Relationship between the Consciousness State and the Default Mode Network in Traumatic Brain Injury.

INTRODUCTION: This study investigated the relationship between Coma Recovery Scale-Revised (CRS-R) and the neural networks between the medial prefrontal cortex (mPFC) and precuneus (PCun)/posterior cingulate cortex (PCC) in disorders of consciousness (DOC) patients with a traumatic brain injury (TBI) using diffusion tensor tractography (DTT). MEASURES: Twenty-five consecutive patients with TBI admitted to the rehabilitation department of a university hospital were enrolled in this study. The Coma Recovery Scale-Revised (CRS-R) was used to evaluate the consciousness state. The pathway of the neural networks between the mPFC and the PCun (mPFC-PCun DMN)/PCC (mPFC-PCC DMN) were reconstructed using DTT. Fractional anisotropy (FA) and the tract volume (TV) were obtained to assess the diffusion tensor imaging parameters. RESULTS: The CRS-R score had strong positive correlations with the FA value and TV of the mPFC-PCun DMN (p < 0.05), while it showed a moderate positive correlation with the TV of the mPFC-PCC DMN (p < 0.05). In addition, the FA value of the mPFC-Pcun DMN showed that it could explain the variability in the CRS-R score. CONCLUSIONS: The close correlation was noted between the consciousness state and the mPFC-PCun DMN and mPFC-PCC DMN in DOC patients with TBI. On the other hand, the mPFC-PCun DMN appeared to be more closely correlated with the consciousness state than the mPFC-PCC DMN.

Relationship of Recovery of Contralesional Ankle Weakness With the Corticospinal and Corticoreticular Tracts in Stroke Patients.

OBJECTIVE: We investigated the relationship between contralesional ankle weakness recovery and the corticospinal tract and corticoreticular tract in stroke patients with complete injuries of the ipsilesional corticospinal tract and corticoreticular tract. DESIGN: Thirty-six patients with complete injuries of the ipsilesional corticospinal tract and corticoreticular tract were recruited. Medical Research Council and the Functional Ambulation Category were used to determine motor function of ankle dorsiflexor and gait function. Patients were assigned into two groups: group A (poor recovery) and group B (good recovery). Fractional anisotropy, apparent diffusion coefficient, and tract volume were obtained for diffusion tensor imaging parameter. RESULTS: A total of 58.3% of patients showed good recovery of contralesional ankle dorsiflexor weakness, with remainder having poor recovery. Tract volume of the contralesional corticoreticular tract in group B was higher than that in group A (P < 0.05); no other diffusion tensor imaging parameters were significantly different between two groups. Tract volume of the contralesional corticoreticular tract and corticospinal tract showed strong (r = 0.521) and moderate (r = 0.399) positive correlations with Medical Research Council score of contralesional ankle dorsiflexor, respectively (P < 0.05). CONCLUSIONS: We found that the number of fibers of the contralesional corticospinal tract and corticoreticular tract was closely related to the recovery of contralesional ankle dorsiflexor weakness in stroke patients with complete injuries of the ipsilesional corticospinal tract and corticoreticular tract. Moreover, the contralesional corticoreticular tract had a closer relationship to recovery than the contralesional corticoreticular tract.

Difference in the ascending reticular activating system between vegetative and minimally conscious states following traumatic brain injury.

OBJECTIVES: We investigated differences in the ascending reticular activating system (ARAS) between vegetative state (VS) and minimally conscious state (MCS) in patients with traumatic brain injury (TBI) by using diffusion tensor tractography. METHODS: We recruited TBI patients and normal subjects. We reconstructed the lower ARAS and five parts of upper ARAS [prefrontal cortex (PFC), premotor cortex, primary motor cortex, primary somatosensory cortex, and posterior parietal cortex]. RESULTS: Significant differences were observed in the fractional anisotropy (FA) and fiber number (FN) values of the five parts of upper ARAS between the VS and control groups and between the MCS and control groups (P < 0.05), but no differences were detected in the lower ARAS (P > 0.05). The FA and FN values of the PFC in the upper ARAS were significantly different between the VS and MCS groups (P < 0.05). No other significant differences in FA and FN values were detected among the other segments of the upper ARAS or in the lower ARAS (P > 0.05). CONCLUSION: The results indicate that the prefrontal portion of the upper ARAS is the critical area for distinguishing between VS and MCS in patients with TBI.

Diffusion Tensor Imaging Studies on Spontaneous Subarachnoid Hemorrhage-Related Brain Injury: A Mini-Review.

Accurate diagnosis of the presence and severity of neural injury in patients with subarachnoid hemorrhage (SAH) is important in neurorehabilitation because it is essential for establishing appropriate therapeutic strategies and developing a prognosis. Diffusion tensor imaging has a unique advantage in the identification of microstructural white matter abnormalities which are not usually detectable on conventional brain magnetic resonance imaging. In this mini-review article, 12 diffusion tensor imaging studies on SAH-related brain injury were reviewed. These studies have demonstrated SAH-related brain injuries in various neural tracts or structures including the cingulum, fornix, hippocampus, dorsolateral prefrontal region, corticospinal tract, mamillothalamic tract, corticoreticular pathway, ascending reticular activating system, Papez circuit, optic radiation, and subcortical white matter. We believe that these reviewed studies provide information that would be helpful in science-based neurorehabilitation of patients with SAH. Furthermore, the results of these reviewed studies would also be useful for clarification of the pathophysiological mechanisms associated with SAH-related brain injury. However, considering the large number of neural tracts or neural structures in the brain, more research on SAH-related brain injury in other neural tracts or structures should be encouraged.