[A case of cerebral infarction presenting as retrosplenial amnesia]

We report a 73-year-old right-handed female who presented with an acute amnesic syndrome. On November 18, 1991, she was admitted to a local hospital complaining of sudden-onset vertigo and nausea, but immediately after the admission she developed an amnesic syndrome. On November 27, she was transferred to our hospital for further assessment of her memory disturbance. Neurologically she was normal except for mild right hemianopsia and increased deep tendon reflexes in the extremities. Neuropsychological assessments were performed over 3 weeks. She was always alert, attentive, and cooperative. She had no confabulation. On the Wechsler Adult Intelligence Scale revised (WAIS-R), her total IQ was 110. Frontal, verbal, and perceptual functions and motor performance were normal. She had no signs of a callosal disconnection. Despite these preserved functions, her memory function was obviously disturbed. Several memory betteries showed that her recent memory for both verbal and visual modalities was impaired, while her immediate memory such as digit span was preserved. For remote memory her retrograde episodic memory concerning both personal and public events was almost intact, although she had a profound anterograde amnesia. In particular she recalled her personal information about just-premorbid events in detail. On the other hand, her semantic memory, for example understanding of proverbs, geography, and scientific law, was preserved. Taken together, her procedural memory on learning tasks, such as "Tower of Hanoi" and mirror drawing, was intact. Computed tomography demonstrated a low-density area medial to the trigon of the left ventricle.(ABSTRACT TRUNCATED AT 250 WORDS)