Preoperative evaluation of the neurovascular compression using magnetic resonance tomographic angiography: our radiologic indications for microvascular decompression to treat trigeminal neuralgia.

Purpose The aim of this study was to introduce our classification of the neurovascular compression (NVC) in trigeminal neuralgia and the radiologic indications for microvascular decompression (MVD) based on magnetic resonance tomographic angiography. Methods From 2003 to 2011, 322 patients with primary trigeminal neuralgia were treated with MVD. The score of NVC was from 0 to 3. Three scores, separately from axial, oblique sagittal, and coronal images, were added together. The degree of NVC was classified as follows: grade 0 (0-1), grade 1 (2-3), grade 2 (4-6), and grade 3 (7-9). Results In summary, 88.3% (182/206) patients with absolute indication, 78.3% (65/83) patients with relative indication, and 90.9% (30/33) without indication showed excellent results. Among the 27 patients with good result, 13 patients (48.1%) were in grade 1, and 3 (11.1%) were in grade 0. Among the 18 patients with poor result, 5 patients (27.8%) were in grade 1 preoperatively. Five patients with severe complications were all in grade 0 with vague NVC. Conclusion The patients with grades 2 and 3 (absolute indications) NVC were recommended with MVD.