Clinical Reasoning: An 80-Year-Old Woman With a Homonymous Hemianopsia.

An 80-year-old woman who was experiencing visual symptoms for 2 years was found to have a left homonymous hemianopsia (HH). On further evaluation the following month, she was noted to have simultanagnosia and alexia. MRI of the brain did not reveal a structural etiology for the symptoms. [ 18 F]-fluorodeoxyglucose (FDG) PET-CT was performed to aid in the diagnostic investigation. This case of posterior cortical atrophy highlights the differential diagnosis of a HH in the absence of a structural lesion on MRI and the role of FDG PET-CT imaging in such patients.