Preoperative visualization of neurovascular anatomy in trigeminal neuralgia

Abstract

The authors report on a novel technique to identify neurovascular compression in trigeminal neuralgia (TN). Using 3D reconstructed high-resolution balanced fast-field echo (BFFE) images fused with 3D time-of-flight (TOF) magnetic resonance (MR) angiography and Gd-enhanced 3D spoiled gradient recalled sequence, it is possible to objectively visualize the trigeminal nerve and nearby arteries and veins. Magnetic resonance imaging was performed in 18 patients with unilateral TN using 3 sequences: BFFE, 3D TOF angiography, and 3D Gd-enhanced imaging. The images were imported into OsiriX imaging software; after their fusion, a 3D false-color reconstruction was produced using surface rendering. The reconstructed images objectively differentiate nerves and vessels and can be viewed from any angle, including the anticipated surgical approach. Fifteen patients were predicted to have neurovascular compression on the symptomatic side (9 arterial and 6 venous compressions). All patients had a vascular structure that was identical in location and configuration to that predicted on preoperative analysis. The 3 patients without predicted compression underwent surgical exploration because they manifested the classic symptoms. As expected, exploration in 2 of these patients revealed no offending vessel. The third patient had a small vein embedded in the trigeminal nerve that was beyond the resolution of the 3D Gd-enhanced study. Combining BFFE with MR angiography and Gd-enhanced MR images capitalizes on the advantages of both techniques, enabling MR angiography and contrast-enhanced MR imaging discrimination of vascular structures at BFFE resolution. This results in an unambiguous 3D image that can be used to identify the neurovascular compression and plan the surgical approach.