Oblique sagittal magnetic resonance imaging visualizing vascular compression of the trigeminal or facial nerve.

An oblique sagittal magnetic resonance (MR) imaging method was developed to provide better visualization of vascular compression of nerves. The MR images of 12 patients with trigeminal neuralgia and 24 with hemifacial spasm were analyzed. The oblique sagittal views were obtained along the nerve identified by the axial view at an angle of 105 degrees between the line along the dorsal brain stem and the line along the margin of the pontomedullary junction (in patients with hemifacial spasm) or by the midsagittal view through the midpons (in patients with trigeminal neuralgia). The T1- and T2-weighted, proton-density, and/or gradient-echo MR images were evaluated to optimize imaging conditions. The oblique sagittal gradient-echo MR image most clearly visualized vascular compression of the nerves as high-intensity lines in six patients with trigeminal neuralgia, which was confirmed intraoperatively in four. Fifteen (75%) of 20 oblique sagittal gradient-echo MR images demonstrated vascular compression of the facial nerves in patients with hemifacial spasm; 12 of these were confirmed intraoperatively. The control study used 15 oblique sagittal gradient-echo MR images of nonaffected contralateral and normal sites. Four false-positive findings were found. Oblique sagittal gradient-echo MR images are a useful planning aid, allowing differential diagnosis prior to microvascular decompression in trigeminal neuralgia and hemifacial spasm.