BACKGROUND Diffusion tensor imaging (DTI) is an advanced magnetic resonance imaging (MRI) method used to identify changes in microstructures in the brain's white matter. Severe brain injuries after trauma are associated with disorders of consciousness (DOC) and may result in hyponatremia due to damage to the hypothalamus. This case-control study aimed to use DTI to evaluate the hypothalamus in 36 patients with hyponatremia and DOC due to severe brain injuries. MATERIAL AND METHODS Thirty-six patients with DOC after traumatic brain injury (TBI) and 36 healthy control subjects were enrolled in this study. The diagnosis of DOC was based on the coma recovery scale-revised (CRS-R). The 36 patients were divided into 2 groups: Group A (18 with hyponatremia, serum sodium level <135 mmol/L) and group B (18 without hyponatremia). The DTI scans were conducted using a 6-channel head coil on a 1.5T Philips Gyroscan Intera scanner. Among the DTI data, fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) of the hypothalamus were analyzed. RESULTS Patient group A had a lower FA value (P=0.044) and higher ADC value (P=0.004) of the hypothalamus and showed a longer length of hospital stay (P=0.03), lower CRS-R score at discharge (P=0.01), and less change in CRS-R score (P=0.004) compared to patient group B. The improvements in the CRS-R score revealed a moderate negative correlation (r=-0.467) with the severity of the hyponatremia (P=0.004). CONCLUSIONS Post-traumatic hyponatremia was associated with hypothalamic injury and the presence and severity of hyponatremia were associated with poor clinical outcomes in DOC patients.

BACKGROUND Little is known about the structural neural connectivity between the primary auditory cortex and cognition-related brain areas in the human brain. This study aimed to evaluate the structural neural connectivity between the primary auditory cortex and cognition-related brain areas in normal subjects, using diffusion tensor tractography (DTT). MATERIAL AND METHODS Forty-three healthy subjects with no prior history of audiological, neurological, physical, or psychiatric illnesses were recruited for this study. Diffusion tensor imaging data analysis was performed using the Oxford Centre for Functional Magnetic Resonance Imaging of Brain (FMRIB) Software Library. In each subject, a region of interest was set on the primary auditory cortex, including the subcortical white matter. We assessed the neural connectivity between the primary auditory cortex and cognition-related brain areas (the dorsolateral prefrontal cortex [DLPFC]; ventrolateral prefrontal cortex [VLPFC]; orbitofrontal cortex [OFC]; hippocampus; parahippocampal cortex; amygdala, anterior and posterior cingulate gyrus; and fornix). RESULTS According to the results of DTT, the primary auditory cortex showed neural connectivity (over 50%) with the following areas: the threshold of 1 streamline - the VLPFC (94.2%), OFC (84.9%), fornix (80.2%), hippocampus (76.7%), parahippocampal cortex(74.4%) and DLPFC (58.1%); the threshold of 5 streamlines - the VLPFC (88.4%), OFC (81.4%), fornix (66.3%), hippocampus (55.8%), and parahippocampal cortex (53.5%); and the threshold of 15 streamlines - the VLPFC (82.6%), OFC (74.4%), and fornix (53.5%). CONCLUSIONS In normal human subjects, DTT showed that the primary auditory cortex had a high degree of neural connectivity with the prefrontal cortex, fornix, hippocampus, and parahippocampal cortex, which are brain areas associated with cognition and memory.

BACKGROUND The pathophysiology of traumatic subarachnoid hemorrhage and brain injury has not been fully elucidated. In this study, we examined abnormalities of white matter in isolated traumatic subarachnoid hemorrhage patients by applying tract-based spatial statistics. MATERIAL AND METHODS For this study, 10 isolated traumatic subarachnoid hemorrhage patients and 10 age- and sex-matched healthy control subjects were recruited. Fractional anisotropy data voxel-wise statistical analyses were conducted through the tract-based spatial statistics as implemented in the FMRIB Software Library. Depending on the intersection between the fractional anisotropy skeleton and the probabilistic white matter atlases of Johns Hopkins University, we calculated mean fractional anisotropy values within the entire tract skeleton and 48 regions of interest. RESULTS The fractional anisotropy values for 19 of 48 regions of interest showed significant divergences (P<0.05) between the patient group and control group. The regions showing significant differences included the corpus callosum and its adjacent neural structures, the brainstem and its adjacent neural structures, and the subcortical white matter that passes the long neural tract. CONCLUSIONS The results demonstrated abnormalities of white matter in traumatic subarachnoid hemorrhage patients, and the abnormality locations are compatible with areas that are vulnerable to diffuse axonal injury. Based on these results, traumatic subarachnoid hemorrhage patients also exhibit diffuse axonal injuries; thus, traumatic subarachnoid hemorrhage could be an indicator of the presence of severe brain injuries associated with acute or excessive mechanical forces.