Hemianopic line bisection error in a patient with Alzheimer's disease.

Visual symptoms are frequently observed in posterior cortical atrophy compared to typical amnestic Alzheimer's disease (AD). We report the case of a patient with amnestic AD with long-lasting homonymous hemianopia. A 62-year-old woman, who was diagnosed in amnestic AD, complained of visual disturbance. She had left homonymous hemianopia in the perimetry test and left tactile extinction. Regardless of posture, retinotopically leftward error was observed on 21 cm line bisection test. Brain single photon emission computerized tomography (SPECT) showed bilateral temporoparietal hypoperfusion, which was more severe to the right than left side. This case suggested that long-lasting hemianopia could occur in the patient with amnestic AD and that hemianopic line bisection error might be compensatory mechanism.