Introduction:
Currently, traumatic brain injury (TBI) is a worldwide
public health problem due to its high prevalence,
morbidity, and mortality. The mechanisms involved in
trauma are complex, and different types of injuries may
be present, including diffuse axonal injury (DAI). DAI is
highly prevalent in victims of moderate and severe
trauma and its prolonged pathophysiological processes
lead to a neurodegenerative brain disease.Purpose:
Our aim was to longitudinally evaluate with diffusion
tensor imaging (DTI) the integrity of cerebral white matter
in patients with moderate and severe DAI at three
moments after trauma. In addition, correlations between
DTI quantitative parameters and neuropsychological
data were also investigated.Materials & Methods:
20 victims of moderate and severe TBI were scanned at
a 3 Tesla MRI at three different times: 2 months
(timepoint 1), 6 months (timepoint 2), and 12 months
(timepoint 3) after trauma. A matched healthy control
group (n=20) was also scanned once. We did
deterministic tractography of the corpus callosum and
bilateral superior longitudinal fascicles (SLF) (Figure 1).
Different cognitive domains were evaluated, such as
attention, verbal fluency, working memory, and estimation
of the intelligence coefficient (IQ). A generalized
estimating equation (GEE) was performed to evaluate
changes over time of DTI parameters and
neuropsychological tests. The Benjamin - Hochberg
procedure for repeated measures was performed.
Pearson and Spearman's tests assessed correlation
coefficients. Results were considered significant with p
<0.05.Results:
The corpus callosum (CC) and both superior longitudinal
fascicles (SLF) demonstrated extensive microstructural
abnormalities, with more noticeable changes in body and
splenium of the CC (Table 1). All DTI parameters
demonstrated changes across time in body, while only FA
changes were seen on both SLFs. In splenium, changes
in the MD and AD were also observed across time. There
was an improvement in attention and memory tests
performances between 6 and 12 months. The FA values
in all segments of the CC demonstrated a positive
correlation with attention, verbal fluency, and IQ
estimation.Discussion and Conclusions:
The results of this study demonstrate that several microstructural
changes in the white matter ensues along one year of the
traumatic event, as detected by DTI. Remarkably, DTI
parameters demonstrated several correlations with the cognitive
domains. The change in these relationships over time confirms the
dynamic and prolonged character of the biological mechanisms
involved.
Acknowledgements:
We are thankful to FAPESP (Sao Paulo Research Foundation).
Grants 2015/18136-1, 2016/05547-6, 2017/17065-9.
There is no conflict of interest in this presentation.

Widespread and dynamic changes in the white matter in moderate and severe TBI victims - how diffuse axonal injury relates to different cognitive domains after trauma

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