[Korsakoff's syndrome as a prominent feature of bilateral paramedian thalamic infarction--a case report].

We reported the first Japanese case of bilateral paramedian thalamic infarction associated with prominent Korsakoff's syndrome. 53-year-old man suffered from semicoma on the morning of September 16th, 1988. After recovery of consciousness disturbance, neurological examination revealed vertical eye gaze palsy, areflexia of lower extremities, apathy with hypersomnia and amnesia. Amnesia was accompanied with prominent confabulation, disorientation and lack of insight into his own disability. While X ray-CT revealed only ambiguous low density area in the bilateral thalamus, MRI of horizontal section by short spin echo revealed symmetrical low signal area restricted in the paramedian area of bilateral thalamus, and that of coronal section revealed characteristic butterfly-shaped lesion. Left BAG revealed that both posterior thalamoperforating arteries showed type 3 variation of Percheron's classification which arisen from artery arcade bridging between both side of interpeduncular segment of posterior cerebral artery. He showed gradual improvement in apathy with hypersomnia and disorientation but not in Korsakoff's syndrome nor ophthalmoplegia.