Microstructural Alteration of Trigeminal Nerve in Patients with Classic Trigeminal Neuralgia Shown by Diffusion Tensor Imaging and Its Correlation with Vascular Compression and Pain

To investigate the value of magnetic resonance diffusion tensor imaging in evaluating the microstructural alteration of trigeminal nerve in patients with classic trigeminal neuralgia (CTN) and its correlation with the degree of vascular compression and patient pain. A total of 108 patients with CTN were enrolled in this study. Patients were divided into 2 groups according to whether the asymptomatic side trigeminal nerve had neurovascular compression (NVC) or not: group A (32 cases) with NVC and group B (76 cases) without NVC. The anisotropy fraction (FA) and apparent diffusion coefficient of bilateral trigeminal nerves were measured. A visual analog scale (VAS) was used to evaluate the pain degree of the patients. The severity of NVC on the symptomatic side was classified as grade I, II, or III by neurosurgeons according to the findings during microvascular decompression. The FA values of the trigeminal nerve on the symptomatic side were significantly lower than those on the asymptomatic side in group A (P < 0.001) and group B (P < 0.001). Thirty-six patients were treated with microvascular decompression. The FA values of the trigeminal nerve were grade I 0.309 ± 0.011, grade II 0.295 ± 0.015, and grade III 0.286 ± 0.022. The difference was statistically significant (P = 0.011). The FA of the trigeminal nerve on the symptomatic side was negatively correlated with the degree of NVC and pain (P < 0.05). Patients with NVC had significant decreases in FA and it negatively correlated with NVC and VAS scores.