Abstract
Introduction: Diffuse traumatic axonal injury (TAI) is one of the key mechanisms leading to impaired consciousness after severe traumatic brain injury (TBI). In addition, preferential regional expression of TAI in the brain may also influence clinical outcome.Aim: We addressed the question whether the regional expression of microstructural changes as revealed by whole-brain diffusion tensor imaging (DTI) in the subacute stage after severe TBI may predict the duration of post-traumatic amnesia (PTA).Method: Fourteen patients underwent whole-brain DTI in the subacute stage after severe TBI. Mean fractional anisotropy (FA) and mean diffusivity (MD) were calculated for five bilateral brain regions: fronto-temporal, parieto-occipital, and midsagittal hemispheric white matter, as well as brainstem and basal ganglia. Region-specific calculation of mean FA and MD only considered voxels that showed no tissue damage, using an exclusive mask with all voxels that belonged to local brain lesions or microbleeds. Mean FA or MD of the five brain regions were entered in separate partial least squares (PLS) regression analyses to identify patterns of regional microstructural changes that account for inter-individual variations in PTA.Results: For FA, PLS analysis revealed two spatial patterns that significantly correlated with individual PTA. The lower the mean FA values in all five brain regions, the longer that PTA lasted. A pattern characterized by lower FA values in the deeper brain regions relative to the FA values in the hemispheric regions also correlated with longer PTA. Similar trends were found for MD, but opposite in sign. The spatial FA changes as revealed by PLS components predicted the duration of PTA. Individual PTA duration, as predicted by a leave-one-out cross-validation analysis, correlated with true PTA values (Spearman r = 0.68, ppermutation = 0.008).Conclusion: Two coarse spatial patterns of microstructural damage, indexed as reduction in FA, were relevant to recovery of consciousness after TBI. One pattern expressed was consistent with diffuse microstructural damage across the entire brain. A second pattern was indicative of a preferential damage of deep midline brain structures.
Highlights
Diffuse traumatic axonal injury (TAI) is one of the key mechanisms leading to impaired consciousness after severe traumatic brain injury (TBI)
Consent for participation was initially given by patient proxy and general practitioner, and if the patient emerged to a state of full consciousness, informed consent was obtained from the patients themselves
We performed partial least square (PLS) regressions of post-traumatic amnesia (PTA) using mean diffusivity (MD), Fractional anisotropy (FA), traumatic microbleed volume, and traumatic microbleed count separately, within the five ROIs to expose the pattern of microstructural changes that precipitated recovery of consciousness
Summary
Diffuse traumatic axonal injury (TAI) is one of the key mechanisms leading to impaired consciousness after severe traumatic brain injury (TBI). Traumatic axonal injury (TAI) is regarded the decisive injury for cognitive functional outcome and occurs when high-velocity accelerative and rotational forces due to the nature of the impact interact with the inertia of the brain, causing abrupt movements inside the skull [2]. TAI of the long-range axons interconnecting the arousal network of the brainstem-midbrain, the medial fronto-parietal cortex, and the deep gray matter (GM) nuclei of thalamus and basal ganglia is believed causal of posttraumatic lowered level of consciousness [3, 4], and degree and duration of disordered consciousness is regarded the single most influential symptom monitoring and prognosticating severity of TBI [5]. Accurate neuroimaging markers of microstructural changes that can be related to physiological function of brain connections for aiding reliable prognostication are highly desirable
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
