Change of trigeminal nerve and brain white matter on diffusion tensor imaging in patients with trigeminal neuralgia

Objective: To explore the relationship between demyelination of trigeminal nerve and brain white matter change in patients with trigeminal neuralgia (TN). Methods: Thirty patients with primary TN and thirty healthy subjects were collected and underwent conventional brain MRI scan and diffusion tensor imaging (DTI) of trigeminal nerve and whole brain. One way ANOVA was used to compare the DTI metrics[fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD)] of trigeminal nerve between the ipsilateral side, the contralateral side, and healthy controls. Voxel-wise analyses were performed with tract-based spatial statistics (TBSS) using DTI metrics between TN patients and healthy controls. Multiple comparisons and correction were used and brain regions with significantly intergroup difference were obtained. Pearson correlation analyses were performed between DTI metrics of the brain regions and trigeminal nerve in patients with TN. Results: The FA value of ipsilateral trigeminal nerve in TN patients was significantly lower than that of contralateral trigeminal nerve and control group (all P < 0.05). The MD value, AD value and RD value of ipsilateral trigeminal nerve in TN patients were significantly higher than those of the contralateral trigeminal nerve and control group (all P < 0.05). The TN group showed significantly reduced FA in contralateral anterior corona radiata (P < 0.05, TFCE and FWE correction). Moreover, the FA value of contralateral anterior corona radiata was positively correlated with the FA value of ipsilateral trigeminal nerve (r = 0.581, P < 0.05) and negatively correlated with the RD value of ipsilateral trigeminal nerve (r = -0.389, P < 0.05). Conclusion: TN results in damage of trigeminal nerve and brain white matter integrity, and there is significant correlation between white matter damage and demyelination of trigeminal nerve. (authors)