In vivo anatomical analysis of arterial contact with trigeminal nerve: detection with three-dimensional spoiled grass imaging.

The purpose of this study was to review the normal in vivo neurovascular relationship between the trigeminal nerve and surrounding arteries without the use of volunteers. 290 nerves in 145 cases were reviewed during a 1-year period. Axial source images and multiplanar reconstructed (MPR) images were used to determine the neurovascular contact and direction of contact. Multiplanar volume reformation (MPVR) was used to identify the contact vessels and to demonstrate the relationship between the nerve and arteries. Vascular contact was found in 29% of the 290 nerves (83 nerves). The arteries involved were the superior cerebellar artery (SCA) or the anterior inferior cerebellar artery (AICA). Vascular contact with two arteries was found in 3%. Of the 286 asymptomatic nerves, the nerve was located between the two vessels in 3% and compression was seen in 1%. Three points of vascular contact by the two arteries were identified in one asymptomatic nerve. The direction of contact between the SCA and the nerve was superior (38%), superomedial (32%) or medial (15%) in most cases. The direction of contact between the AICA and the nerve was inferior, inferolateral or lateral in all cases. Vascular contact at the root entry zone (REZ) was noted in 90%. Four nerves were affected by trigeminal neuralgia, one of which touched an artery and two were compressed. It was concluded that arterial contact can be assessed without difficulty but evaluation of vascular compression is not easy.