A 37-year-old nonhypertensive male suddenly experienced mild left suboccipital pain while driving. In addition to neck pain persisting for 5 days, he began to experience vertigo and cold sensation in the right hand. On admission the patient was alert and cooperative. He had no neck stiffness. Clinical examination revealed typical Wallenberg's syndrome. Routine laboratory investigations were all normal. A computed tomographic scan revealed no abnormalities. Left vertebral angiography showed a fusiform shadow at the proximal posterior inferior cerebellar artery (PICA), but neither double lumen nor pooling of the contrast medium in the venous phase was observed. Left retromastoid suboccipital craniectomy disclosed no evidence of recent subarachnoid hemorrhage. The proximal PICA was enlarged for a distance of 1 cm, beginning 5 mm distal to its vertebral origin. Both the enlarged portion and a segment just distal to it were purplish-red. It was diagnosed as a dissecting aneurysm of the PICA with distal extension. Proximal ligation of the PICA was successful, and the patient was discharged with no deficits.
It must be emphasized that vertebrobasilar aneurysms should be carefully ruled out in patients with Wallenberg's syndrome, particularly those who are fairly young and not predisposed to hypertension or arteriosclerosis, and in whom the initial symptom is unusual headache.