Qian S(2), Jiang Q(1), Li L(1), Wang W(1), Zhang G(1), Sun
Y(1), Sun G(3).
Our purpose was to evaluate mental fatigue associated with mild traumatic brain
injury (MTBI) and investigate the underlying neurological mechanisms. We used a
20-min psychomotor vigilance test (PVT) related ASL-fMRI to evaluate mental
fatigue in 25 MTBI patients in acute phase, 21 MTBI patients in chronic phase,
and 20 healthy subjects. Mental fatigue in patients in acute phase was more
severe than in chronic phase patients and healthy controls. The first 5-min-PVT
increased CBF of patients in acute phase in "bottom-up" and "top-down" attention
areas, and decreased CBF in default mode network (DMN) areas. Twenty-min-PVT
results showed that sustained attention of patients was more fragile than in
healthy subjects, while sustained attention in the acute phase was less stable
than that in the chronic phase. CBF results showed that in patients in the acute
phase, the second, third, and last 5-min-PVT decreased CBF in DMN areas,
increased CBF of "bottom-up" and "top-down" areas; in the chronic phase, the
third and last 5-min-PVT increased CBF of "bottom-up" and "top-down" cortex,
while the second 5-min-PVT only increased CBF of the "top-down" cortex. Mental
fatigue of MTBI patients persists for more than 12 months, and can be mitigated
partly within the first year after injury. The "bottom-up" and "top-down"
deficits result in mental fatigue of MTBI patients.