A Case of Classical Trigeminal Neuralgia Associated with Bilateral Agenesis of the Internal Carotid Arteries

Abstract

　We describe a case of trigeminal neuralgia caused by compensatory enlargement of the basilar artery in a patient with bilateral agenesis of the internal carotid arteries.
　A 46-year-old man experienced sharp, stabbing pain in the left face when washing his face. In imaging examinations, magnetic resonance imaging(MRI)revealed displacement of the left trigeminal nerve due to basilar artery enlargement and leftward deviation, but no brain tumors or other abnormalities. The left internal carotid artery was not visible on magnetic resonance angiography(MRA), but marked enlargement of bilateral vertebral and basilar arteries was seen, along with considerable leftward deviation of the basilar artery. The anterior and middle cerebral arteries constituting the anterior circulation were bilaterally connected with the posterior communicating artery, which was enlarged. Bilateral internal carotid arteries were vestigially interrupted from the bifurcation of the common carotid artery. No carotid canals were apparent on either side on computed tomography(CT). For his symptoms, we managed his pain using carbamazepine, and instructed to follow a low-salt, low-fat diet and to avoid excessive alcohol consumption.
　Our case report suggest that imaging examination(e.g. CT, MRA and MRI)are essential when investigating trigeminal neuralgia, in order to visualize the head and neck region and identify any causal vessels and confirm the presence or absence of tumors. In addition, patients with abnormal hemodynamic status such as agenesis of an internal carotid artery or megadolichobasilar anomaly should undergo regular follow-up due to the high risk of cerebral hemorrhage and cerebral infarction.