The Relation Between Loss of Consciousness, Severity of Traumatic Brain Injury, and Injury of Ascending Reticular Activating System in Patients With Traumatic Brain Injury.

OBJECTIVE

Loss of consciousness is an indicator of the severity of traumatic brain injury and the ascending reticular activating system has been considered as a main structure for consciousness. However, no study on the relation between loss of consciousness and ascending reticular activating system injury in traumatic brain injury has been reported. We investigated the relation between loss of consciousness, severity of traumatic brain injury, and ascending reticular activating system injury using diffusion tensor tractography.

DESIGN

One hundred twenty patients were recruited. Three components of ascending reticular activating system, fractional anisotropy, and tract volume were measured.

RESULTS

In lower dorsal and ventral ascending reticular activating system, fractional anisotropy and tract volume value in mild group were higher than those of moderate and severe groups, and there was no difference between moderate and severe groups. In upper ascending reticular activating system, fractional anisotropy value in mild group was higher than in moderate group, and it was higher than in moderate group than in severe group. Tract volume value in mild group was higher than in severe group. Loss of consciousness showed moderate negative correlations with tract volume value of lower dorsal ascending reticular activating system (r = -0.348), fractional anisotropy value of lower ventral ascending reticular activating system (r = -0.343), and fractional anisotropy value of upper ascending reticular activating system (r = -0.416).

CONCLUSIONS

Injury severity was different among the three traumatic brain injury groups in upper ascending reticular activating system but did not differ between moderate and severe groups in lower dorsal and ventral ascending reticular activating system.