[Thalamic infarction in young adult caused by embolism from an unruptured aneurysm of the posterior cerebral artery--a case report].

A 21-year-old man presented with sudden weakness and dysesthesia of his right limbs. Computerized tomography (CT) scan showed a low density area in the posterolateral part of the left thalamus. Right vertebral angiography revealed a small aneurysm at the P2 segment of the posterior cerebral artery. Magnetic resonance imaging (MRI) demonstrated intra-aneurysmal clot and signal void in the residual lumen. There were no other lesion and no predisposing risk factors that produced cerebral ischemia. It was thought that the aneurysm was the source of emboli resulting in thalamic infarction. The patient underwent a left subtemporal craniotomy, and the aneurysm was clipped. Following surgery, there has been no recurrence of ischemic attacks. The diagnosis and the therapy were discussed, with reference to the literature.