Neuronal Loss in the Medial Cholinergic Pathway From the Nucleus Basalis of Meynert in Patients With Traumatic Axonal Injury: A Preliminary Diffusion Tensor Imaging Study

Objective: The recent development of diffusion tensor imaging (DTI) allows visualization and estimation of the medial cholinergic pathway (MCP), which originates from the nucleus basalis of Meynert and provides cortical cholinergic innervation to the cerebral cortex. We investigated the injury to the MCP in patients with traumatic axonal injury (TAI), using DTI. Design: Retrospective survey. Participants: Fourteen patients with chronic TAI and 14 age-and sex-matched normal control subjects. Main Outcome Measures: Using the Functional Magnetic Resonance Imaging of the Brain (FMRIB) Software Library (FMRIB analysis group, Oxford University, United Kingdom), diffusion tensor images were acquired by using a sensitivity-encoding head coil at 1.5 T DTIs. Fractional anisotropy (FA), mean diffusivity (MD), and tract volume of the MCP were measured. Results: The FA value and tract volume were significantly decreased in the group with TAI compared with those of the control group (P<.05); in contrast, there was no difference in the MD value between the 2 groups (P>.05). Conclusions: Changes in DTI parameters of the TAI group appear to be due to neuronal loss of the MCP. We believe that DTI would be useful for the evaluation of the MCP in patients with TAI.