Relation Between Memory Impairment and the Fornix Injury in Patients With Mild Traumatic Brain Injury: A Diffusion Tensor Tractography Study

Objective We investigated the relation between memory impairment and the fornix injury in patients with mild traumatic brain injury, using diffusion tensor tractography. Design Eighty-six chronic patients with mild traumatic brain injury and 50 normal control subjects were recruited. Fractional anisotropy and fiber volume were measured for each reconstructed fornix. The patients were classified according to the following three types: type A (47 patients), intact integrity of both fornical crura; type B (27 patients), showed a discontinuation in either fornical crus; and type C (12 patients), discontinuations in both fornical crura. The Memory Assessment Scale was used for evaluation of memory function. Results Fractional anisotropy and fiber volume showed weak positive correlations with global memory of Memory Assessment Scale, respectively (r = 0.303, P = 0.006; r = 0.271, P = 0.014). Significant difference in the global memory of Memory Assessment Scale was observed between type A and B and between type A and C without difference between type B and C (P < 0.05). Conclusion It seems that the diffusion tensor tractography parameters of the fornix and the integrity of fornical crus can be used as a biomarker for axonal injury of the fornix in patients with mild traumatic brain injury.