![]() ![]() Therefore, there is currently limited research on patients across all levels of TBI severity that focuses on the brainstem or its subfields as regions of interest (ROIs). 15 however, they used tensor-based morphometry or whole-brain voxel-based morphometry analyses in patients with mild or moderate-severe TBI. Post-TBI brainstem volume reduction has been reported previously in studies by Kim et al. However, this issue has not been extensively investigated. Given that axonal injury in the brainstem is a primary factor in the development of immediate consciousness disorder in DAI or TBI 11, 12, 13, the post-acute-phase volume of the brainstem in DAI is of clinical interest because it likely reflects the severity of acute-phase consciousness disorder. Histopathological observations have revealed that axonal injury in DAI is not evenly diffuse throughout the brain rather, it is concentrated in specific brain regions, one of which is the brainstem 2, 8, 9, 10, 11. DAI is considered a primary cause of consciousness disorder in acute-phase TBI 3.ĭAI leads to post-acute-phase widespread brain atrophy 4, 5, 6, 7, which results from Wallerian degeneration and delayed neuronal cell death, following the process of primary and secondary axotomy because of axonal injury 7. The latter TBI cases likely exhibit diffuse pathology, and diffuse axonal injury (DAI) is a major clinical entity of this type 2. Some patients with TBI have gross focal injury (FI), which is characterized by a large focal lesion caused by an external force, whereas others have no visible FI. Traumatic brain injury (TBI) is a major cause of disability, especially among young people, and is a critical health and socioeconomic problem worldwide 1. Our findings suggest that injury severity, as denoted by the duration of posttraumatic amnesia, is among the factors affecting the chronic-phase brainstem volume in patients with DAI. Moreover, the percentage loss of the whole brainstem, and particularly of the pons and midbrain, was significantly negatively correlated with the duration of posttraumatic amnesia. The average loss of the whole brainstem was 13.9%. We then applied this model to the volume measurements of 22 DAI patients, most of whom were in the long-term chronic phase and had no gross focal injury, to estimate the percentage difference in volume from the expected normal healthy volume in different brain regions, and investigated its association with the duration of posttraumatic amnesia (which is an early marker of injury severity). We obtained volume measurements from 182 healthy adults by analyzing T1-weighted magnetic resonance images, and created an age-/sex-/intracranial volume-based quantitative model to estimate the normal healthy volume of the brainstem and cerebrum. Considering the importance of brainstem damage in DAI, a valid method for evaluating brainstem volume is required. Diffuse axonal injury (DAI) is a subtype of traumatic brain injury that causes acute-phase consciousness disorders and widespread chronic-phase brain atrophy. ![]()
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