Structural brain abnormalities in patients with Parkinson’s disease with visual hallucinations: A comparative voxel-based analysis

Abstract

The objective is to evaluate clinical characteristics and cerebral alterations in Parkinson's disease (PD) patients with diurnal visual hallucinations (VHs). Assessment was performed using magnetic resonance image (MRI) and voxel-based morphometry (VBM). Thirty-nine patients with PD (53.8%) and ten controls were studied. Voxel based morphology analysis was performed. Eleven patients presented diurnal VHs and among these, six had cognitive dysfunction. Patients with VHs performed worse in the mentation-related UPDRS I (p=0.005) and motor-related UPDRS III (p=0.02). Patients with VHs showed significant clusters of reduced grey matter volume compared to controls in the left opercula frontal gyrus and left superior frontal gyrus. PD without hallucinations demonstrated reduced grey matter volume in the left superior frontal gyrus compared to controls. Comparisons between patients with VHs regarding the presence of cognitive dysfunction showed that cases with cognitive dysfunction as compared to those without cognitive dysfunction showed significant clusters of reduced grey matter volume in the left opercular frontal gyrus. Cases without cognitive dysfunction had reduced grey matter substance in the left insula and left trigonal frontal gyrus. Judging from our findings, an abnormal frontal cortex, particularly left sided insula, frontal opercular, trigonal frontal gyrus and orbital frontal would make PD patients vulnerable to hallucinations. Compromise of the left operculum distinguished cases with VHs and cognitive dysfunction. Our findings reinforce the theoretical concept of a top-down visual processing in the genesis of VHs in PD.

Cognitive and neuroanatomical correlates of neuropsychiatric symptoms in Parkinson's disease: A systematic review

“…However, this study included small number of patients. A further study has reported grey matter reduction in the left frontal areas in patients with PD who have developed VH when compared with those patients without VH [107] (In this study the average disease duration for patients was 5.3 years and average age at PD onset was 63.1).…”

“…Most of the earlier imaging studies that attempted to explore psychosis in patients with PD focused on the study of visual hallucination [78,[107][108][109][110][111][112][113] (See table 4). Previous reports suggest that VH in PD patients can be correlated either with cortical or subcortical atrophy [113].…”

Visual Hallucination and Pattern of Brain Degeneration in Parkinson's Disease

“…The PubMed search revealed seven studies that fulfilled our selection criteria [18,19,20,21,22,32,33]. No DTI-based study met the criteria, and only one VBM study analyzed subcortical structures [18].…”

“…Most studies had sample sizes similar to that in the present study. One exceptional study included a large study population, but the PD duration of that study's subjects was outstandingly short (mean 0.3 years) [21], whereas PD duration in the other studies ranged from 7.4 to 13.1 years [18,19,20,22,32,33]. …”

“…In studies including subjects with relatively short disease duration, frontal atrophy was reported in PV patients with [21] or without [32] temporo-parietal region degeneration, which suggested that frontal atrophy might be a contributor to VH in early-stage disease groups. On the other hand, studies including patients with more prolonged disease showed parieto-temporal and occipital atrophy in PV patients in comparison with PNV patients [19,22,33].…”