Visual hallucinations in posterior cortical atrophy

Background: Visual hallucinations have been reported to occur in up to 25% of patients who meet the criteria for posterior cortical atrophy (PCA). It is not known, however, whether patients who meet the criteria for PCA and have hallucinations are different from those who meet the criteria and do not have hallucinations. Objective: To compare the clinical and imaging features of patients with PCA with and without well-formed visual hallucinations. Design: Case-control study. Setting: Tertiary care medical center. Patients: Fifty-nine patients fulfilling the criteria for PCA were retrospectively identified and divided into 2 groups based on the presence (n=13) or absence (n=46) of visual hallucinations. Main Outcome Measures: Statistically significant clinical differences and imaging differences using voxel-based morphometry between the 2 groups. Results: In patients with PCA and hallucinations, parkinsonism and rapid eye movement sleep behavior disorder occurred more frequently, as did myoclonic jerks (P<.001 for both). Voxel-based morphometry showed greater atrophy in a network of structures, including the primary visual cortex, lentiform nuclei, thalamus, basal fore-brain, and midbrain, in patients with hallucinations. Conclusions: Hallucinations in patients with PCA are associated with parkinsonism, rapid eye movement sleep behavior disorder, and myoclonic jerks. The voxel-based morphometry results suggest that hallucinations in PCA cannot be exclusively attributed to atrophy of the posterior association cortices and may involve a circuit of thalamocortical connections.