Unusual findings on PET study of a patient with posterior cortical atrophy.

We present a patient with posterior cortical atrophy in whom positron emission tomography (PET) showed unusual findings. This 65-year-old man had a 5-year history of slowly progressive apperceptive visual agnosia and Balint syndrome, but with a relatively well-preserved intelligence and language ability even in the later stages of illness. No relevant features in this patient or his family were identified. Laboratory and radiographic investigations indicated that cerebral damage was due to primary degeneration. His symptoms resembled those of patients with posterior cortical atrophy. A PET study revealed that cerebral metabolism was reduced in the dorsal regions of the entire cortex and asymmetrical with the main site of damage on the right. The severity in asymmetry increased dorsally. These 2 types of predilection for dorsal regions had not previously been reported in such patients. These unusual PET findings may indicate the presence of pathological changes not yet identified.