Abstract: Objective    To demonstrate that the neurovascular conflict or compression (NVC) is the primary cause of idiopathic trigeminal neuralgia (PTN) by imaging anatomy, so as to perfect the NVC theory. Methods   The brain stem MRI of PTN group (n=48 sides) and painless group (n=84 sides) were reconstructed by multi-modal image fusion and three-dimension volume rendering. The contact ratio of blood vessel and nerve, the bending degree of compressing artery, compression site and angle degree between the arterial loop and the main axis of trigeminal nerve were measured and compared between the PNT group and the painless group.    Results   The contact ratio of artery and nerve in the pain side was higher than that in the non-pain side, the compression site was mostly located in the brain stem area of the trigeminal nerve. On the painful side of patients with PTN, the arterial curvature ( 0.21（0.07）mm^1) and angle degree ( 36.18（12.47）°and 36.68（15.67）°) between the artery and nerve were both significantly higher than those of them (0.12（0.03）mm^1, 24.56（12.09）°and 26.28（17.49）°) on the unaffected side of PTN and without PTN patients. On the painful side, distribution of compression site was significantly focused on root of entrance zone (REZ). There was no significant difference in the compression site, arterial curvature and angle degree between the artery and nerve amongst the healthy sides.   Conclusions   On the painful side of patient with PTN, there is a significantly curved artery pressing on the root of trigeminal nerve at a large angle degree, and this phenomenon is associated with PTN symptoms.    

Key words: Primary trigeminal neuralgia; ,  , Neurovascular conflict theory; ,  , Magnetic resonance imaging; ,  , Three-dimension volume rendering reconstruction