A comparison of the oblique sagittal view obtained by magnetic resonance imaging and the intraoperative findings of vascular compression in cases of trigeminal neuralgia and hemifacial spasm

We show how neurosurgical planning can benefit from the better visualization of the precise vascular compression of the nerves provided by the oblique sagittal and gradient-echo method (OS-GR image) using magnetic resonance images (MRI) and by comparing these results with the findings of microvascular decompression. The scans of 5 patients with trigeminal neuralgia (TN) and 18 with hemifacial spasm (HFS) were analysed for the presence and appearance of the vascular compression of the nerves; all these 23 patients were operated on. Imaging sequences consisted of an OS-GR image (TR/TE: 200/20, 3-mm-thick slice) cut along each nerve shown by the axial view, which was scanned at the angle of 105 degrees taken between the dorsal line of the brain stem and the line corresponding to the pontmedullary junction. The rate of correspondence between the OS-GR images and the intraoperative findings was 80% in the TN's and 89% in the HFS's. In all these OS-GR images, the vascular compressions of the REZ of the trigeminal or facial nerve were well visualized as curvilinear high-intensity lines and/or spots. Furthermore, the relationship between the vascular compressions and nerves could be foreseen preoperatively in 40% of the TN's and in 55.6% of the HFS's. It is concluded that OS-GR images obtained by means of MRI may serve as useful planning aids prior to microvascular decompression for cases of TN and HFS because of the corresponding operative view along the approach. (author)