Magnetic resonance tomographic angiography: diagnostic value in trigeminal neuralgia.

A combination of MRI, MR angiography and MR tomographic angiography (MRTA) was used to study the relationship of the root exit zone of the trigeminal nerve to surrounding vascular structures in seven patients with trigeminal neuralgia (TN) and ten patients with no evidence at a lesion in this region. MRTA is the technique for showing the relationship between vessels, cranial nerves and brain stem. MRTA clearly demonstrated the presence of a vessel at the root exit zone of the trigeminal nerve in all patients with TN. In the ten other patients, examination of 20 trigeminal nerves revealed that only one nerve (5%) was in contact with a vessel at the root exit zone. This study supports vascular compression of trigeminal nerves as a cause of TN, and demonstrates the value of MRTA as noninvasive technique for demonstrating compression.