[Villaret's syndrome caused by internal carotid artery dissection].

We report a patient with Villaret's syndrome (left hypoglossopharyngeal nerve, vagus nerve, accessory nerve, and hypoglossal nerve palsies and left Horner's sign) caused by internal carotid artery dissection. He had neck pain on the left side, Horner's sign on the left side and paralysis of the left hypoglossopharyngeal nerve, vagus nerve, accessory nerve, and hypoglossal nerve. Brain MRI revealed no signal from the left internal carotid artery and no brain infarction, although a tumor-like lesion was observed in the left internal carotid artery. Subsequent MRI studies revealed intramural hematoma in the left internal carotid artery, and on the basis of this finding, he was diagnosed with internal carotid artery dissection. He received anticoagulant and antiplatelet therapy. His symptoms improved gradually. The symptoms of internal carotid artery dissection are neck pain, Horner's sign, brain infarction, and lower cranial nerve palsy. A characteristic feature in this case was that brain infarction was not observed. Only 3 similar cases have been reported in the past In all these cases, the patients had a good clinical course and showed complete recovery from the symptoms. Compared with western countries, in Japan, carotid artery dissection is rare. Carotid artery dissection should be considered as a differential diagnosis of lower cranial nerve palsy.