Gray matter plasticity associated with secondary trigeminal neuralgia in rats.

OBJECTIVE: This study aims to characterize brain regional structural alterations across distinct time points in a rat model of trigeminal neuralgia using MRI. METHODS: A rat model of secondary trigeminal neuralgia was established by injecting a talc suspension into the infraorbital foramen. Sixty Sprague-Dawley rats were randomly assigned to six groups, including three experimental groups and three sham groups. This study employed a cross-sectional design. MRI scans were performed on one experimental group and one sham group at 4, 8, and 12 weeks postoperatively. Whole-brain voxel-based morphometry analysis was conducted using the SIGMA and Tohoku rat brain templates, and cross-template validation was performed using both templates. A two-sample t-test was used for intergroup comparisons, whereas analysis of variance was performed for intragroup analyses. RESULTS: Our results demonstrated that, at 12 weeks after trigeminal neuralgia induction, the volumes of the right hippocampus, right primary visual cortex, right temporal association cortex, and left primary somatosensory cortex were significantly lower in experimental rats than those in the sham group. Cross-template validation consistently confirmed the involvement of the right hippocampus and left primary somatosensory cortex. CONCLUSION: Lower volumes in the ipsilateral hippocampus and contralateral primary somatosensory cortex were observed at 12 weeks following trigeminal neuralgia induction when compared with those in the sham group. Comparisons at the 4- and 8-week cross-sectional sampling time points revealed no significant intergroup differences.