Neural reorganization following bilateral injury of the fornix crus in a patient with traumatic brain injury.

Abstract

OBJECTIVE: We report on a patient who appeared to demonstrate neural reorganization after head trauma resulting in bilateral injury of the fornix crus. CASE REPORT: A 58-year-old male patient and 8 control subjects were recruited. The patient had undergone head trauma as the result of a car accident and had lost consciousness for 30 min. Brain magnetic resonance imaging, performed 3 years after the head trauma, showed no evidence of abnormality. RESULTS: Discontinuation of both crus in the proximal region was observed on diffusion tensor tractography of the fornix. In the right fornix, an abnormal neural tract originating from the right crus passed through the splenium of the corpus callosum to connect with the right inferior longitudinal fasciculus. By contrast, in the left fornix, another abnormal neural tract originating from the left column passed through the left inferior longitudinal fasciculus and the splenium of the corpus callosum. None of these abnormal neural tracts was observed in normal subjects. CONCLUSION: We presume that the abnormal neural tracts of the fornix observed in this patient were the result of neural reorganization triggered by bilateral injury of the fornix crus. The results of this study suggest a mechanism for recovery of the injured fornix following head trauma.